Carebara lignata species complex

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Based on Fernandez 2004.

Species

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Diagnosis

Workers Monomorphic and dimorphic. The minor workers very small; the major workers with massive heads (sometimes with ocellae and/or eyes) and more larger than workers. Dinergatogynes sometimes present. Antennae 9 segmented with club 2-segmented. Mandibles with 4 or 5 teeth. Eyes always absent in minor workers. Setation pattern in minor worker: Two to four standing hairs in the head, near to occipital margin, four in the anterior margin of pronotum, two to four in the propodeum (C. anophthalma secondarily naked). Metanotal groove developed. Propodeum unarmed. Propodeal spiracle large and round. Propodeal lobes small, continued up as lamelated carinae.

Queens Strongly larger than workers. Antennae 10 segmented, the apical segments thicker than basal segments. Palps 3,2. Basal segment of the maxillary palp elongated laterally. Mandibles with 4-6 teeth. Propodeum rounded. Postpetiole very broadly attached to the gaster. Marginal cell closed.

Males Scape short, shorter than each flagelomere. Clypeal median area semiglobular. Notauli absent, parapsidial furrows distinct. Genitalia “prominently exserted; parameres massive, semicircular in section, subtriangular in side view, curving in to meet on the midline; tenth tergite and ninth sternite produced to cover the bases of the parameres; digit long, narrow, flattened; aedeagus small, not serrate ventrally” (Ettershank 1966).

Notes

This is probably an artificial grouping. It is created for convenience in treating the American species with 9-segmented antennae and whose minor workers are eyeless. Analysis of Old World species might better define the limits of this complex. The majority of the species known for it are characterized by large females in contrast with very small workers (Wilson 1971). Nevertheless, Wheeler (1925) drew attention to the existence of both major workers and tiny, eyeless minor workers in C. panamensis. Kusnezov (1951) also pointed out the association of major workers (although in this case dinergatogyne) with tiny workers. I describe 2 species that are more dimorphic (although minor workers of C. tenua have not been found) and there is still a possibility that several of the species normally placed in Carebara, on the basis of just the minor workers, might also have major workers that are either rarely collected or not associated with the minor workers.

In an early draft of this manuscript I proposed keys to separate the species known as the Carebara lignata complex. The recent arrival of new material has shown, though, that there are still more species to describe, or that some of those already described are more variable than at first apparent. I have thus decided to postpone a key until I have been able to examine more material (especially from Central America) and resolve species limits. Although the minute ants of this group are highly homogeneous, a good sample size might allow better definition of some species. Arrangement patterns of erect hairs, the metanotal groove, the metapleural sculpture, and the shape and size of the postpetiole are traits that may help define species. The user can meanwhile read the diagnoses and comments for each species in attempting to identify samples on hand.

References