Lachnomyrmex platynodus Feitosa & Brandão, 2008

Feitosa, Rodrigo M. & Brandão, Carlos Roberto F., 2008, A taxonomic revision of the Neotropical myrmicine ant genus Lachnomyrmex Wheeler (Hymenoptera: Formicidae), Zootaxa 1890, pp. 1-49 : 34

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).

Figures

FIGURE 13. Holotype worker of Lachnomyrmex platynodus from Mt. Ayanganna, Guyana: A, head in full face view; B, lateral view; C, dorsal view. Image by Michele Esposito, specimen CASENT 0173881.

FIGURE 18. Distribution maps for the Lachnomyrmex species (L. fernandezi, L. grandis, L. laticeps, L. lattkei, L. longinoi, L. pilosus, and L. platynodus).