Strumigenys yaleopleura group

Strumigenys yaleopleura group Bolton (2000)

Austral
Apical fork of mandible of 2 spiniform teeth. Mandibles short (MI 33-42), outer margins convex or bowed outwards; mandible distinctly broadest at base and tapering from there to apex. In ventral view outer margin of mandible without an inflected prebasal angle. A single preapical tooth present in the distal third, dentiform to short-spiniform.

Anterior clypeal margin transverse or nearly so, never possessing a narrow U-shaped or V-shaped median notch or impression.

Scape stoutly subcylindrical to slightly dorsoventrally flattened, short, SI 56-69.

Apical antennomere broad basally, broadly articulated with the preapical antennomere.

Ventrolateral margin of head without a preocular notch or impression. With head in profile the dorsal and ventral outlines without impressions except for the shallow postbuccal groove.

Propodeal declivity with a very narrow to moderate lamella, its posterior (free) margin either concave and paralleling the shape of the declivity, or more or less straight.

Spongiform appendages of waist segments all present.

Pilosity. Dorsolateral margin of head with 1-3 freely laterally projecting flagellate hairs; when more than one the posteriormost (on margin of occipital lobe) may be directed more dorsally than laterally. Cephalic dorsum with a single pair of curved to flagellate hairs that straddle the midline close to occipital margin. Pronotal humeral hair flagellate; pronotal dorsum otherwise with 0-1 pair of standing hairs. Mesonotum with 1 pair of erect flagellate hairs. Dorsal (outer) surface of hind basitarsus with 1-2 long erect flagellate hairs; hind tibia with 0-2 similar hairs. First gastral tergite with simple to flagellate hairs at least near base and at apex. Ground-pilosity on head (and usually also on promesonotum) short, slender and closely applied to surface, usually conspicuous.

Sculpture. Dorsal surfaces of head and alitrunk reticulate-punctate, sometimes reduced on pronotum. Side of alitrunk with pleurae and side of propodeum mostly to entirely smooth. Gaster unsculptured except for basigastral costulae.

Malesian-Oriental-East Palaeartic
Apical fork of mandible of 2 spiniform teeth. A single preapical tooth present in the distal third, dentiform to spiniform. Mandibles short (MI 30-35), outer margins convex or bowed outwards; mandible distinctly broadest at base and tapering from there to apex. In ventral view outer margin of mandible without an inflected prebasal angle.

Anterior clypeal margin transverse or nearly so, never possessing a narrow U-shaped or V-shaped median notch or impression.

Scape stoutly subcylindrical to slightly dorsoventrally flattened, short, SI 55-69.

Apical antennomere broad basally, broadly articulated with the preapical antennomere.

Ventrolateral margin of head without a preocular notch or impression. With head in profile the dorsal and ventral outlines without impressions except for the shallow postbuccal groove.

Propodeal declivity with a very narrow to moderate lamella, its posterior (free) margin either concave and paralleling the margin of the declivity or more or less straight.

Spongiform appendages of waist segments all present.

Pilosity. Dorsolateral margin of head with 1-3 freely laterally projecting flagellate hairs; when 3 the posteriormost (on margin of occipital lobe) may be directed more dorsally than laterally. Cephalic dorsum with a single pair of curved to flagellate hairs that straddle the midline close to the occipital margin. Pronotal humeral hair flagellate; pronotal dorsum otherwise with 0-1 pair of standing hairs. Mesonotum with 1 pair of erect flagellate hairs. Dorsal (outer) surface of hind basitarsus with 1-2 long erect flagellate hairs; hind tibia with 0-2 similar hairs. First gastral tergite with simple to flagellate hairs at least near base and at apex. Ground-pilosity on head (and usually also on promesonotum) short, slender and closely applied to surface, usually conspicuous.

Sculpture. Dorsal surfaces of head and alitrunk reticulate-punctate. Side of alitrunk with pleurae mostly to entirely smooth. Disc of postpetiole mostly to entirely smooth, at most with some short costulae anteriorly; never reticulate-punctate. Gaster unsculptured except for basigastral costulae.

Austral
The Austral region has three representatives of this group; Strumigenys yaleopleura, which also occurs in the Malesian region, and the two endemic species described below. Strumigenys yaleopleura is formally treated as part of the Malesian fauna (where two other species are also known). Comments on its separation from the other Austral species of the group are given under the following species.

Malesian-Oriental-East Palaeartic
Three species belonging to this group occur in the Malesian region. Two are apparently restricted to Sulawesi but the third, Strumigenys yaleopleura, has a much wider range that extends through New Guinea and the Solomon Is to Queensland and New South Wales in Australia, where there are also 2 other endemic species of the group. These are discussed and compared with yaleopleura under the section dealing with the Austral fauna. The group may be artificial, the result of convergence in mandible structure, but its component species are linked by the diagnosis above.

The shape of the mandibles in full-face view, broadest basally and tapering from base to apex, is reminiscent of the shape seen in the biroi and lyroessa groups, but in a much less developed condition. In yaleopleura and its allies the basal portion of the mandible is less strongly expanded than in those two groups and the outer margin is curved near the base rather than having an inflected angle. As well as this, all Malesian species of the yaleopleura-group possess flagellate hairs on the dorsolateral margin of the head, a character absent from both the lyroessa- and biroi-groups.