Strumigenys formosensis

Chien and Lin (2015) analyzed the chemical constituents of the venom of five Taiwanese Strumigenys species: Strumigenys chuchihensis, Strumigenys formosensis, Strumigenys liukueiensis, Strumigenys minutula and Strumigenys solifontis for a chemotaxonomy study. The venom was collected from extruded stings and was thought likely to contain a mixture of poison (venom) and Dufour gland secretions. GC/MS profiles showed that three of the five species were clearly differentiated by the chemical composition of their sting secretions. Two remaining two species, S. chuchihensis and S. liukueiensis, showed chemical signatures that were not significantly different from one another.

Identification
Bolton (2000) - A member of the feae complex in the Strumigenys mayri-group. Unique in the complex and the group because of the strange form of its preapical tooth.

Distribution
While S. formosensis has been recorded from Hong Kong (Bolton 2000), Tang et al. (2019) consider these records to refer to  Strumigenys feae.

Distribution based on Regional Taxon Lists
Oriental Region: Taiwan.

Nomenclature

 *  formosensis. Strumigenys feae var. formosensis Forel, 1912a: 52 (w.) TAIWAN. Brown, 1949d: 24 (q.). Raised to species: Brown, 1949d: 19. See also: Terayama & Kubota, 1989: 781; Bolton, 2000: 884.

Worker
TL 2.9-3.0, HL 0.84-0.87, HW 0.54-0.56, CI 63-65, ML 0.39-0.40, MI 46-47, SL 0.52-0.54, SI 93-98, PW 0.25-0.28, AL 0.75-0.78 (4 measured).

Characters of the feae-complex. Preapical tooth of mandible scarcely more than a prominent angle. Length of preapical tooth less than half width of mandible at point where tooth arises, very much shorter than maximum width of mandible. Preapical tooth not directed medially but instead so strongly inclined toward the apicodorsal tooth that its proximal margin forms a single continuous line with the inner mandibular margin. Outer margin of mandible in full-face view approximately straight from close to base to level of preapical tooth. Inner margin of the mandible forms a more or less straight line from its base to the apex of the preapical tooth; inner margins of the two mandibles closely approximated at full closure. Upper scrobe margin with two freely laterally projecting long flagellate hairs, the posterior one in apicoscrobal position. Cephalic dorsum with 4-6 erect flagellate or looped hairs along the occipital margin, a similar but shorter pair at level of highest point of vertex. Preocular notch absent but ventrolateral margin of head narrowed and somewhat constricted immediately in front of eye where it is shallowly and broadly concave. Maximum diameter of eye equal to or slightly less than maximum width of the scape; eye with 3-4 ommatidia in the longest row and about 10-12 ommatidia in total. Pronotal humeral hair flagellate; pronotal dorsum finely reticulate-punctate to almost smooth and without erect hairs; mesonotum with 2 pairs of erect flagellate hairs. Dorsal surfaces of waist segments and first gastral tergite with flagellate hairs. Pleurae and side of propodeum smooth. One or two long fine erect flagellate hairs present on the dorsal (outer) surface of the hind basitarsus and another 1-2 on the hind tibia; similar pilosity present on the other legs. Petiole in profile with anterior face of node slightly shorter than length of dorsum. Disc of postpetiole smooth. Basigastral costulae about equal to length of disc of postpetiole.

Queen
Brown (1949) - Gynetype. TL 3.58 mm., HL 0.92 mm., ML 0.42 mm., WL 0.94 mm., CI 65, MI 46. Agrees quite well with the worker of the species, described in the body of the paper, but differing in the usual sexual characters and in possessing broader petiolar and postpetiolar nodes (the former broader than long). Eyes large, but only moderately convex, mesonotum with fine indistinct longitudinal costulae or rugulae superimposed upon the densely punctulate ground sculpture. Postpetiolar node shining. Propodeal teeth much as in the worker, but less strongly dorsally directed, infradental lamella narrow, concave, of even width its length.

Type Material
Syntype workers, TAIWAN: Pilam (H. Sauter) [examined].