Microrhagus foveolatus (Fleutiaux, 1923)

Seung, Jinbae & Lee, Seunghwan, 2018, Taxonomic review of genus Microrhagus Dejean, 1833 from Korea, with description of a new species (Coleoptera, Eucnemidae, Melasinae, Dirhagini), ZooKeys 781, pp. 81-95 : 81

Microrhagus foveolatus (Fleutiaux, 1923) Fig. 1

Dirhagus foveolatus Fleutiaux, 1923: 308.

Diagnosis.

Body: mostly shiny black. Head: frons with a weak carina at midline; antennae pectinate from antenomere III in male. Prothorax: pronotum with sparse punctures, average distance between punctures greater than puncture diameter, disc with paired dimples near middle; notosternal antennal grooves slightly widened posteriorly. Pterothorax: elytra 2.5 × longer than combined width; metepisternum gradually widened posteriorly, its greatest width narrower than outer edge of metacoxal plate; metacoxal plate expanded inward; abdominal ventrite V narrowly rounded at apex.

Redescription.

Male (Fig. 1A, C–D) 5.1-6.0 mm long and 1.6-1.9 mm wide. Body mostly black; tarsi yellow-brown; surface glossy, with yellow pubescence. Head with circular and regularly sized punctures, denser at frontoclypeal region; frons with a weak carina at midline; frontoclypeal region slightly depressed at base, broadly rounded, with anterior edge slightly sinuate, anterior edge 3.7 × wider than distance between antennal sockets (Fig. 1G). Antennae (Fig. 1E) almost reaching metacoxal plate, with yellow-brown pubescence, and pectinate from antennomere III; processes of antennomeres III, IV, and V 1.1, 2.1 and 2.1 × as long as corresponding antennomeres; antennomere I robust; antennomere II shortest; antennomere III with process near base, 1.7 × longer than II, and 1.3 × longer than IV; antennomere IV with process at mid-length; antennomeres V–X with processes near apex; apical antennomere strongly elongate, curved, 9.5 × longer than wide, and 2.5 × longer than previous one. Pronotum 1.2 × wider than long, subparallel-sided near base, gradually narrowed anteriorly; surface with punctures, average distance between punctures greater than puncture diameter; disc with paired dimples near middle and a short carina at base of midline; anterolateral carina exceeding half as long as pronotum; posterolateral carina almost reaching pronotal mid-length, fused with anterolateral carina in some; antescutellar area almost straight in dorsal view; pronotal posterior angles sharply projecting, exceeding posterior edge of antescutellar area. Scutellum slightly raised, 1.1 × longer than wide, gradually narrowed posteriorly, and rounded at apex; surface coarse, densely punctate, pubescent with dense setae, especially at apex. Elytra 2.5 × longer than combined width, gradually narrowing posteriorly; disc striate, with irregularly sized and spaced punctures; interstriae moderately convex, with several large, deep punctures near apices; apices simply rounded. Prosternum with curved sides, anterior margin shallowly bisinuate; punctures slightly denser anteriorly and posteriorly; prosternal process stout, tapered and curved dorsally at posterior end; hypomeron with punctures less than on prosternum; notosternal antennal grooves (Fig. 1I) slightly expanded posteriorly, sparsely punctate, glabrous, and with pits. Mesoventrite with irregularly sized punctures; mesopleuron with rough surface, especially anteriorly. Metaventrite with finer and denser punctures than on prosternum, especially at middle; disc with a weak median groove, not reaching anterior edge; metepisternum (Fig. 1J) gradually widened posteriorly, its greatest width four-fifths of outer edge of metacoxal plate; metacoxal plate (Fig. 1K) expanded inward, medially 2.3 × wider than laterally. Legs (Fig. 1O) slender; metatarsomere I 1.2 × longer than II–IV combined; metatarsomere II 1.3 × longer than III; metatarsomere V 1.7 × longer than II; claws simple. Abdomen with finer punctures than metaventrite; ventrite V narrowly rounded at apex (Fig. 1L). Aedeagus (Fig. 1 M–N) 4.3 × longer than wide; median lobe slightly curved ventrally, bifurcate at apex; lateral lobes as long as median lobe, feebly curved ventrally, blunt at apex, and with basally attached secondary lateral lobes; secondary lateral lobes shorter than lateral lobes, bent ventrally, parallel-sided, blunt at apex, and with long setae; ventral lobe as long as median lobe, gradually expanded apically, broadly truncate at apex, and densely pubescent; phallobase rectangular, 1.8 × longer than wide, one-third as long as entire aedeagus. Female (Fig. 1B) is distinguished from male by following characters: body stouter, 5.3-6.4 mm long and 1.7-2.1 mm wide; frontoclypeal region with anterior edge, 3.5 × wider than distance between antennal sockets (Fig. 1H); antennae (Fig. 1F) serrate, not reaching metacoxal plate; antennomere II short, as long as IV; antennomere III 1.9 × longer than wide, 1.7 × longer than each length of II and IV; antennomeres IV–X gradually increasing in length, narrowing, and more strongly toothed toward antennal apex; apical antennomere 3.5 × longer than wide, 2.2 × longer than X.

Specimens examined.

<Seoul> 1♀, Gil-dong Natural Ecology Park, Gildong, Gangdong-gu, Seoul-si, N37°32'31.56", E127°9'18.58", 56m alt., 16 May, 2016, B. H. Jung leg. (SNU). <Gyeonggi-do> 1♀, Deoksu-ri, Danwol-myeon, Yangpyeong-gun, N37°33'22.97", E127°41'13.65", 166m alt., Flight intercept trap, 08-22 May, 2016, Seung and Jung leg. (SNU). <Gangwond-do> 1♀, Suha-ri, Daegwanryeong-myeon, Pyeongchang-gun, N37°36'36.29", E128°43'11.47", 803m alt., flight intercept trap, 05-29 June, 2016, Seung and Jung leg. (SNU); 1♀, Hoenggye-ri, Daegwanryeong-myeon, Pyeongchang-gun, N37°40'58.95", E128°45'21.80", 830m alt., flight intercept trap, 05-29 June, 2016, Seung and Jung leg. (SNU). <Jeju Is.> 1♂1♀, Gyorae gotjawal, Gyorae-ri, Jocheon-eup, Jeju-si, N33°26'21.88", E126°40'12.16", 422m alt. 10 June, 2016, J. B. Seung leg. (SNU); 2♂, Gyorae gotjawal, Gyorae-ri, Jocheon-eup, Jeju-si, N33°26'21.15", E126°40'12.75", 428m alt., flight intercept trap, 13 May– 10 June, 2016, Seung and Jung leg. (SNU); 1♂, Seongpanak, Gyorae-ri, Jocheon-eup, Jeju-si, N33°23'10.82", E126°37'13.77", 752m alt., flight intercept trap, 13 May– 10 June, 2016, Seung and Jung leg. (SNU).

Distribution.

Korea (New record), Japan, Russia (Far East).

Remarks.

Microrhagus foveolatus is differentiated from M. ramosus by following characters: with relatively shorter antennal processes; pronotum with sparser punctures, distance between punctures greater than its diameter; elytra relatively more elongate; ventral lobe of aedeagus gradually broadened toward apex. Adults were observed on a standing dead tree with peeling loose bark and covered with hyphae.