Adelomyrmex robustus

Adelomyrmex robustus occurs in mature cloud forest habitats, most often from 1600–1900 m elevation. It can be very abundant, occurring in over 90% of quantitative miniWinkler samples and being frequent at baits on the forest floor. It even appears to forage on low vegetation, occasionally occurring in beating samples. In many sites it is sympatric with Adelomyrmex paratristani, which can also be abundant, and two can be difficult to distinguish in samples. Project LLAMA participant D. J. Cox observed multiple nests in dead wood at a site in Chiapas. Nests of both A. robustus and Adelomyrmex paratristani'' were found in a single dead gall that contained several chambers. In other cases nests were found in close proximity to Perissomyrmex snyderi nests, in the same piece of rotten wood. Nests occurred with brood dispersed in multiple chambers.

Identification
This species can be differentiated from most Adelomyrmex by its size (HW equal or greater than 0.83 mm), tooth of the basal margin robust, as big or bigger than the third tooth of the masticatory margin, sculpturing formed by irregular rugulae mixed with conspicuous piliferous punctures. The propodeal spines are low and triangular. There is uniformity in size and other characteristics in the samples examined, all from Chiapas, Mexico. The workers of this species might be confused with large workers of Adelomyrmex tristani, although there are differences, as pointed out in the previous discussion of this species.

The queens can be differentiated, in addition to the characters already mentioned for the worker, by a single small, inconspicuous ocelli. The striation of the promesonotum is almost complete, with the smooth and shiny area small. The petiole seems to have a ventral anterior swelling.

Key to Adelomyrmex of the New World mainland

Distribution
Southern Mexico, Guatemala.

Distribution based on Regional Taxon Lists
Neotropical Region: Guatemala, Mexico.

Castes
Males have yet to be collected.

Nomenclature

 *  robustus. Adelomyrmex robustus Fernández, 2003b: 26, figs. 4-6, 25-30, 72 (w.q.) MEXICO.

Worker
Holotype (Paratypes, n=10). HL 0.98 (0.93–0.96) HW 0.88 (0.83-0.88) SL 0.61 (0.59-0.64) EL 0.09 (0.10-0.13) WL 0.93 (0.91-0.95) GL 1.08 (1.09-1.13) TL 3.76 (3.59-3.70) CI 90 (89-90) SI 70 (71-73).

Head wider posteriorly. Mandibles with 5 stout teeth, the 3 apical bigger. Clypeal teeth and tooth of basal margin stout, size about medial masticatory teeth. Eyes moderate, with about 20 ommatidia. Hypostomal tooth very small. Promesonotum evenly convex. Propodeum armed with two spines small, pointed. Node of petiole thick, rounded above. Mandibles dorsally with strong longitudinal rugulations. Head frons longitudinally with rugulate, several rugulae irregular, meshed with notable piliferous punctures. Promesonotal dorsum with longitudinal coarse rugulae in the center, the rugulae more irregular in the periphery and with notable foveae. Petiole and postpetiole transversely rugulated. Legs and gaster smooth and shining. Hairs on the promesonotum very long, about 0.25 mm. Body black, appendages dark brown, tarsi yellowish.

Queen
Measurements: HL 0.98 HW 0.91 SL 0.63 EL 0.16 WL 1.03 GL 1.29 TL 4.09 CI 93 SI 69.

As worker, with the modifications typical of myrmicine queens.

Type Material
Holotype worker: MEXICO: Chiapas, 8 mi N Pueblo Nuevo, Solistahuacán, 6000 feet, 26–27.viii.1973, leaf litter forestry floor, A. Newton leg. No. 12a (Deposited in ).

Paratype workers: MEXICO: 36 w, 9 q, Chiapas, 2.1 km NW Pueblo Nuevo, Solistahuacán, Yerbabuena Preserve, 2100 m, in liquid amber forest litter, 23.ix.1992, R.S. Andersen No. 92-114; 20 w, Chiapas, 8 mi Pueblo Nuevo, Solistahuacán, 26.viii.1973; 3 w, 1 q, Chiapas, Tapalapa, 12 km N Capilla, 13.iii.1994, R. Jones HR 4; 3 w, Chiapas, 5 km E Rayón, 1700 m, 23.xii.1991, P.S. Ward No. 11581-8 (PSW). Twenty six paratypes deposited in, 17 paratypes deposited in , 22 paratypes deposited in CEPLAC, , , , , IEXM, , , , , ,.