Ants of Vietnam

The ants of Vietnam has been a ongoing focus of three researchers: Katsuyuki Eguchi, Tuan Viet Bui and Seiki Yamane.

There is a website of Vietnamese ants by Eghuci and Bui.

This antwiki page currently serves to gather in one place some of the information, and links to related pages, about Vietnamese ants. You can see a list of species here: Vietnam.

Amblyoponinae
Key to Vietnamese Amblyoponinae Genera

Myopopone
Morphology. Workers of Vietnamese species have the following features:

Worker monomorphic, but sometimes varying greatly in size; head in full-face view subrectangular, without distinct genal angle beside each mandibular insertion; preoccipital lobe absent dorsally and laterally; frontal carina vestigial or absent; antennal scrobe absent; frontal lobes large, relatively narrowly separated from each other by posteromedian portion of clypeus, expanded anteriad beyond anterior margin of clypeus; antennal sockets in full-face view completely concealed by frontal lobe, located relatively close to anterior margin of head; anteromedian margin of clypeus straight or weakly concave, often with a series of tiny stub-like processes, defined laterally by distinct angles; mandible elongate, narrowly blade-like, with ca. 10 teeth that are indistinctly arranged as two rows; antenna 12-segmented; apical few segments of antenna distinctly flattened in cross-section; eye reduced, consisting of a few ommatidia, situated behind midlength of side of head; mesosoma in lateral view somewhat of box-form; mesonotum present as a conspicuous transverse disc margined anterially by flexible promesonotal suture and posteriorly by distinct metanotal groove; propodeum unarmed; propodeal lobe vestigial; outer surface of middle tibia and basitarsus with thickened peg-like setae mixed with the normal finer pilosity; petiole forming indistinct anterior peduncle, broadly attached to gaster, in lateral view without a free posterior face; subpetiolar process present; abdominal segment III with a free anterior face below helcium only; girdling constriction between abdominal segments III and IV weak; pygidium large, convex across; pygidium and hypopygium unarmed laterally and posteriorly; sting well developed.

Differentiation. The worker of Myopopone is similar to that of Stigmatomma, but in the latter all of the antennal segments terete, not flattened.

The only species of this genus occurring in Vietnam is Myopopone castanea. It occurs in well-developed forests, and nests in large rotting logs. Nest chambers are usually excavated deep inside logs.

Mystrium
Morphology. The worker of the sole Vietnamese species, Mystrium camillae has the following features:

Worker monomorphic; body bearing spatulate hairs; head in full-face view rectangular, with broadly and deeply concave posterior margin, with a short and stout genal spine beside each mandibular insertion; preoccipital carina absent dorsally and laterally; frontal carina and antennal scrobe absent; frontal lobes relatively widely separated by posteromedian portion of clypeus, in full-face view completely concealing antennal sockets, not reaching anterior margin of clypeus; anteromedian portion of clypeus roundly convex anteriad; anterior clypeal margin with a series of 6–8 processes on which a stub-like, very short seta present; mandible elongate, narrowly blade-like, with widened round apex; masticatory margin serrate, with two rows (dorsal and ventral rows) of teeth; antenna 12-segmented, with inconspicuous 4-segmented club; apical segments of antenna never flattened in cross-section; eye absent or present as a single ommatidium; if eye present, it located around midlength of side of head (excluding genal spine); mesosoma in lateral view short and high; promesonotal suture present and flexible; metanotal groove indistinct dorsally; propodeum unarmed; propodeal lobe very low; petiole without distinct anterior peduncle, broadly attached to gaster, in lateral view without a free posterior face; subpetiolar process present; abdominal segment III with a free anterior face below helcium only; girdling constriction between abdominal segment III and IV indistinct; pygidium large, convex across, unarmed laterally and posteriorly; hypopygium armed with a few short spinose setae posteriorly; sting well developed.

Differentiation. The worker of Mystrium is somewhat similar to that of Stigmatomma, but in the latter the apex of mandible is pointed, and the body is covered with simple hairs.

Prionopelta
Morphology. Workers of Vietnamese species have the following features: Worker monomorphic; head in full-face view subrectangular; preoccipital carina absent dorsally and laterally; frontal lobes small, horizontal, separated from each other by a longitudinal sulcus; antennal sockets in full-face view largely concealed by frontal lobe, located relatively far from anterior margin of head; anteromedian portion of clypeus relatively long anteroposteriorly, roundly convex anteriad; anterior clypeal margin with a series of ca. 15 processes on which a stub-like, very short seta present; mandible elongate-triangular; masticatory margin with 3 teeth; antenna 12-segmented; apical 4 segments forming a club; eye reduced, consisting of a few ommatidia, a little behind midlength of side of head; mesosoma in lateral view almost flat dorsally; promesonotal suture present and flexible; metanotal groove usually distinct dorsally; propodeum unarmed; propodeal lobe very low; petiole without anterior peduncle, broadly attached to abdominal segment III, in lateral view without a free posterior face; petiolar process well developed, anteriorly with a conspicuous round depression; abdominal segment III with a free anterior face below helcium only; girdling constriction between abdominal segment III and IV weak; pygidium large, convex across; pygidium and hypopygium unarmed laterally and posteriorly; sting well developed.

Differentiation. The worker of Opamyrma is easily distinguished from that of the other Vietnamese genera of Amblyoponinae by its elongate-triangular mandible.

The only record of this genus is of two individuals of Prionopelta sp. collected in sandy soil of Sang Le Forest, Pu Mat National Park.

Stigmatomma
Morphology. Workers of the Vietnamese species have the following features (see also Schmidt & Shattuck 2014):

Worker monomorphic; head in full-face view usually subrectangular, with genal angle beside each mandibular insertion which is rarely developed well as a small, triangular spine; preoccipital carina weak or absent dorsally and laterally; frontal lobes present, narrowly separated by posteromedian portion of clypeus, or approximate to each other; frontal carina rarely present; antennal scrobe absent; antennal sockets in full-face view at least partly concealed by frontal lobe; anterior margin of clypeus usually with a series of dents (see below); mandible elongate, narrowly blade-like with pointed apex, without basal margin; masticatory margin with one or two rows (dorsal and ventral rows) of teeth; antenna 11- or 12-segmented; eye relatively reduced or absent; eye, if present, situated behind midlength of side of head; mesosoma in lateral view with a flat or weakly arched dorsal outline; promesonotal suture present and flexible; metanotal groove absent dorsally; propodeum unarmed; propodeal lobe low or almost absent; petiole essentially sessile, but rarely with a distinct short anterior peduncle; broadly attached to abdominal segment III, in lateral view without a free posterior face; subpetiolar process present; abdominal segment III with a free anterior face below helcium only; girdling constriction between abdominal segment III and IV moderate to weak; pygidium large, convex across, laterally and posteriorly unarmed; hypopygium often armed with a series of spines posteriorly; sting well developed.

Differentiation. The worker of Stigmatomma is somewhat similar to that of Myopopone, but in the latter a few apical segments of the antenna are distinctly flattened.

A single worker specimen of Stigmatomma sp. eg-4 (collected from a dry dwarf forest of southern central Vietnam) is morphologically very distinct from the other Vietnamese species. It lacks a series of dents on the anterior clypeal margin; instead it has a plate-like projection just dorsal to the junction between the clypeus and labrum. This feature seems to be equivalent to a diagnostic characteristic of the worker of Xymmer discussed by Yoshimura and Fisher (2012) which recorded a male of Xymmer from Thailand. In order to confirm the identity of Stigmatomma sp. eg-4, colony samples containing males may be needed.

