Myrmelachista gagates

A Hispaniola endemic described from a single worker collected in La Visite, Haiti in 1934. A second worker was collected from litter in a deciduous transitional forest, at 1190 m at Los Arroyos, Dominican Republic in 2014. The location is adjacent to the Haitian border and ~ 60 km from the type locality.

Identification
Similar to the Cuban species Myrmelachista rogeri. The only Formicinae with nine antennal segments are Brachymyrmex and Myrmelachista. The latter has a three segmented antennal club. There are two species of this genus known from Hispaniola, gagates and Myrmelachista ramulorum; gagates is distinctive in its smooth jet black body and rectangular shaped head.

Distribution based on Regional Taxon Lists
Neotropical Region: Greater Antilles, Haiti.

Nomenclature

 *  gagates. Myrmelachista gagates Wheeler, W.M. 1936b: 204 (w.) HAITI.

Worker
Length 1.7 mm.

Very similar to Myrmelachista rogeri Ern. Andre of Cuba, but differing in the shape of the head, thorax and petiole, in color and pilosity. Head larger and more sharply rectangular, less narrowed in front, where it is as broad as behind. Eyes larger. Promesonotum longer and somewhat less convex above, epinotum proportionally longer and broader. Petiolar scale decidedly thicker, with convex anterior surface and very sharp superior border, which is more deeply and more angularly excised than in rogeri.

Very smooth and shining, like rogeri, with similar pilosity, but the hairs on the gaster less numerous and longer. Jet black; antennae and mandibles dark brown, scapes darker and more blackish, their tips and the basal funicular joints yellowish brown; femora black; tibiae very dark brown, paler at their bases and tips; tarsi and tibial spurs brownish yellow; last tarsal joint of each leg blackish.

Type Locality Information
Described from a single specimen taken by Dr. Darlington at La Visite, 6000-7000 ft., Haiti.