Pristomyrmex trogor

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Pristomyrmex trogor
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Myrmicinae
Tribe: Crematogastrini
Genus: Pristomyrmex
Species: P. trogor
Binomial name
Pristomyrmex trogor
Bolton, 1981

Pristomyrmex trogor castype13686 profile 1.jpg

Pristomyrmex trogor castype13686 dorsal 1.jpg

Specimen labels

Nothing is known about the biology of Pristomyrmex trogor. It is only known from the type series.

Identification

Wang (2003) - Worker. Frontal carinae absent; ventral surface of dypeus with two toothlike prominences; pronotum with a pair of short spines; dorsal surfaces of head and alitrunk smooth and shining; petiole and postpetiole lacking hairs.

Bolton (1981) - P. trogor is related to Pristomyrmex africanus, Pristomyrmex fossulatus and Pristomyrmex orbiceps but is easily recognizable as in all of these species frontal carinae are strongly developed whereas in trogor they are absent. Besides this the antennal scapes in trogor are relatively long, with SI 100 or more, whereas the scapes are shorter in africanus, fossulatus and orbiceps with SI range 82-90. P. africanus and fossulatus also differ from trogor by having broad foveolate punctures on the dorsum of the head. P. orbiceps lacks the strong pronotal spines seen in trogor, having instead a pair of low broad rounded tubercles.

A member of the Quadridens species group

Keys including this Species

Distribution

Distribution based on Regional Taxon Lists

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


Distribution based on AntMaps

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Distribution based on AntWeb specimens

Check data from AntWeb

Biology

The biology of most Pristomyrmex species is poorly known. From Wang (2003): Most species of Pristomyrmex dwell in the rainforest, foraging as predators or scavengers. An Asian species, Pristomyrmex punctatus, however, occurs in open and disturbed habitats (e.g., bare hills, agricultural areas, and beaches). These ants prefer to nest in soil, litter, or rotten wood; in rotten parts of living trees; in dead standing trees; or around plant roots.

Pristomyrmex is of great interest because it exhibits several unusual biological and evolutionary phenomena. The absence of morphologically normal queens and reproduction primarily by unmated workers in P. punctatus {=P. pungens) is a highly unusual life history in the Formicidae. Ergatoid queens, a special wingless female caste morphologically intermediate between the queen and the worker, are present in at least four species: Pristomyrmex punctatus, Pristomyrmex africanus, Pristomyrmex wheeleri, and Pristomyrmex mandibularis; two of them (P. africanus and P. wheeleri) possess both queen and ergatoid queen castes.

Simulating death, slowness of movement, and nocturnal foraging has been recorded in Pristomyrmex (Donisthorpe, 1946; Taylor, 1965; Weber, 1941). Colony size varies greatly among species, ranging from about a dozen to several thousand workers (Donisthorpe, 1946; Itow et al, 1984; Mann, 1919; Taylor, 1965, 1968).

Castes

Nomenclature

The following information is derived from Barry Bolton's Online Catalogue of the Ants of the World.

  • trogor. Pristomyrmex trogor Bolton, 1981b: 287, figs. 33, 36 (w.m.) DEMOCRATIC REPUBLIC OF CONGO. See also: Wang, M. 2003: 476.

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 4.0, HL 0.96, HW 0.99, CI 103, SL 1.00, SI 101, PW 0.61, AL 0.96.

Mandibles basally with some weak rugular sculpture but this fading out distally so that near the apical margin the blade is smooth. Apical (masticatory) margin with a large apical tooth followed by a slightly smaller preapical, a diastema and two basal denticles which arise at each end of a raised welt representing the fused bases of the two denticles (in worn specimens this would appear as a single broad truncated basal tooth). Median portion of clypeus without a longitudinal median carina except posteriorly where a vestige remains. Anterior clypeal margin with a small median tooth and a couple of smaller denticles on each side. Frontal carinae absent, the posterior extensions of the frontal lobes strongly divergent but short, fading out in front of the level of the anterior margins of the eyes. The genal carina which bounds the outer margin of each antennal fossa strong, curving in towards the extensions of the frontal lobes but not meeting them. Antennal scrobes absent, the scapes relatively long (SI, above). Eyes small, maximum diameter 0.15, about 0.15 x HW. With the head in full-face view the occipital margin indented medially, the sides shallowly but evenly convex. Pronotum armed with a pair of short triangular spines, propodeum with a pair of slightly larger spines. Metapleural lobes fairly large, rounded. Dorsum of alitrunk flat to shallowly concave between the pronotal spines and between the lateral hair-bearing welts of the mesonotum. Petiole node high in profile, the dorsum sloping downwards posteriorly and rounding into the posterior face. Anterior and dorsal faces of postpetiole in profile forming a single evenly curved surface. In dorsal view the petiole node about as long as broad, the postpetiole very slightly longer than broad and broadening from front to back. Entirety of head and body smooth and glossy, unsculptured except for a few ridges on the metapleuron leading up to the orifice of the metapleural glands. Dorsum of head with numerous fine curved hairs, some of which are very long. Mandibles, clypeal margin and ventral surface of head with equally dense but generally shorter fine hairs; similar hairs also present on anterior coxa. Alitrunk without hairs except for 2 pairs arising from the mesonotal welt. Petiole, postpetiole and first gastral tergite without hairs; apex of gaster and sternites behind the first with a few hairs present. Scapes and tibiae with short, fine, apically directed hairs. Colour uniform glossy chestnut-brown.

Paraypes. TL 3.4-4.0, HL 0.88-0.96, HW 0.89-0.98, CI 101-103, SL 0•90-0.98, SI 100-102, PW 0.56-0.61, AL 0.86-0.98 (4 measured). Maximum diameter of eye 0.14-0.16, about 0.14-0.16 x HW. As holotype but some darker brown in colour.

Male

Wang (2003) - One paratype male has the same data as holotype and was originally mounted together with two paratype workers on the same pin: TL 2.92, HL 0.55, HW 0.57, CI 104, SL 0.30, SI 53, HWE 0.74, EL 0.28, PW 0.82, AL l.16 (n = 1).

Head, including the eyes, distinctly broader than long. Clypeus narrow and convex, its anterior margin rather straight. Frontal carinae absent. Maximum diameter of the median ocellus 0.10. Scapes longer than the other antennal segments, except for the apical ones. On the mesoscutum, notauli distinct, forming a Y shape; parapsidal furrows absent. Scutoscutellar sulcus with about 10 narrow short ridges. Propodeum weakly tuberculate, lacking teeth or spines. Metapleural lobes subtriangular. Middle and hind tibiae without any spurs. Waist abnormally shaped, with a huge segment formed by the fusion of petiole and postpetiole; entire posterior face of the waist attached to first gastral segment. Dorsum of head . smooth and shining, but frontal area with a median longitudinal carina; a short ruga present below each antennal socket. Alitrunk gene rally smooth and shining, except for those marked sutures. Petiole, postpetiole, and gaster smooth and shining. All dorsal surfaces with abundant long hairs. Scapes and tibiae with numerous erect or suberect short hairs. Color somewhat blackish-brown; wings white.

Type Material

Holotype worker, Zaire (B. Congo on data label): S. Slope of Mt Kahuzi, 1900 m, 5.ix.1957 (E. S. Ross & R. E. Leech) (California Academy of Sciences). Paratypes, 19 workers and 1 male with same data as holotype (The Natural History Museum, Museum of Comparative Zoology, CASC).

References