Dorylinae
Key to Vietnamese Dorylinae Genera

Aenictus
Morphology. Workers of Vietnamese species have the following features (see also Terayama & Kubota 1993; Bolton 1994; Jaitrong & Yamane 2011; Jaitrong & Hashimoto 2012; Jaitrong et al 2012; Jaitrong & Yamane 2013):

Worker monomorphic, but sometimes varying widely in size; head in full-face view usually round or subrectangular; preoccipital carina usually present dorsally and laterally; frontal lobe present as narrow vertical carinae, very narrowly separated from each other by a longitudinal strip of posteromedian portion of clypeus, and sometimes fused together posteriorly; antennal socket in full-face view fully exposed, very close to the anterior margin of head; parafrontal carina often present; clypeus narrow from front to back especially in front of antennal insertion; mandible linear to triangular; when mouthparts fully closed, prementum not visible, or largely concealed behind labrum and stipites of maxillae that meet along the midline (see fig. 35 of Eguchi 2011); antenna 10- segmented; eye absent; mesosoma in lateral view box-shaped, or with sinuate dorsal outline; promesonotal suture absent; metanotal groove usually indistinct or absent but rarely distinct dorsally; metapleural gland orifice concealed beneath a ventrally directed cuticular flap or flange; propodeum unarmed, but posterior face often margined dorsally and laterally with distinct ridges; propodeal lobe usually (but not always) low or indistinct; apicoventral part of metatibia with a longitudinally elongate gland opening; waist consisting of two small segments (petiole and postpetiole); petiole sessile to subsessile; spiracles on abdominal segments V–VII shifted backwards, usually not concealed by posterior margins of preceding segments; pygidium reduced to a narrow U-shaped sclerite, laterally and posteriorly unarmed (lacking teeth or peg-like spines); sting developed.

Differentiation. The worker of smaller species of Aenictus is somewhat similar to that of Leptanilla, but in the latter the promesonotal suture is present and flexible, and the spiracles on abdominal segments V–VII are concealed by the posterior margins of the preceding segments.

The Aenictus ceylonicus group is in need of revision. The species determined as Aenictus dentatus by Zryanin may be Aenictus paradentatus. At present, Aenictus dentatus is assumed to not be present in Vietnam.

Cerapachys
Morphology. Workers of Vietnamese species have the following features.

Worker monomorphic, but sometimes varying widely in size; head in full-face view usually subrectangular; posterolateral portion of head usually (but not always) expanded posteroventrad as a lobe or forming a flange; preoccipital carina usually distinct dorsally and laterally; frontal lobes vertically raised, very narrowly separated from each other by a longitudinal strip of median portion of clypeus, and often fused together posteriorly; antennal socket in full-face view fully exposed; antennal scrobe absent, but in most species area around antennal socket somewhat impressed or flattened, margined laterally by parafrontal carina (in the Cerapachys sexspinus group (=Yunodorylus) parafrontal carina completely absent); clypeus narrow from front to back especially in front of the antennal insertion, sometimes forming an anterolateral projection just above each mandibular insertion; mandible subtriangular, edentate or armed with minute teeth on masticatory margin; antenna 9- to 12-segmented; scape clavate, short, not exceeding beyond posterior corner of head; apical segment usually bolbous; eye varying from vestigial to well developed, or sometimes absent; mesosoma in lateral view relatively robust and box-shaped, often strongly marginate anterodorsally; promesonotal suture absent or vestigial dorsally; metanotal groove absent; metapleural gland orifice concealed beneath ventrally directed cuticular flap or flange; propodeum unarmed; posterior face margined with distinct ridge dorsally and/or laterally; propodeal lobe usually developed well; mesotibia and metatibia with a pectinate spurs; pretarsal claw of all legs sometimes with a preapical tooth; petiole sessile to subsessile, with subpetiolar process; abdominal segment III with a graded reduction from a full-sized segment (as in the C. sexspinus group =Yunodorylus) to a small postpetiole; abdominal segments IV, V and VI without girdling constriction separating them; abdominal spiracles V–VII shifted backwards, usually not concealed by posterior margins of preceding segments; pygidium large; the dorsum flattened or impressed, with lateral and posterior margins armed with a series of small teeth or peg-like spines; sting large and strongly developed.

Differentiation. The worker of Cerapachys is similar to that of Simopone, but in the latter the frontal lobes are relatively broadly separated from each other by the median portion of clypeus, the antennal socket in full-face view is partly concealed by the frontal lobe, and tibial spurs are absent from middle legs (at most a setiform vestige may remain).

Bionomics. Cerapachys species nest in rotting logs and wood fragments, under stones, and in leaf litter and soil. Some species seem to be semi-nomadic, and their colony size is much larger than cryptic congeners of which colony size may not exceed a hundred.

Dorylus
Morphology. Workers of Vietnamese species have the following features (see also Bolton 1994, Eguchi et al. 2014):

Worker polymorphic; head in full-face view usually subrectangular (but rarely heart-shaped in minor worker); preoccipital carina absent; frontal lobes present as narrow vertical carinae, narrowly separated from each other by a longitudinal strip of median portion of clypeus, and in minor worker often fused together posteriorly; antennal socket in full-face view fully exposed, very close to anterior margin of head; clypeus usually narrow from front to back especially in front of antennal insertion (but in minor worker median portion of clypeus occasionally produced anteriad as a round or triangular lobe); mandible usually (but not always) falcate; antenna 8 to 12- segmented; eye absent; mesosoma in lateral view box-shaped; promesonotal suture conspicuous but pronotum and mesonotum fused, immobile with respect to each other; metanotal groove absent; metapleural gland orifice concealed beneath a ventrally directed cuticular flap or flange; propodeum unarmed; orifice of propodeal spiracle subtended by an endophragmal pit and a longitudinal impression (the impression often inconspicuous); propodeal lobe absent; metatibial gland present; waist consisting of a single small segment (petiole); petiole without tergosternal fusion; subpetiolar process usually (but not always) developed as a lobe; abdominal segment III with tergosternal fusion; spiracles on abdominal segments V–VII shifted backwards, not concealed by posterior margins of preceding segments; pygidium large; its dorsum flattened or impressed, posteriorly with a pair (or rarely two pairs) of spines; sting reduced.

Differentiation. The worker of Dorylus is superficially similar to that of the Cerapachys sexspinus group, but in the latter the promesonotal suture is completely absent, and the pygidium is armed with a series of peg-like spines posteriorly.

Simopone
Morphology. Although no Vietnamese specimens of this genus were examined in the present study, according to Radchenko (1993b) and Bolton & Fisher (2012), workers of a known Vietnamese species of this genus (Simopone oculata) may show the following features:

Head in full-face view elongate, with sides almost parallel, without a differentiated vertical posterior surface above occipital foramen (instead vertex slopes evently down to upper margin of occipital foramen); preoccipital carina distinct; frontal lobe not vertically raised, in full-face view concealing at least inner margins of antennal sockets; the lobes relatively widely separated from each other by posteromedian portion of clypeus; frontal carina reaching dorsal margin of eye; parafrontal ridge almost reaching anterior margin of eye; mandible subtriangular, armed with minute teeth on masticatory margin; antenna 11-segmented; scape clavate, short; segment II to apical segment short and gradually incrassate; eye large; ocelli present but minute; mesosoma elongate with its dorsolateral borders right-angled; pronotum marginate anteriorly; promesonotal suture represented by transverse trace dorsally but distinct laterally; metanotal groove poorly visible dorsally but distinct laterally; mesotibia without spurs (at most a setiform vestige may remain that cannot be distinguished by light microscopy from other setae at tibial apex); metatibia with a single pectinate spur; metabasitarsus ventrally with a longitudinal glandular groove that occupies at least basal half of tarsomere length; pretarsal claws of all legs with a single preapical tooth on inner margin; propodeum unarmed, but posterior face margined dorsally and laterally with a distinct ridge; petiole in lateral view elongate and compressed dorsoventrally, with a transverse anterior carina.

Differentiation. The worker of Simopone is similar to that of Cerapachys, but in the latter the frontal lobes are very narrowly separated from each other by a longitudinal strip of the median portion of clypeus, the antennal socket is in full-face view almost completely exposed, and one or two tibial spurs are present on middle legs.

Bionomics. Radchenko (1993b) mentioned that the holotype (worker) of S. oculata was collected under a stump in a secondary tropical forest, but the life history of the species is unknown.

