Pristomyrmex fossulatus

Every Ant Tells a Story - And Scientists Explain Their Stories Here
Jump to navigation Jump to search
Pristomyrmex fossulatus
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Myrmicinae
Tribe: Crematogastrini
Genus: Pristomyrmex
Species: P. fossulatus
Binomial name
Pristomyrmex fossulatus
(Forel, 1910)

Pristomyrmex fossulatus casent0909181 p 1 high.jpg

Pristomyrmex fossulatus casent0909181 d 1 high.jpg

Specimen Labels

Nothing is known about the biology of Pristomyrmex fossulatus.

Identification

Wang (2003) - Worker. Masticatory margin of mandible with a long diastema after the preapical tooth; palp formula 4,3; eyes with 8 to 10 ommatidia in the longest row; pronotum lacking teeth or spines; dorsal surfaces of head and alitrunk with scattered foveolate punctures.

Bolton (1981) - P. fossulatus is related to Pristomyrmex africanus and Pristomyrmex orbiceps. It separates easily from the former as its eyes are much larger (0.26-0.29 x HW as opposed to 0.12-0.15 x HW) and its alitrunk lacks the sharp pronotal teeth or broad spines seen in africanus. The eye size of orbiceps is closer to that of fossulatus (but still smaller); orbiceps lacks the foveolate cephalic sculpture of fossulatus and also lacks the very distinctively shaped petiole node seen in the latter.

A member of the Punctatus species group

Keys including this Species

Distribution

Distribution based on Regional Taxon Lists

Afrotropical Region: South Africa (type locality).


Distribution based on AntMaps

AntMapLegend.png

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 New General Catalogue, a catalogue of the world's ants.

  • fossulatus. Tetramorium (Xiphomyrmex) fossulatum Forel, 1910e: 428 (w.) SOUTH AFRICA. Menozzi, 1942: 172 (q.). Combination in Pristomyrmex: Santschi, 1916a: 51; in Hylidris: Weber, 1952: 17; in Pristomyrmex: Bolton, 1981b: 285. See also: Wang, M. 2003: 406.

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

Description

Worker

Bolton (1981) - TL 2.7-3.2, HL 0.65-0.72, HW 0.62-0.70, CI 95-97, SL 0.54-0.60, SI 82-90, PW 0.46-0.52, AL 0.68-0.70 (3 measured).

Mandibles with vestiges of striate sculpture basally but mostly smooth with scattered small pits. Apical (masticatory) margin of mandible with strongly developed apical and preapical teeth followed by a diastema and a basal tooth which may be truncated. Clypeus with a sharp median longitudinal carina. Median portion of clypeus with the anterior margin shallowly concave and armed with denticles; a median denticle and 2-3 others on each side. Frontal carinae present and distinct, running back to the level of the posterior margins of the eyes and forming the dorsal margins of the narrow, short antennal scrobes. Lower margin of scrobe delimited by a longitudinal ruga above the eye, which runs back from the antennal fossa approximately to the midlength of the eye. Eyes large, maximum diameter c. 0.18, about 0.26-0.29 x HW, with 8-10 ommatidia in the longest row. With the head in full-face view the side convergent behind the eyes and rounding into the occipital margin which is straight to very feebly and shallowly concave. With the alitrunk in profile the pronotum only with a low, broad, blunt tubercle, without the teeth or spines frequently encountered in this genus; in dorsal view the tubercles appear as low, bluntly rounded angles. Propodeum with a pair of strong spines which are distinctly longer than their basal width. Metapleural lobes narrow and strongly prominent. Petiole in profile wedge-shaped, strongly tapering dorsally and with the apex of the triangular shape blunted. In dorsal view the petiole node broader than long. Subpetiolar process a long narrow low flange. Dorsum of head between frontal carinae with scattered large shallow foveolate punctures. Similar punctures also present on the sides of the head but generally less conspicuous. Dorsal alitrunk also with foveolate punctures but here they are very sparse, widely separated, very shallow and inconspicuous. Apart from these punctate areas the entirety of the head and body smooth and shining, with pedicel segments and gaster completely unsculptured. Hairs present on mouthparts and gastral apex, otherwise the dorsum only with 4-5 pairs on the head behind the level of the antennal insertions, following. the line of the frontal carinae; alitrunk with a single pair, on the mesonotum; petiole with 0-1 and postpetiole with 1-2 pairs dorsally; first gastral tergite hairless. Colour glossy light brown.

