Strumigenys hirsuta

Strumigenys hirsuta appears to be widespread in Hong Kong and has been collected from multiple locations in Hong Kong Island, the New Territories, and Lantau Island. Considering the widespread distribution of this species in Hong Kong and its association with disturbed secondary forests or forest remnants, we hypothesize that the geographic range of this species might extend further. It seems likely that this species also occurs in Guangdong province (China). The known elevation range is from 1 to 459 m.

Identification
Dorsolateral margin of head in full-face view with at most 4 freely laterally projecting flagellate hairs: 1 on the upper scrobe margin posterior to the level of eye, 1 at apicoscrobal position, 0–2 posterior to this on the lateral margin of occipital lobe. Cephalic dorsum, dorsal mesosoma and side of pronotum densely and strongly reticulate-punctate; metapleuron and side of propodeum reticulate-punctate but weaker and fainter than on the dorsum; katepisternum mostly smooth and shining. Dorsal and ventral surfaces of femur with numerous fine erect to suberect hairs. SI 61–63.

Strumigenys hirsuta is a member of the caniophanes complex in the Strumigenys caniophanes-group (Bolton 2000). There are six other species (Strumigenys dipsas, Strumigenys paraposta, Strumigenys lacunosa, Strumigenys benulia, Strumigenys daithma, and Strumigenys pliocera) from the species group that also have unsculptured (or at least not completely sculptured) katepisternum as in S. hirsuta. In comparison, S. dipsas and S. paraposta both have reticulate-rugulose sculpture with fine punctulate on the cephalic dorsum, and predominant longitudinal rugulose sculpture on the pronotal dorsum (instead of simply predominant reticulate-punctate on both cephalic and pronotal dorsum as in S. hirsuta); S. lacunosa, S. benulia, and S. daithma have their entire pleurae and side of propodeum mostly smooth (instead of katepisternum only); S. pliocera has no erect hairs on the dorsal surface of its hind femur, unlike S. hirsuta.

Strumigenys hirsuta (HL 0.71–0.74, HW 0.53–0.55, ML 0.74–0.78) is a smaller species than S. dipsas (HL 0.80–0.86, ML 0.87–0.90) and S. pliocera (HL 0.89, ML 0.90); and a larger species than S. benulia (HL 0.56, HW 0.39, ML 0.56). Strumigenys hirsuta (SI 63–65) also has a markedly relatively shorter scape than those 6 species from the caniophanes-complex: S. benulia (SI 72), S. dipsas (SI 73–76), S. paraposta (SI 73–78), S. lacunosa (SI 75), S. daithma (SI 85), and S. pliocera (SI 84).

Distribution based on Regional Taxon Lists
Palaearctic Region: China.

Biology
Malaise traps in Hong Kong (Tang et al. 2019) yielded female alates in sampling conducted over the entire month of June.

Nomenclature

 *  hirsuta. Strumigenys hirsuta Tang, Pierce & Guénard, 2019: 18, figs. 6A-C, 7A-C (w.q.) CHINA.

Worker
Holotype: TL 3.1, HL 0.74, HW 0.55, MandL 0.30, SL 0.35, EL 0.054, PW 0.31, ML 0.79, PL 0.35, PH 0.15, DPW 0.14, PPL 0.22, GL 0.69, CI 75, MI 41, SI 63, OI 10, LPI 42, DPI 40. Paratypes (n = 5): TL 2.9–3.1, HL 0.71–0.74, HW 0.53–0.55, MandL 0.29–0.30, SL 0.34–0.35, EL 0.050–0.057, PW 0.29–0.31, ML 0.74–0.78, PL 0.32–0.34, PH 0.13–0.15, DPW 0.14, PPL 0.20–0.21, GL 0.63–0.70, CI 73–75, MI 40–42, SI 63–65, OI 9–11, LPI 41–44, DPI 43–45.

Head: In full-face view occipital margin evenly concave; occipital corners well developed and bluntly rounded; anterior clypeal margin transverse to very shallowly concave across its width. Scapes subcylindrical, marginated but not converging anteriorly to form a thin lamella at the leading edge. Mandible in full-face view long, narrow and elongated, with an elongated preapical tooth located close to the apicodorsal tooth; at the basal third of their length diverging from one another and curving inward, then running straight and parallel at the middle third, and curving inward and converging at the apical third; width of mandible fairly constant from the basal portion to where the preapical tooth first arose; the preapical tooth about the same to slightly longer than the width of mandible at the point where the tooth arises; apicodorsal tooth is markedly longer than apicoventral tooth.

