Lachnomyrmex regularis 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 : 38-40

Lachnomyrmex regularis Feitosa & Brandão , new species

Figures 15 , 19

Holotype worker. COSTA RICA: Guanacaste: Estr. Pitilla, 9km S Sta. Cecília, 11º04'N 85º24'O, 6– 19.viii.1993, P. Ríos col., no. INBIOCRI001613693 [ INBC].

Paratypes. same data as holotype; no. INBIOCRI001613661 (1 worker) [ BMNH]; same data, nos. INBIOCRI001613662/INBIOCRI001613666/INBIOCRI001613673/INBIOCRI001613676 (4 workers) [ INBC]; same data, nos. INBIOCRI001613677/INBIOCRI001613681 (2 workers) [ MZSP].

Worker diagnosis. Body densely covered by fine and continuous rugae; eyes well developed, with about 10 facets at maximum diameter; dorsum of postpetiole entirely smooth and shining, bearing around four long hairs; gaster distinctly darker than body and with the first tergite completely devoid of long flexuous hairs.

Holotype measurements. HL 0.84; HW 0.79; ML 0.29; SL 0.55; EL 0.20; WL 0.98; PSL 0.30; PL 0.39; PPL 0.20; GL 1.02; TL 3.73; CI 93; SI 70; OI 26.

Worker measurements (n=7). HL 0.82–0.90; HW 0.76–0.83; ML 0.25–0.31; SL 0.53–0.58; EL 0.19– 0.22; WL 0.98–1.09; PSL 0.27–0.31; PL 0.38–0.47; PPL 0.17–0.24; GL 0.96–1.10; TL 3.57–4.11; CI 91–93; SI 69–71; OI 25–28.

Worker description. Color light reddish-brown to dark brown, contrasting with blackish gaster; appendages slightly lighter than body. Head and mesosoma densely covered by continuous, fine rugae, transverse on anterior portion of pronotum, grading to longitudinal on rest of promesonotum, mesopleura, and propodeum; rugae on cephalic dorsum subparallel and exceptionally dense, leaving no spaces among them; mandibles with short longitudinal striae restricted to basal portion; petiole and postpetiole only feebly rugose on lateral faces. Abundant pilosity on head and dorsum of promesonotum; dorsum of petiolar node and postpetiole with about six and four long hairs, respectively; first tergite of gaster entirely devoid of long flexuous hairs.

Head noticeable longer than broad, with vertexal margin weakly convex; frontal lobes somewhat angulate laterally; eyes relatively large, with around 10 facets at greatest diameter. Promesonotum considerably convex in profile, well above propodeum level; metanotal groove relatively narrow and markedly impressed; propodeal spines straight and relatively long; teeth of propodeal lobes widen basally, with about one-third of propodeal spines length. Petiolar node strongly elevated and subtriangular in lateral view; dorsum of postpetiole with a raised prominence medially and a well developed anteroventral projection directed anteriorly.

Gyne. Unknown.

Etymology. This species is named after its regular pattern of body sculpturation in comparison with other Lachnomyrmex species. From Latin, regularis : regular.

Comments. The sculpturation pattern and the presence of a subpostpetiolar projection are similar to L. haskinsi . However, L. regularis is easily distinguishable by its larger body size, rugae on head dorsum distinctly denser, eyes more developed, postpetiole dorsum entirely smooth, and body color variably brown contrasting with darker gaster.

The only collection of L. regularis so far was made in northern Costa Rica, at 700m elevation. There is no information on the biology of this species.

Figures

FIGURE 15. Holotype worker of Lachnomyrmex regularis from Guanacaste, Costa Rica: A, head in full face view; B, lateral view; C, dorsal view. Image by Michele Esposito, specimen INBIOCRI 001613693.

FIGURE 19. Distribution maps for the Lachnomyrmex species (L. haskinsi, L. mackayi, L. nordestinus, L. plaumanni, L. regularis, and L. scrobiculatus).