Ocymyrmex shushan

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

Ocymyrmex shushan casent0900410 p 1 high.jpg

Ocymyrmex shushan casent0900410 d 1 high.jpg

Specimen Labels

Nothing is known about the biology of Ocymyrmex shushan.

Identification

A member of the hirsutus group. This bright orange species is characterized by a gastral constriction, an impressed clypeal margin, the strongly convex anterior portion of the dorsal alitrunk, and the shape of the petiole. (Bolton 1981)

Keys including this Species

Distribution

Distribution based on Regional Taxon Lists

Afrotropical Region: Namibia (type locality), South Africa.

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.

  • shushan. Ocymyrmex shushan Bolton, 1981b: 277, fig. 31 (w.) NAMIBIA.

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 6.7, HL 1.66, HW 1.58, CI 95, SL (antennae missing), PW 1.02, AL 2.14.

Anterior clypeal margin with a small but distinct median semicircular impression, which is flanked by a pair of short, acute teeth. Maximum diameter of eye 0.34, about 0.22 x HW. Sides of head behind eyes evenly convex and narrowing, rounding into the occipital margin with which, if it were not for the median impression in the latter, they would form a very regular arc. In profile the posterior pronotum and anterior part of mesonotum high and strongly convex, forming a dome-like outline above the level of the mesothoracic spiracles. Pronotum in front of this and mesonotum behind it sloping away evenly, increasing the dome-like appearance. Posterior portion of mesonotum and dorsum of propodeum more or less flat in profile, the latter rounding broadly into the convex declivity. Metapleural lobes small and low, rounded. Peduncle of petiole flat dorsally but sinuate ventrally. Petiole node in profile low dome-like, smoothly and evenly rounded. Postpetiole in profile subglobular. In dorsal view the petiole node much broader than long, all surfaces smoothly rounded; postpetiole slightly longer than broad. Base of first gastral tergite constricted and forming a neck behind the postpetiole. Dorsum of head finely and densely longitudinally rugulose, the rugulae diverging away from the midline posteriorly. Ground-sculpture between the rugulae a strong and conspicuous punctulation which in places seems as strongly developed as the rugular sculpture. Pronotum with a few strong transverse costulae on the cervical shield but behind this the costulae which arch up from the sides become very faint or vestigial when traversing the dorsum. Between the mesothoracic spiracles and extending for a short distance forwards and backwards is a patch of low longitudinal rugosity. Remainder of alitrunk and propodeal declivity transversely rugose or costulate. Petiole node smooth and shining, the anterior peduncle with some very faint transverse striae. Postpetiole unsculptured. Body everywhere lacking the conspicuous punctulate ground-sculpture which is so well developed on the head. All dorsal surfaces of head and body with numerous hairs, those on the first gastral tergite shorter and sparser than those on the alitrunk. Colour uniform bright orange.

Holotype Specimen Labels

Type Material

Holotype worker, South West Africa: Gobasis, 17.xii.l933 (J. Ogilvie) (The Natural History Museum).

References