Centromyrmex decessor

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Centromyrmex decessor
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Ponerinae
Tribe: Ponerini
Genus: Centromyrmex
Species: C. decessor
Binomial name
Centromyrmex decessor
Bolton & Fisher, 2008

Centromyrmex decessor casent0102993 profile 1.jpg

Centromyrmex decessor casent0102993 dorsal 1.jpg

Specimen labels

Nothing is known about the biology of Centromyrmex decessor.

Identification

A member of the feae species group. The dentition of the mandible is unique among Afrotropical species. The number of thickened spiniform setae on the anterior surface of the metatibia varies from 5 to 7, but 6 appears to be the number most commonly encountered, all located on about the apical third of the length of the metatibia. C. decessor is easily separated from the much larger raptor by the characters noted in the key. (Bolton and Fisher 2008)

Keys including this Species

Distribution

Distribution based on Regional Taxon Lists

Afrotropical Region: Cameroun, Democratic Republic of Congo, Gabon (type locality).

Distribution based on AntMaps

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Distribution based on AntWeb specimens

Check data from AntWeb

Biology

All of the species in the genus appear to be termitophagous and all are superbly adapted to this specialised predatory life style. Observations of some species have found them to be rather helpless when placed in an exposed, open situation. Weber described what happened when he found a worker “just beneath the soil surface under a thin cover of dead leaves”. The ant was “completely helpless when exposed to the daylight and writhed about when placed on the ground or in my palm. It made no attempt to run away, curling and uncurling without stinging, though it had a long, stout sting”. In other words, it seemed unable to walk when removed from its specialised habitat and placed on a surface where it could not use its specialised legs. If not discovered within a termite nest, individuals are occasionally found in the top soil or the root-mat below the leaf litter layer, where their short, powerful, spiny legs facilitate their movement. (Weber 1949, Bolton and Fisher 2008).

Castes

Worker

Nomenclature

The following information is derived from Barry Bolton's New General Catalogue, a catalogue of the world's ants.

  • decessor. Centromyrmex decessor Bolton & Fisher, 2008c: 17, figs. 11, 12 (w.q.m.) GABON.

Unless otherwise noted the text for the remainder of this section is reported from the publication that includes the original description.

Description

Worker

Holotype. TL 7.9, HL 1.28, HW 1.34, CI 105, ML 0.94, MI 73, SL 0.94, SI 70, PW 1.12, WL 2.32.

With characters of the genus and the feae group. Masticatory margin of mandible with 5 low-triangular blunted teeth separated by feebly concave diastemata that are much longer than the teeth are high. Margins of diastemata are unarmed or have reduced denticles or crenulation between the main teeth. Mandibles smooth with scattered small punctures. Head capsule slightly broader than long in full-face view. Dorsum of head with scattered punctures on smooth cuticle, the punctures denser on the sides of the head, especially anteriorly, and also with weak striation or punctate-striation within the antennal fossae. Pronotum more sharply marginate anteriorly, more bluntly laterally. Pronotal dorsum a flat to shallowly convex plateau behind the margination. Mesonotum weakly marginate behind the promesonotal suture. In profile the sloping face of the propodeum behind the mesonotum forms a long, deep concavity and the posterior propodeum is raised into a distinct tumulus. Metatibia with a few darkly coloured spiniform setae near the apex of the dorsum, and with similar but more numerous setae on the apical third of the anterior surface. Orifice of propodeal spiracle higher than wide but elliptical, not slit-shaped. Petiole node in dorsal view broader than long. Subpetiolar process short-spiniform. Petiolar spiracle on the peduncle, at base of anterior face of node. Pronotal dorsum, and anterior mesonotum, with widely scattered broad, shallow punctures that may be almost effaced. Pronotum also with vestiges of some very weak oblique costulae. Colour glossy brownish yellow to light brown, the head and mandibles darkest, the gaster lightest in shade.

Paratypic and non-paratypic. TL 7.0-7.9, HL 1.18-1.30, HW 1.20-1.34, CI 102-105, ML 0.85-0.96, MI 71-75, SL 0.84-0.96, SI 70-75, PW 0.94-1.12, WL 2.04-2.34 (11 measured). As holotype but mandible with 5–6 larger teeth. Sculpture of pronotum and anterior mesonotum dosally is variable. In some the punctures are more sharply defined than in others, and the weak pronotal costulae may be easily visible to almost effaced. In the most weakly sculptured individuals the punctures are little more than vague depressions in the surface.

Queen

TL 9.3-9.80, HL 1.36-1.40, HW 1.42-1.43, CI 102-104, OI 28-29, ML 0.96, MI 69-71, SL 1.35-1.38, SI 70-71, PW 2.84-2.86 (2 measured). The queen will run out in the key to workers. In particular, the unique dentition of the worker is duplicated in the queen caste.

Holotype Specimen Labels

Type Material

Holotype worker (top specimen of three on pin), Gabon: Prov. Woleu-Ntem, 31.3 km. 108º ESE Minvoul, 2º04.8’N, 12º24.4’E, 600 m., 14.ii. 1998, # 1716-1, ex rotten log, rainforest (B.L. Fisher) (California Academy of Sciences).

Paratypes. 4 workers with same data as holotype (2 are middle and bottom specimens on same pin as holotype); 2 workers with same data but # 1699-1; 1 worker with same data but # 1719-1; 1 worker with same data but # 1725-2 (California Academy of Sciences).

References