Pogonomyrmex schmitti

Wheeler and Mann (1914) reported: nests in the ground in crater nests, but sometimes also under stones. It is a harvesting ant like the other species of the genus, and like these is also fond of eating insects, for the junior author often saw workers carrying whole insects or fragments of them into the nest.

Identification
Johnson and Cover (2015) - The dorsum of the postpetiole and base of the first gastral tergum varies intranidally. These areas of a worker may be smooth and shining, show traces of fine punctures at the base, or be punctate and dull.

Worker. Small (HW = 0.90–1.17 mm); dorsum of mesosoma rugoreticulate to vermiculate; posterior surface of petiolar node viewed from behind and above broadly fan-shaped and about as wide as long; in dorsal view, petiolar node about as wide as postpetiole (PW/PPW = 0.87–1.03); anterior surface of petiolar node mostly smooth and shining, forming a noticeably obtuse angle with peduncle of petiole; dorsum of postpetiole and first gastral tergum smooth and shining to partly or completely punctate, weakly shining.

Queen. With caste-specific morphology of the mesosoma related to wing-bearing and presence of ocelli on head. Small (HW = 0.87–1.19 mm), rarely larger than conspecific workers; in dorsal view, petiolar node fan-shaped, relatively broad (width/length > 0.90), relatively broad compared to postpetiole (PW/PPW > 0.80); anterior surface of petiolar node largely smooth and shining; posterior surface of petiolar node, dorsum of postpetiole, and first gastral tergum smooth and shining to completely punctate, weakly shining.

Pogonomyrmex schmitti co-occurs with Pogonomyrmex saucius in south-central Hispaniola. The two species are easily separated as P. schmitti has a rugoreticulate-vermiculate mesosoma and the posterior surface of the petiolar node is shining to strongly punctate. In P. saucius, the dorsum and sides of the mesosoma and posterior surface of the petiolar node have wavy to weakly irregular longitudinal rugae. Pogonomyrmex aterrimus might also co-occur with P. schmitti given that the two species have been taken in proximate locales. Pogonomyrmex schmitti is separated from P. aterrimus using the following characters: (1) P. schmitti is smaller (HW = 0.90–1.17 mm), (2) in dorsal view, the petiolar node is fan-shaped and nearly as broad to slightly broader than the postpetiole (PW/PPW = 0.87–1.03), (3) the anterior surface of the petiolar node is smooth and shining, and (4) the dorsum of postpetiole and first gastral tergum are usually weakly shining to shining, not densely punctate. Workers of P. aterrimus are larger (HW = 1.11–1.35 mm), in dorsal view, the petiolar node is elongate and notably narrower than the postpetiole (PW/PPW = 0.78–0.90), the anterior surface of the petiolar node is at least partly granulate, weakly shining, and the dorsum of the postpetiole and anterior portion of first gastral tergum densely punctate, dull. Moreover, several individual characters can separate these two species, but the above suite of characters provides a much more definitive diagnosis.

Distribution based on Regional Taxon Lists
Neotropical Region: Dominican Republic, Greater Antilles, Haiti.

Biology
When foraging these ants are very fast moving and difficult to capture.

Johnson and Cover (2015) – Little is known about the biology of P. schmitti. Most collections come from coastal areas at elevations that range from 10–150 m, though Darlington collected one colony at approximately 605 m near Poste Terre Rouge (see Wheeler 1936). Pogonomyrmex schmitti has been collected in disturbed evergreen tropical dry forest, secondary semi-evergreen shrub, coastal evergreen dry forest, and urban areas, e.g., the Santo Domingo Botanical Garden.

Pogonomyrmex schmitti is the most widely distributed and most frequently collected Pogonomyrmex on Hispaniola; it occurs throughout most coastal and lower elevation areas, and it represents approximately 75% of the series examined in this study. Nest microhabitats range from full shade to open, exposed sites, and Wheeler and Mann (1914) found crater nests in the ground or sometimes under rocks. Pogonomyrmex schmitti harvests seeds and insects (Wheeler & Mann 1914), and colonies appear to contain less than 200 workers, often fewer than 50 (S.P. Cover, pers. obs.).

Little information is available relative to timing of sexual production or mating flights for P. schmitti. One alate queen was collected on 13 February (WL Brown; MCZ) and one dealate queen was collected on 27 May while sifting litter (A Clark; MCZ); this latter queen was probably a foundress from a recent mating flight. Queens of P. schmitti are unusual because of their very small size, which is similar to that of workers. All of three standard body size measurements (head width, head length, width of the pronotum) were similar to those of 35 workers (one queen was smaller than all workers for all three measures, one queen was slightly larger than all workers.

