Lachnomyrmex platynodus Feitosa & Brandao, new species

Lachnomyrmex platynodus Feitosa & Brandão, new species

Figures 13, 18

Holotype worker. GUYANA: Guyana Esequiba: Mt. Ayanganna, 5º 22.483N 59º 57.969W, 13.x.2002, T.R. Schultz, J. Lapolla, C. Marshall & R. Williams cols, no. 413878, specimen code CASENT0173881 [USNM].

Worker diagnosis. Body predominantly blackish and irregularly rugose; promesonotum strongly convex and elevated well above propodeum level; metanotal suture obsolete; teeth of propodeal spines relatively thin; petiolar node dorsally flat, without a posterior slope; postpetiolar dorsum only minimally convex and mostly smooth; first tergite of gaster with around five long flexuous hairs.

Holotype measurements. HL 0.72; HW 0.72; ML 0.22; SL 0.46; EL 0.14; WL 0.87; PSL 0.16; PL 0.35; PPL 0.19; GL 0.94; TL 3.28; CI 101; SI 63; OI 19.

Worker description. Color predominantly black, with ferruginous reflections, appendages dark brown. Body covered by vermiculate, relatively sparse short rugae, forming irregular areolae on promesonotum; rugae somewhat longer and longitudinal on head dorsum, and slightly sparser on mesopleura and lateral surfaces of propodeum; mandibles with longitudinal striae barely visible and almost reaching the masticatory margin; lateral faces of petiole and postpetiole irregularly rugose; dorsum of petiolar node and postpetiole predominantly smooth, with a few short, fine irregular rugae. Abundant pilosity, except by dorsal surface of propodeum; dorsum of petiolar node and postpetiole each with more than 10 long hairs; first gastral tergite with around five long, sparse flexuous hairs.

Head as long as broad, with vertexal margin virtually flat; frontal lobes subquadrate; eyes with approximately five facets on maximum diameter. Promesonotum strongly convex in profile, elevated well above the propodeum level; metanotal groove obsolete, so that the promesonotum outline reaches the propodeum in a slight declivity; propodeal spines straight; teeth of propodeal lobes relatively thin, slightly surpassing propodeal spines half-length. In lateral view, petiolar node moderately elevated and flat, without a posterior slope; postpetiole somewhat elongate and only weakly convex, with sternite feebly projected.

Gyne. Unknown.

Etymology. This is species is named after its flat petiolar node. From Greek, platy: flat and from Latin, nodus: node.

Comments. This species is known only by the holotype; however, it is unlikely to be confounded with any other congener. The combination of blackish color, dorsum of waist predominantly smooth, petiolar node flat, and first gastral tergite with a few sparse hairs is unique in the genus.

The only individual known for Lachnomyrmex platynodus was collected in a leaf litter sample from a submontane wet forest (1300m) at Mt. Ayanganna, Guyana. A high ant endemicity at Mt. Ayanganna is indicated by taxonomic and survey studies (LaPolla 2004; LaPolla et al. 2006).