Strumigenys szalayi group

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Strumigenys szalayi group Bolton (2000)

Species

Malesian-Oriental-East Palaeartic

Strumigenys szalayi also occurs in the Austral region.

Worker Diagnosis

Apical fork of mandible of 2 spiniform teeth; a small intercalary tooth or denticle present (2 in Strumigenys nidifex). A single stoutly spiniform preapical tooth present close to the apicodorsal tooth. Mandibles linear and moderately long, MI 43-60.

Anterior clypeal margin shallowly concave medially; behind anterior margin the clypeus raised into a tumulus on each side over the mandibular bases.

Scape long to very long, SI 83-117; usually oddly curved so that it fits the contours of the side of the head when laid back, these curves giving the scape a strangely kinked or deformed appearance (best seen from above and behind, with the scape extended). Apical antennomere long, tapering and narrow basally, sometimes very slender at its junction with the preapical segment.

Ventrolateral margin of head with a preocular impression or notch, usually deep and conspicuous; this notch is continued dorsally as a concavity up the side of the head in front of the relatively large eye and continued ventrally as an impression that extends onto the ventral surface (absent in 1 species).

Head with depressed dorsal surfaces to the occipital lobes; ventral surface of head variably impressed (see below).

Scrobe absent behind level of eye.

Propodeal teeth free; margin of declivity at most with a narrow flange or mere carina, never with a broad lamella.

Petiole node in dorsal view at least as long as broad, usually longer than broad; disc of postpetiole narrow.

Spongiform appendages of waist segments very reduced or absent. In profile usually entirely absent from petiole (present in nidifex); on postpetiole present only as narrow or vestigial margins to the sclerites (larger only in nidifex). Spongiform tissue absent from base of first gastral sternite.

Pilosity. Dorsolateral margin of head with 1-2 simple standing hairs that project more dorsally than laterally. Cephalic dorsum with 4-8 standing hairs along occipital margin and a pair close to highest point of vertex. Pronotal humeral hair simple, short and stiff; 1-2 similar pairs present on mesonotum and postpetiole. First gastral tergite usually with sparse stiff erect hairs, rarely with sparse flagellate hairs. Posterior basitarsus may have a long fine projecting hair. Ground-pilosity everywhere sparse to vestigial, inconspicuous.

Sculpture. Either the usual reticulate-punctate sculpture on head and alitrunk or with parts reduced from this. Disc of postpetiole usually reticulate-punctate, only rarely with the sculpture reduced. Gaster un sculptured except for short to moderate basigastral costulae.

Notes

A group of moderate to large, slender-bodied species primarily of New Guinea and surrounding islands but also with some more widely distributed forms. Members of the group are easily identified by their lack of scrobes behind the eye and strangely deformed scapes, coupled with the much-reduced spongiform tissue of the waist segments.

The ventral surface of the head has a complex shape in most species. In profile there is nearly always a deep V-shaped or narrowly U-shaped postbuccal groove (shallow and inconspicuous only in nidifex). Posterior to this is an impression immediately in front of the eye, where the preocular notch extends round on to the ventral surface (feeble in Strumigenys yasumatsui). Behind the level of the eye the ventrolateral margin has a shallowly to markedly concave section that in many species extends as a transverse impression across the ventral surface (inconspicuous in Strumigenys lancea, absent in yasumatsui).

The bulla of the femoral gland is variably developed. In most species it is not visible on the hind femur; when present it is very small and inconspicuous.

The szalayi-group was fully revised by Brown (1971) who also presented notes on what is known of the biology of the species. The group remains much as he left it. Diagnostic notes are therefore minimal except where variation is discussed.

References