Miruantennus cuneiformis, , Otto, 2017

Otto, Robert L., 2017, Descriptions of six new species of false click beetles (Coleoptera: Eucnemidae: Macraulacinae), with new identification keys for one tribe and two genera, Insecta Mundi 2017 (558), pp. 1-19 : 11-12

Miruantennus cuneiformis sp. nov.

Fig. 23–27

Diagnosis. Black coloration and strongly cuneiform habitus will distinguish the new species from M. basalis and M. chinensis .

Description. Male holotype: Length, 7.0 mm. Width, 1.25 mm. Body subcylindrical, elongate, strongly cuneiform toward elytral apex; uniformly black; scape and antennomeres VI–XI black, pedicel and antennomeres III–V dark brown; femur and tibiae dark brown, tarsi dark brown; head, apical 2/3 of pronotum and much of elytra clothed with short, recumbent whitish setae; basal 1/3 of pronotum, elytral humeri and sutural areas with elongate, recumbent whitish setae ( Fig. 23–24 ).

Head: Densely punctate, almost rugose, subspherical; frons convex, without median carina or fovea above frontoclypeal region; surfaces shiny; apical margin of frontoclypeal region rounded, about 2.0 times wider than base; mandibles stout, bidentate, densely punctate.

Antenna ( Fig. 25 ): Capitate from antennomeres VIII–XI, attaining elytral humeri; antennomere III short, as long as II; antennomere IV slightly shorter than III, as long as V; combined lengths of antennomeres IV and V longer than III; antennomeres VI and VII quadrate, both larger than V; antennomeres VIII–XI each much longer than wide, as long as the combined lengths of III–V together.

Pronotum: Surfaces dull, densely rugose to granulose; longer than wide, with moderate, sharp hind angles; lateral sides arcuate, slightly constricted basally above hind angles; disc convex with shallow median groove, without circular fovea; base sinuous, slightly depressed at either side above scutellum.

Scutellum: Short, sub-triangular, medially elevated and distally rounded.

Elytra: Indistinctly striate, except along elytral humeri and sutural areas; interstices flattened; surfaces shiny with dense punctures.

Legs: First tarsomere as long as the combined lengths of the remaining four on mesothoracic and metathoracic tarsi; tibiae rounded in cross section; metathoracic tarsomeres I–III simple; metathoracic tarsomere IV excavated; metathoracic tarsomere V elongate with basally swollen claws.

Venter: Closely punctate, with elongate, recumbent whitish setae; hypomeron simple, without lateral antennal grooves; metathoracic episternum apically wide; metathoracic coxal plates medially 3 times wider than laterally.

Variation. One male and one female paratype were examined. Male paratype measured 6.5 mm long and 1.0 mm wide, slightly shorter and narrower than the holotype. Female paratype ( Fig. 26 ) measured 4.5 mm long and 1.0 mm wide, also shorter and narrower than the holotype. Male paratype differs from the holotype on a number of features. Firstly, arrangement of elongate setae on the basal 1/3 of the pronotum as well as elytral humeri and sutural areas are absent in the male paratype. Secondly, median groove on the pronotal disc is also absent in the paratype. Lastly, pedicel and antennomeres III–V are darker than the holotype. Female paratype differs from the male holotype based on two features. First, the last abdominal segment is hidden beneath the elytra, exposed beyond elytral apices in males. Second, female antennal structures ( Fig. 27 ) are markedly different than the holotype. For female paratype, antennomere III much longer than IV; combined lengths of antennomeres IV and V as long as III; antennomere VI as long as V; antennomere VII slightly longer and wider than VI, shorter than VIII; antennomeres VIII–X each wider than VII, quadrate; antennomere XI slightly longer than X.

Type Material. Holotype, ♂: “ Borneo, Sabah, 1240m, Crocker Range, IV.2013, Kota Kinabalu → Tambunan, N5°51’33.7” E116°17’24.1”, General collecting” / “ BMNH {E} 2013-58, M.V.L.Barclay, B.H.Garner, H.Mendel and A.Giusti” / “ BMNH (E), 1221775” (label upside-down) / “ HOLOTYPE:, Miruantennus , cuneiformis, Otto , det. R.L. Otto, 2015” (♂ handwritten behind species name on label) [red printed label]. Holotype deposited in BMNH.

Paratypes. 1♂, 1♀: MALAYSIA: 1♂, “Borneo, 15– 27.4.1993, Sabah Crocker Mt., Gunong Emas env., Jenis and Strba leg.” / “Collection of the Global, Eucnemid Research Project, (Robert L. Otto)” (green framed white label) / “ PARATYPE:, Miruantennus , cuneiformis, Otto , det. R.L. Otto, 2015” (♂ handwritten behind species name on label) [yellow printed label]; 1♀, “W MALAYSIA – Pahang, Cameron Highlands Mts., Tanah Rata, 1000–1500m, 2–9.iv.1997, P. Čechovský leg.” / “Collection of the Global, Eucnemid Research Project, (Robert L. Otto)” (green framed white label) / “ PARATYPE:, Miruantennus , cuneiformis, Otto , det. R.L. Otto, 2015” (♀ handwritten behind species name on label) [yellow printed label]. Paratypes are retained in GERP.

Distribution. This species is known from two localities; one of which is the mountainous region on Peninsular Malaysia and the second, a mountain range on Bornean Malaysia.

Biology. One specimen was taken in the low to mid-elevation tropical highland forest on the peninsula. Two specimens were taken from a montane forest near Sabah in the northern areas of Borneo. Larvae and pupae are unknown.

Etymology. Specific epithet is derived from the overall general form of the new species, that being strongly cuneiform, compared with two other congeners of the group.

Remarks. Although many groups within the tribe exhibit some form of sexual dimorphism among each species; none is more extreme as Miruantennus , with stark differences in antennal structures and last visible ventrite between males and females in the recently described group. Males are highly diagnostic. Females are a bit more difficult to diagnose. Female Miruantennus are very similar to Nematodes and Trigonopleurus . Female Miruantennus differs from any Nematodes species based on the metathoracic episterna, apically wide in Miruantennus and parallel-sided in Nematodes . Female Miruantennus is further diagnosed from Trigonopleurus based on the combined lengths of antennomeres IV and V in relation to antennomere III; IV and V together shorter than III in Trigonopleurus versus as long as or longer in Miruantennus .

Figures

Figures 23–27. Miruantennus cuneiformis sp.nov. 23) Male holotype (BMNH), dorsal habitus. 24) Male holotype (BMNH), lateral habitus. 25) Male holotype (BMNH), antenna, dorsal view. 26) Female paratype (GERP), dorsal habitus. 27) Female paratype (GERP), antenna, dorsal view. Scale line = 1.0 mm.