Dirrhagofarsus unicolor (Hisamatsu, 1960), comb. n.

Seung, Jinbae, Muona, Jyrki & Lee, Seunghwan, 2018, Taxonomic review of the genus Dirrhagofarsus in Korea (Coleoptera, Eucnemidae), ZooKeys 781, pp. 97-108 : 97

Dirrhagofarsus unicolor (Hisamatsu, 1960), comb. n. stat. n. Figure 3

Dirrhagus modestus f. unicolor Hisamatsu, 1960: 102.

Diagnosis.

Body: mostly coloured brown. Head: frons simple, without medio-longitudinal carina; anterior edge of frontoclypeal region 3 × wider than distance between antennal sockets in male, 2.8 × wider in female; antennomere III 1.5 × longer than IV in male, 1.75 × longer in female. Pronotum: anterolateral carina one-sixth as long as pronotum; posterolateral carina four-fifths as long as pronotum. Pterothorax: elytra 2.5 × longer than combined width, apices with weakly convex apices in lateral view. Leg: metatarsomere II 1.3 × longer than III, metatarsomere V 1.2 × longer than II. Aedeagus: 4.5 × longer than wide; lateral lobes slightly longer than median lobe; phallobase rectangular, almost one-fifth as long as aedeagus.

Redescription.

Male (Fig. 3A, C–D) 4.3-5.3 mm long and 1.2-1.5 mm wide. Body brown with yellow-brown tarsi; surface moderately glossy, covered with golden pubescence. Head moderately inserted into prothorax; surface with circular and regularly sized punctures, denser near frontoclypeal region; frons simple, without medio-longitudinal carina; frontoclypeal region (Fig. 3G) weakly depressed at base, feebly trilobate at anterior edge, anterior edge 3 × wider than distance between antennal sockets. Antennae (Fig. 3E) serrate, almost reaching metacoxal plate, with yellow-brown pubescence; antennomere II conical and shortest; antennomere III rectangular, 2.3 × longer than wide, 2 × longer than II, and 1.5 × longer than IV; antennomeres IV–X subequal, gradually narrowed apically; antennomere XI 3.8 × longer than wide, and 1.7 × longer than X. Pronotum as long as wide and arcuate anteriorly; surface rougher than head; disc weakly depressed at middle; with a short median carina at base; anterolateral carina one-sixth as long as pronotum; posterolateral carina four-fifths as long as pronotum. Scutellum triangular, 1.3 × wider than long, gradually narrowed posteriorly to slightly rounded posterior edge; surface coarse, densely pubescent. Elytra 2.5 × longer than combined width; disc barely striate, with irregularly sized and spaced punctures; several large, deep punctures present near apices; apices weakly compressed and simply rounded near sutural region in lateral view (Fig. 3I). Prosternum wider than long, parallel-sided; surface with punctures like as on head, slightly larger laterally; prosternal process gradually tapered and curved dorsally posteriorly; hypomeron with coarse surface, with punctures more irregularly sized than on prosternum; with deep pore at posterior fossae; antennal grooves (Fig. 3J) well-developed, notosternal, parallel-sided, with lateral marginal carina, barely punctate, and glabrous. Mesoventrite with coarse surface, with irregularly sized and spaced punctures. Metasventrite with punctures like as on prosternum, slightly larger and denser laterally; median groove present, not reaching anterior edge; metepisternum (Fig. 3K) slightly widened posteriorly, and widest part 1.5 × wider than outer edge of metacoxal plate; metacoxal plate (Fig. 3L) medially four × longer than laterally. Legs (Fig. 3P) with metatarsomere II 1.3 × longer than III; metatarsomere V 1.2 × longer than II; claws simple. Abdomen with denser punctures than on metaventrite (Fig. 3M). Aedeagus (Fig. 3 N–O) 4.5 × longer than wide; median lobe almost straight, gradually narrowed distally, deeply and narrowly bifurcate apically; endophallus reaching basal piece; lateral lobes slightly longer than median lobe, slightly curved ventrally, with basally attached secondary lateral lobes; secondary lateral lobes subparallel-sided, weakly pointed apically; phallobase rectangular, almost one-fifth as long as aedeagus.

Sexual dimorphism.

Female (Fig. 3B) can be distinguished from male by following characters: body slightly stouter, 4.5-5.7 mm long and 1.3-1.7 mm wide; base of frontoclypeal region slightly wider, anterior edge 2.8 × wider than distance between antennal sockets (Fig. 3H); antennomere III 1.75 × longer than IV; antennomeres IV–X stouter (Fig. 3F).

Specimens examined.

Seoul-Si 4♂, Mt. Gwanak, Daehak-dong, Gwanak-gu, Seoul-si, N37°27.06', E126°56.82', 184m alt., 18 January 2016, J. B. Seung leg. (collected in overwintering larval stage, 03. iv. 2016, adult emergence) (SNU); Gyeonggi-Do 2♂, Mt. Bara, Hagui-dong, Uiwang-si, N37°22.34', E127°1.37', 189m alt., light trap, 22 June 2015, J. B. Seung leg. (SNU); 1♂, Mt. Bara, Hagui-dong, Uiwang-si, N37°22.38', E127°1.34', 174m alt., light trap, 01 June 2016, J. B. Seung leg. (SNU); 1♂, Mt. Bara, Hagui-dong, Uiwang-si, N37°22.38', E127°1.34', 174m alt., light trap, 04 June 2016, M. S. Oh leg. (SNU); 2♀, Baekgok-ri, Mado-myeon, Hwaseong-si, N37°10.65', E126°43.64', 115m alt., flight intercept trap, 06-28 June 2016, Seung and Yeom leg. (SNU).

Distribution.

Korea (New record), Japan.

Remarks.

Last instar larvae of Dirrhagofarsus unicolor were collected in standing dead A. japonica trees in January. They remained in U-form in oval larval cells. Adults emerged together with other eucnemid species, Dirrhagofarsus modestus and Hylis sp., 70 days later following rearing at room temperature. Most of specimens were collected by light trap, occasionally by flight intercept traps. They were observed clicking as well as flying and running.