Eusphinctus

Eusphinctus is a species-poor South East Asian genus with apparently small colonies.

Identification
Diagnosis. Worker. Eusphinctus workers belong to dorylines with conspicuous gastral constrictions visible between abdominal segments IV, V, and VI. This morphology is also seen in Aenictogiton, certain species of Leptanilloides, Sphinctomyrmex, and Zasphinctus. Eusphinctus is unique in the combination of propodeal spiracle situated low on the sclerite and propodeal lobes present, a large pygidium armed with modified setae, pronotomesopleural suture present, and cinctus of abdominal segment IV simple and not cross-ribbed. This genus is thus far known only from India, Bangladesh, Myanmar, and Thailand and the only lineage with gastral constriction that is currently known to overlap with it is Zasphinctus. In Zasphinctus the pronotomesopleural suture is fused, in Aenictogiton the propodeal spiracle is positioned high and there are no propodeal lobes, Leptanilloides has a reduced and unarmed pygidium, and the neotropical Sphinctomyrmex has 12-segmented antennae and the cinctus on abdominal segment IV smooth. The relative proportions of abdominal segments are also different, with segments IV, V, and VI being about equal in size in Sphinctomyrmex and Zasphinctus, while in Eusphinctus segment IV is the largest of the three.

Distribution
Indomalayan, known from India, Bangladesh, Myanmar, and Thailand.

Species richness
Species richness by country based on regional taxon lists (countries with darker colours are more species-rich). View Data



Biology
A. B. Soans and W. L. Brown collected two colonies of E. furcatus in Kottiyoor, Kerala, India. One was located in leaf litter near a rotting log and the other one was found under a stone in a shaded creek bottom. There were about 50 workers in each of the observed nests, and one colony contained two ergatoid gynes (Brown 1975).

Nomenclature

 *  EUSPHINCTUS  [Dorlyinae]
 * Eusphinctus Emery, 1893a: cclxxv. Type-species: Eusphinctus furcatus, by monotypy.
 * Eusphinctus subgenus of Sphinctomyrmex: Emery, 1895k: 456.
 * Eusphinctus revived status as genus: Wheeler, W.M. 1918a: 219.
 * Eusphinctus junior synonym of Sphinctomyrmex: Brown, 1975: 31.
 * Eusphinctus as genus: Borowiec, 2016: 138.