Leptanillinae
Key to Vietnamese Leptanillinae Genera

Leptanilla
Morphology. Workers of Vietnamese species have the following features:

Worker monomorphic; body slender; head in full-face view oval or subrectangular, and somewhat flattened dorsoventrally; preoccipital carina present dorsally and laterally; frontal lobe, frontal carina and antennal scrobe absent; antennal sockets in full-face view fully exposed, very close to the anterior margin of head, separated from each other by a median longitudinal ridge of clypeus; median portion of clypeus produced anteriad as a lobe; lateral portion of clypeus narrow from front to back in front of antennal insertion; mandible narrowly blade-like and curved; masticatory margin with 3 distinct teeth; inner face of basal shaft of mandible with a spatulate lobe; antenna 12-segmented; eye absent; mesosoma slender, in lateral view flattened dorsally; promesonotal suture present and flexible; metanotal groove vestigial or absent dorsally; propodeum unarmed; propodeal lobe absent; waist consisting of two small segments (petiole and postpetiole); petiole without anterior peduncle; its tergosternal fusion complete, without trace of a sutrue; petiolar and postpetiolar spiracles located on lateral face of anteriormost part of petiolar and postpetiolar nodes, respectively; postpetiolar sternite swollen strongly; spiracles on abdominal segments V–VII concealed by posterior margins of preceding segments; pygidium relatively large, convex across, laterally and posteriorly unarmed (lacking teeth or peg-like spines); sting well developed.

Differentiation. The worker of Leptanilla is somewhat similar to that of the smaller species of Aenictus and Cerapachys, but in the latter two genera the promesonotal suture is absent and the spiracles on abdominal segments V–VII are usually not concealed by the posterior margins of the preceding segments.

Opamyrma
Morphology. Worker presumably monomorphic; body long and slender, with long legs; head in full-face view subrectangular, and somewhat flattened dorsoventrally; preoccipital carina complete, almost encircling the head slightly before its posterior margin; frontal lobe, frontal carina and antennal scrobe absent; median part of clypeus rather clearly divided into posterior horizontal portion and anterior steep slope; the posterior portion distinctly separated from frons with a continuous carina, and broadly inserted between antennal sockets; lateral part of clypeus narrow from front to back; mandible slender, with long but bluntly tapered apical tooth followed by a trapezoidal lobe and three inconspicuous teeth; labrum on its outer face with at least two rows of peg-like denticles; eye absent; antennal sockets completely exposed in full-face view, located in a large, roundly excavated area whose anterior wall is steep just behind posterior margin of clypeus; antenna 12-segmented, gradually incrassate from segment II to XII; mesosoma slender, in lateral view flattened dorsally; promesonotal suture present and flexible; metanotal groove absent dorsally; propodeum unarmed; orifice of propodeal spiracle round, situated relatively low on lateral face of propodeum; propodeal lobe much reduced; mid- and hind tibiae each with a reduced barbulate anterior spur in front of a well-developed pectinate posterior spur; waist consisting of a single segment (petiole); petiole extremely elongate, virtually without anterior peduncle, narrowly attached to abdominal segment III; tergo-sternal sutures of petiole present; petiolar spiracle located anteriorly on lateral face of petiole at its mid-height; gaster (consisting of abdominal segments III–VII) extremely elongate; abdominal segment III above helcium with free anterior face; spiracles on segments V–VII concealed by the preceding segments; segment VII longest among the segments III–VII; pygidium and hypopygium unarmed laterally and posteriorly.

The worker of Opamyrma hungvuong, the only species of this genus in Vietnam, is distinguishable by a combination of the following features: petiole narrowly attached to abdominal segment III (gastral segment I); abdominal segment III above helcium with free anterior face; frontal lobe completely absent, thus antennal socket in full-face view fully exposed.

Protanilla
Morphology. Workers of Vietnamese species have the following features.

Worker monomorphic; head in full-face view somewhat elongate trapezoidal; preoccipital carina present but weak dorsally and laterally on head; frontal lobe, frontal carina and antennal scrobe absent; antennal sockets in full-face view fully exposed, very close to anterior margin of head, widely separated from each other by clypeal disc; clypeal disc trapezoidal, raised, and flattened or weakly concave medially, margined laterally with a sharp edge running from mandibular insertion to junction with frons; mandibles subtriangular; masticatory margin of mandible with small peg-like teeth; inner surface of mandible with peg-like teeth (modified setae) and thick setae; antenna 12-segmented; eye absent (but intercaste often with reduced eye consisting of a few ommatidia); mesosoma in lateral view with almost straight dorsal outline, or promesonotum feebly raised; promesonotal suture present and flexible; metanotal groove conspicuous dorsally; propodeum unarmed; orifice of propodeal spiracle round, situated relatively low on lateral face of propodeum; propodeal lobe absent; waist consisting of two small segments (petiole and postpetiole) which have clearly differentiated posterior faces; petiole without anterior peduncle; its tergosternal fusion complete, without trace of sutrue; its sternite swollen strongly and forming anteroventral flange; petiolar and postpetiolar spiracles located on the side of anteriormost part of the petiolar and postpetiolar nodes, respectively; postpetiole almost as long as or longer than broad, not distinctly broader than petiole, lacking tergosternal fusion; its sternite swollen strongly; abdominal spiracles V–VII concealed by the posterior margins of the preceding segments; pygidium large, convex across its width, laterally and posteriorly unarmed; sting well developed.

Differentiation. The worker of Protanilla is easily distinguished from that of the other genera known from Vietnam by a combination of features: antennal sockets in full-face view fully exposed; clypeal disc trapezoidal, raised and flattened, margined laterally with a sharp edge; inner surface of mandible with peg-like teeth; promesonotal suture present and flexible; waist consisting of two small segments (petiole and postpetiole) which have clearly diffintiated posterior faces.

Myrmicinae
Key to Vietnamese Myrmicinae Genera

Myrmica
Key to Myrmica of Vietnam

Pheidole
Key to Pheidole of North Vietnam

Ponerinae
Key to Vietnamese Ponerinae Genera

Anochetus
Morphology. Workers of Vietnamese species have the following features (see also Schmidt & Shattuck 2014):

Worker monomorphic; lateral outline of head in full-face view with a distinct convexity of which the anterodorsal face has eye; vertexal lobe well developed; vertex without a median longitudinal carina; preoccipital carina distinct dorsally and laterally; posterior face of head inside a conspicuous preoccipital carina without a pair of dark lines; frontal lobe horizontal, partly to largely concealing antennal socket; antennal scrobe absent; submedian portion of clypeus more or less expanded above each mandibular base; posteromedian portion of clypeus relatively narrowly inserted between frontal lobes; mandible long and straight, inserted in the middle of anterior margin of head; two or three apical teeth elongate and forming a fork; subapical tooth often present as an angle or small triangular tooth; masticatory margin edentate or serrate, ventrally with a row of several long setae; antenna 12-segmented, filiform; scape elongate, a little flattened in its apical part; eye usually developed well, but rarely reduced (consisting of less than 10 ommatidia); mesosoma in lateral view with a straight dorsal outline, or pronotum weakly raised dorsad; promesonotal suture completely separating pronotum and mesonotum; mesonotum sometimes raised as a transverse ridge; metanotal groove shallowly to moderately impressed, or indistinct dorsally; mesopleuron well defined dorsally and posteriorly by carinae and/or grooves; propodeal spines usually absent (but rarely present as small teeth); orifice of propodeal spiracle round; propodeal lobe absent; apicoventral part of foretibia usually with a small simple spur behind a large pectinate spur; apicoventral part of mid tibia with a simple spur in front of a simple to barbulate spur, with a single simple spure only, or without any spurs; apicoventral part of hind tibia with a simple spur in front of a large pectinate spur, or with a single pectinate spur only; petiole at most with a very short anterior peduncle; petiolar node in lateral view high, but not forming a single spinous apex; subpetiolar process developed well as a lobe; girdling constriction between abdominal segments III and IV usually inconspicuous; abdominal sternite III with a distinct anteroventral flange beneath helcium; sting well developed.

