Polycaon sinensis Liu & Beaver, 2023

Liu, Lan-Yu & Beaver, Roger A., 2023, The first Asian species of Polycaon Castelnau, and a new montane species of Melalgus Dejean from China (Coleoptera: Bostrichidae: Polycaoninae), Zootaxa 5315 (3), pp. 271-281 : 273-275

Polycaon sinensis Liu & Beaver sp. n.

Figs. 1 a–g

Type material. Holotype: Male: CHINA: Zhejiang, Gutianshan NNR, 118.15°E, 29.25°N, 880m, 2010, local collector. (Deposited in NME.)

Allotype: Female : CHINA: same data as holotype. (Deposited in NME.)

Paratypes: same data as for the holotype (3♁, 3♀ NME) ; as previous but: 118.11°E, 29.24°N, secondary forest, 410m (1♁, 1♀ LYLC; 1♁ RABC; 2♁, 2♀ IOZ) ; as previous but: 118.11°E, 29.25°N, 507m (2♁, 2♀ IOZ, 1♀ RABC) .

Male.

Body. 13.5‒17.0mm long (mean = 14.2, n = 11), 2.75‒3.7 times as long as wide. Head, thorax and abdomen black to dark reddish-brown, elytra dark reddish-brown at base becoming paler towards apex.

Head. As wide as the anterior margin of pronotum, shining, broadly transversely impressed behind eyes; fronto-clypeal area with a broad median impression extending to upper margin of eyes, more deeply impressed in centre at level of obsolete fronto-clypeal suture; surface densely granulate, except for a narrow median band extending from frons across post-ocular transverse impression, granules rounded, weakly developed in fronto-clypeal impression, each granule bearing a long, fine, semi-recumbent, hair-like seta, or less often a longer, erect seta; vertex domed with granules concentrically arranged around summit; clypeus truncate anteriorly above labrum, its anterior margin broadly emarginate, surface granulate except on the impunctate anterior slope; labrum short, arcuately emarginate, almost smooth, finely punctured, fringed on anterior margin with dense, short, yellowish setae; mandibles large, robust, asymmetrical, the right excavated on the antero-ventral face, and toothed on its inner margin, lateral face concave. Eyes round, globose, strongly projecting. Antennae with 10 antennomeres, with a few semierect setae; third segment distinctly shorter than fourth; funicle half as long as club, three club antennomeres subequal in length, first two antennomeres subtriangular, last antennomere oblong-oval, each with two fine longitudinal canaliculi on both anterior and posterior sides, in the last antennomeres, the canaliculae connect apically to form a deep Cshape.

Pronotum. 1.2 times wider than long, narrower than base of elytra, widest near apical fourth, with a narrow, impressed, median line extending about half the length from the base, and a large heart-shaped depression in middle of disc; sides convex, broadly rounded anteriorly, obliquely narrowly posteriorly; surface moderately shining, granulate basally and at sides, punctate dorsally in anterior three-quarters, punctures fine, moderately dense, each bearing a long, erect hair-like seta.

Scutellum. Visible part short, weakly linguiform, densely punctured, punctures with short, very fine, hair-like setae.

Elytra. 2.2 times longer than wide, parallel-sided in anterior two-thirds, then slightly narrowed to broadly conjointly rounded, explanate apex, arcuately declivous posteriorly, moderately shining, very finely, moderately densely punctured in basal third, punctures becoming more closely spaced posteriorly, each bearing a short, recumbent hair-like seta; lateral margin with a fine carina extending from base almost to apex of elytra.

Abdomen. Very finely, densely punctate, punctures bearing rather long, fine, appressed hair-like setae, a few erect setae towards sides.

Protibia. Long, gradually widening towards apex, without a basal constriction, exterior margin with a row of small, pointed teeth, terminal spur strong, anterior face very finely, densely granulate with dense, short hair-like setae, posterior face more coarsely and less densely granulate, with longer setae.

Female.

Generally resembling male, 11.0‒16.0 mm in length (mean = 13.75, n = 10), 2.9‒3.6 times as long as wide, pronotum 1.1 times wider than long, elytra 2.2 times longer than wide.

Distinguished from male by head narrower than pronotum, without a wide median fronto-clypeal impression, but a small pit in in middle of frontal-clypeal suture, sometimes with recumbent pubescence towards centre of pit, not transversely impressed behind eyes, more finely, weakly granulate, becoming punctate in a narrow median band extending to vertex; clypeus not truncate anteriorly, obliquely sloping, almost flat, its anterior margin very weakly concave. Pronotum slightly less wide than long, without a distinct impression medially, densely granulate over whole surface. Elytra more strongly and distinctly punctured, weakly granulate close to base. Protibia with apical spurs shorter and weaker.

Diagnosis. The species can be distinguished from other Chinese Polycaoninae by the characters given in the key above, and in the diagnosis of Polycaon . It is distinguished from all American species, except P. granulatus Van Dyke by the antennae with 10 antennomeres not 11. It is distinguished from P. granulatus by the smooth elytra, lacking the rounded granules covering the elytral surface in P. granulatus . The male is also distinguished by the jointly rounded elytral apices (emarginate and with a sharp denticle on each side in P. granulatus ).

Distribution. China (Zheijiang).

Etymology. The specific name refers to the country where the specimens were collected.

Remarks. The new species is the first species of Polycaon found in the Oriental region. The senior author received numerous specimens from NME collected during the long-term investigation at Gutianshan. They were collected between 410m and 903m altitude. The lack of elytral granules and the jointly rounded elytral apices of the male suggest that the species may be more closely related to the American species with 11 antennomeres, rather than P. granulatus with only 10. Compared with the American species, the new species is rather female-like. It is smaller, the head is narrower than the pronotum, and the vestiture is denser and longer.

Figures

FIGURE 1. Polycaon sinensis sp. nov. a. Female dorsal view. b. Female lateral view. c. Male frontal view. d. Female frontal view. e. Male elytral declivity. f. Female elytral declivity. g. Antenna.