Dirrhagofarsus modestus (Fleutiaux, 1923)

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

Dirrhagofarsus modestus (Fleutiaux, 1923) Figure 2

Dirrhagus modestus Fleutiaux, 1923: 308.

Rhacopus modestus Hisamatsu, 1985: 50.

Dirrhagofarsus modestus Muona, 1993: 46.

Diagnosis.

Body: mostly coloured black. Head: frons with a weak medio-longitudinal carina; anterior edge of frontoclypeal region 2.9 × wider than distance between antennal sockets in male, 2.7 × wider in female; antennomere III 1.35 × longer than IV in male, 1.7 × longer in female. Pronotum: anterolateral carina one-sixth as long as pronotum; posterolateral carina four-fifths as long as pronotum. Pterothorax: elytra 2.7 × longer than combined width, apices with fairly convex apices in lateral view. Leg: metatarsomere II 1.6 × longer than III, as long as V. Aedeagus: 5.3 × longer than wide; lateral lobes as long as median lobe, phallobase trapezoidal, one-sixth as long as aedeagus.

Redescription.

Male (Fig. 2A, C–D) 4.5-5.9 mm long and 1.2-1.5 mm wide. Body black; antennae, mouthparts, anterior and posterior edge of pronotum red-brown; tibiae and tarsi brown to red-brown; surface shiny, covered with yellow-brown pubescence. Head deeply inserted into prothorax; surface coarse, with circular, irregularly sized and spaced punctures, rugose and more irregular near frontoclypeal region; frons with a weak medio-longitudinal carina; frontoclypeal region (Fig. 2G) weakly depressed at base, obtusely rounded at anterior edge, anterior edge 2.9 × wider than distance between antennal sockets. Antennae (Fig. 2E) weakly serrate, almost reaching abdominal ventrite II, with yellow-brown pubescence; antennomere II conical and shortest; antennomere III rectangular, 2.5 × longer than wide, two × wider than II, and 1.35 × longer than IV; antennomeres IV–X gradually lengthened and narrowed apically; antennomere XI 5.5 × longer than wide, and 1.7 × longer than X. Pronotum as long as wide and rounded anteriorly; surface with finer and denser punctures than on head, gradually more rugose laterally; disc with a medio-longitudinal carina at basal half; anterolateral carina one-sixth as long as pronotum; posterolateral carina approximately four-fifths as long as pronotum. Scutellum with straight anterior edge, gradually narrowed posteriorly with rounded apex; surface rough, sparsely pubescent. Elytra 2.7 × longer than combined width; disc weakly striate, with shallow, scattered punctures on intervals; several large, deep punctures present near apices; apices simply convex in lateral view in both sexes, apices blunt and contact with ventrite V (Fig. 2I). Prosternum slightly wider than long, parallel-sided; punctures more regularly spaced than on head, finer and denser at anterior and posterior regions; prosternal process gradually tapered and curved dorsally posteriorly; hypomeron with coarse surface, more irregularly sized than on prosternum; antennal grooves well-developed, notosternal, parallel-sided, with lateral marginal carina, barely punctate, and glabrous (Fig. 2J). Mesoventrite with rough surface. Metaventrite with finer, sparser, punctures than on prosternum, especially at middle; metepisternum (Fig. 2K) parallel-sided, width of posterior edge as wide as outer edge of metacoxal plate; metacoxal plate (Fig. 2L) medially four × longer than laterally. Legs (Fig. 2P) with metatarsomere II 1.6 × longer than III, as long as V. Abdomen with finer punctures than on metaventrite (Fig. 2M). Aedeagus (Fig. 2 N–O) 5.3 × longer than wide; median lobe almost straight, gradually narrowed distally, deeply bifurcate at apex; endophallus reaching basal piece; lateral lobes as long as median lobe, with basally attached secondary lateral lobes; secondary lateral lobes slender, subparallel-sided, weakly pointed apically; phallobase trapezoidal, 1.25 × longer than wide and one-sixth as long as aedeagus.

Sexual dimorphism.

Female (Fig. 2B) can be distinguished from male by following characters: body larger and stouter, 5.2-6.8 mm long, 1.4-1.9 mm wide; base of frontoclypeal region wider, anterior edge 2.7 × wider than distance between antennal sockets (Fig. 2H); antennae (Fig. 2F) relatively shorter, almost reaching metacoxal plate; antennomere III 1.7 × longer than IV; antennomeres IV–X stouter; antennomere XI 3.3 × longer than wide.

Specimens examined.

Seoul-Si 7♂9♀, 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 1♀, Mt. Bara, Hagui-dong, Uiwang-si, N37°22.34', E127°1.37', 189m alt., light trap, 22 June 2015, J. B. Seung leg. (SNU); 2♂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); Gangwond-Do 1♂, Beopheung-ri, Suju-myeon, Yeongwol-gun, N37°22.69', E128°15.26', 550m alt., flight intercept trap, 19 June– 02 July 2015, Seung and Lee leg. (SNU); 1♀, Deokgu-ri, Sangdong-eup, Yeongwol-gun, N37°5.57', E128°48.99', 648m alt., flight intercept trap, 19 June– 02 July 2015, Seung and Lee leg. (SNU); 1♀, Beopheung-ri, Suju-myeon, Yeongwol-gun, N37°22.69', E128°15.26', 550m alt., flight intercept trap, 03-16 July 2015, leg. Seung and Lee leg. (SNU); 1♀, Hoenggye-ri, Daegwanryeong-myeon, Pyeongchang-gun, N37°40.84', E128°45.78', 902m alt., flight intercept trap, 05-29 June 2016, Seung and Jung leg. (SNU); 3♀, Suha-ri, Daegwanryeong-myeon, Pyeongchang-gun, N37°36.60', E128°43.19', 803m alt., flight intercept trap, 05-29 June, 2016, Seung and Jung leg. (SNU); Jeollanam-Do 2♀, Jungdae-ri, Ganjeon-myeon, Gurye-gun, N35°6.44', E127°35.90', 668m alt., flight intercept trap, 04-15 July 2016, Seung and Lee leg. (SNU); Jeju-Do (Is.) 2♂, Gyorae gotjawal, Gyorae-ri, Jocheon-eup, Jeju-si, N33°26.35', E126°40.21', 428m alt., flight intercept trap, 10 June– 21 July 2016, Seung and Jung leg. (SNU).

Distribution.

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

Remarks.

Mature larvae of Dirrhagofarsus modestus were observed in U-form in oval larval cells in standing dead Alnus japonica (Thunb.) Steudel ( Fagales , Betulaceae ) in January. Adults emerged at the same time as eucnemid species, Dirrhagofarsus unicolor and Hylis sp. 70 days later following rearing at room temperature.They were commonly collected at light traps. They were observed clicking as well as flying and running.