Differentiation. The worker of Anochetus is most similar to that of Odontomachus, but in the latter the posterior face of the head (inside preoccipital carina) has a pair of dark lines which meet together at or near the dorsalmost part of preoccipital carina, and the vertex has a median longitudinal carina which meet together at the dorsalmost part of the preoccipital carina.

Bionomics. Anochetus spp. usually occur in well-developed forests and other woody habitats. They nest in rotting logs and wood fragments, and in litter and soil.

Brachyponera
Morphology. Workers of Vietnamese species have the following features (see also Schmidt & Shattuck 2014): Worker monomorphic; body (excluding mesopleuron and metapleuron) covered with a dense fine pubescence, and sparsely with standing hairs; head in full-face view subrectangular; preoccipital carina inconspicuous dorsally and laterally; frontal lobes horizontal, relatively small, separated from each other just with a longitudinal sulcus; antennal scrobe absent; median portion of clypeus moderately convex, with anteromedian margin truncate or weakly concave; mandible triangular with ca. 8–10 teeth on masticatory margin; basal portion of mandible with a pit or groove dorsolaterally (but the pit/groove sometimes obsolete); antenna 12-segmented, gradually incrassate from segment III to XII; eye moderate in size, located on side of head relatively close to mandibular insertion; promesonotum forming a dome which is in lateral view distinctly higher than anterior border of propodeal dorsum; promesonotal suture completely separating pronotum from mesonotum; metanotal groove deeply impressed; mesonotum present as a distinct disc well margined anteriorly by promesonotal suture and posteriorly metanotal groove; mesopleuron separated well from mesonotum and metapleuron with distinct sutures, not divided by a transverse groove; propodeum unarmed; orifice of propodeal spiracle small and round; propodeal lobe almost absent; apicoventral part of foretibia without small simple spur behind a large pectinate spur; apicoventral part of mid and hind tibiae with a simple spur in front of a large pectinate spur; outer surface of middle tibia with normal pilosity only; petiole without anterior peduncle; petiolar node squamiform, in lateral view high and thin; subpetiolar process developed, anteriorly without a conspicuous round depression, posteroventrally with an acute angle or a pair of acute angles; girdling constriction between abdominal segments III and IV weak; anteroventral frange/carina of abdominal sternite III (prora) reduced and not externally visible; sting well developed.

Differentiation. The worker of Brachyponera is most similar to that of Pseudoponera, but the latter lacks the basal mandibular pits, deep metanotal groove, and raised promesonotal dome. The worker of small species of Brachyponera are most similar in general appearance to that of Hypoponera, but in the latter the apicoventral part of the mid and hind tibiae lacks a smaller, simple spur in front of the pectinate large spur.

Radchenko (1993a) described Brachyponera mesoponeroides from Vietnam (type locality: Cuc Phuong), and Bolton (1995) and Schmidt & Shattuck (2014) combined the species in Pachycondyla. However, Sk. Yamane’s examination of the type series suggests that the species belongs to Hypoponera. The problem will be solved in a future study.

Bionomics. Pachycondyla spp. usually occur in well-developed forests and other wooded habitats. They nest in rotting logs and wood fragments, and in litter and soil.

Buniapone
Morphology. Workers of Vietnamese species have the following features (see also Schmidt & Shattuck 2014):

Worker monomorphic; head in full-face view subrectangular; preoccipital carina almost absent; frontal lobes horizontal, separated from each other just with a longitudinal sulcus; antennal scrobe absent; anteromedian margin of clypeus forming a rectangular projection; mandible elongate-triangular, with 6–7 teeth on masticatory margin; basal portion of mandible with a narrow groove dorsolaterally; antenna 12-segmented, gradually incrassate from segment III to XII; eye extremely reduced (consisting of a few ommatidia), located before midlength of side of head in lateral view; promesonotum in lateral view slightly raised; promesonotal suture completely separating pronotum from mesonotum; metanotal groove absent; mesopleuron separated well from mesonotum and metapleuron with distinct sutures, not divided by a transverse groove; metapleural gland bulla, when seen through the sclerite, bean-shaped, large in size (the anterior margin of bulla reaching midlength of metapleuron); metapleural gland orifice opening posterolaterad, with anterior and posterior cuticular flanges; propodeum unarmed; orifice of propodeal spiracle oval; propodeal lobe present but very low; apicoventral part of foretibia with a small simple spur behind a large pectinate spur; apicoventral part of mid and hind tibiae with a simple spur in front of a large pectinate spur; outer surface of middle tibia without peg-like or spiniform setae among background pilosity (but relatively long and thick standing setae present among background pilosity; a few stout setae present near tarsus but never extending along length of tibia); petiole without anterior peduncle; petiolar node squamiform, in lateral view high and thin; subpetiolar process triangular; girdling constriction between abdominal segments III and IV weak; abdominal sternite III usually with a distinct anteroventral kiel beneath helcium; sting well developed.

Differentiation. The worker of Buniapone most closely resembles that of Centromyrmex, but in the latter eye completely absent, and the anteromedian margin of clypeus does not form a rectangular projection. The worker of Buniapone is also similar to that of Myopias, but in the latter metanotal grooves distinct dorsally, and petiolar node in lateral view thick.

Bionomics. Workers of Buniapone amblyops have been collected by digging up the ground in well-developed forests.

Centromyrmex
Morphology. Workers of Vietnamese species have the following features (see also Schmidt & Shattuck 2014):

Worker monomorphic; head in full-face view subtrapezoidal; frontal lobe horizontal, developed well, completely concealing antennal socket; antennal scrobe absent; anteromedian margin of clypeus weakly convex; posteromedian portion of clypeus narrowly inserted between frontal lobes; mandible elongate-triangular, with serrate masticatory margin; basal angle inconspicuous; basal portion of mandible without a distinct circular fovea or elongate depression dorsolaterally; antenna 12-segmented, gradually incrassate from segment III to XII; scape flattened basally; apical 4 segments somewhat flattened; eye absent; pronotum in lateral view angulate anterodorsally, flattened dorsally; promesonotal suture completely separating pronotum and mesonotum; anterior margin of mesonotum distinctly higher than posterior margin of pronotum; mesopleuron distinctly margined dorsally and posteriorly; metanotal groove absent, instead a distinct broad constriction separating mesonotum from propodeum; dorsum of propodeum in lateral view much lower than anterior part of mesonotum; propodeum unarmed; orifice of propodeal spiracle elliptical; propodeal lobe almost absent; forecoxa massive; outer surface of middle tibia and middle basitarsus with thickened peg-like setae mixed with the normal finer pilosity; apicoventral part of foretibia always with a simple spur behind a large pectinate spur; apicoventral part of midtibia with two simple spurs; apicoventral part of hind tibiae with a simple spur in front of a large pectinate spur; petiole with an anterior peduncle; petiolar node in lateral view somewhat cubic; subpetiolar process developed well as a penant-shaped lobe; girdling constriction between abdominal segments III and IV present but very weak; abdominal sternite III with an anteroventral U-shaped ridge; sting well developed.

Differentiation. The worker of Centromyrmex is most similar to that of Cryptopone, but in the latter the basal portion of the mandible has a distinct circular fovea or elongate depression dorsolaterally.

Cryptopone
Morphology. Workers of Vietnamese species have the following:

Worker monomorphic; head in full-face view subrectangular or subtrapezoidal; frontal lobes horizontal, separated from each other by a longitudinal sulcus; antennal scrobe absent; anteromedian margin of clypeus weakly convex; mandible subtriangular, with a distinct apical tooth followed by 3–8 teeth on masticatory margin; basal portion of mandible with a distinct circular fovea or elongate depression dorsolaterally; antenna 12- segmented, gradually incrassate from segment III to XII, or with a 4-segmented club; eye absent, or present but reduced, consisting of a few ommatidia; eye, if present, located on the side of head close to mandibular insertion; mesosoma in lateral view with straight or weakly arched dorsal outline, or dorsum of propodeum lower than pronotum and mesonotum; mesosomal dorsum in dorsal view constricted behind mesonotum; mesonotum well margined anteriorly by promesonotal suture and posteriorly by metanotal groove; mesopleuron defined weakly from mesonotum by a faint suture or not defined from mesonotum, and defined well from metapleuron by a suture and/or groove; propodeum unarmed; orifice of propodeal spiracle oval or elliptical; propodeal lobe much reduced; outer surface of tibia and basitarsus of mid leg with thickened peg-like setae mixed with finer normal pilosity; apicoventral part of foretibia always with a simple spur behind a large pectinate spur; apicoventral part of mid and hind tibiae often with an additional smaller, simple or barbulate spur in front of a large pectinate spur; petiole without anterior peduncle; petiolar node in lateral view high, with an inverted V- or U-shaped outline; subpetiolar process present as a thin lamella, variable in size, anteriorly without a conspicuous round depression, posteroventrally without a pair of angles; girdling constriction between abdominal segments III and IV weak to distinct; abdominal sternite III with an anteroventral U-shaped ridge; sting well developed.

