Strumigenys lantaui

Strumigenys lantaui is currently only known from a single location where it was collected by leaf-litter extraction at the inner edge of a secondary forest.

Identification
Anterior clypeal margin medially shallowly convex with 6 anteriorly projecting strap-like hairs; lateral margin each with 3 anteriorly directed spatulate hairs that are smaller than those on the clypeal margin. Mandibles without preapical tooth. Antenna 4-segmented. Orbicular hairs present on dorsal surface of scapes, head, pronotum and mesonotum. Mesonotum in profile not forming a differentiated surface between pronotum and propodeum.

Strumigenys lantaui is a member of the argiola complex in the Strumigenys argiola group and shares all the characters (Bolton 2000). S. lantaui is well distinguished from all other Oriental species in the species group by its 4-segmented antennae, and absence of any scale-like, orbicular, or spoon-shaped hairs on the surface of the mandibles. In addition, unlike Strumigenys hirashimai or Strumigenys lachesis, projecting strap-like hairs on the anterior clypeal margin are not directed nor curved towards the midline. It is unlike Strumigenys hexamera and Strumigenys tisiphone, in the absence of preapical teeth, and the mesonotum, in profile, not forming a differentiated surface between pronotum and propodeum.

Strumigenys lantaui (HL 0.36–0.37, HW 0.31–0.33, ML 0.39–0.41) is also a smaller species than all other Oriental species in the species group: S. hirashimai (HL 0.40–0.46, HW 0.36–0.40, ML 0.42–0.48), S. lachesis (HL 0.39, HW 0.39, ML 0.42), S. hexamera (HL 0.50–0.53, HW 0.53–0.55, ML 0.57–0.60), S. tisiphone (HL 0.50, HW 0.48, ML 0.53), and S. sinensis (HL 0.52, HW 0.46, ML 0.50).

Distribution based on Regional Taxon Lists
Palaearctic Region: China.

Nomenclature

 *  lantaui. Strumigenys lantaui Tang, Pierce & Guénard, 2019: 23, figs. 9A-D (w.) CHINA.

Worker
Holotype: TL 1.6, HL 0.36, HW 0.31, MandL 0.10, SL 0.18, EL 0.026, PW 0.20, ML 0.39, PL 0.19, PH 0.09, DPW 0.11, PPL 0.13, GL 0.40, CI 86, MI 28, SI 58, OI 8, LPI 51, DPI 57. Paratype workers (n = 2): TL 1.6–1.7, HL 0.37, HW 0.32–0.33, MandL 0.10–0.11, SL 0.19, EL 0.019–0.022, PW 0.21, ML 0.41, PL 0.19, PH 0.10, DPW 0.11, PPL 0.13–0.14, GL 0.43–0.45, CI 86–89, MI 27–30, SI 58–59, OI 6–7, LPI 53, DPI 55–57.

Head: In full-face view occipital margin broadly concave; occipital corner evenly rounded; lateral margin broadly convex and slightly diverging from one another, then forming blunt angle with the strongly converging upper scrobe margin; anterior clypeal margin broadly concave across its width. In profile vertex at or near its highest point evenly curved and convex, without a raised transverse crest. Antenna 4-segmented; scape dorsoventrally flattened and board; subbasal angle expanded anteriorly into a large subbasal lobe. Mandible in full-face view narrow, elongate, curvilinear and without preapical tooth. Proximal to apices with a prominent diastema between the mandibles, through which the labral lobes are visible. Apex of mandible with a nearly vertical series of minute teeth or denticles; apicoventral teeth markedly enlarged.

Mesosoma: In profile view the dorsum of mesosoma broadly, shallowly convex; pronotum bluntly marginate laterally; mesonotum not forming a differentiated surface between pronotum and propodeum; in dorsal view lateral margin with a bluntly rounded angle on each side and meet anteriorly into a broadly convex anterior margin. Propodeum unarmed, declivity with a lamella running down each side. Waist Segments: Petiole in profile elongate and subclavate; peduncle does not grade evenly into the node; node in dorsal view long about the same as broad. Disc of postpetiole in dorsal view broader than long and slightly shorter or about the same as petiolar node. Spongiform tissues present on both petiole and postpetiole; ventral lobes of postpetiole in particular extensive; lateral lobe of petiole restricted to posterior portion of the node in profile; in dorsal view present along the posterior margin of the petiolar node, and surrounding disc of postpetiole.

Pilosity: Anterior clypeal margin with 6 anteriorly projecting strap-like hairs; lateral margin each with 3 anteriorly directed spatulate hairs that are smaller than those on clypeal margin. Leading edge of scape with row of basally directed spatulate hairs. Orbicular hairs present on dorsal surface of scapes and all over the cephalic dorsum, including clypeal dorsum, and promesonotal dorsum; dorsal surface of mandibles with short appressed simple or spatulate hairs. Dorsal surfaces of tibiae with short appressed spatulate hairs. Petiolar node and disc of postpetiole with posteriorly directed spatulate hairs, and at most a few decumbent to suberect short simple hairs on the disc of postpetiole; first gastral tergite with numerous short, simple standing hairs.

Sculpture: Cephalic dorsum, including surface of antennal scrobe and antenna, areolate. Dorsum of mesosoma and side of pronotum areolate to densely reticulate-punctate, and with fine reticulopunctate; mesopleuron and side of propodeum mostly smooth and shining, while in some specimens those can appear opaquer but with undefined sculpture. Dorsum of petiolar node and disc of postpetiole generally smooth and shining; basigastral costulae short and arise across entire width of tergite.

Type Material

 * Holotype worker: Hong Kong, Lantau Island, Penny’s Bay, 22.3271N, 114.0335E, 9 m, 25 October 2017 (M. Pierce) (collection code WC-PBNON-06), Winkler [IBBL, ANTWEB1009620].
 * Paratype workers (n = 2): same data as holotype.

Etymology
This species is named after Lantau Island, the type locality and currently only known location for the species.