Wang (2003) - TL 2.63-2.92, HL 0.62-0.71, HW 0.64-0.75, CI 98-106, SL 0.56-0.61, SI 81- 88, EL 0.17- 0.18, PW 0.44-0.50, AL 0.64- 0.74, PPW 0.26- 0.28, PPL 0.16-0.19, PPI 147- 163 (11 = 5).

Mandibles smooth and shining. Dentition of the masticatory margin of mandible: an apical tooth + a preapical tooth + a long diastema + a truncated basal tooth. Basal margin of mandible lacking a toothlike prominence or curved lobe. Clypeus with a strong median longitudinal carina. Anterior clypeal margin with a median denticle and two to three others on each side, but sometimes two lateral denticles are fused together. Lateral portions of clypeus reduced to margins, and antennal fossae reaching the lateral anterior margins of clypeus. Ventral center of clypeus with a short transverse ruga. Palp formula 4,3. Frontal carinae extending to the level of the posterior margins of eyes. Antennal scrobe short, shallow, but distinct, margined by the frontal carina and a longitudinal ruga. Frontal lobes absent; thus, the antennal articulations are completely exposed. Antennal scapes, when lying on the dorsal head, close to the occipital margin of head. Eyes large, containing 8 to 10 ommatidia in the longest row. Pronotum with a pair of blunt tubercles, lacking teeth or spines. Propodeum armed with a pair of spines, about as long as the distance between their bases. Metapleural lobes subtriangular. Petiole node in profile wedge-shaped, with a triangular apex. Subpetiole with a narrow flange. Postpetiole in profile higher than long, with a rounded dorsum, in dorsal view transverse-rectangular and much broader than long. Dorsum of head, except for the scrobal areas, with numerous scattered foveolate punctures. Similar but sparser punctures present on the dorsal surface of alitrunk. Petiole and postpetiole each usually with a longitudinal ruga on each side. Gaster unsculptured. Several pairs of hairs present on the dorsum of head beyond the level of the antennal insertions. A row of forward-projecting hairs present on the anterior clypeal margin. Hairs on the rest of the body as follows-mesonotum (one pair), petiole (zero to one pair), and postpetiole (one to two pairs dorsally)-frequently lost by abrasion (Bolton, 1981: p. 286). First gastral tergite lacking erect or suberect hairs. Scapes and tibiae with short hairs. Color reddish-brown; appendages yellow-brown.

Queen

Wang (2003) - I have not seen the queen of this species, but Menozzi (1942: 172) gave a description of this caste.

Type Material

Bolton (1981) - Syntype workers, South Africa: Natal, Will Broak [Willbrook] (Wroughton) (Musee d'Histoire Naturelle Genève) [examined].

References

  • Bolton, B. 1981b. A revision of six minor genera of Myrmicinae (Hymenoptera: Formicidae) in the Ethiopian zoogeographical region. Bull. Br. Mus. (Nat. Hist.) Entomol. 43: 245-307 (page 285, Combination in Pristomyrmex)
  • Forel, A. 1910f. Note sur quelques fourmis d'Afrique. Ann. Soc. Entomol. Belg. 54: 421-458 (page 428, worker described)
  • Menozzi, C. 1942a. Formiche dell'isola Fernando Poo e del territorio del Rio Muni (Guinea Spagnola). 24. Beitrag zu den wissenschaftlichen Ergebnissen der Forschungsreise H. Eidmann nach Spanisch-Guinea 1939 bis 1940. Zool. Anz. 140: 164-182 (page 172, queen described)
  • Santschi, F. 1916a. Description d'un nouveau Formicide (Hym.) de l'Afrique occidentale. Bull. Soc. Entomol. Fr. 1916: 50-51 (page 51, Combination in Pristomyrmex)
  • Wang, M. 2003. A Monographic Revision of the Ant Genus Pristomyrmex (Hymenoptera:Formicidae). Bull. Mus. Comp. Zool. 157(6): 383-542 (page 406, see also)
  • Weber, N. A. 1952a. Studies on African Myrmicinae, I (Hymenoptera, Formicidae). Am. Mus. Novit. 1548: 1-32 (page 17, Combination in Hylidris)