Differentiation. The worker of Cryptopone is most similar to that of Centromyrmex, but in the latter the basal portion of mandible lacks a distinct circular fovea or elongate depression dorsolaterally. It is also similar in general appearance to that of Ponera and Hypoponera, but in the latter two genera the basal portion of the mandible lacks a distinct circular fovea or elongate depression dorsolaterally, and the dorsal surface of the middle tibia lacks thickened setae. In the worker of Hypoponera the foretibia always lacks a simple spur behind a large pectinate spur (in the worker of Ponera the simple spur is often present but less distinct than in that of Cryptopone).

Bionomics. Cryptopone spp. usually occur in well-developed forests. They nest in rotting logs and wood fragments, under bark of logs, and in litter.

Diacamma
Morphology. Workers of Vietnamese species have the following features:

Worker monomorphic; head in full-face view elliptical, with a distinct preoccipital carina dorsally and laterally; frontal lobes horizontal, narrowly separated by posteromedian portion of clypeus, partly concealing antennal sockets; antennal scrobe absent; median portion of clypeus strongly and triangularly produced anteriad; mandible subtriangular, with ca 10–15 teeth on masticatory margin; antenna 12-segmented; eye developed well, strongly convex, located around or a little before midlength of side of head in lateral view; mesosoma in lateral view with gently convex dorsal outline, or pronotum slightly raised; mesonotum present as a transverse strip between promesonotal suture and metanotal groove; mesopleuson defined dorsally by a conspicuous excavation (in ergatoid queen the excavation filled with gemma), and posteriorly with sulcus; propodeum elongate anteriad, unarmed; orifice of propodeal spiracle slit-like; propodeal lobe indistinct; apicoventral part of foretibia with a small simple spur behind a large pectinate spur; apicoventral part of mid tibia with a simple spur in front of a simple to barbulate spurs; apicoventral part of hind tibia with a simple spur in front of a large pectinate spur; pretarsal claws of hind leg simple, without inner tooth; petiole without anterior peduncle; petiolar node in lateral view thick, with convex anterodorsal face and vertical posterior face; posterodorsal margin armed with a pair of acute spines; subpetiolar process present; its anteroventral and posteroventral corners acutely produced; girdling constriction between abdominal segments III and IV relatively weak; abdominal sternite sternite III with a distinct anteroventral flange beneath helcium; sting well developed; head, mesosoma and waist strongly rugose.

Differentiation. The worker of Diacamma spp. are in general appearance somewhat similar to that of Leptogenys, but in the latter a conspicuous excavation is absent above mesopleuron, and pretarsal claws of the hind leg are armed with one to many teeth on the inner margin.

Radchenko (1993a) treated Diacamma geometricum as an independent species not a junior synonym of D. rugosum, and recorded it from Nghe An and Ha Noi.

The following subspecies were also described from Vietnam: D. rugosum gibbosum Karavaiev, 1935 (type locality: Dalat, Lang Biang [Mt. Lang Bian, Lam Dong Prov.]); D. rugosum longiceps Santschi, 1932 [originally D. geometricum longiceps] (type locality: Ha Noi); D. rugosum ovale Karavaiev, 1935 (type locality: Ba-Me-Thout, Prov. Danlac [Buon Ma Thuot, Dak Lak Prov.]).

Bionomics. Diacamma spp. usually occurs in wooded habitats. They usually nest in rotting logs, under stones, and in the soil around tree bases. Gastropod guests (Prosobranchia: Pupinidae, and Pulmonata: Subulinidae) are often found inside nests of D. sculpturatum complex (Eguchi, Bui & Janssen 2005).

Ectomomyrmex
Morphology. Workers of Vietnamese species have the following features:

Worker monomorphic; head, mesosoma and petiole conspicuously striate, rugoso-reticulate or punctate, and gaster usually finely punctate; head in full-face view subrectangular or subtrapezoidal; preoccipital carina inconspicuous dorsally; frontal lobes horizontal, separated from each other just with a longitudinal sulcus; antennal scrobe absent; anteromedian margin of clypeus roundly convex, sometimes with a weak median emargination or an indistinct tooth (but never forming a rectangular projection); mandible subtriangular, with 7–10 teeth on masticatory margin; basal portion of mandible without a circular or near-circular pit or fovea dorsolaterally; antenna 12-segmented, gradually incrassate from segment III to XII; eye small to moderate in size, located on side of head relatively close to mandibular insertion; mesosoma in lateral view with a straight or weakly convex dorsal outline; promesonotal suture completely separating pronotum from mesonotum; metanotal groove absent or reduced to an inconspicuous suture; mesopleuron separated well from mesonotum and metapleuron with distinct sutures, divided by a transverse groove; propodeum unarmed; orifice of propodeal spiracle slit-like; propodeal lobe very low or almost absent; apicoventral part of foretibia with a small simple spur behind a large pectinate spur; apicoventral part of mid and hind tibiae with a simple spur in front of a large pectinate spur; outer surface of middle tibia with normal pilosity only; petiolar node squamiform to nodiform, in lateral view high and relatively thick; subpetiolar process developed, but simple in shape, without an anterior fenestra/fovea and a pair of teeth; girdling constriction between abdominal segments III and IV distinct; abdominal sternite III usually with a distinct anteroventral flange beneath helcium, or with a U-shaped or V-shaped ridge below helcium; abdominal tergite III weakly punctate; sting well developed.

Differentiation. The worker of Ectomomyrmex is similar to that of Pseudoneoponera or Bothroponera. In the worker of Pseudoneoponera, however, posterior margin of petiole has a row of small teeth or denticles, and the abdominal tergite III is longitudinally striated. In the worker of Bothroponera, mesopleuron is usually not divided by a transverse groove. Furthermore, the worker of the Asian species of Bothroponera lacks the strongly sculptured body. The worker of the smaller species of Ectomomyrmex is somewhat similar to that of some Euponera spp., but in the latter the basal portion of mandible has a pit dorsolaterally.

One subspecies has been also described from Vietnam: Ectomomyrmex astutus obscurus (Karavaiev, 1935) (type locality: Phu-ho, Tonkin [possibly Phu Ho, Phu Tho Prov.]).

Bionomics. Ectomomyrmex spp. usually occur in well-developed forests and other wooded habitats. They nest in rotting logs, wood fragments, under stones and in soil.

Euponera
Morphology. Workers of Vietnamese species have the following features:

Worker monomorphic; head in full-face view subrectangular; preoccipital carina absent dorsally; frontal lobes horizontal, separated from each other just with a longitudinal sulcus; antennal scrobe absent; median portion of clypeus with a median longitudinal ridge; anteromedian margin of clypeus roundly convex, but with a weak median emargination; mandible subtriangular, with ca. 8 teeth on masticatory margin; basal portion of mandible with a distinct pit dorsolaterally; antenna 12-segmented, gradually incrassate from segment III to XII; eye small to moderate in size, located on side of head close to mandibular insertion; mesosoma in lateral view usually with a straight or weakly convex dorsal outline; promesonotal suture completely separating pronotum from mesonotum; metanotal groove absent; mesopleuron separated well from mesonotum and metapleuron with distinct sutures, not divided by a transverse groove; propodeum unarmed; orifice of propodeal spiracle slit-like; propodeal lobe very low or almost absent; apicoventral part of foretibia with a small simple spur behind a large pectinate spur; apicoventral part of mid and hind tibiae with a simple spur in front of a large pectinate spur; outer surface of middle tibia with normal pilosity only; petiole without anterior peduncle; petiolar node squamiform, in lateral view high and relatively thick; subpetiolar process trapezoidal, without an anterior fenestra/fovea and a pair of teeth; girdling constriction between abdominal segments III and IV relatively distinct; abdominal sternite III usually with a distinct anteroventral flange beneath helcium; sting well developed.

