Adelomyrmex mackayi

This species is now known from one area in north central Chiapas and two sites in central Guatemala. The three sites are high montane cloud forest between 1900 and 2100 m elevation. It is clearly a high elevation specialist. At Biotopo El Quetzal in Guatemala, the cloud forest on the slopes around 1700 m were dominated by Adelomyrmex robustus and Adelomyrmex paratristani. Adelomyrmex mackayi was only found by hiking up to the ridge crests at 2000 m. Adelomyrmex mackayi is in danger of mountain-top extinction resulting from climate change. (Longino 2012)

Identification
Adelomyrmex mackayi is immediately recognizable by being sharply bicolored, with dark head and mesosoma and light yellow brown gaster. Such sharply contrasting coloration is unique in the genus. (Longino 2012)

Key to Adelomyrmex of the New World mainland

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

Castes
Males have yet to be collected.

Nomenclature

 *  mackayi. Adelomyrmex mackayi Fernández, 2003b: 22 (w.) MEXICO.

Worker
Measurements. Holotype. HL 0.69 HW 0.59 SL 0.43 EL 0.06 WL 0.66 GL 0.84 TL 2.78 CI 86 SI 73.

Mandibles with 5 teeth decreasing in size from apical teeth. Clypeal carinae not prolongued into frontal carinae. Eyes small, with approximately 5–6 ommatidia. Hypostomal tooth small, sharp pointed. Promesonotum evenly convex. Metanotal groove deep, distinct. Propodeal spines short, notably wider than higher. Head, pronotum and mesonotum coarsely reticulate-rugose. Transverse rugae between propodeal spines. Petiole and postpetiole smooth and shining with a few carinae in the sides. Mandibles smooth with longitudinal rugae feebly marked on outer half. Mandibles, legs and gaster smooth and shining. Hairs yellowish, long and flexuous on the body, more short and appressed on antennae and legs. Body brown, antennae, legs and gaster brown-yellowish.

Queen
Longino (2012) - Similar to worker except for queen-specific characters of large compound eyes, ocelli, and enlarged mesosoma with queen-typical sclerites; pronotum smooth medially, reticulate rugose laterally; dorsal mesonotum smooth and shining anteriorly and on median strip, longitudinally rugulose posterolaterally; scutellum longitudinally rugose; katepisternum smooth and shining; anepisternum smooth ventrally, rugose dorsally; side of propodeum rugose.

Type Material
Holotype worker: MEXICO: Chiapas, 2.1 km NW Pueblo Nuevo, Solistahuacán, Yerbabuena preserve, 2070 m, 23.ix.1992, R.S. Anderson No. 92-114 (Deposited in ).