Microrhagus opacus 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 : 10-11

Microrhagus opacus Otto , new species

Adults

( Fig. 30–33 )

Diagnosis. Within the group, M. opacus is distinguished by its duller, coarsely, deeply punctate to rugose pronotal surfaces, as well as presence of slightly elevated scutellum, anterior lateral pronotal ridge directed posteriorly and lateral side of pronotal hind angles with broadly rounded apices. Whereas, M. audax is characterized by finely punctate, shiny pronotal surface, flattened scutellum, anterior lateral pronotal ridge sinuous, directed ventrally as well as lateral sides of pronotal hind angles with narrowly rounded apices.

Description. Male holotype: Length, 3.25 mm. Width, 1.25 mm. Body subcylindrical, moderately elongate and tapering towards the elytral apex; uniformly black; antennae brownish-black, except antennomere I–II infuscate reddish-brown; femur and tibiae dark brown; tarsi yellowish-brown; head, pronotum and elytra clothed with yellow recumbent setae ( Fig. 30 ).

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

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

Pronotum: Coarsely, deeply punctate; surface dullish; longer than wide, with moderate hind angles; basal two-third parallel-sided, apical third arcuate; disc with shallow median groove extending from base up three-fourths the length; base sinuous, with short, median carina above scutellum; sides ( Fig. 31 ) with two lateral ridges; anterior lateral pronotal ridge short, obliquely bent, directed posteriorly, about one-fourth the length of pronotum; posterior lateral pronotal ridge extending up to third the length of pronotum; lateral sides of pronotal hind angles broadly rounded apically.

Scutellum: Slightly elevated, punctate, longer than wide, triangular and distally rounded.

Elytra: Striae absent; surfaces densely punctate to rugose.

Legs: First tarsomere as long as 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. 32 ): Deeply punctate, with recumbent yellowish setae; hypomeron with notosternal antennal grooves; metathoracic episternum caudally widened; elytral epipleurae sulcate; metathoracic coxal plates medially 2.0 times as wide as laterally.

Male aedeagus ( Fig. 33 ): Basal piece wide, oblong, somewhat elliptical; remaining aedeagus about twice as long as basal piece, basally narrowed, apical three-fourths widened; lateral lobes short, simple, apically narrowed; secondary lateral lobes fused with lateral lobes; median lobe widened, elongate, apically bilobed.

Female allotype: 3.75 mm long; antennae weakly serrate, reaching half the length of the body; frons with pair of circular foveae; legs and antennae dark reddish-brown; pronotum parallel-sided.

Variation. Seven paratypes were examined. Three female paratypes range in size 3.75–4.25 mm long. Four male paratypes range in size 3.50–3.75 mm long. Antennae and legs in one of the paratypes are completely reddish-brown, lighter than holotype and allotype. Two other paratypes have darker reddishbrown antennae and legs, similar to the allotype. One female paratype lacks a pair of circular foveae on the frons. Exoskeletal structures are similar to both holotype and allotype.

Type material. Holotype, male, with label data: “ Ala. Dale Co., Ft. Rucker Mil. Res., 16 May 2003, R. Turnbow ” / “ HOLOTYPE:, Microrhagus , opacus, Otto , det. R.L. Otto, 2014 ” (♂ handwritten behind species name on label)[red printed label] . Allotype, female, with label data: “N.Y.” / “TYPE NO. 3399” (3399 handwritten) [red card] / “ M. audax, Horn ” (handwritten) / “M.C.Z., Holotype, 33718” (33718 handwritten) [red card] / “NOT Syntype, Muona - 96” (handwritten) [pink card] / “Aug-Dec 2004, MCZ Image, Database” (small picture of camera on left side of label” / “ ALLOTYPE:, Microrhagus , opacus, Otto , det. R.L. Otto 2014 ” (♀ handwritten behind species name on label)[yellow printed label]. Holotype is transferred from GERP to WIRC. Allotype is at the MCZ.

Paratypes. 7, from the following locality: 2, ALABAMA: Dale Co.: Ft. Rucker Mil. Res. , 4–20 June 2011, 13 May 2013, R. Turnbow ( RHTC) ; 1, FLORIDA: Leon Co.: Tall Timbers Research Station , 4–11–V–1993, M. Lara ( FSCA) ; 1, GEORGIA: Wheeler Co.: V–VI/00, R. Morris ( GERP) ; 1, INDIANA: Morgan Co.: April 7–July 14, 2012, Kyle E. Schnepp ( KESC) ; 1, KANSAS: Douglas Co.: 3.2 km N Baldwin, Breidenthal Reserve , 7–14 June 1996 ( SEMC) ; 1, Jefferson Co.: The Falin Property, 1.5 km N jct. 94th Street and Kingman Rd. , 39° 13.38’N, 95° 24.24’W, 7–10–VI–2005 ( SEMC). Each specimen labeled: “ PARATYPE:, Microrhagus , opacus, Otto , det. R.L. Otto, 2014 ” (either ♂ or ♀ handwritten behind species name on label) [yellow printed label]. All paratypes are deposited in GERP, KESC, RHTC, SEMC and WIRC .

Distribution. The species is known from USA: Alabama, Florida, Georgia, Indiana, Kansas, and New York.

Biology. In Alabama, one beetle was taken from a Manuka/Phoebe Oil baited Lindgren funnel trap. One beetle was taken from a clear bottle trap baited with rotting fruit in Indiana. In Florida, a single specimen was taken from a Malaise trap. In Kansas, each specimen was taken from either a Malaise trap or a flight intercept trap in 1996 and 2005.

Etymology. The name of the new species is derived from its dull or opaque luster of the pronotum in relation to the elytra.

Note. Otto (2013a) figured Microrhagus audax ( Fig. 8–9 ); unaware the eucnemid actually belongs to this new species. The specimen deposited in MCZ was thought to be the type of M. audax . In 1996, Muona added a label indicating the specimen was not a syntype. The actual holotype of M. audax is deposited in the Ulke collection at the Carnegie Museum. The MCZ specimen was compared against images of the holotype provided by Dr. Robert Davidison and surmised the specimen is quite different, based on these four characteristics.

Figures

Figures 30–33. Microrhagus opacus Otto. 30) Holotype, dorsal view. 31) Holotype, lateral view. 32) Holotype, ventral view. 33) Aedeagus of paratype. Scale line = 2.0 mm (adult), 0.5 mm (aedeagus).

Figures 3–8. Nearctic Microrhagus. 3) Microrhagus audax, pronotum, lateral side. 4) Microrhagus carinicollis, pronotum, pronotal hind angles circled. 5) Microrhagus brunneus, pronotum, pronotal hind angles circled. 6) Microrhagus carinicollis, vertex. 7) Microrhagus lecontei, antennomeres 3–6. 8) Microrhagus triangularis, antennomeres 3–6.

Figures 9–14. Nearctic Microrhagus. 9) Microrhagus pectinatus, spiracular collar on abdominal segments 1–3, lateral view. 10) Microrhagus breviangularis, spiracular collar on abdominal segments 1–3, lateral view. 11) Microrhagus brunneus, abdominal segments IV–VI, dorsal view. 12) Microrhagus carinicollis, abdominal segments IV–VI, dorsal view. 13) Microrhagus triangularis, abdominal segments IV–VI, dorsal view. 14) Microrhagus audax, abdominal segments IV–VI, dorsal view.