Ocymyrmex laticeps

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Ocymyrmex laticeps
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Myrmicinae
Tribe: Crematogastrini
Genus: Ocymyrmex
Species: O. laticeps
Binomial name
Ocymyrmex laticeps
Forel, 1901

Ocymyrmex laticeps casent0909074 p 1 high.jpg

Ocymyrmex laticeps casent0909074 d 1 high.jpg

Specimen Labels

Nothing is known about the biology of Ocymyrmex laticeps.

Identification

A member of the laticeps group

Bolton (1981) - This species, known only from the type-series, is closest related to Ocymyrmex cursor, which is also from Angola. They differ as follows

laticeps Smaller species, HW 1.70-1.74, SL 1.56, PW 1.08-1.14. Head slightly broader than long, CI 102-103. Metapleural lobes vestigial, scarcely or not visible in absolute profile. Anterior half of propodeal dorsum sloping downwards, posterior half more or less level. Petiole node in profile with a short, narrowly rounded dorsum. Postpetiole longer than broad in dorsal view.

cursor - Larger species, HW 2.04, SL 1.94, PW 1.30. Head slightly longer than broad, CI 98. Metapleural lobes large, conspicuous in absolute profile. Anterior half of propodeal dorsum shallowly concave, posterior half rising and shallowly convex. Petiole node in profile with an elongate, almost flat dorsum. Postpetiole broader than long in dorsal view.

Sculpture in the two species is very similar and they also share the characters of lacking a semicircular clypeal impression and possessing a broad ventral process on the peduncle of the petiole. Five other known species do not have a semicircular impression in the middle of the anterior clypeal margin, Ocymyrmex cavatodorsatus, Ocymyrmex velox, Ocymyrmex ankhu, Ocymyrmex zekhem and Ocymyrmex turneri, but none of these has the strongly developed constriction of the first gastral tergite seen in laticeps and cursor, and all lack a subpetiolar process. Apart from this turner; is small (HW < 1.30) and has large eyes which break the outline of the sides in full-face view; velox has a high, strongly convex petiole node and very feeble cephalic sculpture; and cavatodorsatus has the alitrunk strongly saddle-shaped in profile and the posterior half of the cephalic dorsum unsculptured.

Keys including this Species

Distribution

Distribution based on Regional Taxon Lists

Afrotropical Region: Angola (type locality).


Distribution based on AntMaps

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Distribution based on AntWeb specimens

Check data from AntWeb

Biology

Little is known about the biology of this species but a few species of Ocymyrmex have been studied in some detail. From this we can form some ideas about the biology of the genus as a whole. The following is summarized from Bolton and Marsh (1989). More details can also be found on the Ocymyrmex genus page.

Arnold (1916) observed that Ocymyrmex species with which he was acquainted nested in the ground in hot arid areas. The nests themselves went very deep into the ground, usually in loose sandy soil, and had a crater-like entrance. The ants used their well-developed psammophores to carry soil particles excavated from the nests. Recently both Marsh and Robertson (pers. comm.) have observed that workers of Ocymyrmex fortior close the nest entrance with small stones during periods of nest inactivity. Also, in Zimbabwe, fortior workers have been seen adding small stones to the crater-like nest entrance that were picked up from the ground some distance away from the nest. Species are now known which nest in very rocky soil and the nests may extend through the bedrock itself, necessitating the use of a large crowbar to expose the nest-chambers (H. Robertson, pers. comm.). Careful excavations of nests in well-structured sandy soil by one of us (Marsh) have revealed a simple nest structure. For example, nests of foreli typically have one entrance that opens into a vertical tunnel which terminates in a broad chamber at a depth of about 30 cm. Other brood and food chambers branch off from the tunnel at various intermediate levels. In most nest excavations the ergatoid queen was discovered near the bottom of the nest. In very unstructured loose sand, such as in the dry river beds of the Namib Desert, the tunnels and chambers of Ocymyrmex nests followed the root systems of shrubs and trees, and the major tunnel was therefore not necessarily vertical. Colonies of Ocymyrmex range in size from 200 to 1000 individuals (Marsh, 1987).

Other general aspects of their biology include workers that move rapidly, erratically, and are often active during the hottest part of the day. Specifics of their diet seem to vary by species but can include seeds and insects. For most species where queens are known they are worker-like ergatiod forms that are nonetheless clearly a morphologically distinct caste, as opposed to many intercaste ergatiods known from other genera that are intermediate between workers and more robust queens. Males of Ocymyrmex are often collected at lights but males associated with conspecific workers and females have rarely been collected.

Castes

Known only from the worker caste.

Nomenclature

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

  • laticeps. Ocymyrmex laticeps Forel, 1901d: 306 (w.) ANGOLA. [Also described as new by Forel, 1903e: 561.] See also: Bolton, 1981b: 271.

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 7.2-7.6, HL 1.66-1.70, HW 1.70-1.74, CI 102-103, SL 1.56, SI 90-92, PW 1.08-1.14, AL 2.20-2.24 (2 measured).

Middle of anterior clypeal margin flat to very feebly concave, without a semicircular notch or impression. With head in full-face view the occipital margin with only the shallowest of faint indentations medially. Maximum diameter of eye 0.36-0.38, about 0.21-0.22 x HW. Alitrunk in profile with promesonotum evenly shallowly convex, the posterior part of the mesonotum very shallowly concave and sloping down to the propodeum, the anterior half of which is itself slightly sloping; behind this the propodeum levels out before rounding broadly and evenly into the declivity. Metapleural lobes vestigial, merely a thin laminar strip on each side of the petiolar articulation, their width distinctly much less than (about half of) the width of the propodeal spiracle. The anterior peduncle with a broad low triangular process about half way along its ventral surface. Petiole node in dorsal view narrow, its maximum width c. 0.35, less than the distance from the spiracle to the posterior collar of the petiole. Postpetiole in profile swollen, low in front then forming an evenly convex low dome; the sternite strongly developed and bulging. In dorsal view the postpetioie much longer than broad, gradually increasing in width from front to back. First gastral tergite strongly constricted basally, forming a narrow neck behind the postpetiole. Dorsum of head with longitudinal fine dense rugulae which become less regular and more disorganized away from the midline and which tend to arch outwards posteriorly, towards the occipital corners, where they become fainter. Spaces between the rugulae with punctulate ground-sculpture except in the median strip behind the frontal lobes. Genae and sides of head below eyes regularly costulate, the costulae fine and dense, sharply defined and fading out on the occipital corners. Sides of alitrunk costulate to rugose, the sculpture finer on the sides of the pronotum, coarser elsewhere, regular except for an area in front of the propodeal spiracle where some wavy rugae are present. Petiole and postpetiole unsculptured except for a vestigial superficial patterning; the petiole ventrally with vestiges of a few transverse rugulae which are faint or incomplete. Dorsal alitrunk transversely or arched-transversely rugulose except between the mesothoracic spiracles where longitudinal sculpture is present. Convex portion of promesonotum less strongly sculptured than remainder of dorsal alitrunk. All dorsal surfaces of head and body with sparse hairs which are apparently absent from the first gastral tergite, but the specimens available have been much abraded so this is not certain. Colour red, the alitrunk darker than the head and pedicel segments where the cuticle has an orange tint. Base of gaster yellowish orange, much darker posteriorly.

Type Material

Bolton (1981) - Syntype workers, Angola: Mossamedes, Cubango-Cuito (H. H. Braun & Van der Kellen) (Musee d'Histoire Naturelle Genève) [examined].

References