Mesosoma: In profile pronotal dorsum broadly convex, with the rest of the dorsum of the mesosoma more or less flat transversely; pronotum marginate dorsolaterally. In dorsal view, lateral margins of the pronotum evenly convex. Propodeal teeth short, triangular and acute, and not subtended by lamella.

Waist Segments: Petiole in profile claviform, the node long and low; the peduncle grade evenly into the node without a marked change of slope; node in dorsal view longer than broad. Disc of the postpetiole in dorsal view very slightly broader than long, and slightly shorter than petiolar node. Spongiform tissues present on both petiole and postpetiole; ventral lobes of petiole and postpetiole extensive. In profile view, spongiform tissues present ventrally on the peduncle of the petiole notably larger than that under the petiolar node portion, and markedly thicker than the height of the peduncle. Lateral lobe of petiole restricted to posterior half of the node in profile; in dorsal view present along the posterior margin of the petiolar node and surrounding the disc of postpetiole.

Pilosity: Dorsolateral margin of head in full-face view with at most 4 pairs of freely laterally projecting flagellate hairs: 1 on the upper scrobe margin posterior to the level of eye, 1 at apicoscrobal position, 0–2 posterior to this on the lateral margin of occipital lobe. Cephalic dorsum, against ground pilosity of short, suberect to decumbent, simple hairs, with several erect flagellate hairs close to the occipital margin but without erect hairs anterior to this. Leading edge of scape with apically directed, decumbent simple hairs. Pronotal humeral hair long, flagellate or looped apically. Dorsum and side of mesosoma covered with ground pilosity of short, suberect hairs arising and curving in various directions. Dorsal and ventral surfaces of femur with numerous fine erect to suberect hairs against ground pilosity of appressed hairs; dorsal surface of tibia and basitarsus with 1–4 long filiform erect hairs on each segment. Petiolar node and postpetiole with numerous erect to suberect, flagellate hairs against ground pilosity of posteriorly directed, shorter decumbent hairs; first gastral tergite with numerous curved to subflagellate erect hairs.

Sculpture: Cephalic dorsum densely and strongly reticulate-punctate. Dorsal mesosoma and side of pronotum densely and strongly reticulate-punctate, occasionally with very weak and faint rugulose; metapleuron and side of propodeum also reticulate-punctate to punctate, with reticulation limited to the dorsal half of the propodeum, and weaker and fainter than on the dorsum or side of pronotum, sometimes even partially smooth and shining; katepisternum mostly smooth and shining, with some light punctation and vestiges of sculpture around the margins. Anterior coxae with weak transverse rugulae. Petiole and disc of postpetiole densely and strongly reticulate-punctate. Basigastral costulae arise across the entire width of tergite, short and limited to the basal third or fourth of tergite.

Queen
Holotype queen: TL 3.6, HL 0.78, HW 0.59, MandL 0.31, SL 0.37, EL 0.12, PW 0.38, ML 0.89, PL 0.44, PH 0.19, DPW 0.19, PPL 0.23, GL 0.90, CI 76, MI 40, SI 62, OI 21, LPI 43, DPI 44.

Similar to all points to the worker caste except for the reproductive caste morphological characters (presence of 3 ocelli, enlarged eyes and thorax), and the following: in profile view, most of anepisternum and katepisternum distinctly smooth and shiny.

Type Material

 * Holotype worker: Hong Kong, Hong Kong Island, Lung Fu Shan, 22.27899N, 114.13717E, 211 m, 18 November 2014 (M. Wong) (collection code F2W-m2) [IBBL, ANTWEB1009855].
 * Paratype workers (n = 5): same data as holotype worker.
 * Paratype (not holotype) queen: same data as holotype worker.

Etymology
The species is named for the multiple standing and convoluted hairs present on most of the body.

References based on Global Ant Biodiversity Informatics

 * Tang K.L., Pierce M.P., and B. Guénard. 2019. Review of the genus Strumigenys (Hymenoptera, Formicidae, Myrmicinae) in Hong Kong with the description of three new species and the addition of five native and four introduced species records. ZooKeys 831: 1-48.