Research Article |
Corresponding author: Seunghwan Lee ( seung@snu.ac.kr ) Academic editor: Hume Douglas
© 2018 Jinbae Seung, Seunghwan Lee.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Seung J, Lee S (2018) Taxonomic review of genus Microrhagus Dejean, 1833 from Korea, with description of a new species (Coleoptera, Eucnemidae, Melasinae, Dirhagini). ZooKeys : 81-95. https://doi.org/10.3897/zookeys.781.21106
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The genus Microrhagus Dejean, 1833 is reviewed with four species from Korea: Microrhagus foveolatus (Fleutiaux, 1923), Microrhagus jejuensis sp. n., Microrhagus mystagogus (Fleutiaux, 1923), and Microrhagus ramosus (Fleutiaux, 1902). Herein, all Korean Microrhagus species are redescribed. A key to species of Korean Microrhagus and photographs of the diagnostic characters are also provided.
Eucnemidae , Korea, Microrhagus , new species, taxonomy
The tribe Dirhagini Reitter, 1911 is a large group of the subfamily Melasinae with a worldwide distribution. Dirhagini is characterized by crenulate or incomplete pronotal lateral carina, most also with well-developed notosternal antennal grooves, an apical sex-comb on male protarsomere I, and without basal struts of the aedeagal median lobe (
The genus Microrhagus Dejean, 1833 is the largest genus in its tribe, with more than 130 species worldwide and 17 species in the Palaearctic Region, including seven species from Japan (
The genus Microrhagus is distinguished from other genera by strongly approximate antennal sockets, hypomeron with pits close to procoxae, well-developed notosternal antennal grooves, simple elytral apices, laterally narrowed metacoxal plates, and apically notched median lobe and long ventral lobe of aedeagus (
We review genus Microrhagus with four species, including an undescribed species, Microrhagus jejuensis sp. n., and two previously unreported species, Microrhagus foveolatus (Fleutiaux, 1923) and M. mystagogus (Fleutiaux, 1923) from Korea. A key to species of Korean Microrhagus, diagnoses, redescriptions, and photographs for the diagnostic characters are provided.
Most samples examined were collected using flight intercept traps between 2015 and 2016. Samples were preserved in 95% ethanol and made into dried specimens by double mounted method (pinned with a micropin to a block of cork, which is mounted on a standard insect pin) for exact identification. To examine the antennae, legs, and aedeagus, specimens were softened in boiling water for 30–60 minutes and dissected using forceps and micro-pin probes. Dried specimens were examined under a microscope (S8APO, Leica, Germany) and separate organs were observed under a microscope (DM4000B, Leica, Germany). Photographs were taken using EOS-600D, CANON camera, through MP-E 65mm lens.
All specimens (including types) are deposited in the insect collection of the College for Agriculture and Life Sciences, Seoul National University (CALS, SNU, Seoul, Korea).
The concept of genus Microrhagus follows
Identification of species was done using
Microrhagus Dejean, 1833: 85. Type species: Elater pygmaeus Fabricius, 1792.
Head: pits present between eyes and antennal sockets; frontoclypeal region strongly narrowed at base; antennae serrate or pectinate; antennomere III not longer than antennomeres IV–V combined. Prothorax: pronotal lateral carina divided into anterolateral carina and posterolateral carina; notosternal antennal grooves well developed. Pterothorax: mesepimeron fused with mesepisternum; metepisternum subparallel-sided or widened posteriorly; metacoxal plate expanded inward. Leg: male protarsomere I with apical sex-comb; metatarsomere I not shorter than metatarsomeres II–III combined, metatarsomere IV slightly dilated. Abdomen: abdominal ventrites connate; abdominal ventrite V obtusely produced or simply rounded at apex in ventral view; median lobe of aedeagus bifurcate at apex and secondary lateral lobes small (
1 | Frons with carina or groove at midline; pronotum narrowed anteriorly, with paired dimples near middle; male antennae pectinate from antennomere III | 2 |
– | Frons without carina or groove (Fig. |
M. mystagogus (Fleutiaux) |
2 | Pronotum without groove at midline; elytra less than 2.5 × longer than combined width; male antennomere III with process at base, antennomere IV with process at mid-length, antennomeres V–X with processes at apex; lateral lobes of aedeagus narrowly produced apically | 3 |
– | Pronotum with a longitudinal groove at midline (Fig. |
M. jejuensis sp. n. |
3 | Pronotum less densely punctate, average distance between punctures greater than puncture diameter; antennal process III as long as length of antennomere III (Fig. |
M. foveolatus (Fleutiaux) |
– | Pronotum very densely punctate, average distance between punctures smaller than puncture diameter; antennal process III 1.4 × longer than length of antennomere III (Fig. |
M. ramosus Fleutiaux |
Dirhagus foveolatus Fleutiaux, 1923: 308.
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.
Male (Fig.
Microrhagus foveolatus (Fleutiaux, 1923). A, C–E, G, I–O male B, F, H female. A, B dorsal habitus C ventral habitus D lateral habitus E–F antenna G–H frons I antennal groove J metepisternum K metacoxal plate L abdominal ventrite V M–N aedeagus O metatarsus. Scale bar: 1 mm (A–F); 0.5 mm (G–O).
