Key to Pristomyrmex workers

This worker key is based on: Wang, M. 2003. A Monographic Revision of the Ant Genus Pristomyrmex (Hymenoptera:Formicidae). Bulletin of the Museum of Comparative Zoology 157(6): 383-54

Note: Pristomyrmex fuscipennis and Pristomyrmex reticulatus, whose worker castes are presently unknown, are not included in the key.

Species described after 2003 (Pristomyrmex cebuensis, Pristomyrmex distinguendus, Pristomyrmex hamatus, Pristomyrmex rugosus, Pristomyrmex schoedli and Pristomyrmex tsujii) are also not included here.

1

 * Dorsum of alitrunk in profile not arched, with mesonotum much higher than propodeal dorsum, that is, a vertical cliff present between mesonotum and propodeal dorsum. Antennal scrobes well developed and deep. Basal margin of mandible with a strong tooth adjacent to the basal tooth of masticatory margin so that five teeth are set close together. Base of antennal scape without a circling lamella (profundus group; Asia: Sabah) . . . . . Pristomyrmex profundus


 * Dorsum of alitrunk in profile, excluding armaments, more or less arched-shaped, never showing a vertical cliff between mesonotum and propodeal dorsum. Antennal scrobes absent or shallow. Tooth on basal margin of mandible either absent or present; if present, it is on about midway, not adjacent to the basal tooth of masticatory margin. Base of antennal scape with a circling lamella . . . . . 2

2
return to couplet #1


 * Masticatory margin of mandible with four teeth; the third tooth, counting from the apex, smallest, distinctly smaller than the basal one; diastema absent between the preapical and the third tooth (levigatus group; Asia, Australia) . . . . . 3


 * Masticatory margin of mandible with three to five teeth ; if four teeth present, then the third tooth, counting from the apex, similar in size to the basal one; diastema either present or indistinct between the preapical and the third tooth . . . . . 14

3
return to couplet #2


 * Propodeum unarmed. Petiole node in profile wedge-shaped (Asia: Papua New Guinea) . . . . . Pristomyrmex inermis


 * Propodeum armed with a pair of teeth or spines. Petiole node in profile nodiform, not wedge-shaped . . . . . 4

4
return to couplet #3


 * Pronotum armed with a pair of teeth (Asia and Pacific Is.: Papua New Guinea; Indonesia; Pohnpei Is.; Palau Is.; Yap 1.; Tonga Is.; Wallis Is.; found rarely in N. Queensland, Australia)  . . . . . Pristomyrmex minusculus


 * Pronotum unarmed . . . . . 5

5
return to couplet #4


 * Postpetiole in profile with an arched anterior face and a steeply sloping posterior face and the apex of postpetiole pointing posterior-upwardly; in dorsal view, postpetiole usually longer than broad, very rarely about as long as broad. Petiole node with a single evenly blunt-rounded apex. Head broader; HW mostly > 1.00 (Asia: Papua New Guinea) . . . . . Pristomyrmex lucidus


 * Postpetiole in profile with a somewhat evenly convex dorsum, lacking an abruptly steep posterior face and in dorsal view broader than long. Petiole node in profile with a distinct anterodorsal angle (Head narrower; HW < 1.00 . . . . . 6

6
return to couplet #5


 * Dorsum of petiole node late rally compressed and in dorsal view distinctly longer than broad (Asia: New Guinea) . . . . . Pristomyrmex longus


 * Dorsum of petiole node not laterally compressed and in dorsal view about as broad as or broader than long, not longer than broad . . . . . 7

7
return to couplet #6


 * Dorsum of alitrunk unsculptured, smooth and shining. Dorsum of head between frontal carinae usually smooth and shining, except for a few punctures bordering frontal carinae . . . . . 8


 * Dorsum of alitrunk with some scattered foveolate punctures. Dorsum of head between frontal carinae with scattered foveolate punctures or foveolate-reticulate sculpture . . . . . 12

8
return to couplet #7


 * Eyes smaller, with two to three ommatidia in the longest row (Asia: New Guinea) . . . . . Pristomyrmex boltoni


