Pogonomyrmex schmitti Forel 1901

Johnson, Robert A. & Cover, Stefan P., 2015, A taxonomic revision of the seed-harvester ant genus Pogonomyrmex (Hymenoptera: Formicidae) on Hispaniola, Zootaxa 3972 (2), pp. 231-249 : 244-247

Pogonomyrmex schmitti Forel 1901

( Figures 9–10 )

Pogonomyrmex schmitti Forel, 1901: 339 , fig. 9 (worker); Olsen, 1934: plate 8, fig. 1. Syntypes examined: 1 worker [MCZ], 1 worker [MHNG], 1 worker [NMW]; HAITI—no additional locale data given (P.J. Schmitt leg.) (NMW worker here designated LECTOTYPE [CASENT0173356]).

Pogonomyrmex (Ephebomyrmex) schmitti Forel ; Wheeler, 1902: 390. First combination in P. ( Ephebomyrmex ); Wheeler & Mann, 1914: 29, fig. 9 (queen).

Ephebomyrmex schmitti (Forel) : Kempf, 1972: 106. First combination in Ephebomyrmex .

Pogonomyrmex schmitti Forel ; Bolton, 1995: 341. Revived combination in Pogonomyrmex .

Pogonomyrmex (Ephebomyrmex) schmitti var. sublaevigatus Wheeler & Mann, 1914: 29 (worker, queen). Syntypes examined: 4 workers [MCZ], HAITI, Ennery; 9 workers [AMNH], 2 workers, 1 dealate queen [USNM], Manneville (MCZ worker here designated LECTOTYPE [ANTWEB1008774]). NEW SYNONOMY

Pogonomyrmex (Ephebomyrmex) schmitti sublaevigatus Wheeler & Mann ; Wheeler, 1936; 197. Raised to subspecies.

Ephebomyrmex schmitti sublaevigatus (Wheeler & Mann) ; Kempf, 1972: 106. First combination in Ephebomyrmex .

Pogonomyrmex schmitti sublaevigatus Wheeler & Mann ; Bolton, 1995: 341. Revived combination in Pogonomyrmex .

Worker. Diagnosis. 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 ( Figure 9 ).

Measurements. 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. Diagnosis. 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 ( Figure 4 A); 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 ( Figure 10 ).

Measurements (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.

Male. Unknown.

Additional material examined. DOMINICAN REPUBLIC: La Altagracia: 1 km NW Boca de Yuma, Feb 13, 1975 (WL & DE Brown; MCZ); 3 km NW Boca de Yuma, Feb 13, 1975 (WL & DE Brown; LACM, MCZ); 3 km S El Macao, Feb 14, 1975 (WL & DE Brown; MCZ, LACM); Punta Cana, Indigenous Eyes Nature Preserve, 30’, Mar 24, 2002 (SP Cover; MCZ, RAJC); Parque Nacional del Este, Caseta de Guaraguoa, 30’, Mar 30, 2004 (SP Cover; MCZ, RAJC); Parque Nacional del Este, Boca de Yuma, 60’, Apr 3, 2004 (SP Cover; MCZ); Parque Nacional del Este, Punta Cana, 140’, Mar 25, 2002 (SP Cover; MCZ). Le Vega: Constanza, 3,000–4,000’, Aug 1938 (PJ Darlington; MCZ). Monte Cristi: Villa Elisa, Dec 8, 2003 (M Deyrup; MCZ); 1.6 mi N Villa Elisa, 150 m, Dec 8, 2003 (G Alpert; MCZ, RAJC); Parque Nacional Monte Cristi, 20 m, Dec 8, 2003 (SP Cover, L Davis, M Deyrup; CAS, LACM, MCZ); Monte Cristi, May 2 & Jun 1–2, 2008 (A Clark; MCZ). Pedernales: Pedernales, May 27, 2008 (A Clark; MCZ). Santiago: Foothills Cordillera Central, south of Santiago, Jun 1938 (PJ Darlington; MCZ); Parque Nacional Jaragua, 5–166 m, Mar 29–31, 2012 (D Lubertazzi; MCZ); Parque Nacional Jaragua, 400 m, Mar 27, 2014 (D Lubertazzi; MCZ). Santo Domingo: Santo Domingo Botanical Garden, 54 m, Dec 9, 2003 (L Davis, M Deyrup; MCZ). Valverde: Parque Nacional Monte Cristi, 20 m, Dec 8, 2003 (SP Cover; MCZ: G Alpert; MCZ, RAJC). HAITI. Centre: Poste Terre Rouge, Oct 5, 1934 (PJ Darlington; MCZ)(reported as Port Terre Rouge by Wheeler, 1936). Nord: Cap-Haitien, no date (WM Mann; LACM, MCZ, NHMG). Quest: Diquini, no date (WM Mann; AMNH, LACM, NHMG); Manneville, Nov 16–17, 1934 (PJ Darlington; MCZ: WM Mann; LACM, USNM); Monace, no date (WM Mann; USNM), Petionville, no date (WM Mann; USNM), Port-au-Prince, no date (G Keitel; MHNG, USNM: WM Mann; AMNH, USNM: KWC; USNM).

Etymology. This species was named after Rev. P.J. Schmitt, who collected the syntype series of workers.

Discussion and biology. Pogonomyrmex schmitti co-occurs with P. 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) ( Figure 4 C), 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 ( Figure 1 ). Moreover, several individual characters can separate these two species, but the above suite of characters provides a much more definitive diagnosis.

Pogonomyrmex schmitti subsp. sublaevigatus was described as differing from P. schmitti subsp. schmitti because the dorsum of the postpetiole and base of the first gastral tergum were smooth and shining or with only traces of fine punctures at the base, whereas both areas are punctate and dull in typical P. schmitti . We examined large series of workers, and found that these characters vary intranidally, from workers with the dorsum of the postpetiole and the first gastral tergum smooth and shining to those in which both areas were punctate and dull. Thus, we synonomize P. schmitti subsp. laevigatus under P. schmitti .

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; Figure 4 A).

Figures

FIGURE 1. Photograph of Pogonomyrmex aterrimus Wheeler lectotype worker: (A) frontal view of head, (B) lateral view of body, and (C) dorsal view of body (CASENT 0217240). Photographs by Erin Prado from www. antweb. org.

FIGURE 4. Bivariate plots for workers and queens of Pogonomyrmex aterrimus, Pogonomyrmex “ darlingtoni ”, and Pogonomyrmex schmitti: (A) head width versus head length, (B) head width versus maximum length of hind femur, and (C) head width versus the ratio of maximal petiolar node width / maximal postpetiole width. Sample size for each caste is in parentheses.

FIGURE 9. Photograph of Pogonomyrmex schmitti Forel worker: (A) frontal view of head, (B) lateral view of body, and (C) dorsal view of body (CASENT 0103066). Photographs by April Nobile from www. antweb. org.

FIGURE 10. Photograph of Pogonomyrmex schmitti Forel alate queen: (A) frontal view of head, (B) lateral view of body, and (C) dorsal view of body (CASENT 0217246). Photographs by Erin Prado from www. antweb. org.