Nomenclature

 *  schmitti. Pogonomyrmex schmitti Forel, 1901e: 339 (w.) HAITI. Wheeler, W.M. & Mann, 1914: 28 (q.). Combination in P. (Ephebomyrmex): Wheeler, W.M. 1902c: 390; in Ephebomyrmex: Kempf, 1972a: 106; in Pogonomyrmex: Bolton, 1995b: 341. Senior synonym of sublaevigatus: Johnson & Cover, 2015: 244.
 * sublaevigatus. Pogonomyrmex (Ephebomyrmex) schmitti var. sublaevigatus Wheeler, W.M. & Mann, 1914: 29 (w.q.) HAITI. Combination in Ephebomyrmex: Kempf, 1972a: 106; in Pogonomyrmex: Bolton, 1995b: 341. Junior synonym of sublaevigatus: Johnson & Cover, 2015: 244.

Worker
From Wheeler and Mann (1914): Length 3.5-4 mm.

Head subrectangular, a little longer than broad, as broad in front as behind, with rather straight sides and feebly excised posterior border. Mandibles convex, with 6 subequal teeth. Clypeus short, convex; its anterior border entire and broadly rounded. Frontal area elongate, triangular. Antennre rather stout, their scapes not reaching to the posterior border of the head ; joints 2-7 of the funiculi somewhat broader than long. Thorax short and broad, but little longer than the head, with the mandibles, including the neck nearly twice as long as broad, evenly convex above in profile, without promesonotal and mesoepinotal sutures. Epinotum sloping, its base and declivity subequal, bearing two short, stout spines, which are directed backward, upward and outward and are longer than broad at their bases and shorter than their distance apart. Metasterna prolonged upward and backward into a pair of similar but somewhat shorter spines, which are slightly curved forward. Petiole from above fully twice as long as broad, with a slender peduncle occupying half its length and provided with a stout, triangular tooth on its ventral surface. The node, which is as broad as half the length of the whole segment, when seen in profile has a straight anterior surface rising at a right angle from the peduncle and half as long as the sloping posterior surface. The two surfaces meet at a sharp ridge, which, seen from above, forms the broadly rounded anterior margin of the node; its sides are straight and converge posteriorly to the postpetiole, which is broader than the petiole, a little broader than long, campanulate and provided with a large swelling on its anteroventral surface. Gaster slender, elongate-elliptical, with a powerful sting. Legs long and stout.

Mandibles and head opaque, the former and the clypeus rather finely and regularly longitudinally rugose, the head somewhat more coarsely, the rugre with reticulate-punctate spaces between them and diverging somewhat from the median line on the posterior portion of the head. Thorax still more coarsely and somewhat more irregularly and reticulately, longitudinally rugose. Petiole, postpetio􀋵e and basal third or half of first gastric segment opaque and densely punctate the posterior surface of the petiolar node also longitudinally rugulose. Posterior portion of- first gastric segment and the remaining segments shining, very superficially shagreened or reticulate, with small, sparse, piligerous punctures. Legs and scapes densely punctate, the former feebly shining, the latter opaque.

Hairs short, stiff, pointed, dark brown or blackish, moderately abundant, erect on the body, somewhat more reclinate on the legs and scapes. Gula without ammochretre.

Black; mandibles, tip of gaster, tarsi beyond the first joint and sometimes also the peduncle of the petiole, the legs and clypeus (in immature specimens?), deep red.

Johnson and Cover (2015) - Lectotype (n = 34). HL 1.12 (0.97–1.25); HW 0.97 (0.90–1.17); MOD 0.19 (0.19–0.25); OMD 0.24 (0.21–0.30); SL 0.70 (0.71–0.92); PNW 0.74 (0.65–0.90); HFL 0.93 (0.83–1.16); ML 1.30 (1.09–1.59); PW 0.42 (0.37–0.48); PPW 0.43 (0.38–0.52). Indices: SI 72.16 (68.97–88.30); CI 86.61 (88.79–99.15); OI 19.59 (17.95–24.47); HFI 95.88 (81.37–103.33).

Queen
From Wheeler and Mann (1914): Length 5.5 mm.

Closely resembling the worker, but differing in the following characters. The rugre on the mesonotum, scutellum and pleurae are more regularly longitudinal and the epinotum and posterior surface of the petiolar node are coarsely reticulaterugose. The epinotal spines are stouter and proportionally longer than the metasternal spines, and the gaster, though small, is proportionally broader than in the worker.

Johnson and Cover (2015) - (n = 4). HL 0.94–1.26; HW 0.87–1.19; MOD 0.21–0.26; OMD 0.22–0.25; SL 0.69–0.87; PNW 0.66–0.99; HFL 0..88–1.07; ML 1.29–1.80; PW 0.34–0.48; PPW 0.42–0.57. Indices: SI 71.57–79.31; CI 89.47–94.44; OI 21.62–24.14; HFI 73.95–106.90.

Etymology
Dedicated to Rev. P. J. Schmitt, O. S. B.