Ocymyrmex laticeps Forel

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, pp. 245-307: 271-272

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Ocymyrmex laticeps Forel


Ocymyrmex laticeps Forel  HNS 

(Fig. 29)

Ocymyrmex laticeps Forel  HNS  , 1901: 306. Syntype workers, Angola: Mossamedes, Cubango-Cuito (H. H. Braun & Van der Kelleri) (MHN, Geneva) [examined].

Worker. 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. Petiole in profile as in Fig. 29, 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 postpetiole 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.

This species, known only from the type-series, is closest related to cursor  HNS  , which is also from Angola. They differ as follows

laticeps  HNS 

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  HNS  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, cavatodorsatus  HNS  , velox  HNS  , ankhu  HNS  , zekhem  HNS  and turneri  HNS  , but none of these has the strongly developed constriction of the first gastral tergite seen in laticeps  HNS  and cursor  HNS  , and all lack a subpetiolar process. Apart from this turneri  HNS  is small (HW <1 - 30) and has large eyes which break the outline of the sides in full-face view; velox  HNS  has a high, strongly convex petiole node (Fig. 32) and very feeble cephalic sculpture; and cavatodorsatus  HNS  has the alitrunk strongly saddle-shaped in profile and the posterior half of the cephalic dorsum unsculptured.