| Ocymyrmex flaviventris|
Forder and Marsh (1989) observed from dissections that the ergatiod like queens of this species have larger, and many more, ovaries than workers.
A member of the hirsutus group. O. flaviventris is characterized by its light orange-yellow colour, keel-like process below the petiole peduncle, broad node, prominent metapleural glands and uneven cephalic sculpture. It is closest related to Ocymyrmex shushan and Ocymyrmex hirsutus, but in the former the promesonotum forms a conspicuous high dome and the latter lacks a keel-like subpeduncular process as well as having the cephalic sculpture transverse behind the level of the eyes. (Bolton 1981)
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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.
The following information is derived from Barry Bolton's New General Catalogue, a catalogue of the world's ants.
- flaviventris. Ocymyrmex hirsutus var. flaviventris Santschi, 1914a: 431 (w.) TANZANIA. Bolton, 1981b: 261 (q.). Raised to species: Bolton, 1981b: 268. See also: Bolton & Marsh, 1989: 1295.
Unless otherwise noted the text for the remainder of this section is reported from the publication that includes the original description.
Bolton (1981) - TL 7.1-7.4, HL 1.64-1.80, HW 1.54-1.70, CI 93-97, SL 1.44-1.58, SI 90-96, PW 0.98-1.04, AL 2.04-2.28 (17 measured).
Anterior clypeal margin with a narrow but deep semicircular impression medially, the impression flanked by a pair of teeth. Occipital corners broadly rounded, the margin medially with a small indentation. Eyes with maximum diameter 0.38, about 0.22 x HW. Promesonotum in profile evenly shallowly convex, the propodeal dorsum posteriorly rounding narrowly into the declivity which is almost vertical. Metapleural glands swollen and projecting strongly to the rear, in profile concealing all but the extreme tips of the meta pleural lobes ; the projection of the metapleural glands enhanced by the near-vertical propodeal declivity. Peduncle of petiole ventrally with an elongate keel-like process which is semitranslucent and unsculptured, evenly shallow convex throughout its length. Petiole node small in profile, evenly rounded. In dorsal view the petiole node broader than long, the maximum width of the node about equal to the distance from the spiracle to the apex of the collar where the petiole articulates with the postpetiole. Postpetiole in dorsal view slightly longer than broad. Base of first gastral tergite constricted and forming a neck. Dorsum of head longitudinally very densely finely rugulose, the rugulae close-packed and irregular, being narrowly wavy or even minutely vermiculate in places. Ground-sculpture a conspicuous granulation or punctulation. Rugulae between and on median strip just behind the frontal lobes more regular than elsewhere. Dorsal alitrunk transversely densely rugose, the sculpture longitudinal only between the mesothoracic spiracles and on the arched portion of the pronotum. Sides of alitrunk rugose everywhere. Petiole with a few transverse rugae beneath the node and on the dorsum of the peduncle. Elsewhere on the petiole sculpture is vestigial to absent. Post petiole unsculptured except for faint superficial patterning. All dorsal surfaces of head and alitrunk with numerous hairs of varying length. PropodeaJ dorsum with long hairs arising from a fairly dense mat of much shorter hairs. First gastral tergite with sparse scattered hairs which are much shorter than those on the alitrunk. Colour bright orange-yellow, the gaster lighter and more yellow than the head and alitrunk.
Bolton (1981) - Holotype worker, South West Africa: Windhoek (Viehmeyer) (NM, Basle) [examined].
- Bolton, B. 1981. A revision of six minor genera of Myrmicinae (Hymenoptera: Formicidae) in the Ethiopian zoogeographical region. Bulletin of the British Museum (Natural History) Entomology. 43:245-307. PDF (page 261, queen described; page 268, Raised to species)
- Bolton, B. and A. C. Marsh. 1989. The Afrotropical thermophilic ant genus Ocymyrmex (Hymenoptera: Formicidae). Journal of Natural History. 23:1267-1308.PDF
- Forder, J. C. and A. C. Marsh. 1989. Social organization and reproduction in Ocymyrmex foreli (Formicidae: Myrmicinae). Insectes Sociaux. 36:106-115.
- Santschi, F. 1914a . Mélanges myrmecologiques. Ann. Soc. Entomol. Belg. 57: 429-437 (page 431, worker described)