Strumigenys wallacei group

Strumigenys wallacei group Bolton (2000)

Austral
Apical fork of mandible of 2 spiniform teeth, with 0-2 intercalary denticles. A single long spiniform preapical tooth arises from the dorsal surface of the mandible (not from its inner margin), it arches mesad and passes over the inner margin. Preapical tooth widely separated from apicodorsal tooth. Mandibles slender, linear and moderately long, MI 47-63.

Anterior clypeal margin concave medially or with a small median notch.

Scape short to moderate, SI 56-89, dorsoventrally flattened and with a sharp leading edge; broadest distal of midlength.

Apical antennomere not strongly tapered basally.

Ventrolateral margin of head with a deep and very conspicuous preocular impression; this impression continues dorsally as a concavity up the side of the head in front of the eye but does not interrupt the frontal carinae.

Ventral surface of head anteriorly with a broad deep transverse trench that occupies all the space between the level of the eyes and the posterior margin of the buccal cavity; this impression represents a fusion of postbuccal groove and ventral preocular impression into a single trench and is confluent laterally with the preocular impression of the ventrolateral margin.

Scrobe absent to distinctly present behind level of eye.

Propodeal teeth free; lateral margin of declivity at most with a narrow flange or mere carina, never with a broad lamella; base of declivity may have a prominent cuticular lobe.

Spongiform appendages of waist segments present but small; ventral curtain of petiole may be very narrow and lateral lobe of petiole node is no more than a slight expansion of the posterior collar.

Pilosity. Varying among species (see descriptions) but simple or flagellate hairs are entirely absent on body and appendages; any hairs present are remiform, clavate or squamate. Leading edge of scape with a row of stiffly projecting hairs that are conspicuously flattened or expanded apically.

Malesian-Oriental-East Palaeartic
Apical fork of mandible of 2 spiniform teeth; with 0-2 intercalary denticles. A single long spiniform preapical tooth, that is widely separated from the apicodorsal tooth, arises from the dorsal surface of the mandible (not from its inner margin), it arches mesad and passes over the inner margin. Mandibles slender and linear, MI 47-63.

Anterior clypeal margin concave medially or with a small median notch.

Scape short to moderate, SI 56-85, dorsoventrally flattened and with a sharp leading edge; broadest distal of midlength.

Apical antennomere not strongly tapered basally.

Ventrolateral margin of head with a deep and very conspicuous preocular impression; this impression continues dorsally as a concavity up the side of the head in front of the eye but does not break the frontal carinae.

Ventral surface of head anteriorly with a broad deep transverse trench that occupies all the space between the levels of the eyes and the posterior margin of the buccal cavity; this impression represents a fusion of postbuccal groove and ventral preocular impression in to a single trench and is con fluent laterally with the preocular impression of the ventrolateral margin.

Scrobe absent to distinctly present behind level of eye.

Propodeal teeth free; lateral margin of declivity at most with a narrow flange or mere carina, never with a broad lamella; base of declivity may have a prominent cuticular lobe.

Spongiform appendages of waist segments present but small; ventral curtain of petiole may be very narrow and lateral lobe of petiole node is no more than a slight expansion of the posterior collar.

Pilosity. Varying among species (see descriptions) but entirely lacking simple or flagellate hairs on body and appendages; any hairs present are remiform, clavate or squamate.

Leading edge of scape with a row of stiffly projecting hairs that are conspicuously flattened or expanded apically.

Austral
A single species of this mainly Malesian group (Strumigenys opaca) occurs in, and appears to be restricted to, the Cape York area of Queensland, Australia. The group is immediately characterised by the specialised anteroventral groove across the head, formed by the amalgamation of the postbuccal groove and preocular ventral impression into a single wide deep transverse trench. The peculiar development of the preapical tooth, that arises upon the dorsal surface of the mandible and arches mesad across part of the dorsum and the inner margin, is also developed in Australia in Strumigenys chyzeri. However, this species should not be confused with opaca as chyzeri has, among many differentiating characters, distinctly separated postbuccal groove and ventral preocular impression, standing hairs present posteriorly on the head and on the mesonotum, projecting stiff humeral hairs, mandibles whose inner margins become concave distal of the preapical tooth, a deep concavity in the upper scrobe margin above and just anterior to the eye, and a well developed roughly triangular ventral spongiform lobe on the postpetiole.

Malesian-Oriental-East Palaeartic
The small wallacei-group is immediately characterised by the specialised anteroventral groove across the head, formed by the amalgamation of the postbuccal groove and preocular ventral impression into a single wide deep transverse trench. The peculiar development of the preapical tooth, that arises upon the dorsal surface of the mandible and arches mesad across part of the dorsum and the inner margin, is also developed in Strumigenys chyzeri (loriae group) and the fuarda group. The first of these, however, has distinctly separated postbuccal groove and ventral preocular impression whilst the second lacks ventral impressions in the head capsule except for a very feeble postbuccal groove.

Most species of the wallacei-group are Malesian, but a single species, Strumigenys opaca, is found in Australia.