Protalaridris armata

Known from premontane to montane forests with the highest altitudinal records from Panama at close to 2400 m and the lowest in Ecuador at 680 m. Specimens have been found by leaf little sampling in a number of habitats including oak forest, ridgetop montane forest, wet ravine, and moss forest. Most records are from few individuals but in central Ecuador they may be common in the Otongachi Reserve and to a lesser extent in one site along the Toachi River. At the southern limit of its range it may be sympatric or parapatric with Protalaridris loxanensis but field work is necessary to corroborate this conjecture.

Identification
Lattke et al. (2018) - Worker: Mandibular shaft with two massive overlapping ventromesially projecting teeth, dorsal mandibular margin lacking preapical teeth or denticles except for a single denticle at base of apical tooth; mandibular shaft slender, in full-length view very gradually tapering apicad. Lateral margin of labrum with three anterolaterally projecting hairs; abdominal tergite IV with 12–16 erect hairs.

This is the type species for the genus. Protalaridris armata is easy to separate from other species on account of its two very prominent ventral teeth on each mandible. All other species have only one such tooth. Compared with other Protalaridris these ventral teeth project mesad more than ventrally, in lateral view their length is relatively less than that of other species. Some specimens of Protalaridris loxanensis may have a well-developed ventral tooth apicad of the basal ventral tooth that approaches the condition in Protalaridris armata. Protalaridris armata has the dorsal mandibular margin mostly devoid of denticles whilst other armata group species have several. Protalaridris armata has distinct posterolateral occipital lobes; each lobe has a dorsal convex surface, distinct from the curvature of the rest of the posterodorsal cephalic surface. The lobes in Protalaridris punctata are relatively smaller and lack distinct curvature. In all species the frontovertexal ridge, upon reaching the lateral cephalic margin, curves and continues anterad until reaching the antennal fossae, defining the dorsal cephalic surface. The eye in Protalaridris armata is placed at the edge of the dorsal cephalic surface, forming part of its lateral margin, but in most other species the eye is separated from the dorsal surface by at least one ocular diameter, half a diameter in Protalaridris arhuaca. This location of the eye, along with the well-impressed antennal scrobe in Protalaridris armata combines to give the impression the eye is situated along a ridge as wide as the eye. All other species have the eye on a broadly curving surface, either because of the distance separating it from the dorsal cephalic surface or because of a shallowly impressed antenna scrobe, or both.

Protalaridris armata specimens have their mandibles, part of the mesosoma, and gastral tergum frequently encrusted with debris that obscure features such as denticles and sculpturing. On the mesosoma the presence of decumbent hairs seem to coincide with the dorsolateral parts with crusts. The number and arrangement of erect hairs on the gastral tergum is variable. Specimens from Panama are more ferruginous in color and have the anterolateral edges of the head carinate, their mandibular denticulation is more variable in other populations, and their anterior ventral tooth is not as developed as in samples from Colombia and Ecuador. The tooth between the two massive ventral teeth is smaller and sometimes placed closer to the anterior tooth, which may be apically cleft. Panama specimens have the transverse cephalic crest consistently well-developed, whilst in specimens from other sites the crest may be poorly developed. Specimens from Chocó are generally darker with the gastral sternites shining and finely punctate.

Brown (1980) - General characters as in Rhopalothrix and Talaridris, but with the following differences: Antennae 9-merous; segments III- VII short and transverse. Mandibles long, slender, their insertions remote, but the shafts converging to cross at apices when closure is complete, each tapering toward an acute, incurved, straight apical spine. As seen from the side, shafts curved markedly dorsad from base toward apex away from main axis of cranium, much as in Talaridris. Inner margins of mandibular shafts each armed with 2 long, spaced, slender teeth and 3 smaller teeth or denticles in addition to apical spine.

Rhopalothrix and Talaridris are similar but have antennae 7-merous. In Talaridris, mandibles are also upcurved, but are short compared to Protalaridris armata, and the shorter and longer teeth are concentrated in a small area near to the apex, though they still appear to be homologous with the more widely-spaced teeth of Protalaridris.

Distribution based on Regional Taxon Lists
Neotropical Region: Colombia, Ecuador, Panama, Venezuela.

Biology
These ants are part of a group of species with similar characteristics (cryptobiotic, small size, litter dwelling, tropical distribution) that includes some unusual pilosity and a tendency to have soil bound to their bodies. A study by Hölldobler and Wilson (1986) of the hairs of a number of these species revealed that they all possess what they called brush and holding hairs that were well suited to holding soil particles. The hairs were different across the species and genera examined but the binding of soil to the ants is believed to serve as a means of camouflage that helps protect individuals from predators.

