Pseudomyrmex obtusus Ward

Ward, Philip S., 2017, A review of the Pseudomyrmex ferrugineus and Pseudomyrmex goeldii species groups: acacia-ants and relatives (Hymenoptera: Formicidae), Zootaxa 4227 (4), pp. 524-542 : 539

Pseudomyrmex obtusus Ward , sp. nov.

( Fig. 7 )

Pseudomyrmex psw001; Chomicki et al. (2015: 4).

Type material. Holotype worker. VENEZUELA Barinas: 10 km WNW Santa Barbara , 280 m, 7°51ʹS, 71°16ʹW, 29 Aug 1987, ex dead twig of thorny vine, edge of second-growth rainforest, P. S. Ward PSW09027 ( MZSP) (CASENT0794100) . Paratypes. Series of workers, 3 dealate queens, same data as holotype ( CASC, JTLC, MCZC, PSWC, UCDC, USNM).

Other material examined ( LACM, MZSP, PSWC, UCDC). BRAZIL Mato Grosso: Sinop (M. Alvarenga) ; COSTA RICA Puntarenas: Res. Biol. Carara, 500 m (J. Longino); Reserva Biol. Carara , 500 m (P. S. Ward); PANAMA Colón: Pipeline Rd. (G. G. Montgomery & Y. Lubin) ; PERU San Martín: 24 km NNE Tarapoto , 220 m (P. S. Ward) ; SURINAM Para: Zanderij I (Boven) ; VENEZUELA Barinas: 10 km WNW Santa Barbara , 280 m (P. S. Ward).

Worker measurements (n = 9). HL 0.86–0.93, HW 0.71–0.78, MFC 0.007–0.013, LHT 0.48–0.54, CI 0.80– 0.85, REL 0.63–0.66, REL2 0.75–0.81, FCI 0.010–0.017, FI 0.50–0.52, PLI 0.62–0.71, PWI 0.52–0.64.

Worker diagnosis. Larger species (HL 0.86–0.93, HW 0.71–0.78) with elongate eyes (REL 0.63–0.66) and with broader head than other species in the P. goeldii group (CI 0.80–0.85); masticatory margin of mandible with 5–6 teeth; palp formula 5,3; juncture between dorsal and declivitous faces of propodeum subangulate, and with conspicuous lateral tubercles ( Fig. 7 b); anterodorsal face of petiole ascending rapidly, often steeper than posterodorsal face ( Fig. 7 b). Front of head between eyes densely punctulate and opaque, becoming sparsely punctulate and shiny around the ocelli, then densely punctulate and opaque again at the posterior margin; mesosoma finely coriarious-imbricate and opaque; petiole, postpetiole and gaster with very fine dense pubescence, imparting a matte appearance. Standing pilosity very sparse, absent from mesosoma, petiole and postpetiole. Medium to dark brown, the petiole, postpetiole and most of gaster a contrasting light yellowish-brown; mandibles, frontoclypeal complex, tibiae and tarsi also lighter than most of body, the pronotum variably so.

Comments. Within the P. goeldii group this species is recognized by its large size (HW>0.70), broad head (CI>0.79), and dense punctulate sculpture on the front of the head. Other distinctive features are the matte appearance of most of the body and the absence of standing pilosity on the mesosoma, petiole and postpetiole.

Distribution and biology. P. obtusus is known from scattered collections from Costa Rica to Peru and Brazil. Collections with habitat information come from rainforest, rainforest edge, and ( Costa Rica) successional pasture near rainforest. I have made four nest collections: two from dead twigs of Ficus sp., one from a dead twig of a thorny vine, and one from a dead twig of an unidentified woody plant.

Figures

FIGURES 7 – 8. Pseudomyrmex goeldii group, workers, full-face dorsal view of head (a) and lateral profile of body (b). 7, P. obtusus, Venezuela (CASENT 0794100); 8, P. parvulus, Brazil (CASENT 0762994). Images from AntWeb (www. antweb. org); photographer Matthew Prebus.