Strumigenys datryx Bolton, 2000

Musfira, S. H., Rafi, M., Gusti, M., Putri, D. H. & Satria, R., 2022, New data on the genus Strumigenys (Hymenoptera: Formicidae) from Sumatra, Zoosystematica Rossica (Zoosyst. Rossica) 31 (1), pp. 74-86 : 78-79

Strumigenys datryx Bolton, 2000

( Fig. 1A–D )

Strumigenys datryx Bolton, 2000: 806 (worker; type locality: Sumatra, 10 km W of Padang Panjang , 250 m).

Material examined. Indonesia, West Sumatra Prov., Padang, Pauh, Limau Manis , Sarasah Uwak waterfall, 0°54′47.7″S 100°28′54.8″E, ca. 380 m, 6.II.2021, 1 dealate queen (individual code SEMU- T 2iv2021, colony code RS6ii21), 3 workers (colony code RS6 ii21), R. Satria leg.

Description of dealate queen. Measurements: TL 1.86 mm, HW 0.34 mm, HL 0.45 mm, ML 0.17 mm, EL 0.07 mm, SL 0.23 mm, WL 0.49 mm, PW 0.22 mm, PTH 0.1 mm, PTL 0.22 mm, PPTH 0.11 mm, PPTL 0.12 mm, GL 0.41 mm, GW 0.33 mm, CI 75, MI 38, SI 68.

General appearance of queen similar to that of worker described by Bolton (2000). Head in full-face view subtriangular, longer than broad, with posterior margin deeply concave, with posterolateral margin roundly convex ( Fig. 1A ). Ocelli present; distance between lateral ocelli equal to distance between lateral and median ocelli, and twice as long as major axis of median ocellus; ocelli in lateral view slightly protruded dorsally. Eye large, circular or elliptical, with about 27 ommatidia. Antenna 6-segmented; 3rd and 4th segments reduced, appearing as a single segment; apical segment of antenna large, elongate, cylindrical. Anterior clypeal margin almost straight. Mandibles elongate, linear; outer and inner mandibular margins evenly curved; apex of mandible with two spiniform teeth; intercalary denticle absent; single spiniform tooth present on preapical dentition.

Mesosoma with main sclerites associated with wing function ( Fig. 1B, D ), in dorsal view short and stout. Anterodorsal slope of pronotum gentle in lateral view; anterodorsal outline of mesoscutum relatively gentle in lateral view. On propodeum in lateral view, lamella dorsally adjoining to base of ventral margin of tooth.

Head, mesoscutum and mesoscutellum entirely reticulate-punctate. Pronotum generally reticulate-punctate, with dorsolateral part smooth and shiny; lateral face of mesonotum and propodeum smooth and shiny. Petiole generally reticulate-punctate, with its dorsum smooth and shiny; dorsum of postpetiole smooth and shiny. Gaster entirely smooth and shiny; first gastral tergite with basigastral costulae ( Fig. 1C ).

Body entirely covered with erect and appressed simple hairs. Apiscrobal hair present, long and flagelliform; clypeus densely covered with appressed hairs; antennal scape and funiculus entirely covered with fine appressed hairs; mandibles covered with fine appressed hairs. Pronotal humeral hair present, flagellate, very long and slender; pronotum with some erect hairs shorter than pronotal humeral hairs; mesonotum with erect hairs; propodeal declivity covered with spongiform structures; dorsal (outer) surface of hind basitarsus with one freely projecting filiform hair being very long and suberect to erect. Petiole, postpetiole and gaster covered with long fine flagelliform hairs. Ventral face of petiole in lateral view with longitudinal spongiform structures.

For colour pattern, see Fig. 1A–D ; body and appendages yellowish brown.

Comparison. Bolton (2000) noted that Strumigenys datryx is superficially similar in the worker morphology to S. rofocala . The work- er of S. datryx can be distinguished from that of S. rofocala by the following characters: a flagellate hair present on the hind basitarsus (vs. absent in S. rofocala ), the apical antennal segment broad basally and broadly articulat- ed to the preapical segment (vs. the base of the apical antennal segment attenuated and narrowly articulated to the preapical antennomere in S. rofocala ) ( Bolton, 2000). In the present study, we found clear differences in the queen morphology between S. datryx and S. rofocala (CASENT0104944, paratype, queen): in S. datryx , the distance between the lateral ocelli is equal to the distance between the lateral and median ocelli and twice as long as the major axis of the median ocellus (vs. the distance between the lateral ocelli is shorter than the distance between the lateral and median ocelli and four times as long as the major axis of the median ocellus in S. rofocala ), the lateral surface of the pronotum is partially smooth and shiny (vs. entirely sculptured in S. rofocala ), the mesonotum and the propodeum are entirely smooth and shiny (vs. generally smooth and shiny, with its dorsolateral part sculptured), and the mesoscutum is densely covered with erect and appressed hairs (vs. sparsely covered with erect and appressed hairs).

Distribution. West Malaysia ( Guénard et al., 2017), Java ( Guénard et al., 2017) and Sumatra ( Bolton, 2000; present study); Bolton (2000) recorded this species from two provinces of Sumatra, West Sumatra and Jambi.

Figures

Fig. 1. Strumigenys datryx Bolton, 2000, dealate queen (individual code SEMUT2iv2021). A, head in dorsal view; B, body in lateral view; C, gaster in dorsal view; D, body in dorsal view. Scale bars: 0.25 mm (A, C), 0.5 mm (B, D).