Castes
Males have yet to be collected.

Nomenclature

 *  armata. Protalaridris armata Brown, 1980a: 37, figs. 1-8 (w.) ECUADOR. Combination in Basiceros: Baroni Urbani & De Andrade, 2007: 90. See also: Hölldobler & Wilson, 1986a: 16.

Worker
Worker, holotype: TL 3.2, HL 0.82, HW 0.87 (CI 106), ML (foreshortened on full-face view of head) 0.36 (MI 44), full exposed L of mandible 0.53, eye L 0.06, antennal scape L (bend to apex) 0.48, WL 0.81 mm. (Measurements and indices standard for recent works on ant tribes Basicerotini and Dacetini, e.g., Brown & Kempf, 1960, Studia Ent. (n.s.) 3:l67-l68).

Paratype workers, 22 specimens from 4 localities in Ecuador and one in Colombia, range downward in size from holotype, the largest specimen seen. Full type series: TL 2.2-3.2, HL 0.56-0.82, HW 0.62-0.87 (CI 105-114), ML (foreshortened) 0.22-0.36 (MI 39-44), eye L 0.03-0.06, antennal scape L 0.32-0.48, WL 0.54-0.81 mm. The smaller specimens often tend to have proportionately wider heads and shorter mandibles, but these allometric differences are slight and not fully constant.

Particularly to be noted are the broad, blunt, transverse temporal ridge, in the form of a broadly open, inverted V, and the median longitudinal carina representing the frontal area, extending back from the middle posterior margin of the clypeus; epistomal (clypeal) suture distinct. Vertex both above and below temporal ridge feebly but broadly impressed on each side. Mandibles strongly upcurved, but the two largest teeth on each preapical margin curving ventromesad to form a sort of cradle as the opposite teeth overlap at full closure. The largest tooth, situated near mandibular midlength, tends to have an unequally bifid apex, very difficult to see unless the mandibles are open. The 3 smaller teeth or denticles are found between the larger teeth, and occasionally an additional small denticle occurs on or near the base of one of the larger teeth.

Labrum extended in all specimens seen; bilobed, with surface pilosity and special flattened fringing hairs; sometimes the fringing hairs have longer, attenuated apices. Under-mouthparts not investigated. Antennal scapes flattened, but still rather thick and with convex dorsal surfaces; anterior basal bend slightly expanded, with a subdorsal cultrate margin. Antennomere II (pedicel) campaniform, slightly longer than broad; III-VII short and transverse; VIII slightly longer than broad; IX (apical) about as long as the rest of the funiculus taken together.

When cranium is viewed from the rear, the fine carina separating vertex and back of head distinct. The antenna issues on each side through a deep semicircular notch in the dorsolateral cephalic margin.

Trunk subpyriform as seen from above, broadest across anterior pronotum; cervix marked off by a blunt, arcuate margin. No sutures evident across the dorsum, except for a shallow, narrow furrow, usually obscured by whitish particulate matter, immediately in front of the carina marking the top of the concave upper part of the propodeal declivity, and presumably indicating the anterior margin of the propodeum. This transverse carina is often distinct in actual specimens. The low propodeal teeth and the concave declivity are well shown. Petiole short, with summit transverse in dorsal view, obliquely subtrancate in lateral view; postpetiole about twice as wide as petiole, rounded above, with a trace of a median longitudinal sulcus posteriad, and a weak median posterior emargination. The greatly dominant first gastric tergum has narrowly rounded sides above its lateral margins forming overhanging margins of a sort, and in length it makes up about 4/5 of the total gaster.

Legs short and compact; femora gradually thickened apicad, and tibiae even thicker, sausage-like; tarsi much more slender, but still not very long; claws long and slender. Underside of petiole biconvex, but without a toothlike process.

Body generally densely punctulate, the punctures small, round, but often deep; legs and scapes finely and densely reticulate-punctulate. Integument opaque, except for dorsal and apical surfaces of mandibles, apicodorsal surface of scape, and the narrow interpunctural spaces of the gaster, which are weakly shining. Dorsum of alitrunk with slightly coarser sculpture, consisting of foveolae in which the reclinate hairs are set, separated by very short ridges, mainly oriented in a longitudinal direction. The surface is often fouled and obscured by a whitish, granular substance, chiefly covering parts of the dorsum of head and following tagmata; it may represent a secretion from the ant itself, or else a defensive allomone or hemolymph from the prey.

