Probolomyrmex petiolatus Weber, 1940

Oliveira, Aline M. & Feitosa, Rodrigo M., 2019, Taxonomic revision of the genus Probolomyrmex Mayr, 1901 (Hymenoptera: Formicidae: Proceratiinae) for the Neotropical Region, Zootaxa 4614 (1), pp. 61-94 : 90-91

Probolomyrmex petiolatus Weber, 1940

( Figs. 26 , 27 )

Holotype: PANAMÁ: Canal Zone : Barro Colorado Island, 30.vi.1938, N.A. Weber, 906-32203 (worker) [ MCZ] [examined].

Diagnosis: Postero-ventral lobe of petiole long and subquadrate. Subpetiolar process well developed and subrectangular. Prora and dorsal protuberance on posterior region of first gastral tergite absent.

Worker measurements: (n=3) HL 0.50–0.57; HW 0.34–0.37; SL 0.26–0.30; WL 0.63–0.69; PL 0.26–0.30; PW 0.27–0.30; PH 0.28–0.30; TL 2.13–2.33; CI 61.5–68.5; SI 51.5; PI 93.5–107.

Worker description: Frontoclypeal shelflike projection micropunctate. Mandibles foveated, interval between foveae covered by micropunctures; external surface of mandibular basal margin smooth ( Fig. 26B – esm); tip of apical segment of antennae bearing minute pits ( Fig. 26C – Ap). Mesopleuron and metapleuron alveolate and foveated; lateral faces of propodeum foveated and micropunctate; alveoli denser just above metapleural gland orifice; opening of metapleural gland narrow, with smooth anterior region, surrounded by rows of hairs ( Fig. 26D ). Petiolar node and postero-ventral lobe of petiole with incomplete foveae and micropunctures; subpetiolar process alveolate ( Fig. 26E ). Posterior region of second gastral tergite with foveae ( Fig. 26A ).

Space between mesosomal foveae covered by dense pubescence. Pygidium with dense pubescence and some long and thick hairs.

Head 1.5 times longer than wide ( Fig. 27B ). Hypostomal margin curved ( Fig. 26B – he). Antennal scapes extend head midlength, distance from scape apex to of head more than two times the pedicel length (SI 51.5). Propodeum emarginated posteriorly on each side by a narrow carina, with teeth at their apexes. Petiole as long as high (PI 93.5–107), without teeth; posterior face short, straight and smooth; postero-ventral lobe long and subquadrate; subpetiolar process well developed and subrectangular, with the postero-ventral angle acute and directed ventrally ( Fig. 26E ). First gastral segment without prora and dorsal protuberance on posterior region of tergite ( Figs 26A , 27A ).

Distribution ( Fig. 28 ): Guatemala, Mexico, and Panama.

Comments: The subrectangular shape of the subpetiolar process makes this species similar to P. dentinodis . However, the latter has a pair of petiolar teeth, the postero-ventral lobe of the petiole is short and rounded, and there are a prora and dorsal protuberance on the gaster. The holotype of P. petiolatus was collected among leaves and humus on the rainforest floor in Panama. There is a Brazilian record in the literature for this species ( Delabie et al. 2001), but these are described here as a new species, P. dentinodis .

Additional material examined (n=11): GUATEMALA: Petén: Parq. Nac. Tikal, 17.24037 - 89.61990, 270m, 22.v.2009, LLAMA, #Wa-B- 05-2-47 CASENT0610407 (1 worker) [ JTLC] . MEXICO: Chiapas: 8km SE Salto de Agua , 17.51438° N 92.29498° W 70m, 14.vi.2008, LLAMA, Wa-A- 08-1-04 JTLC000014514 (1 worker) [ JTLC] . PANAMA: Canal Zone: Barro Colorado Island: LN 9°9’ LW 079°51’ 20-50m, v-viii.2007, J.Z.Shik, Mekou 064252 (1 worker) [ DZUP]; Mekou 063866 (2 workers) [ MZSP]; Mekou 063803 (3 workers) [ MZSP]; 1.vi.1983, L.A Mound, CASENT0102222 (1 worker) [ BMNH]; 30.vi.1938, A. Newton, Leaf litter forest floor (1 worker) [ MCZ] .

Figures

FIGURE 26. SEM micrography of Probolomyrmex petiolatus (worker - CASENT0610407). A. Habitus. B. Mandibles (he = hypostomal margin; esm = external surface of basal region of mandible). C. Antenna (ap = antennal pit; lah = long appressed hair; sh = short hair). D. Metapleural gland. E. Petiole (pil = postero-inferior lobe of petiole; sp = subpetiolar process).

FIGURE 27. Probolomyrmex petiolatus (worker - JTLC00014514). A. Habitus. B. head in frontal view. C. dorsal view.

FIGURE 28. Distribution map for the Neotropical species of Probolomyrmex.