Ocymyrmex weitzeckeri

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Ocymyrmex weitzeckeri
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Myrmicinae
Tribe: Crematogastrini
Genus: Ocymyrmex
Species: O. weitzeckeri
Binomial name
Ocymyrmex weitzeckeri
Emery, 1892

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Specimen Labels

Synonyms

Nothing is known about the biology of Ocymyrmex weitzeckeri.

Identification

A member of the weitzeckeri group. Bolton and Marsh (1989) - This apparently rare species appears to be closely related to the much more common and widespread Ocymyrmex fortior. In available material workers of the two may be distinguished as follows. In general weitzeckeri workers are very dark in colour and relatively dull, being very dull reddish black to blackish with a dull red tint. Cephalic sculpture is distinctly disorganized rather than regular. Usually on the dorsum of the head there is a broad area of wavy or markedly irregular rugulae on each side of, and converging medially on, a longitudinal strip of more obviously parallel rugulae at the centre of the dorsum. The petiole node is short and wide in dorsal view, distinctly much broader than long and the node very obviously much broader than the posterior petiolar peduncle. In contrast fortior workers are much lighter in colour and more glossy, being orange-red to shiny dark red. On the head the sculpture everywhere consists of regular fine dense and strikingly parallel longitudinal costulae which run in a fore-and-aft direction across the entire width of the dorsum. (There are some rare exceptions, noted under fortior.) The petiole node is narrower and more gracile in dorsal view, usually scarcely broader than the posterior petiolar peduncle.

Keys including this Species

Distribution

Distribution based on Regional Taxon Lists

Afrotropical Region: Kenya, Lesotho (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

Worker

Nomenclature

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

  • weitzeckeri. Ocymyrmex weitzeckeri Emery, 1892a: 116 (footnote) (w.) LESOTHO. Arnold, 1916: 197 (m.); Bolton, 1981b: 280 (q.). Senior synonym of wroughtoni: Bolton, 1981b: 280. See also: Bolton & Marsh, 1989: 1306.
  • wroughtoni. Ocymyrmex weitzeckeri subsp. wroughtoni Forel, 1910f: 13 (w.m.) SOUTH AFRICA. Junior synonym of weitzeckeri: Bolton, 1981b: 280.

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 6.8-7.8, HL 1.70-1.80, HW 1.62-1.72, CI 94-99, SL 1.44-1.58, SI 88-94, PW 1.02-1.10, AL 2.16-2.30 (8 measured).

Anterior clypeal margin with a conspicuous semicircular median impression flanked by a pair of short teeth. Occipital margin in full-face view with a median indentation. Maximum diameter of eyes 0.36-0.40, about 0.22-0.23 x HW. Promesonotum evenly convex in profile, the propodeal dorsum flat to very shallowly convex, rounding evenly into the declivity which is almost vertical. Metapleural lobes small but prominent, their apices narrowly rounded. Petiole in profile. Petiole node in dorsal view very broad, distinctly broader than long and its width greater than the distance from the spiracle to the apex of the collar where the petiole articulates with the postpetiole. Postpetiole node in dorsal view broader than long (excluding the anterior articulating portion). Base of first gastral tergite strongly constricted behind the postpetiole and forming a distinct neck. Head finely and densely rugulose everywhere, with punctulate or granular ground-sculpture. Pattern of the rugulae varying between individuals. On the dorsum from the level of the eyes to the occiput the rugulae never all running straight back. Either the rugulae away from the median strip diverge towards the occipital corners, or the rugulae close to the inner or posterior margins of the eyes are irregular to vermiculate; in some the rugulae are extensively vermiculate on the head. Dorsal alitrunk and propodeal declivity transversely rugose except for the area between the mesothoracic spiracles where the sculpture is longitudinal. Other components of the pronotal sculpture arch around the anterior end of these longitudinal rugae. In some workers the pronotum appears to be entirely longitudinally rugose in dorsal view as the median rugae extend so far forward that the more laterally situated rugae must parallel them almost to the cervical shield before arching round. Petiole with a few transverse rugae ventrally which may extend for some distance up the sides; the node with a few weak to vestigial transverse rugulae, those traversing the peduncle in front of the node stronger than those on the node itself. Postpetiole unsculptured except for the usual faint superficial patterning. All dorsal surfaces of head and body with fairly dense pilosity, the hairs of varying length; those on the first gastral tergite shorter and sparser than elsewhere on the body. Colour everywhere dark red to blackish red, in some specimens very dark indeed, almost entirely black.

Type Material

Bolton (1981):

Syntype workers, Lesotho: Leribe (Weitzecker) (Museo Civico di Storia Naturale, Genoa) [examined].

Ocymyrmex weitzeckeri subsp. wroughtoni Syntype workers, male, South Africa: Natal (Wroughton) (Musee d'Histoire Naturelle Genève) [examined].

References