Larger, specialized hairs stiffly erect, weakly to moderately clavate apicad, their apices rounded, truncate or weakly subfimbriate; it may be ehat some are secretory setae; limited to: (1) a row of 8 or 9 on the anterior edge of each scape, decreasing in size and spacing toward scape apex; the longest hair is on the cultrate edge of the basal bend and arises slightly dorsal to the rest of the series, and it is tapered apicad and curved gently dorsad, unlike the rest; (2) a group of about 36 on posterior 2/3 of gastric dorsum, arranged in straight or curved transverse rows of 2-6 hairs each, those on the end of the gaster, and about 20 more on the venter, mostly fine and not much enlarged at apex; (3) a pair, one long and one short, at the apex of each tibia (only one on each fore tibia); rather numerous, curved, slightly broadened, decumbent and subdecumbent hairs clothe the tibial apices and the tarsi. Very short, fine, erect hairs are distributed over the undersides of the mandibles and on the funiculi. Appressed and decumbent pubescence mostly pennant-shaped, abundant on dorsal surfaces and appendages but not hiding surface.

Color dark brown to deep red-brown; appendages-- especially legs-lighter, reddish-ferruginous. Sting long, tapering from a stout base.

Lattke et al. (2018) - (n = 10): HL 0.60–0.87; HW 0.69– 0.93; ML 0.40–0.58; EL 0.04–0.09; SL 0.36–0.47; PW 0.40–0.64; WL 0.64–0.87; PH 0.21–0.29; PL 0.22–0.27; DPW 0.11–0.27 mm. CI 0.95–1.15; MI 0.53–0.65; OI 0.06–0.11; SI 0.50–0.53; LPI 0.83–1.20; DPI 0.42–1.10.

Head slightly wider than long in dorsal view; posterior margin mostly broadly convex to bluntly angular, occipital lobe projects posterad as blunt angle, lateral cephalic margin posterior to eye broadly convex to bluntly angular. Cephalic lateral margins anterad of maximum head width converge anteriorly; anterior clypeal margin medially concave, anterolaterally forming blunt angle, clypeus bordered posterolaterally by antennal fossa. Eye distinct, partially visible in frontal view, oval, apparently 4–5 partially fused ommatidia, facing anterolaterally, separated from antennal fossa by one diameter or less in lateral view, dorsal ocular margin at same level as dorsal cephalic margin in lateral cephalic view. Head widest along dorsolateral ridge. Cephalic lateral surface elongate, facing lateroventrad in lateral view, mostly occupied by broad and shallow antennal scrobe that fades posteriorly at same distance as dorsal transverse carina; head widest along dorsolateral ridge. Cephalic dorsum mostly densely punctate with abundant brief longitudinal rugae, commonly encrusted with dirt and debris that obscure cuticle; dorsum traversed at widest point by broadly concave to bluntly angular carina that forms elevated crest dividing cephalic dorsum into two sloping surfaces; frontovertexal ridge always obvious but may vary in vertical development. Low but distinct longitudinal carina present between posterior clypeal midpoint and frontovertexal ridge. Cephalic dorsum with short appressed, mostly transverse lanceolate ground hairs; posterolateral and ventral cephalic surfaces densely punctate, pilosity sparse.

Mandibles form cradle mainly bound by the main axis of each mandible as well as two prominent ventral teeth. Mandible in full length view progressively tapers apicad, mostly straight, bending mesad just before base of apical tooth, in lateral view dorsal mandibular margin sinuous, convex up to level of basal ventral tooth and concave apicad. Base of mandible at cephalic insertion expands into flange with smooth rim and areolate dorsal surface. Mandibular dorsum mostly punctate with scattered rugulae basad, abundant appressed and elongate to lanceolate or linear hairs that arch anterad present throughout mandibular shaft, densest on basal half; ventral mandibular surface mostly shining, with scattered punctulae. Mandibular dorsal margin sinuous in lateral view, forms weak obtuse angle with dorsal cephalic surface, mandibular base emarginate at junction with clypeus; massive ventral teeth pointing mostly mesad, ventral projection of tooth in lateral view less than contiguous thickness of mandibular shaft. Dorsal mandibular margin lacking preapical dentition except for denticle close to base of apical tooth. Mandibular ventral margin with 4 preapical teeth: teeth 1 and 3 massive, mesoventrally directed and overlapping with their counterparts, basal tooth largest, apically cleft; tooth 3 simple; tooth 2 small, closer to tooth 3 than tooth 1, tooth 4 at base of apical tooth. Ventral tooth in dorsal view tapering apicad; in anterior view relatively straight with decumbent tooth along anterodorsal margin. Mandibular apical tooth dark brown shining and sharply pointed.