Differentiation. The worker of Euponera is somewhat similar to that of the smaller species of Ectomomyrmex, but in the latter the basal portion of mandible lacks a pit dorsolaterally.

Gnamptogenys
Morphology. Workers of Vietnamese species have the following features:

Worker monomorphic; head in full-face view elongate, subrectangular or subpentagonal, often with conspicuous vertexal lobe; antennal socket mostly to entirely covered by horizontal frontal lobe, located a little behind the line across mandibular bases; antennal scrobe absent; anteromedian margin of clypeus more or less convex anteriad, with a narrow, transverse strip of lammellate cuticule; posteromedian portion of clypeus widely inserted between frontal lobes; mandible triangular, with serrate or almost edentate masticatory margin; antenna 12-segmented, gradually incrassate from segment III to XII; eye varying from small to well developed, located at or behind midlength of side of head in lateral view; mesosoma in lateral view with almost straight or weakly arched dorsal outline; promesonotal suture absent or weak dorsally (pronotum and mesonotum completely fused); metanotal groove indistinct or absent dorsally; propodeum unarmed, or with a pair of small teeth or spines; orifice of propodeal spiracle round; propodeal lobe usually developed moderately, but sometimes very low; metacoxal dorsum with a lobe, denticle or tubercle; inner curvature of pretarsal claws equipped with a tooth behind apical point; petiole without anterior peduncle; subpetiolar process developed well as a lobe; abdominal sternite III with well-developed anteroventral flange beneath helcium; abdominal segment IV strongly down-curved; its sternite in lateral view small, in lateral view triangular; sting well developed.

Differentiation. The worker of Gnamptogenys is in general appearance similar to that of Proceratium, but in the latter the antennal sockets are in full-face view mostly to entirely exposed, and located a little in front of the line across mandibular bases, and the metacoxal dorsum lacks a distinct lobe, denticle or tubercle.

Bionomics. Gnamptogenys spp. usually occur in well-developed forests, but G. bicolor occurs in forests with open canopy, second growth vegetation, and forest edges. They nest in rotting logs and wood fragments, and in litter and soil.

Harpegnathos
Morphology. Workers of Vietnamese species have the following features:

Worker monomorphic; head in full-face view subrectangular; preoccipital carina present dorsally and laterally; frontal lobe horizontal, almost completely concealing antennal socket; antennal scrobe absent; anteromedian margin of clypeus almost straight; posteromedian part of clypeus relatively narrowly inserted between frontal lobes; labrum with a median process that is visible in full-face view; mandible with an elongate and linear blade which has two rows of many small teeth; ventral part of base of each mandibular blade forming a large extensional triangular flange; antenna 12-segmented, filiform; eye extremely large, located on anteriormost part of side of head; small median and lateral ocelli present; mesosoma in lateral view with an almost gently arched dorsal outline; promesonotal suture completely separating pronotum from mesonotum; mesopleuron not separated from mesonotum by a suture, and feebly separated from metapleuron by a faint suture; metanotal groove absent; propodeum unarmed; orifice of propodeal spiracle elliptical or slit-like; propodeal lobe inconspicuous; inner curvature of pretarsal claws equipped with a tooth in addition to the pointed apex; apicoventral part of foretibia with a small simple spur behind a large pectinate spur; apicoventral part of mid tibia with a simple spur in front of a barbulate spur; apicoventral part of hind tibia with a simple spur in front of a large pectinate spur; petiole without a distinct anterior peduncle, with a triangular subpetiolar process anteroventrally; petiolar node in lateral view much longer than high; girdling constriction between abdominal segments III and IV distinct; abdominal sternite III with a distinct anteroventral flange beneath helcium; sting well developed.

Differentiation. The worker of this genus is easily distinguished from that of the other ponerine genera by its extraordinarily modified mandible and extremely developed eye.

Bionomics. Harpegnathos venator, the only species found in Vietnam, is rare here. It probably occurs in forest edges and relatively sparse forests. We found an undergound nest along a dirt trail in a sparse forest.

Hypoponera
Morphology. Workers of Vietnamese species have the following features:

Worker monomorphic; head in full-face view subrectangular; frontal lobes horizontal, separated from each other by a longitudinal sulcus; antennal scrobe absent; anteromedian margin of clypeus convex; mandible elongate-triangular; its distinct apical tooth followed by a series of small teeth or serration on masticatory margin; basal portion of mandible without a distinct circular or near-circular pit or fovea dorsolaterally; antenna 12-segmented, gradually incrassate from segments III to XII; eye present, but often reduced, consisting of a single or a few ommatidia; eye located on the side of head close to the mandibular insertion; dorsal outline of mesosoma in lateral view continuous and straight, or interrupted between pronotum, mesonotum and propodeum; promesonotal suture completely separating pronotum from mesonotum; mesopleuron distinctly to faintly demarcated from mesonotum by a suture, and distinctly from metapleuron by a suture and/or groove; metanotal groove usually distinct dorsally; propodeum unarmed; orifice of propodeal spiracle round to elliptical; propodeal lobe absent; outer surface of middle tibia with fine normal pilosity only; apicoventral part of foretibia always without a simple spur behind a large pectinate spur; apicoventral part of mid and hind tibiae with a single pectinate spur; petiole without anterior peduncle; petiolar node squamiforem in lateral view high; subpetiolar process developed well as a lobe, anteriorly without a conspicuous round depression, posteroventrally without a pair of angles; girdling constriction between abdominal segments III and IV relatively distinct; abdominal sternite III with an anteroventral U-shaped ridge below helcium or a distinct anteroventral flange beneath helcium; sting well developed.

Differentiation. The worker of Hypoponera is in general appearance most similar to that of Ponera and Cryptopone. In the worker of Ponera, however, the subpetiolar process in lateral view has an anterior round depression (fenestra) and a pair of posteroventral acute angles. In the worker of Cryptopone the basal portion of mandible has a distinct circular fovea or elongate depression dorsolaterally, and the dorsal (outer) surface of middle tibia bears thickened peg-like setae among background pilosity. The worker of some large species are somewhat similar to that of Brachyponera, but in the latter the apicoventral part of hind tibia has two spurs (a large pectinate spur and a smaller, simple spur in front of the pectinate spur).

Bionomics. Hypoponera spp. usually occur in well-developed forests and other wooded habitats. They nest in rotting logs and wood fragments, and in litter and soil.

Leptogenys
Morphology. Although the species of this genus are highly variable in worker morphology, Workers of Vietnamese species have the following features:

Worker monomorphic; head in full-face view roughly oval or subrectangular; preoccipital carina usually conspicuous dorsally and laterally; frontal lobes horizontal or suberrect, narrowly separated from each other by posteromedian portion of clypeus, or a longitudinal sulcus; antennal socket in full-face view largely exposed; antennal scrobe absent; median portion of clypeus strongly produced anteriad as a triangular, subrectangular or round lobe that usually bears 1 to several peg-like setae at apex; mandible variable in shape, subtriangular, linear or falcate; mandible with apical tooth or corner; basal angle usually (but not always) present as a corner or tooth; masticatory margin edentate or with less than 10 teeth; basal margin sometimes with several small dents; antenna 12-segmented; eye always present, but variable in size, usually (but not always) located before midlength of side of head in lateral view; mesosoma in lateral view with a straight or weakly convex dorsal outline, or pronotum more or less raised; promesonotal suture completely separating pronotum from mesonotum; metanotal groove often distinct dorsally; mesonotum often present as a distinct disc well margined anteriorly by promesonotal suture and posteriorly by metanotal groove; mesopleuron defined dorsally and posteriorly by carinae or sulci; propodeum usually unarmed, but sometimes with a process or ridge just above metapleural gland; orifice of propodeal spiracle round or elliptical; propodeal lobe indistinct or absent; apicoventral part of foretibia without a small simple spur behind a large pectinate spur; apicoventral part of mid and hind tibiae with a small, simple or barbulate spur in front of a large barbulate or pectinate spur; pretarsal claws of hind leg armed with several teeth on the inner margin (the teeth usually remarkable, but rarely very small); petiole without distinct anterior peduncle; petiolar node in lateral view variable in shape; subpetiolar process variable in size and shape, located at anteroventral part of petiole; girdling constriction between abdominal segments III and IV weak to distinct; abdominal sternite III usually with an anteroventral flange beneath helcium (flange sometimes indistinct and/or hidden by posterolateral margin of petiole); sting well developed.

