Baracidris

Hita Garcia, Wiesel and Fischer (2013) - The genus Baracidris is very species-poor with just three described species. The genus is restricted to the Afrotropical region (Bolton, 1981a; Fernández, 2003; Bolton, 2012). Bolton (1981a) recognised two West African species and later Fernández (2003) described a third species from Uganda and Kenya, and updated the species key from Bolton's previous work. Not much is known about the natural history of these rare ants. All three species seem to inhabit forest habitats and were mainly collected from leaf litter (Fernández, 2003).

Identification
Bolton (1981) - Among the Myrmicinae of the Ethiopian zoogeographical region Baracidris is unique in possessing 12-segmented antennae with a 2-segmented club. This character, coupled with the very closely approximated frontal lobes with the median clypeus narrowly inserted between them, the short 5-dentate mandibles, reduced palp formula of 2, 2 and the shape of the pedicel segments, renders Baracidris quickly recognizable. The genus most closely related to Baracidris is Adelomyrmex.

Baracidris - Basal border of mandibles unarmed. Maxillary palp 2-segmented. Median strip of clypeus raised into a narrow ridge; anterior clypeal margin unmodified or with a simple lobe. Hairs absent from dorsal surfaces of head and body. Postpetiole short-cylindrical in dorsal view, with a large truncated ventral process. Petiole low in profile. Metapleural lobes very large and continuous with, the propodeal teeth above. Range: West & Central Africa.

Adelomyrmex - Basal border of mandibles with a tooth at or proximal to the midlength of the border. Maxillary palp 1-segmented. Median portion of clypeus swept upwards into a strongly raised sharp-edged longitudinal platform which projects sharply forwards into a lobe; anterior clypeal margin sweeping downwards and outwards away from and behind the apex of this lobe. Hairs present on dorsal surfaces of head and body. Postpetiole not short-cylindrical in dorsal view, usually without a truncated ventral process. Petiole usually high and narrow in profile, only rarely low. Metapleural lobes small, separated from the propodeal spines above. Range: Neotropics, New Guinea, Fiji, Samoa.

Fernández (2004) created a generic group consisting of Cryptomyrmex, Adelomyrmex and Baracidris that shared the following characters: With characters of solenopsidine tribe group (Bolton, 2003:57). Mandibles with four to seven teeth in the masticatory border (Fig. 4). Basal margin of mandibles simple to armed. Internal side of mandibles with a row of 2-3 to 5-6 hairs modified as lamelliform setae. Clypeus with median longitudinal plate, ridge or strip raised (Fig. 3). A median clypeal seta usually present. Palpal formula 2,2 or less. Antennae 12 segmented, with club 2-segmented. Propodeum angulated or armed with teeth. U-shaped sulcus in the basalmost portion of the first tergum. Monomorphic.

These three genera can be separated using the following key:

1

 * Mandibles with four teeth in the masticatory border; frontal area lacking; petiolar node low; Brazil and Paraguay . . . . . Cryptomyrmex 


 * Mandibles with 5-7 teeth in the masticatory border; frontal area present, reduced; petiolar node high (Fig. 2) . . . . . 2

2
return to couplet #1
 * Clypeal lateral teeth present; basal margin of mandible with teeth and notch; hypostomal teeth present, usually small; Neotropics, New Guinea, Fiji, Samoa and New Caledonia . . . . . Adelomyrmex


 * Clypeal lateral teeth absent; basal margin of mandible without teeth; hypostomal bridge without teeth; Africa . . . . . Baracidris

Biology
The minute ants of the genus Baracidris seem to be endemic in the wet forest zones of West and Central Africa where they inhabit the leaf-litter and topsoil layers.

Worker Morphology
These characters are collated in the Worker Morphology table.

Nomenclature

 *  BARACIDRIS [Myrmicinae: Adelomyrmecini]
 * Baracidris Bolton, 1981b: 252. Type-species: Baracidris meketra, by original designation.

Worker
Minute monomorphic myrmicine ants. Mandibles narrow, the apical (masticatory) margin armed with 5 teeth which decrease in size from apical to basal, the two basal most teeth small. Basal borders of mandibles unarmed; the mandibles enclosing a space between their basal borders and the anterior clypeal margin when their apical margins are overlapping. Palp formula 2, 2, the first maxillary palpomere small (worker and queen of meketra dissected). Median portion of clypeus sharply raised centrally and in the form of a narrow longitudinal ridge which runs from the anterior margin to the frontal lobes. Anterior clypeal margin projecting medially (meketra) or in the form of a truncated lobe (sitra). Lateral portions of clypeus unmodified, not prominent not raised into a wall in front of the antennal insertions. Frontal lobes small, very closely approximated, almost touching anteriorly and separated only by the extremely narrow strip of the median clypeus which is inserted between them. The frontal lobes end immediately behind the antennal fossae; frontal carinae and antennal scrobes are absent. Antennae with 12 segments, the flagellum ending in a strong 2-segmented club of which the apical segment is much the larger. Scapes short, when laid back on the head conspicuously failing to reach the occipital margin. Eyes minute and inconspicuous, situated approximately at the midlengths of the sides of the head. Promesonotum fused and forming a single long shallow convexity in profile. Metanotal groove impressed. Propodeum short, much shorter than the promesonotum, armed with a pair of blunted, broad but short, triangular teeth. Metapleural lobes very broad and rounded, strongly prominent, linked to the propodeal teeth above by a lamella. Petiole nodiform with a short, thick anterior peduncle; in dorsal view the peduncle about as broad as the node. Postpetiole with a strongly projecting blunt or truncated ventral process in profile; cylindrical in dorsal view. Standing hairs absent from dorsal surfaces of head and body, present only on the clypeus and gastral apex.