Labrum entirely visible in frontal view, basal margin posteriorly convex, labrum wider posterad than anterad; bilobed with apically blunt median cleft almost extending to labral mid-length, lateral margin weakly concave. Ventral surface mostly shining, dorsal surface with scattered punctulae, not as shining. Labral margins with lanceolate flattened hairs; lateral margin with 3 anterolaterally directed hairs, progressively becoming longer anterad, anterior margin with 2 hairs, and internal margin with 2–3 anteromedially directed hairs. Palpal formula unknown. Scape in dorsal view with longitudinal rugulae anterad, posterad sparsely punctate, subparallel anterior and posterior margins, slightly wider basad than apicad, posterior margin broadly concave, anterior margin broadly convex, anterobasal lobe weakly expanded anterad, thin longitudinal lamella usually present between anterobasal lobe and apex; dorsum with arched hairs particularly anterad. Crosssection of scape at mid-length subrectangular, dorsal margin broadly convex, ventral margin mostly straight, anterior margin concave to convex, posterior margin straight to weakly concave; scape anteroventral margin bears 8 prominent apically truncate hairs; basal hair simple and longest, other hairs spatulate, weakly arching anterad, apical-most 4 hairs smallest of all.

Mesosomal dorsum in lateral view weakly convex, dorsal propodeal margin very brief; propodeal tooth broadly triangular, posterior base prolonged ventrally as broadly concave lamella, in dorsal view relatively thick not lamellate. Pronotum, mesosomal dorsal and dorsolateral surfaces rugulose, including anepisternum and dorsal extremes of metapleuron and lateral propodeum. Numerous decumbent ground hairs on lateral pronotum, mesonotum and propodeum, mostly directed postero to posteromesad; no decumbent hairs on mesometapleuron; no erect hairs on dorsum of head, mesosoma, petiole, and postpetiole. Katepisternum, most of metapleuron, and base of propodeal tooth punctate to areolate; katepisternum lacking transverse rugulae. Pronotum with defined anterior face separated from dorsal face by abrupt curvature, collar with few longitudinal carinae; promesonotal suture barely distinguishable.

Petiolar node subquadrate with anterior petiolar margin evenly and broadly concave in lateral view, dorsal margin straight to weakly convex, posterior margin brief and vertical, length less than half that of dorsal margin. Petiolar anteroventral process shaped as weak angle to absent, ventral margin posterad of process broadly concave to sinuate; postpetiolar dorsal margin in lateral view mostly broadly convex, curvature more pronounced posterad. Petiolar node and postpetiole transverse in dorsal view; postpetiole broadly concave anteriorly and convex posteriorly, dorsum and dorsolateral surfaces of petiolar node and postpetiolar tergum areolate-rugulose with posteriorly directed appressed, linear to lanceolate ground hairs. Petiolar anterior surface smooth and shining with abundant punctae, laterally and ventrally opaque and areolate; postpetiolar ventrum transverse, opaque and areolate.

Dorsal margin of abdominal tergite IV broadly convex in lateral view, ventral margin of sternite IV markedly convex except for brief, anterior vertical margin; tergum densely punctulate, space between depressions less than their diameters; ventrite IV densely punctate, space between the depressions may be opaque to shining. Abdominal tergum IV with transverse carina along anterodorsal margin that separates dorsum from very narrow transverse anterior surface. Pilosity on tergite IV consisting of 12–16 erect to suberect arched spatulate hairs generally forming 4 longitudinal rows on the posterior half: 2 median rows of 3 or more hairs each flanked by a row of 2 or more hairs, 2 median hairs present just anterad of mid-length. Ground pilosity consists of abundant arched and appressed lanceolate hairs mostly pointing posterad on dorsal surface, pilosity much reduced to absent along lateral face of tergum and most of ventrum. Tarsal claws simple and slender, about as long as fifth tarsomere; legs stout; protibial apex with long spatulate hair anterolaterally, plus another more slender hair just posterad; rest of hairs on protibia mostly short and arched, hairs towards tibial apex longer. Mesotibial and metatibial apex each with two prominent spatulate hairs, one longer than the other; lateral surface of meso- and metatarsi each with two longitudinal rows of elongate, spatulate hairs. Body mostly dark brown; antennae and legs lighter; mandible mostly brown with apical tooth dark brown.

Queen
dealate, 4 km E Santo Domingo, Ecuador: TL 3.6, HL 0.81, HW 0.90 (CI 111), ML (foreshortened) 0.34 (MI 42), ML (exposed) 0.48, eye L 0.15, antennal scape L 0.46, WL 0.96 mm. Resembles worker, but with the usual caste differences. Mesonotum boldly vermiculate-costate in a longitudinal direction; scutellum produced caudad, its posterior margin medially emarginate. Postpetiole with a broad median sulcus. Erect, apically broadened gastric hairs more numerous than in worker, and occurring over the front as well as the rear of tergum.