The ergatoid queen is morphologically very similar to the worker, but the former usually has a larger propodeum, thinner petiolar node (in lateral view) and more or less expanded gaster. This may cause misdetermination at the species level.

Differentiation. The worker of Leptogenys is easily distinguished from that of the other Ponerinae known from Vietnam by the combination of the following features: the anteromedian portion of clypeus being well produced anteriad; the pretarsal claws of the hind leg armed with 1 to many teeth on the inner margin.

One subspecies has been described from Vietnam: L. kraepelini baccha Santschi (type locality: Tonkin: Chapa [Sa Pa]).

Bionomics. Leptogenys spp. usually occur in well-developed forests and other woody habitats. They forage on insects and other invertebrates living on the ground and in litter, and nest in rotting logs and wood fragments, and in litter and soil. Part of the species are nomadic. A few Vietnamese species seem to be subterranean (captured often by underground bait trapping). Colony sizes are variable among the species, probably less than 100 to over 10,000.

Mesoponera
Morphology. Workers of Vietnamese species have the following features:

Worker monomorphic; body covered with a dense fine pubescence, and sparsely with standing hairs; head in full-face view subrectangular; preoccipital carina very fine dorsally; frontal lobes horizontal, small and narrow, separated from each other just with a longitudinal sulcus; antennal socket in full-face view only partly concealed by frontal lobe; antennal scrobe absent; median portion of clypeus with a median longitudinal ridge; anteromedian margin of clypeus convex and with a blunt median point; mandible elongate-triangular, very long, with ca. 15 teeth on masticatory margin; basal portion of mandible without a pit dorsolaterally; antenna 12-segmented, gradually incrassate from segment III to XII; eye moderate in size, located on side of head relatively close to mandibular insertion; promesonotum in lateral view with a continuous round dorsal outline; promesonotal suture completely separating pronotum from mesonotum; metanotal groove deep; mesonotum present as a distinct disc well margined anteriorly by promesonotal suture and posteriorly metanotal groove ; mesopleuron separated well from mesonotum and metapleuron with distinct sutures, not divided by a transverse groove; propodeum unarmed; orifice of propodeal spiracle round and small; propodeal lobe almost absent; apicoventral part of foretibia usually with a small simple spur behind a large pectinate spur; apicoventral part of mid and hind tibiae with a simple spur in front of a large pectinate spur; outer surface of middle tibia with normal pilosity only; petiole without anterior peduncle; petiolar node squamiform, in lateral view high; subpetiolar process elongate rectangular; girdling constriction between abdominal segments III and IV relatively weak; abdominal sternite III with a distinct anteroventral flange beneath helcium; sting well developed.

Differentiation. The worker of Mesoponera is somewhat similar to that of Brachyponera, but in the latter the basal portion of mandible has a pit or groove dorsolaterally (but the pit/groove is sometimes obsolete), mandible is not elongate, and prora is reduced and notexternally visible.

Bionomics. Mesoponera sp. eg-1 occurs in well-developed forests, and nest in rotting logs and wood fragments.

Odontomachus
Morphology. Workers of Vietnamese species have the following features:

Worker monomorphic; head in full-face view subrectangular, with a constriction a little behind midlength of head; vertexal lobe well developed; vertex with a median longitudinal carina which meet the dorsalmost part of preoccipital carina; posterior face of head (inside preoccipital carina) with a pair of dark lines which meet together at or near dorsalmost part of preoccipital carina; frontal lobe horizontal, partly to largely concealing antennal insertion; antennal scrobe absent; submedian portion of clypeus weakly expanded above each mandibular base; posteromedian portion of clypeus relatively narrowly inserted between frontal lobes; mandible long and straight, inserted at middle of anterior margin of head; three apical teeth forming a fork; subapical tooth often present as an angle or small triangular tooth; masticatory margin serrate, and ventrally with a low of several long setae; antenna 12-segmented, filiform; scape slender and long; eye located on anterodorsal face of anterolateral convexity of head; mesosoma relatively long and slender; pronotum and mesosoma in lateral view forming a low dome; promesonotal suture completely separating pronotum from mesonotum; mesopleuron defined strongly to faintly from mesonotum by a suture and/or carina, and defined well from metapleuron by a suture and/or carina; metanotal groove shallowly to moderately impressed, or sometimes inconspicuous dorsally; propodeum in lateral view with a relatively long and straight dorsal outline; propodeal spines absent; orifice of propodeal spiracle elliptical to slit-like; propodeal lobe very low or absent; apicoventral part of foretibia with a small simple spur behind a large pectinate spur; apicoventral part of mid and hind tibia with a simple spur in front of a large pectinate spur; anterior peduncle of petiole reduced or absent; petiolar node in lateral view high, tapering to a single spinous dorsal apex; subpetiolar process developed as a lobe; girdling constriction between abdominal segments III and IV indistinct; abdominal sternite III with a distinct anteroventral flange beneath helcium; sting well developed.

Differentiation. The worker of Odontomachus is most similar to that of Anochetus, but in the latter the posterior face of head inside preoccipital carina lacks a pair of dark lines; vertex lacks a median longitudinal carina.

Bionomics. Odontomachus spp. usually occur in well-developed forests and other wooded habitats. They nest in rotting logs and wood fragments, and in litter and soil.

Odontoponera
Morphology. Workers of Vietnamese species have the following features:

Worker monomorphic; head and mesosoma distinctly rugose; head in full-face view subrectangular; preoccipital carina low but distinct dorsally and laterally; posteromedian portion of vertex of head with a low triangular mound; frontal lobes horizontal, narrowly separated by posteromedian portion of clypeus, completely concealing antennal sockets; antennal scrobe absent; anteromedian margin of clypeus convex, with ca. 7–9 distinct teeth; mandible subtriangular, with 5–6 teeth on masticatory margin (the basal one much smaller than the other five, or nearly absent); antenna 12-segmented, gradually incrassate from segments III to XII; eye developed well, located before midlength of side of head in lateral view; pronotum and mesonotum in lateral view with a continuous weakly convex dorsal outline; pronotum with a pair of distinct humeral spines; anterolateral corner of pronotum angulate; promesonotal suture completely separating pronotum from mesonotum; mesopleuron separated well from mesonotum by a suture, but weakly separated from metapleuron by an incomplete suture; metanotal groove inconspicuous or absent dorsally; propodeum unarmed, instead upper part of posterior slope of propodeum usually margined each side with a coarsely serrate ridge; dorsal face of propodeum distinctly longer than posterior slope in lateral view; orifice of propodeal spiracle elliptical; propodeal lobe inconspicuous or absent; petiole without anterior peduncle; petiolar node in lateral view high and thin, with an inverted V-shaped outline; subpetiolar process developed as a rectangular lobe; apicoventral part of foretibia with a small simple spur behind a large pectinate spur; apicoventral part of mid and hind tibiae with a simple spur in front of a large pectinate spur; girdling constriction between abdominal segments III and IV present; abdominal sternite III with an anteroventral flange beneath helcium; sting well developed.

