Microrhagus breviangularis Otto, 2015

Otto, Robert L., 2015, Eucnemid larvae of the Nearctic region. Part V: Fifth instar larval descriptions for eight species of Microrhagus Dejean, 1833 (Coleoptera: Eucnemidae: Melasinae: Dirhagini), with descriptions of four new species and notes on their biology, Insecta Mundi 2015 (421), pp. 1-46 : 11-12

Microrhagus breviangularis Otto , new species

Adults

( Fig. 34–37 )

Diagnosis. Simply serrate, darker colored antennae will distinguish the species from M. brunneus . Whereas M. brunneus is distinguished by its lighter colored, strongly serrate to asymmetrically serrate antennae.

Description. Male holotype: Length, 3.0 mm. Width, 1.0 mm. Body subcylindrical, moderately elongate and tapering towards the elytral apex; uniformly black; antennae dark brownish-black, except antennomeres I–II reddish; femur dark brown; tibiae and tarsi medium brown; head, pronotum and elytra clothed with yellow recumbent setae, more apparent on pronotal base and elytra ( Fig. 34 ).

Head: Closely punctate, subspherical with convex frons; surface shiny; apical margin of frontolclypeal region feebly trilobed, about 2.5 times wider than base; mandibles stout, bidentate, densely punctate.

Antennae: Moderately serrate from antennomeres V–X, reaching almost three-fourths the length of the body, setose. Antennomere III longer than IV; antennomeres IV–X each subequal, slightly longer than wide; antennomere XI slightly longer than X.

Pronotum: Closely, shallowly punctate; surface shiny; longer than wide, with short hind angles; laterally parallel-sided, slightly wider apically; disc simple; base sinuous, with short, median carina above scutellum; sides ( Fig. 35 ) with two lateral ridges; anterior lateral pronotal ridge short, obliquely bent, about one-third the length of pronotum; posterior lateral pronotal ridge extending up to half the length of pronotum.

Scutellum: Punctate, short, wider, triangular and distally rounded.

Elytra: Indistinctly striate; interstices flattened; surfaces densely punctate to transversely rugose at basal third, closely punctate in remaining two-third.

Legs: First tarsomere longer than the combined lengths of the remaining four on mesothoracic and metathoracic tarsi; tibiae rounded in cross section; lateral surfaces of mesothoracic and metathoracic tibiae with single spines; metathoracic tarsomeres I–III simple; metathoracic tarsomeres IV truncate and excavated; metathoracic tarsomere V elongate with simple claws.

Venter ( Fig. 36 ): Punctate, with recumbent yellowish setae; hypomeron with notosternal antennal grooves; metathoracic episternum caudally widened; metathoracic coxal plates medially 2.5 times as wide as laterally.

Male aedeagus ( Fig. 37 ): Basal piece oblong, narrow, rectangular, about as long as remaining aedeagus; remaining aedeagus short, narrow, as wide as basal piece; lateral lobes short, simple, apically narrowed; secondary lateral lobes fused with lateral lobes; median lobe widened, elongate, apically bilobed.

Female allotype: 4.0 mm long; antennae strongly serrate, reaching two-third the length of the body; legs and antennae slightly darker; pronotum parallel-sided.

Variation. Twenty-two adult paratypes were examined. Thirteen male paratypes varied in length from 3.0– 3.75 mm. Nine female paratypes varied in length from 3.5–4.0 mm. Females are on average slightly larger than the males. Pronotal basal carina above the scutellum shows some degree of structural variation, ranging from near absent to more pronounced. All paratypes except for one female lack the infuscate brownish coloration along the elytral suture. Antennal coloration showed some variability. In four specimens, antennae are brownish, most likely attributed to their slightly teneral state at the time of preservation. In general, antennae are similar to the holotype, that being brownish-black with reddish antennomere II. The posterior lateral pronotal ridge is slightly longer in all paratypes, reaching as long as two-thirds the length of the pronotum, shorter in the holotype.

Figures

Figures 34–37. Microrhagus breviangularis Otto. 34) Holotype, dorsal view. 35) Holotype, lateral view. 36) Holotype, ventral view. 37) Aedeagus of paratype. Scale line = 0.5 mm.