Lattke et al. (2018) - (n = 3): HL 0.76–0.82; HW 0.82–0.98; ML 0.49–0.60; EL 0.13–0.13; SL 0.38–0.49; PW 0.60–0.76; WL 0.87–1.00; PH 0.24–0.29; PL 0.31–0.36; DPW 0.40–0.51 mm. CI 1.09–1.19; MI 0.59–0.62; OI 0.14–0.16; SI 0.45–0.50; LPI 0.79–0.93; DPI 1.29–1.57.

Head very much as in worker but with 3 ocelli, lateral ocelli directed laterally and anterior ocellus directed anterad. Compound eye large, 12–15 ommatidia across. Mesonotum with mostly longitudinal rugulae. Petiolar node relatively smaller, lower and peduncle more elongate than in worker. All of lateral mesosoma densely punctate. Propodeal tooth triangular with posterior weakly convex keel.

Type Material
Holotype one of a series from Ecuador, Pichincha Prov.: 20-30 km ENE Alluriquin on road to Chiriboga, 1400-1800 m, in mossy forest, Sample B-30l, S. and J. Peck leg. Paratypes from the same country and province: Tinalandia, 16 km SE Santo Domingo de los Colorados, 680 m, sample B-300; 4 km SE Santo Domingo de los Colorados, 500 m, B-342; 3 km E Tandapi, 1300 m, litter in wet ravine, B-303, all litter-humus berlesates collected by S. and J. peck. In addition, I have 4 workers from Colombia, Depto. Choco: Finca Los Guaduales, 10 km SW San Jose del Palmar on the Rio Torito, litter of Guadua bamboos on hillside at about 800 m, C. Kugler leg.

Lattke et al. (2018) - ECUADOR. Pichincha: 20–30 km ENE Allurquin on Chiriboga Rd., VI-1975, S. & J. Peck, 1w, B-301, moss forest (holotype); Tinalandia, 16 km SE Santo Domingo de los Colorados, 9.V.1976, S. & J. Peck, 1w MCZC P-106 (paratype); Tinalandia, 16 km SE Santo Domingo de los Colorados, 680 m, no date, S. & J. Peck, 1w MCZC B-300 (paratype); 3 km E Tandapi, 1300 m, 2.VI.1975, S. & J. Peck, 1w MCZC, litter, wet ravine (paratype); 3 km E Tandapi, 1300 m, 2.VI.1975, S. & J. Peck, 2w MCZC B-303 (paratype); 3 km E Tandapi, 1300 m, VI.1975, S. & J. Peck, 1w MCZC (paratype); Tinalandia, 16 km SE Santo Domingo de los Colorados, 680 m, 1975, S. & J. Peck, 1w MCZC B-300 (paratype); Tinalandia, 16 km SE Santo Domingo de los Colorados, 4.VI.1975, S. & J. Peck, 1w MCZC (paratype); 4 km SE Santo Domingo de los Colorados, 500 m, 8.VI.1976, S. & J. Peck, 1q MCZC B-342 (paratype); 20–30 km ENE Allurquin on Chiriboga Rd., 1400–1800 m, 1975, S. & J. Peck, 1w MCZC B-301, moss forest (paratype).

References based on Global Ant Biodiversity Informatics

 * Brandao, C.R.F. 1991. Adendos ao catalogo abreviado das formigas da regiao neotropical (Hymenoptera: Formicidae). Rev. Bras. Entomol. 35: 319-412.
 * Brown W. L., Jr. 1980. Protalaridris armata species nov. Pilot Register of Zoology Card No. 37: 1-2.
 * Fernández F., E. E. Palacio, W. P. Mackay, and E. S. MacKay. 1996. Introducción al estudio de las hormigas (Hymenoptera: Formicidae) de Colombia. Pp. 349-412 in: Andrade M. G., G. Amat García, and F. Fernández. (eds.) 1996. Insectos de Colombia. Estudios escogidos. Bogotá: Academia Colombiana de Ciencias Exactas, Físicas y Naturales, 541 pp
 * Fernández, F. and S. Sendoya. 2004. Lista de las hormigas neotropicales. Biota Colombiana Volume 5, Number 1.
 * Lattke J. E., T. Delsinne, G. D. Alpert, and R. J. Guerrero. 2018. Ants of the genus Protalaridris (Hymenoptera: Formicidae), more than just deadly mandibles. European Journal of Entomology 115: 268-295.