Lachnomyrmex grandis Fernández & Baena, 1997

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 : 15-17

Lachnomyrmex grandis Fernández & Baena, 1997

Figures 4 , 18

Lachnomyrmex grandis Fernández & Baena, 1997: 111 , fig. 2. Holotype worker, Colombia: Nariño, Barbacoas, Berlín, El Diviso, 520m, 22.viii.1994, F. Escobar col., no. 277 [ICNC] (examined); Paratype worker, same data as holotype, no. 294 [MCZC] (not examined).

Worker diagnosis. Comparatively large species (HW ≥ 0.90mm, WL ≥ 1.20mm); metanotal groove broadly impressed; first tergite of gaster with extremely long hairs.

Holotype measurements. HL 0.96; HW 0.91; ML 0.38; SL 0.69; EL 0.16; WL 1.28; PSL 0.32; PL 0.49; PPL 0.25; GL 1.18; TL 4.54; CI 95; SI 76; OI 18.

Worker measurements. HL 0.94; HW 0.91; ML 0.35; SL 0.69; EL 0.17; WL 1.26; PSL 0.30; PL 0.49; PPL 0.25; GL 1.06; TL 4.35; CI 96; SI 75; OI 19.

Gyne measurements. HL 1.04; HW 0.99; ML 0.41; SL 0.72; EL 0.26; WL 1.51; PSL 0.32; PP 0.63; PPL 0.31; GL 1.52; TL 5.43; CI 95; SI 73; OI 26.

Worker description. Color light to dark reddish brown, with lighter appendages. Body densely covered by vermiculate rugae, forming irregular areolae on promesonotum; rugae somewhat longer and longitudinal on cephalic dorsum, and slightly sparser on mesopleura and lateral surfaces of propodeum; mandibles longitudinally striate, except for the apical and masticatory portions; petiole and postpetiole irregularly rugose. Abundant pilosity; dorsum of petiolar node and postpetiole each with more than 10 long hairs; first gastral tergite bearing extremely long flexuous hairs.

Head longer than broad, with vertexal margin weakly convex; frontal lobes subquadrate; eyes well developed, with about seven facets on maximum diameter. Promesonotum moderately convex in profile; metanotal groove broadly impressed; propodeal spines long and straight; teeth of propodeal lobes well developed, but not surpassing the half-length of propodeal spines. Petiolar node elevated, almost subtriangular in profile, but dorsally rounded, and with the posterior face gently sloped in lateral view; postpetiole dorsally convex and with a discrete anteroventral projection.

Gyne (first description). Similar to worker. Head and pronotum strongly areolate-rugose; mesopleura and lateral faces of propodeum longitudinally rugose. Eyes with around 16 facets at maximum diameter. Propodeal spines shorter than in the conspecific workers. Petiolar node relatively low (see picture in the “Ants of Costa Rica ” website).

Etymology. The name refers to the relative large size of this species. From Latin, grandis : large.

Comments. Lachnomyrmex grandis is the largest species known for the genus. Besides its size, this species can be separated from the others by the combination of irregular sculpture, metanotal groove broadly impressed, and the presence of very long hairs on the gaster. In some individuals, long hairs occur only on the anterior third, while in other specimens they cover nearly entirely the surface of first gastral tergite.

This species was known previously only by the type series (two workers from Colombia). The study of Costa Rican material revealed new records of this rarely collected species. The presence of this species in Costa Rica and Colombia, suggests that it may probably occur in Panama.

According to the original description, the Colombian specimens were collected manually while foraging in the vegetation of a 520m elevation wet forest. The Costa Rica material was extracted from sifted litter samples from Atlantic slope to 500m elevation forests ( Longino 2007).

Additional material examined. COSTA RICA: Heredia: 11km SE La Virgen, 450–550m, 10º20’N 84º04’W, 19.iv.2003, no. INBIOCRI003605521 (1 gyne) [ INBC]; same data, no. INBIOCRI003605522 (1 worker) [ MZSP]; La Selva Biological Station, SCH, 10º43’N 84º01’W, 18.vi.1999, R. Vargas col., no. INBIOCRI002720565 (1 worker) [ INBC].

Figures

FIGURE 4. Worker of Lachnomyrmex grandis from Heredia, Costa Rica: A, head in full face view; B, lateral view; C, dorsal view. Image by John Longino, specimen INBIOCRI 002720565.

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