 * Eyes larger, usually with five to seven ommatidia in the longest row . . . . . 9

9
return to couplet #8


 * Larger species, with HW 0.90-0.96 and HL 0.90- 0.90 (Pacific Is.: Pohnpei I.) . . . . . Pristomyrmex largus


 * Smaller species; HW < 0.80, HL < 0.80 . . . . . 10

10
return to couplet #9


 * Ventral surface of petiole with a long pinlike process (Pacific Is.: New Heblides) . . . . . Pristomyrmex acerosus


 * Ventral surface of petiole without a long pinlike process . . . . . 11

11
return to couplet #10


 * Each side of petiole with a longitudinal carina that separates the tergite from the sternites. Basal margin of mandible with a short, broad tooth (Asia and Pacific Is.: Papua New Guinea, Solomon Is., Nama Is., New Britain Is.) . . . . . Pristomyrmex levigatus


 * Sides of petiole unsculptured and smooth, lacking a longitudinal carina. Basal margin of mandible with a prominent tooth (Pacific Is.: Fiji ) . . . . . Pristomyrmex mandibularis

12
return to couplet #7


 * Entire first gastral tergite evenly clothed with numerous erect or suberect hairs (Pacific Is.: Solomon Is.) . . . . . Pristomyrmex obesus


 * Only a few hairs present usually near the base of the first gastral tergite . . . . . 13

13
return to couplet #12


 * Dorsum of head, except for the scrobes, with foveolate-reticulate sculpture; punctures often aligned so that it seems that several longitudinal rugae appear between frontal carinae. Eyes smaller, EL = 0.06-0.08, with three to four ommatidia in the longest row (Asia: Papua New Guinea) . . . . . Pristomyrmex coggii


 * Dorsum of head between frontal carinae with some scattered foveolate punctures; space between foveolae smooth. Eyes large r, EL = 0.09-0.12, usually containing five (rarely four) ommatidia in the longest row (Asia: Papua New Guinea) . . . . . Pristomyrmex simplex

14
return to couplet #2


 * Masticatory margin of mandible with four teeth, lacking a distinct diastema. Lamella, circling the base of antennal scape, with a broad and deep notch on the center of the dorsal surface. Petiole node in profile longer than high (umbripennis group; Asia) . . . . . 15


 * Masticatory margin of mandible with three to five teeth; usually with a distinct diastema; if (very rarely) diastema indistinct, masticatory margin with five teeth. Lamella, circling the base of antennal scape, entire, without a notch on the center of the dorsal surface. Petiole node in profile usually higher than long . . . . . 17

15
return to couplet #14


 * Eyes larger, usually consisting of 20 or more ommatidia, containing six to seven ommatidia in the longest row. Propodeum with a pair of toothlike armaments that are shorter than the distance between their bases. About one-third of antennal scape usually laterally compressed near the base (Asia: Papua New Guinea, Indonesia) . . . . . Pristomyrmex umbripennis


 * Eyes smaller, generally consisting of less than 10 ommatidia, with three to four ommatidia in the longest row. Propodeum with a pair of spines that are longer than the distance between their bases. Antennal scape not laterally compressed near the base . . . . . 16

16
return to couplet #15


 * Propodeal spines longer and strongly upcurved at their apices. Larger species with HL 1.42-1.54, HW 1.42- 1.58 (Asia: W. Malaysia, Borneo) . . . . . Pristomyrmex pollux


 * Propodeal spines shorter and not strongly upcurved at their apices. Smaller species with HL 1.04-1.36, HW 1.02-1.40 (Asia: Papua New Guinea, Indonesia, Singapore, Malaya, Sabah, Brunei, Philippines) . . . . . Pristomyrmex picteti

17
return to couplet #14


 * Pronotum unarmed. Eyes larger, usually containing seven or more (very rarely six) ommatidia in the longest row. Dorsal surfaces of head and alitrunk with well developed rugoreticulum or many foveolate punctures (punctatus group; Asia, Africa) . . . . . 18


 * Pronotum usually with a pair of teeth or spines; if (very rarely) pronotal teeth or spines absent, then either eyes smaller, with two to five ommatidia in the longest row, or dorsal surfaces of alitrunk and head between frontal carinae unsculptured and smooth . . . . . 22

18
return to couplet #17


 * Dorsum of alitrunk with well developed coarse reticulum. Propodeum armed with a pair of long spines. Antennal scapes longer, usually > 0.78; one-sixth to one-fifth of the length of the scapes projecting beyond the occipital margin. Palp formula 5,3 . . . . . 19


 * Dorsum of alitrunk with scattered foveolate punctures. Propodeum armed with a pair of short spines. Antennal scapes shorter, with the length 0.54-0.60, only close to the occipital margin. Palp formula 4,3 (South Africa) . . . . . Pristomyrmex fossulatus

19
return to couplet #18


 * Lateral portions of clypeus, in front of antennal fossae, developed and not reduced to narrow margins. Anterior clypeal margin lacking distinct denticles. Median portion of clypeus not flat . . . . . 20


 * Lateral portions of clypeus reduced to a narrow margin in front of the antennal fossae. Anterior clypeal margin with five to seven denticles. Median portion of clypeus more or less flat . . . . . 21

20
return to couplet #19


 * Dorsum of head with scattered foveolate punctures; spaces between foveolae smooth. Frontal carinae short, not extending to the level of the posterior margins of eyes in full-face view. Alitrunk in dorsal view with a deep longitudinal furrow at middle (Asia: Philippines) . . . . . Pristomyrmex divisus


 * Dorsum of head entirely sculptured with coarse reticulum. Frontal carinae long, extending to the level of the posterior margins of eyes in full-face view. Alitrunk in dorsal view lacking a deep longitudinal furrow at the midline (Asia: Malaya) . . . . . Pristomyrmex pulcher

21
return to couplet #19


 * Two or more pairs of erect hairs present on the dorsum of petiole node. Basal margin of mandible almost straight, without a distinct tooth. Ventral surface of clypeus lacking toothlike prominences. Dorsal alitrunk more or less depressed, with marginate sides. Sculpture of the sides of pedicel segments lighter and finer (widespread in the east and south of Asia; occasionally intercepted at entry ports in North America) . . . . . Pristomyrmex punctatus


 * A pair of hairs present on the dorsum of petiole node. Basal margin of mandible with an acute or broad-based triangular tooth. Ventral surface of clypeus usually with two minute toothlike prominences. Dorsal alitrunk convex, not depressed. Sculpture of the sides of pedicel segments more coarse (Asia: Thailand, Malaya, Sarawak, Sabah, Brunei, Sumatra) . . . . . Pristomyrmex rigidus

22
return to couplet #17


 * Promesonotal suture present. Propodeal spines developed and long, in dorsal view joining together at base and forming a "fork". Alitrunk in profile with a convex promesonotum and a deeply concave propodeal dorsum. Dorsum of head, at least on the genae and around the antennal sockets, with regular striate sculpture, lacking foveolate punctures or rugoreticulum (trispinosus group; Indian Ocean Islands) . . . . . 23


 * Promesonotal suture absent. Propodeal armaments in dorsal view usually well separated at the base and not resembling a fork. In rare case, where the propodeal spines are set close together at the base, the dorsum of alitrunk, in profile, lacks a deeply concave propodeum. Dorsum of head smooth or sculptured with foveolate punctures or with rugoreticulum, but never shoving regular striate sculpture . . . . . 25

23
return to couplet #22


 * Propodeal spines in dorsal view divergent, in profile almost straight. Larger species with HW > 1.00, HL > 1.10, SL > 1.30 . . . . . 24


 * Propodeal spines in dorsal view subparallel, in profile view bent at about a right angle near the base. Smaller species with HW 0.82-0.90, HL 0.88-1.01, SL 0.80-0.97 (Indian Ocean Is.: Mauritius, Reunion I.) . . . . . . Pristomyrmex browni

24
return to couplet #23


 * Dorsum of head and alitrunk entirely covered with regular long coarse striations. Mesonotum with a pair of strong, blunt digitlike prominences (Indian Ocean Is.: Mauritius) . . . . . Pristomyrmex trispinosus


 * Dorsum of head smooth and shining, with rugae only present around the antennal fossae, on the genae and sometimes around the centrical disc of dorsal head. Dorsum of alitrunk smooth and shining. Mesonotum lacking well-developed digitlike prominences (Indian Ocean Is.: Mauritius) . . . . . Pristomyrmex bispinosus

25
return to couplet #22


 * Sides of postpetiole with several coarse longitudinal rugae. In profile view, the posterodorsal and posteroventral corners of the petiole node right-angled. Palp formula 4,3 (cribrarius group; Africa: Mozambique, South Africa) . . . . . Pristomyrmex cribrarius


 * Sides of postpetiole unsculptured or at most with a single longitudinal ruga. In profile view, the posterodorsal and posteroventral corners of the petiole node not right-angled. Palp formula 1,3 or 2,2 or 2,3 (quadridens group; Asia, Australia, Africa) . . . . . 26

26
return to couplet #25


 * Mandibular dentition arranged as an apical tooth + a preapical + a diastema + three small denticles of similar size. Sometimes, the three small denticles are fused together so that they are not clearly visible, but the length of the masticatory margin covered by the three small denticles is slightly longer than that of diastema. Pronotum either unarmed or armed with a pair of short triangular spines that are shorter than the propodeal spines . . . . . 27


 * Mandibular dentition arranged as an apical + a preapical + a diastema + one or two denticles, and the length of the masticatory margin covered by the one or two den tides is distinctly shorter than that of diastema. If (very rarely) mandibular dentition not as described previously but arranged as an apical + a preapical + a small denticle + a very short diastema (or diastema indistinct) + two small denticles, then the pronotum is armed with a p air of long robust spines that are much longer than propodeal spines . . . . . 29

27
return to couplet #26


 * Pronotum unarmed. Eyes smaller, with three ommatidia in the longest row (Asia: Sumatra) . . . . . Pristomyrmex eduardi


 * Pronotum armed with a pair of short triangular spines. Eyes larger, usually with five to six (rarely with four) ommatidia in the longest row . . . . . 28

28
return to couplet #27


 * Dorsal surfaces of head and alitrunk only with scattered shallow foveolate punctures; dorsum of alitrunk with a smooth and unsculptured median longitudinal strip (Asia: Indonesia) . . . . . Pristomyrmex quindentatus


 * Dorsal surfaces of head, except for scrobal areas, and alitrunk entirely covered with well developed coarse rugoreticulum (Asia: Sarawak, Sabah) . . . . . Pristomyrmex occultus

29
return to couplet #26


 * Dorsal surfaces of both alitrunk and head between frontal carinae either smooth or with some scattered foveolate punctures but lacking foveolate-reticulate sculpture or rugoreticulum . . . . . 30


 * Dorsal surfaces of both alitrunk and head with foveolate-reticulate sculpture or rugoreticulum . . . . . 42

30
return to couplet #29


 * Area of dorsal head between frontal carinae unsculptured and smooth. Dorsum of alitrunk without foveolate punctures . . . . . 31


 * Dorsal surfaces of both alitrunk and head between frontal carinae with some scattered foveolate punctures . . . . . 40

31
return to couplet #30


 * Alitrunk, in dorsal view, with a transverse ridge at the approximate position of metanotal groove. Anterior clypeal margin with three strong teeth . . . . . 32


 * Alitrunk, in dorsal view, unsculptured, lacking a transverse ridge at the approximate position of metanotal groove. Anterior clypeal margin usually with five to seven small denticles . . . . . 34

32
return to couplet #31


 * First gastral tergite with numerous, evenly distributed, suberect hairs. Alitrunk in dorsal view with several short rugae pre sent at the juncture between the pronotum and the mesonotum (Australia: New South Wales) . . . . . Pristomyrmex erythropygus


 * First gastral tergite lacking any suberect hairs. Alitrunk in dorsal view without rugae at the juncture between the pronotum and the mesonotum . . . . . 33

