SUBFAMILY MYRMICINAE - Genus Oligomyrmex
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The Ants of
Africa SUBFAMILY MYRMICINAE - Genus Oligomyrmex |
| Contents - Myrmicinae - Carebara sensu Fernandez - Introduction |
In Tribe PHEIDOLOGETONINI. Genus in need of revision, although some examination was made by Ettershank (1966).
Diagnostic Features - Dimorphic, major workers with massive heads. Median portion of clypeus longitudinally bicarinate. Antennae 9-, 10- or 11-segmented, with a 2-segmented club. Eyes present but small. Promesonotal suture absent, metanotal groove impressed. Propodeum armed with a pair of teeth or at least sharply angulate. Yellow to deep brown.
Now [November 2007] regarded by Fernández (2004) as in the genus Carebara
.
African subgenera Aeromyrma Forel (1891b: 198; subgenus status by Emery, 1915c: 59); Aneleus Emery (1900c: 327 as subgenus of Pheidologeton; raised to genus by Emery, 1914a: 41; senior synonymy of Sporocleptes, by Consani,1951: 169); Crateropsis (Patrizi, 1948: 174); and, Nimbamyrma (Bernard, 1953b: 240).
Mayr's (1867a) genus definition and description of the type specimen, a queen of O.
concinnus, with 9-segmented antennae, is at 
; the workers and male remain unknown. He likened the general form of the queen to that of a Solenopsis, i.e. with a rectangular or sub-rectangular head in full face view [S. fugax was well known to him; S. geminata & S. molesta also were known at that time], and gave the size as TL 4 mm
Forel's (1891b) definition of Aeromyrma,
with 11-segmented antennae, is at 
and 
. Emery's (1900c) definition of Aneleus,
with 11-segmented antennae, is at 
. Patrizi's (1948) definition of Crateropsis
is at 
. Bernard's (1952) definition of Nimbamyrma
is at 
.
Bolton (1995) did not maintain any subgenera, attributing synonymisation to Ettershank (1966). The latter described examining Malpighian tubules from three undetermined species from Ivory Coast and synonymised several former genera. However, he appears to have felt separation into subgenera on the basis of the number of antennal segments might be justified; thus Aneleus has 11-joints, Aeromyrma has 10; Oligomyrmex has 9; and Octella has 8.
According to Ettershank's review (1966) colonies are generally rather small, or broken up into small subcolonies. Collections usually come from under the bark of logs, in rotten wood, in leaf litter, or in other generally humid places. Most may be lestobiotic, probably feeding on arthropod eggs. There is no modern taxonomic revision.
Bernard (1952) not only maintained the early genera but defined a new genus Nimbamyrma. From his notes, six species of Aneleus were known but only one was taken at Mt. Nimba, Guinea, silvestrii of which he was able to describe the male, a first for the genus (see below). From Aeromyrma he wrote of 3 isolated females, each of a distinct species, taken by Lamotte at Nion (700 m), Ravine I of Mount Tô (forest). The revision by Weber (1950) had been limited by the major caste being the only well known morph. However Bernard, who described the first male of the then genus Aneleus (silvestrii, see below) noted that the male morphology suggested Aneleus might be no more than a subgenus of Oligomyrmex; although the major and minor workers had 11-segmented antennae compared to the 10-segmented antennae of Oligomyrmex. In a footnote, Bernard added that an important collection of subterranean ants, by A. Machado, had just been received by him from Angola, and that included numerous workers of Nimbamyrma.
The synonymy of Nimbamyrma (villiersi) with Oligomyrmex by Ettershank seems questionable. Bolton (1973) who refers to Ettershank, has Oligomyrmex with the clypeus bicarinate and the propodeum with a pair of teeth or at least sharply angulate. Bernard (1952) wrote of (translated) "the clypeus without carina", the propodeum has two pairs of spines, as often seen in Tetramorium species, and (perhaps by default) there is no knowledge of dimorphism in Nimbamyrma. Similarly Wheeler (1922) listing features of Aeromyrma noted clypeus without carina.
My feeling is that the distinctive species, O. (Aneleus) politus (Santschi), which appears to have only a minor worker and not a major, perhaps merits elevation to monotypic Genus status see Oligomyrmex politus for details and the synonymy of villiersi. The revisionary paper by Fernández (2004) resolves this by placing all in Carebara, although he did not consider the likely synonymy of Nimbamyrma villiersi under O. politus.
Santschi's (1913e) early key is at 
- NOTE infimus now is in the genus
Paedalgus, and antennal counts are not used. Weber's (1952) key
to Aeromyrma is at 
. He also provided notes on the biology of
the genus, these are at 
.
Key to major workers : Key to minor workers : Key to global Oligomyrmex
Species from West Africa listed only by code letters
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MYRMICINAE Introduction |
© 2007, 2008, 2010 - Brian Taylor CBiol FSB FRES 11, Grazingfield, Wilford, Nottingham, NG11 7FN, U.K. |
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