Wen-I Chou click-beetle (Homotechnes choui), a new species from Guangxi

NEWS - Wen-I Chou click-beetle (Homotechnes choui sp. nov.), a new species from Guangxi, China, with antennae extend beyond hind angle of pronotum by about one and a half apical antennomeres. Pronotum with large central black spot, sides subparallel. Legs almost black in dorsal view.

Homotechnes Candèze 1882 (Elateridae: Hypnoidinae) consists of 14 species distributed in China (7 species), Japan (5 species), India (1 species) and Vietnam (1 species), but the actual phylogenetic position within Elateridae still requires further investigation.

H. choui can be distinguished from Homotechnes mertliki Platia 2017 and Homotechnes opacicollis Platia 2017 by the pronotum with a narrow central elongate depression, while the latter two species have an elongate central impunctate carina. The new species differs from other Chinese species by the black legs and subparallel pronotum sides in males.

It can be distinguished from Homotechnes kucerai Platia, Mertlik & Dušánek 2023 and Homotechnes emeiensis Platia 2017 by antennae extending beyond the posterior corner of the pronotum by about one and a half apical antenomeres, while the latter two species have antennae that do not reach the apex of the posterior corner of the pronotum, reduced by about one antenomere.

H. choui occurs in broadleaf forests from April to May. Named after Dr. Wen-I Chou, holotype collector. Male holotype has length 14.4 mm; width 3.4 mm; antenna length 5.5 mm; pronotum length 3.5 mm, width 3.5 mm; elytron length 9.8 mm. Elongate, flattened.

Body smooth, bicolor, head, antennae, center and hind angles of pronotum, elytra, scutellar shield, legs, prosternum and mesoventrite black, claws and hind tibiae lighter; lateral portions of pronotum, chin piece, hypomeron, metasternum, abdomen, reddish brown trochanter.

Head: weakly depressed in middle, anterior margin complete, elevated. Punctures large, umbilicate; intervals between punctures subequal to their diameter. Antenna beyond hind angle of pronotum about one and a half apical antennomeres; serrate from antennomere IV. Scape robust, slightly curved, antennomere III about 1.4 times longer than antennomere II; antennomeres IV to X triangular; apical subrhomboid antennomere.

Thorax: pronotum almost as wide as long, sides subparallel, widest at hind angles. Area before hind angle slightly angularly arched. Hind angle elongated, slightly divergent and curved inward apically, apical portion slightly protruded at inner margin and tapered at apex; carina of hind angle present, short, not reaching hind third of pronotum.

Disc of pronotum weakly convex, center with a longitudinal shallow furrow. Punctures small, intervals between punctures at disc about 4–6 times their diameter, punctures denser and larger laterally, intervals between punctures about 3–4 times their diameter. Pubescence of pronotum curved.

Hypomeron very coarse, with dense punctures; intervals between punctures less than one puncture diameter. Prosternal lobe normally convex, carinate along margin, coarsely punctured, with large umbilicate punctures. Prosternal process straight, apical portion tapered. Metacoxal plate widened inwards, and narrowed from basal third to the outer end.

Scutellum depressed, surface with small and shallow punctures. Elytra elongate, lateral margin weakly arched, widest near middle, 2.9 times as long as pronotum; apical half narrowed, with margins slightly arched. Elytral striae distinctly lined; interstriae flat, with sparse punctures. Hindwings fully developed.

Abdomen: tergite VIII sub-triangular, apical portion weakly enlarged, apex obtuse triangular; sternite VIII membrane, with two dark portions laterally, basally with a narrowed part; tergite IX with hind margin concave, distal portion with two protruded lobes, apices tapered, with long setae, middle shallowly concave; tergite X large, tongue-shaped, apex blunt; sternite IX elongate, hind margin narrowed and protruded in middle, basal portion transparent medially, distal portion narrowed, apex setose, rounded.

Genitalia: median lobe as long as parameter, tapered towards apex, apex rounded. Paramere slender, distal portion with sharp subapical hook, apical portion rounded, slightly elongated and weakly narrowed, outer portion less sclerotized, with small setae laterally.

Male paratypes: body length 13.8–14.7 mm, several specimens from Jinxiu with more narrowed pronotum. In all other respects similar to holotype. The individual of guilin has the lateral portions of pronotum yellow-reddish brown. one specimen from Maoershan having the boundary between the two colors of pronotum indistinct. The shapes of metacoxal plate, tergite VIII, tergite X, sternite IX and apices of parameters may show some variations in different specimens.

Female: similar to male. Body length 15.1–15.3 mm. Body width usually larger than in males. Pronotum with more arched lateral margins, denser punctures, and hind angle with more enlarged apical portion.

Abdominal tergite VIII subtriangular, basal portion in middle less sclerotized; sternite VIII longer than wide, sub-triangular, apical portion pointed, spiculum ventrale slender, about 2.7 times the length of sternite VIII. ovipositor long; coxite with apical portion darkened and elongated, with small pubescence, stylus very small, attached almost near apex . Bursa copulatrix with a pair of large sclerotized plates and a pair of smaller sclerotized plates. All plates bearing dense and long spines.

Homotechnes species from China can be divided into two groups. One consists of H. opacicollis Platia 2017 and H. mertliki Platia 2017 characterized by a pronotum with a narrow mid-longitudinal impunctate carina, the other group contains the remaining species characterized by a pronotum with a shallow mid-longitudinal depression.

Most species of the second group are rather uniform in morphology. They are similar in coloration and have low variability in the form of aedeagus. This species is usually black dorsally, with a striking bicolor pronotum (reddish brown or yellowish brown with a large black spot in the center).

The most useful characters for distinguishing these species are the outline, punctures and color of the pronotum, the color of the legs and the ventral side , and sclerites of the copulatory bursa in females. However, interspecific variation in these characteristics is largely subtle. For a morphologically homogeneous group such as Homotechnes, molecular data and additional morphological evidence must be relied upon.

Original research

Lu Qiu & Yong-Ying Ruan (2024). A new species of genus Homotechnes Candèze, 1882 from Guangxi, China (Coleoptera: Elateridae: Hypnoidinae). Zootaxa 5528 (1): 125–132, DOI:10.11646/zootaxa.5528.1.11

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