Leptogenys pubiceps complex

Formicidae, Hymenoptera, Insecta, Arthropoda, Animalia


worker lateral view

worker face view

Image of petiole.

Range

Caribbean basin, Costa Rica to northern South America. Costa Rica: Atlantic lowlands.

Identification

When mandibles are in their usual resting position, with tips crossed, they project beyond anterior border of clypeus, leaving a distinct gap; mandibles slightly arched, of uniform width; clypeus reduced, leaving labrum largely exposed; hypostomal teeth reduced, barely or not visible in full-face view; eye large and convex, diameter occupying more than one-fourth the length of the lateral cephalic margin with head in frontal view; head subquadrate, not narrowed posteriorly; face smooth and shining; length of second antennal segment two-thirds length of third; dorsal and posterior faces of petiole meeting at an acute angle, forming a posteriorly directed crest or blunt tooth, generally overhanging posterior margin in lateral view, posterior node margin sinuate in lateral view; legs and scapes orange, contrasting with the dark brown head and mesosoma.

Worker metrics (n=9). HL 1.28-1.55; HW 1.21-1.42; ML 0.88-1.15; EL 0.30-0.40; SL 1.35-1.72; WL 2.19-2.63 mm. CI 0.84-0.95; MI 0.70-0.84; OI 0.24-0.29; SI 1.08-1.32.

Natural History

These ants have been collected in numerous habitats that range from dry forests to humid and cloud forests, lowland and montane, besides coffee plantations. They have been found beneath rotten logs and in leaf litter. The usual reaction of the ants upon disturbance to the nest is to rapidly flee and hide amongst the leaf litter. Longino reports 7 collections of this species from La Selva, and 2 from Tortuguero. He has observed two nests, one in dead wood on the ground, and another in the crown debris of a small “basket palm”. The latter contained isopod remains. Males have been collected from blacklight sheets, and other collections have been of stray workers on the ground.

Comments

This species complex has a distribution range restricted to the Caribbean Basin. It is found on the mainland from Heredia and Limon Provinces of Costa Rica to northern Colombia, the northern slopes of the Venezuelan Andes, the Venezuelan Coastal Range and Trinidad. It is found on both the Greater and Lesser Antilles with no records from the Bahamas nor southern Florida. Some members of this species complex could be confused with L. arcuata on account of similar Gestalt, both sharing the same general shape and with overlapping ranges in the Guianas and some of the Lesser Antilles. L. arcuata is smaller and lacks the presence of the crest or tooth on the petiolar apex and has the posterior petiolar margin usually straight to weakly sinuate in lateral view, a margin that is always strongly sinuate in the pubiceps complex. The third antennal segment is more than twice longer than wide in the pubiceps complex, whilst it is less than twice its apical width in L. arcuata. L. arcuata also has the eyes laterally placed on the head, a trait that resembles some L. pubiceps populations. The propodeal declivity in L. arcuata tends to be flat and separated from the lateral propodeal face by a relatively sharp margin, this in contrast with the blunt, curved margin which prevails in L. pubiceps.

The species in this complex have a bewildering array of morphological diversity that challenges analysis. Variations in overall size, scape length, head shape, mandibular width, color, and development of the apical petiolar process will distinguish different populations, yet when all series are taken into account there is enough crossing of characters from one population to the next to throw any sense of order into disarray. The shape of the node apex permits rough separation of two trends within this complex: one has the petiolar node topped by a very modest posterior crest, whilst the other has a distinct blunt tooth on the node apex. Samples from Grenada, Jamaica, St. Vincent, Trinidad, northern Colombia, northwestern Venezuela, Panama, and Costa Rica have a definite blunt point on the node apex. The Costa Rica specimens are rather homogenous and quite distinct on account of their broad head and particularly massive mandibles and may actually represent a distinct species, provisionally called JTL-002. There are five names associated with this complex, but none of them correspond to the Costa Rican populations. In the course of revisionary studies of the New World Leptogenys it was tempting to synonymize a series of names, as well as describing the Costa Rican, and Trinidad populations as distinct species. Nevertheless the degree of subjectivity involved in such decisions would be great, since arguments could be made for recognizing the species status of several other populations. While such action could give the illusion of order, it would also hide the obviously complex situation of many of these populations and Lattke has choosen not to make formal changes. This species complex should eventually be the subject of a thorough revision, but more material from many localities is needed before there is any hope of obtaining better resolution.

The following names are associated with this complex:

Leptogenys pubiceps Emery 1890:62 w northern Venezuela, La Guaira (MCSN) Holotype by Monotypy.

Leptogenys pubiceps var. vincentensis Forel 1901: 328 w St. Vincent, Antilles.

Leptogenys mucronata var. columbica Forel, 1901:328 w northern Colombia (MHNG).

Leptogenys pubiceps st. cubaensis Santschi,1930:76, wm, Cuba (NHMB).

Leptogenys mucronata Forel 1893:360 w St. Vincent, Antilles (MHNG).


Page authors:
John E. Lattke piquihuye@gmail.com
John T. Longino longinoj@evergreen.edu


Date of this version: 3 March 2009.
Previous versions of this page: 28 May 1999.
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