Differentiation. The worker of Odontoponera is easily distinguished from that of the other Vietnamese ponerine genera by the combination of the following features: anteromedian margin of clypeus with ca. 7–9 dents; pronotum with a pair of distinct humeral spines.

O. transversa (F. Smith) was listed by Radchenko (1993a) from northern Vietnam (Cuc Phuong, Ha Noi, nr. Ha Noi, Hoa Binh), and by Zryanin (2011) from Cat Tien National Park, but those identifications need reconfirmation (see Yamane 2009).

Bionomics. Odontoponera denticulata occurs in wooded habitats including forest edges and disturbed areas, and usually nests in soil and forages on the ground surface.

Parvaponera
Morphology. According to Schmidt & Shattuck (2014), the worker of the Vietnamese species may show the following features:

Worker monomorphic; body small and slender, finely punctate, covered with dense pubescence, and sparsely with standing hairs; mandibles triangular, lacking a basal groove or pit; clypeus with a central tooth or short projection; frontal lobes moderately small; eyes small in size (consisting of 2–4 ommatidia) or absent, located fairly anterior on head; mesopleuron lacking a transverse groove; metanotal groove present or absent; propodeum not narrowed dorsally; orifice of propodeal spiracle elongate or slit-like; apicoventral part of hind tibiae with a simple spur in front of a large pectinate spur; outer surface of middle tibia with normal pilosity only; petiolar node squamiform; subpetiolar process triangular, with an anterior fenestra and/or a pair of teeth; girdling constriction between abdominal segments III and IV distinct; abdominal sternite III usually with a distinct anteroventral flange or ridge below helcium.

Differentiation. The worker of Parvaponera is most similar in general appearance to that of Cryptopone, but in the latter the outer surface of middle tibia bears thickened peg-like setae, and the subpetiolar process lacks an anterior fenestra and a pair of posteroventral teeth. It is also similar to that of Ponera, but in the latter the apex of metatibia ventrally has a large pectinate spur only.

Platythyrea
Morphology. Workers of Vietnamese species have the following features:

Worker monomorphic; body densely and finely punctured, covered with fine pubescence, without standing hairs; head in full-face view elongate, subrectangular; antennal socket mostly covered by horizontal frontal lobe; antennal scrobe absent; anteromedian margin of clypeus convex; posteromedian portion of clypeus widely inserted between frontal lobes; mandible subtriangular, with an apical tooth followed by serrate masticatory margin; antenna 12-segmented, gradually incrassate from segment III to XII; eye well developed, located before midlength of side of head in lateral view; mesosoma in lateral view with almost straight dorsal outline; promesonotal suture distinct; mesopleuron separated well from both mesonotum and metapleuron by distinct sutures; metanotal groove absent dorsally; propodeum unarmed, but with corners where dorsal and posterior faces of propodeum meet with each other; orifice of propodeal spiracle round; propodeal lobe present but low; metacoxal dorsum with a triangular process; apicoventral part of foretibia usually without a small simple spur behind a large pectinate spur; apicoventral part of mid and hind tibia with a barbulate or pectinate spur in front of a large pectinate spur; inner curvature of pretarsal claws equipped with a tooth behind apical point; petiole without anterior peduncle; petiolar node longer than high; anteroventral part of petiole with subpetiolar process developed well as a lobe; girdling constriction between abdominal segments III and IV distinct; abdominal sternite III without an anteroventral U-shaped ridge or flange below/beneath helcium; sting well developed.

Differentiation. The worker of Platythyrea is easily distinguished from that of the other ponerine genera known from Vietnam by the following combination of features: median portion of clypeus broadly inserted between frontal lobes; metatibia with 2 pectinate spurs.

Bionomics. A fragment of a colony of Platythyrea sp. eg-1 was collected under dead epiphytes on a living tree in a dry forest.

Ponera
Morphology. Workers of Vietnamese species have the following features:

Worker monomorphic; head in full-face view subrectangular; frontal lobes horizontal, separated from each other by a longitudinal sulcus; antennal scrobe absent; anteromedian margin of clypeus convex; mandible subtriangular; its distinct apical tooth followed by a series of small teeth or serrate margin; basal portion of mandible without a distinct circular or near-circular pit or fovea dorsolaterally; antenna 12-segmented, gradually incrassate from segment III to XII; eye present, but often reduced (consisting of one or a few ommatidia); eye located on side of head close to mandibular insertion; mesosoma in lateral view with a flat or weakly arched dorsal outline; promesonotal suture completely separating pronotum from mesonotum; mesopleuron hardly demarcated from mesonotum by a suture, and weakly from metapleuron by a suture; metanotal groove absent or present dorsally as a weak transverse sulcus; propodeum unarmed; orifice of propodeal spiracle oval; propodeal lobe indistinct; outer surface of middle tibia with fine normal pilosity only; apicoventral part of foretibia often with a thin, simple spur behind a large pectinate spur; apicoventral part of mid and hind tibia with a single pectinate spur; petiole without anterior peduncle; petiolar node in lateral view high; subpetiolar process developed well as a lobe, anteriorly with a conspicuous round depression, posteroventrally with a pair of acute angles; girdling constriction between abdominal segments III and IV relatively distinct; abdominal sternite III with an U-shaped anteroventral ridge below helcium; sting well developed.

Differentiation. The worker of Ponera is in general appearance most similar to that of Hypoponera and Cryptopone, but in the latter two genera the subpetiolar process lacks an anterior round depression and a pair of posterolateral angles. Furthermore, in the worker of Cryptopone, the basal portion of mandible has a distinct circular or near-circular pit or fovea dorsolaterally, and the outer surface of midtibia bears thickened peg-like setae mixed with finer normal pilosity. The worker of Ponera is also similar to that of Parvaponera, but in the latter the apex of metatibia ventrally has a simple spur in front of a large pectinate spur.

Bionomics. Ponera spp. usually occur in well-developed forests and other wooded habitats. They nest in rotting log and wood fragments, and in litter and soil.

Pseudoneoponera
Morphology. Workers of Vietnamese species have the following features:

Worker monomorphic; body densly covered with short standing hairs; head and mesosoma coarsely sculptured, and abdominal tergite III strongly striate longitudinally; head in full-face view subrectangular; preoccipital carina conspicuous dorsally and laterally; frontal lobes horizontal, separated from each other just with a longitudinal sulcus; antennal scrobe absent; median portion of clypeus with a steep anterior face, with a pair of median carinae; anteromedian margin of clypeus convex, sometimes with an indistinct median point; mandible subtriangular, with ca. 8–10 teeth on masticatory margin (teeth often worn away); basal portion of mandible without a circular or near-circular pit or fovea dorsolaterally; antenna 12-segmented, gradually incrassate from segment III to XII; eye moderate in size, located before midlength of side of head in lateral view; mesosoma in lateral view straight or with a weakly convex dorsal outline; promesonotal suture completely separating pronotum from mesonotum; metanotal groove inconspisuous or absent; mesopleuron separated well from mesonotum and metapleuron with distinct sutures, sometimes divided by an inconspicuous transverse groove; propodeum unarmed; orifice of propodeal spiracle slit-like; propodeal lobe almost absent; apicoventral part of foretibia usually with a small simple spur behind a large pectinate spur; apicoventral part of mid and hind tibiae with a simple spur in front of a large pectinate spur; outer surface of middle tibia with normal pilosity only; petiole without anterior peduncle; petiolar node in lateral view high and thick, in dorsal view semicircular; its posterodorsal margin with a row of small denticles;subpetiolar process developed, with anteroventral and posteroventral angles; girdling constriction between abdominal segments III and IV distinct; abdominal sternite III usually with a distinct anteroventral flange beneath helcium; sting well developed.

Differentiation. The worker of Pseudoneoponera most closely resembles Bothroponera, and to a lesser extent Ectomomyrmex, but in the latter two genera the posterodorsal margin of petiolar node lacks a row of small denticles, and the abdominal tergite III is not striate longitudinally.

Bionomics. Pseudoneoponera rufipes usually occurs in wooded habitats.

Proceratiinae
Key to Vietnamese Proceratiinae Genera