<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).
Korea (New record), Japan, Russia (Far East).
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.
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.
Holotype male (Fig.
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).
Korea (Jeju Island).
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.
The species is named refers to its occurrence locality, Jeju Island.
Dirhagus mystagogus Fleutiaux, 1923: 309.
Body: mostly dull black. Head: antennae pectinate from antennomere IV in male. Prothorax: pronotum convex, as long as wide; notosternal antennal grooves subparallel-sided. Pterothorax: elytra 2.3 × longer than combined width; metepisternum narrow, slightly widened posteriorly, its greatest width narrower than outer edge of metacoxal plate; metacoxal plate expanded inward; abdominal ventrite V simply rounded at apex.
Male (Fig.
Microrhagus mystagogus (Fleutiaux, 1923). A, C–E, G, I–O male B, F, H, female A, B dorsal habitus C ventral habitus D lateral habitus E–F antenna G–H frons I antennal groove J metepisternum K metacoxal plate L abdominal ventrite V M–N aedeagus O metatarsus. Scale bar: 1 mm (A–F); 0.5 mm (G–O).
<Gyeonggi-do> 1♀, Deoksu-ri, Danwol-myeon, Yangpyeong-gun, N37°33'22.97", E127°41'13.65", 166m alt., flight intercept trap, 29 June–16 July, 2016, Seung and Jung leg. (SNU). <Gangwon-do> 1♀, Yeongheung-ri, Yeongwol-eup, Yeongwol-gun, N37°12'19.84", E128°27'17.77", 308m alt., flight intercept trap, 19 June–02 July, 2015, Seung and Lee leg. (SNU); 1♂, Beopheung-ri, Suju-myeon, Yeongwol-gun, N37°22'41.19", E128°15'15.50", 550m alt., flight intercept trap, 03–16 July. 2015, Seung and Lee leg. (SNU); 1♂2♀, Beopheung-ri, Suju-myeon, Yeongwol-gun, N37°22'41.19", E128°15'15.50", 550m alt., flight intercept trap, 05–29 June, 2016, Seung and Jung leg. (SNU).
Korea (New record), Japan, Russia (Far East).
Microrhagus mystagogus is easily distinguished from other Korean Microrhagus species by its antennae: male antennae pectinate from antennomere IV. Also, convex pronotum and structure of aedeagus are characteristic. Its aedeagal structure is well-illustrated in
Microrhagus ramosus Fleutiaux, 1902: 24.
Body: mostly weakly shiny black. Head: frons with a weak carina at midline; antennae pectinate from antennomere III in male. Prothorax: pronotum with dense punctures, average distance between punctures smaller than puncture diameter, disc with paired dimples at middle; notosternal antennal grooves slightly expanded posteriorly. Pterothorax: elytra 2.2 × longer than combined width; metepisternum gradually widened posteriorly, its greatest width wider than outer edge of metacoxal plate; metacoxal plate expanded inward. Abdomen: abdominal ventrite V weakly narrowly rounded at apex.
Male (Fig.
Microrhagus ramosus (Fleutiaux, 1902). A, C–E, G, I–O male B, F, H female A, B dorsal habitus C ventral habitus D lateral habitus E–F antenna G–H frons I antennal groove J metepisternum K metacoxal plate L abdominal ventrite V M–N aedeagus O metatarsus. Scale bar: 1 mm (A–F); 0.5 mm (G–O).
<Gangwon-do> 3♂1♀, Beopheung-ri, Suju-myeon, Yeongwol-gun, N37°22'41.19", E128°15'15.50", 550m alt., flight intercept trap, 19 June–02 July, 2015, Seung and Lee leg. (SNU); 2♂1♀, Deokgu-ri, Sangdong-eup, Yeongwol-gun, N37°5'34.46", E128°48'59.53", 648m alt., flight intercept trap, 19 June–02 July 2015, Seung and Lee leg. (SNU); 3♂, Deokgu-ri, Sangdong-eup, Yeongwol-gun, N37°5'34.46", E128°48'59.53", 648m alt., flight intercept trap, 02–16 July, 2015, Seung and Lee leg. (SNU); 5♂, 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); 1♂, Jindong-ri, Girin-myeon, Inje-gun, N37°58'11.10", E128°24'23.97", 619m alt., 13 July, 2016, M. S. Oh leg. (SNU). <Jeollanam-do> 1♂, Donggok-ri, Ongnyong-myeon, Gwangyang-si, N35°5'13.37", E127°36'48.93", 577m alt., flight intercept trap, 04–15 July, 2016, Seung and Lee leg. (SNU). <Jeju Is.> 1♂, 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).
Korea, Japan.
Microrhagus ramosus shows morphological variation as below: pronotal anterolateral carina and posterolateral carina obscure in some, appearing fused in some; ventral lobe of aedeagus sub-parallel sided in some, slightly widened near apex.
We are thankful to J Muona (Finnish Museum of Natural History, Zoological Museum) for confirmation of identifications. We are also grateful to RL Otto (Department of Entomology, University of Wisconsin – