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Strumigenys olsoni group
Strumigenys olsoni group Bolton (2000)
Species
Malagasy
Worker Diagnosis
Mandibles in full-face view and at full closure triangular, stoutly constructed, serially dentate and engaging throughout their lengths. In profile the dorsal surface of the mandible distal of the clypeus markedly downcurved, its apical portion almost at a right-angle to the long axis of the head. In ventral view the outer mandibular margin with a weak inflected prebasal angle. MI 17-19.
Dentition. With 6 stout conical recurved teeth basally, followed by a series of 4 denticles to give a total dental count of 10. Posterior margin of basal tooth fused to anterior margin of basal lamella for part of its height.
Basal lamella of mandible a broad high truncated lobe that is taller than the basal three teeth; not visible when mandibles fully closed.
Labrum terminates in a pair of broad flat lobes that are bluntly rounded and separated by a marked median impression.
Clypeus with anterior margin broad and transverse. Lateral margins of clypeus slightly convergent posteriorly. Outer margins of mandibles intersect the anterior clypeal margin very close to the clypeal anterolateral angles.
Clypeal dorsum with minute appressed hairs. Lateral margins without freely projecting hairs of any form.
Preocular carina only visible through notch between clypeus and frontal lobe in full-face view, behind this overhung and concealed by the frontal lobe and frontal carina.
Ventrolateral border of head marginate in front of the eye, the margination concave and terminating anteriorly in a small tooth. Postbuccal impression deep and conspicuous.
Cuticle of side of head within scrobe smooth and shining.
Scape short, SI 55-60, slightly dorsoventrally flattened and with a sharp leading edge that is shallowly convex.
Leading edge of scape with minute appressed hairs that are directed toward the apex of the scape.
Pronotum without a median longitudinal carina, not marginate laterally, the dorsum transversely convex.
Spongiform appendages present on petiole and postpetiole, almost lamelliform. Base of first gastral sternite without trace of spongiform tissue.
Pilosity. Apicoscrobal hair short, simple and stiff. Pronotal humeral hair long and filiform.
Dorsal (outer) surfaces of tibiae with minute closely applied pubescence only.
Flagellate hairs entirely absent.
Notes
The sole Pyramica species currently known from Madagascar that has broad labral lobes and bear trap-like mandibles with fewer than 12 teeth and denticles in total. Strumigenys olsoni appears to be related to, or derived from, the Afrotropical loveridgei group but has probably been isolated for a long time. The key characters will provide an instant diagnosis of this species.
References
- Bolton, B. 2000. The ant tribe Dacetini. Memoirs of the American Entomological Institute. 65:1-1028.