33
return to couplet #32


 * Propodeal spines longer, subequal to or longer than pronotal spines. Ventral center of clypeus with a weak and short ruga. Head broader, with HW 0.97- 1.34 and CI 103-116 (Australia: New South Wales, SE Queensland) . . . . . Pristomyrmex wheeleri


 * Propodeum with a pair of teeth or short spines, much shorter than pronotal spine. Ventral surface of clypeus with a long, well-developed transverse ridge. Head narrower, with HW 0.80-1.08 and CI 93-101 (Australia: New South Wales, Queensland) . . . . . Pristomyrmex quadridentatus

34
return to couplet #31


 * Pronotum tuberculate, lacking teeth or spines (Africa: Ivory Coast, Ghana, Nigeria, Cameroon, Gabon, Congo and Angola) . . . . . Pristomyrmex orbiceps


 * Pronotum armed with a pair of teeth or spines . . . . . 35

35
return to couplet #34


 * Petiole and postpetiole without erect hairs. Frontal carinae absent. Pronotum with a pair of triangular short spines. Ventral surface of clypeus with two toothlike prominences (Africa: Zaire) . . . . . Pristomyrmex trogor


 * Petiole and postpetiole with at least one to two pairs of hairs. Frontal carinae present and usually extending to the level of the posterior margins of eyes. In rare cases where the frontal carinae are very short or absent, the pronotum is armed with a pair of well-developed, long spines that are longer than the distance between their bases. Ventral surface of clypeus either with a transverse ruga, or with a tooth at center, or without any ruga or tooth, but never showing two toothlike prominences . . . . . 36

36
return to couplet #35


 * Pronotum with a pair of triangular short spines, much shorter than the distance between their bases . . . . . 37


 * Pronotum with a pair of long spines, longer than distance between their bases . . . . . 38

37
return to couplet #36


 * Petiole node in profile lacking distinct anterior face distinguishable from the upper surface of peduncle. Larger species, with HW 0.98-1.04, HL 0.94-1.02, EL 0.22-0.24 (Asia: Philippines) . . . . . Pristomyrmex flatus


 * In profile, anterior face of petiole node distinct from the dorsal surface of peduncle. Smaller species, with HW 0.77-0.94, HL 0.82-0.94, EL 0.14-0.18 (Asia: Philippines) . . . . . Pristomyrmex collinus

38
return to couplet #36


 * Propodeal spines short or moderately long, much shorter and slender than pronotal spines . . . . . 39


 * Propodeal spines exceptionally long, subequal in length to or slightly longer than pronotal spines (Australia: Queensland) . . . . . Pristomyrmex wilsoni

39
return to couplet #38


 * Petiole node in profile lacking distinct anterior face distinguishable from the upper surface of peduncle. Clypeus unsculptured, lacking a median longitudinal carina. Frontal carinae short, not extending to the level of the posterior margins of eyes (Asia: Philippines) . . . . . Pristomyrmex longispinus


 * In profile, anterior face of petiole node distinct from the dorsal surface of peduncle. Clypeus with a median longitudinal carina. Frontal carinae long, extending to the level of the posterior margins of eyes (Asia: Philippines) . . . . . Pristomyrmex curvulus

40
return to couplet #30


 * Petiole and postpetiole lacking erect hairs. Ventral surface of clypeus with two toothlike prominences (Africa: Ghana, Cameroon, Gabon, Angola, Kenya, Zaire, Sudan) . . . . . Pristomyrmex africanus


 * Petiole and postpetiole, respectively, with one to five pairs of erect hairs. Ventral surface of clypeus either with a transverse ruga or with a toothlike prominence  . . . . . 41

41
return to couplet #40


 * Smaller species (HW 0.82-1.02, HL 0.82- 1.02, EL 0.14-0.20). Ventral center of clypeus with a toothlike prominence. Usually one to two pairs of hairs present, respectively, on the dorsal surfaces of petiole node and postpetiole (Asia and Pacific Is .: Papua New Guinea; Indonesia; Pohnpei Is.) . . . . . Pristomyrmex quadridens


