Microrhagus jejuensis, Seung, Jinbae & Lee, Seunghwan, 2018

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 jejuensis sp. n. Fig. 2

Diagnosis.

Body: shiny black. Head: frons with a groove at midline; antennae pectinate from antennomere III in male. Prothorax: pronotum with paired dimples at middle and a groove at midline; notosternal antennal grooves slightly widened posteriorly, with outer marginal carina. Pterothorax: scutellum slightly elevated; elytra 2.7 × longer than combined width; metepisternum narrow, slightly widened posteriorly, its greatest width as wide as outer edge of metacoxal plate; metacoxal plate expanded inward. Abdomen: abdominal ventrite V narrowly rounded at apex.

Description.

Holotype male (Fig. 2A, C, D) 5.2 mm long and 1.5 mm wide. Body mostly black; antennomere II, antennal processes, mandible, and tibiae red-brown; maxillary palpi and tarsi yellow-brown; surface glossy, with yellow pubescence. Head with circular, irregularly sized punctures, especially at frontoclypeal region; frons with a short median groove; frontoclypeal region slightly depressed at base, broadly bifurcate and feebly concave at anterior edge, anterior edge 3.9 × wider than distance between antennal sockets (Fig. 2G). Antennae (Fig. 2E) almost exceeding abdominal ventrite I, with yellow-brown setae, and pectinate from antennomere III; processes of antennemeres III, IV, and V 1.1, 1.7, and 1.8 × as long as corresponding antennomeres; antennomere I robust; antennomere II shortest; antennomere III 1.7 × longer than II, as long as IV; antennomeres III–X with processes near apex, gradually lengthened apically; apical antennomere elongate, curved, 7.3 × longer than wide, and 1.9 × longer than previous one. Pronotum 1.3 × wider than long, subparallel-sided near base, gradually narrowed anteriorly from basal two-thirds; surface mostly with finer, sparser, and more regularly sized and spaced punctures than on head, larger and denser at sides; disc with a paired dimples near middle and a groove at midline, weakly swollen posteriorly; anterolateral carina short, almost one-third as long as pronotum; posterolateral carina almost reaching three-fifths length of pronotum; antescutellar area almost straight, weakly sinuate in dorsal view; pronotal posterior angles sharply projecting, slightly extended outward, and exceeding posterior edge of antescutellar area. Scutellum slightly raised; 1.2 × longer than wide, gradually narrowed posteriorly, and rounded at apex; surface coarse, densely pubescent. Elytra 2.7 × longer than combined width, parallel-sided, gradually narrowing near apices; disc striate, with irregularly sized and spaced punctures; interstriae weakly convex, with several large and deep punctures near apices; apices simply rounded. Prosternum with curved sides, slightly widened anteriorly, and anterior margin shallowly bisinuate; surface mostly with larger, sparser, and more regularly sized and spaced punctures than on head, especially at center; prosternal process robust, gradually tapered and curved dorsally at posterior end; hypomeron with rough surface, with larger, denser punctures than on prosternum; surface rugose at coxal cavities; notosternal antennal grooves (Fig. 2I) slightly widened posteriorly, with outer marginal carina, with several irregularly sized and spaced punctures posteriorly, glossy, and with pits. Mesoventrite with coarse surface, with shallow punctures; mesopleuron with rough surface, especially anteriorly. Metaventrite mostly with finer and denser punctures than on prosternum; disc with a groove at midline, not reaching anterior edge; metepisternum (Fig. 2J) narrow, gradually widened posteriorly, its greatest width as wide as outer edge of metacoxal plate; metacoxal plate (Fig. 2K) expanded inward, medially 1.6 × wider than laterally. Legs (Fig. 2O) slender; metatarsomere I 1.5 × longer than II–IV combined; metatarsomere II 1.3 × longer than III; metatarsomere V 1.2 × longer than II; claws simple. Abdomen with finer and denser punctures than on metaventrite; ventrite V narrowly rounded at posterior edge (Fig. 2L). Aedeagus (Fig. 2 M–N) 4.3 × longer than wide; median lobe curved ventrally near apex, broadly bifurcate at apex with setae; lateral lobes slender with apical tooth inward, truncate and with long setae at apex; ventral lobe shorter and broader than median lobe, almost truncate at apical edge; phallobase globose basally with concave sides near apex, 1.5 × longer than wide, one-third as long as entire aedeagus. Allotype female (Fig. 2B) like male, except for following characters: 6.1 mm long and 1.8 mm wide; frontoclypeal region with anterior edge, 3.7 × wider than distance between antennal sockets (Fig. 2H); antennae (Fig. 2F) serrate, not exceeding metacoxal plate; antennomere III subrectangular, approximately twice longer than wide, 1.7 × longer than II, and 1.3 × longer than IV; apical antennomere 5.3 × longer than wide, and 1.8 × longer than X.

Type meterial.

Holotype: Korea: 1♂, Jeju Is., Hwasun gotjawal, Hwasun-ri, Andeok-myeon, Seogwipo-si, N33°15'52.88", E126°19'53.59", 120m alt., 12 May, 2016, J. B. Seung leg. (SNU). Allotype: Korea: 1♀, Jeju Is., Gyorae gotjawal, Gyorae-ri, Jocheon-eup, Jeju-si, N33°26'21.15", E126°40'12.75", 428m alt., flight intercept trap, 12 May– 10 June, 2016, Seung and Jung leg. (SNU). Paratypes: Korea: 1♀, Jeju Is., Donnaeko, Sanghyo-dong, Seogwipo-si, N33°18'1.34", E126°34'49.02", 280m alt., 12 May, 2016, J. B. Seung leg. (SNU); 1♀, Jeju Is., Gyorae gotjawal, Gyorae-ri, Jocheon-eup, Jeju-si, N33°26'21.15", E126°40'12.75", 428m alt., flight intercept trap, 12 May– 10 June, 2016, Seung and Jung leg. (SNU); 2♂1♀, Jeju Is. Hwasun gotjawal, Hwasun-ri, Andeok-myeon, Seogwipo-si, N33°15'52.62", E126°19'52.43", 128m alt., flight intercept trap, 12 May– 10 June, 2016, Seung and Jung leg. (SNU); 1♂2♀, Seongpanak, Gyorae-ri, Jocheon-eup, Jeju-si, N33°23'10.82", E126°37'13.77", 752m alt., flight intercept trap, 12 May– 10 June, 2016, Seung and Jung leg. (SNU).

Distribution.

Korea (Jeju Island).

Remarks.

Microrhagus jejuensis sp. n. similar to M. foveolatus , but is distinguished from M. foveolatus by following characters: frons with a groove at midline; pronotum with a short groove at midline; elytra elongate, width 2.7 × longer than combined width; lateral lobes of aedeagus short and truncate at apex. The structure of aedeagus resembles that of M. pectinicornis , but the latter species differs from the new species in longer processes of antennomeres (processes of antennomeres III, IV, and V 2.2, 3.6, and 4 × as long as corresponding antennomeres). Additionally, each process of male antennomeres III and IV is near base in M. pectinicornis , and not in M. jejuensis .

Etymology.

The species is named refers to its occurrence locality, Jeju Island.