Ceratus antennatus Otto, 2015

Otto, Robert L., 2015, A new genus and four new species of false click beetles (Coleoptera: Eucnemidae) from Southeast Asia, Insecta Mundi 2015 (404), pp. 1-11 : 9-10

Ceratus antennatus Otto , new species

Fig. 7–10

Diagnosis. Much longer than wide, asymmetrically serrate antennomeres will distinguish this new species from other Ceratus species in the Philippines and remaining Southeast Asia.

Description. Male holotype: Length, 5.0 mm. Width, 1.5 mm. Body subcylindrical, moderately elongate, tapering towards the elytral apex; uniformly black; antennae dark brown; legs dark reddish-brown; head, pronotum and elytra clothed with short, white recumbent setae ( Fig. 7 ).

Head: Very closely punctate, subspherical; frons convex, with very delicate median carina; surface shiny; epistomal part of epicranium with interoccular carina at base; apical margin of epistomal part of epicranium feebly trilobed, more than 2.5 times wider than base; mandibles stout.

Antennae ( Fig. 8 ): Strongly, asymmetrically serrate; nearly as long as the length of the body; setose; antennomere II and III short, combined shorter than IV; antennomeres IV weakly serrate, slightly shorter than V; antennomere V serrate, slightly shorter than VI; antennomeres VI–X each strongly and asymmetrically serrate, subequal and longer than wide; antennomere XI elongate, slightly longer than X.

Pronotum: Very closely punctate, almost rugose; surface shiny; slightly longer than wide, with short, sharp hind angles; laterally parallel-sided, rounded anteriorly; disc simple, convex; base sinuate, with short, median groove above scutellum.

Scutellum: Shallowly punctate, shining, oblong, sub-triangular and distally rounded.

Elytra: Very shallowly striate; interstices flattened; surfaces very closely punctate.

Legs: First tarsomere shorter than the combined lengths of the remaining four on mesothoracic and metathoracic tarsi; tibiae rounded in cross section; metathoracic tarsomeres I–III simple; metathoracic tarsomeres IV excavate-emarginate; metathoracic tarsomere V elongate with simple claws.

Venter ( Fig. 9 ): Closely punctate, with short, recumbent white setae; hypomeron with well-developed basally opened lateral antennal grooves, widest near middle; hypomeral pit present near anterior end of antennal groove; metathoracic episternum caudally widened; metathoracic coxal plates medially 3.0–6.0 times wider than laterally.

Male aedeagus ( Fig. 10 ): Basal piece oblong, apically tapered; median lobe elongate, narrowly bilobed; lateral lobes short, apically rounded; secondary lateral lobes basally attached to lateral lobes, elongate, apically rounded.

Variation. Five adult male paratypes were examined. Lengths of five specimens measured 5.0 mm; consistent with the holotype. Three paratypes were measured at 1.5 mm wide. The remaining two were wider, measuring 1.75 mm. Several specimens show a slight brownish coloration on the elytra, which may be attributed to its slight teneral state at the time of collection. On those same three specimens, antennal and leg colorations are slightly lighter. There are no variations in the exoskeletal structures among the paratypes in relation to the holotype.

Type material. Holotype, male, with label data: “W. THAILAND: 300 m., Thung Yai Wildlife Sanctuary, 15º 30’ N- 98º 48’ E ” / “ Tak Province, Umphang District, Mae Chan / Mae Klong confluence, 27.iv.– 6.v.1988 ” / “oak/bamboo forest, M.J.D. Brendell, B.M. 1988–183.” / “ HOLOTYPE:, Ceratus , antennatus, Otto , det. R.L. Otto, 2014” (♂ handwritten behind species name on label) [red printed label] . Holotype in BMNH .

Paratypes. 5, each with label data: “W. THAILAND: 300 m., Thung Yai Wildlife Sanctuary, 15º 30’ N 98º 48’ E ” / “ Tak Province, Umphang District, Mae Chan/Mae Klong confluence, 27.iv.–6.v.1988 ” / “oak/ bamboo forest, M.J.D. Brendell, B.M. 1988–183.” / “ PARATYPE:, Ceratus , antennatus, Otto , det. R.L. Otto, 2014” (♂ handwritten behind species name on label) [yellow printed label]. Paratypes in BMNH and GERP.

Distribution. The species is known from a single locality in western Thailand.

Biology. All specimens were taken in a mixed forest consisting of oaks ( Quercus spp.; Fagaceae ) and bamboo ( Bambusa spp; Poaceae ). Developmental stages remain unknown.

Etymology. The specific epithet is derived from the presence of its elongate, asymmetrically serrate antennae.

Remarks. Fleutiaux (1926) provided a key to most species from the Philippines. Cobos (1986) described two new species from the Philippines, but did not provide an updated key for the group. The presence of a delicate median carina on the frons along with the interocular carina above the epistomal part of epicranium as well as the antennal structures will distinguish the new species from known Ceratus species in the region.

Figures

Figures 6–10. Two new species of Eucnemidae. 6) Spinifornax elongatus Otto, n. sp., dorsal of holotype. 7) Ceratus antennatus Otto, n. sp., dorsal of holotype. 8) Ceratus antennatus Otto, n. sp., antenna of paratype. 9) Ceratus antennatus Otto, n. sp., venter of paratype. 10) Ceratus antennatus Otto, n. sp., aedeagus of paratype, dorsal view.