 * Larger species (HW 1.22-1.24, HL 1.10-1.16, EL 0.24- 0.25). Ventral surface of clypeus with a transverse ruga, lacking a toothlike prominence at center. Four to five pairs of short hairs present, respectively, on the dorsal surfaces of petiole node and postpetiole (Asia: New Guinea) . . . . . Pristomyrmex nitidissimus

42
return to couplet #29


 * First gastral tergite with numerous, evenly distributed, erect or suberect hairs. Petiole node with a single evenly blunt-rounded apex (Asia: Philippines) . . . . . Pristomyrmex hirsutus


 * First gastral tergite lacking erect hairs. Petiole node not showing a single evenly blunt-rounded apex but with a higher anterodorsal angle than the posterodorsal . . . . . 43

43
return to couplet #42


 * Masticatory margin of mandibles with five teeth; diastema very short or indistinct between the preapical and the third tooth. Basal margin of mandible with a central, broadly curved lobe. Anterior clypeal margin with three prominences, that is, a median tooth and a broad, low convex lobe on each side (Asia: Sarawak, Sabah, Borneo) . . . . . Pristomyrmex trachylissus


 * Masticatory margin of mandibles with three to four teeth; diastema distinct and long, present between the preapical and the third tooth. Basal margin of mandible almost straight, without a distinctly curved lobe. Anterior clypeal margin usually with five to seven denticles . . . . . 44

44
return to couplet #43


 * Pronotal spines exceptionally long, usually exceeding 0.40 (very rarely 0.37), usually longer than the distance between the bases of two pronotal spines (Asia: Sumatra, Java, Malaya, Sarawak, Sabah, Borneo, Philippines) . . . . . Pristomyrmex bicolor


 * Pronotum armed with a pair of teeth or spines (≤ 0.32) that are always shorter than the distances that separate their bases . . . . . 45

45
return to couplet #44


 * Propodeal spines long (0.19-0.30), much longer than the pronotal armaments, palp formula 2,3 . . . . . 46


 * Propodeal spines short (0.04- 0.13), usually shorter than but sometimes slightly longer than the pronotal armaments, palp formula 1,3 . . . . . 47

46
return to couplet #45


 * Postpetiole in dorsal view much broader than long, with PPI 133- 150. Antennal scapes shorter (SL 0.70-0.82, SI 81-93) (Australia: Queensland) . . . . . Pristomyrmex foveolatus


 * Postpetiole in dorsal view slightly broader than long, with PPI 109-121. Antennal scapes longer (SL 0.86- 0.98, SI 97-103) (Australia: Queensland) . . . . . Pristomyrmex thoracicus

47
return to couplet #45


 * Petiole node in profile slightly longer than high, with the anterodorsal angle on approximately the same level as or weakly higher than the posterodorsal; dorsum and sides of petiole node with seven to eight foveolate punctures (Asia: Sarawak) . . . . . Pristomyrmex modestus


 * Petiole node in profile higher than long, with the anterodorsal angle distinctly elevated above the posterodorsal; dorsum and sides of petiole node without foveolate punctures . . . . . 48

48
return to couplet #47


 * Ventral surface of clypeus lacking a central prominent tooth but usually bearing a transverse ruga (Asia: Malaya, Singapore, Sarawak, Borneo, Sabah, Philippines) . . . . . Pristomyrmex costatus


 * Ventral surface of clypeus with a central prominent tooth . . . . . 49

49
return to couplet #48


 * Pronotum with a pair of moderately long spines (0.14- 0.20), usually much longer (sometimes slightly longer) than the propodeal armaments (0.07- 0.1.3) (Asia: Malaya, Thailand, Nepal, Burma, China) . . . . . Pristomyrmex sulcatus


 * Pronotum with a pair of teeth or short spines (0.06-0.10), usually similar in length to or slightly shorter than the propodeal armaments (0.04-0.12) (Asia: Sumatra, Sulawesi, Malaya, Sarawak, Sabah, Thailand, Philippines, Taiwan, Japan) . . . . . Pristomyrmex brevispinosus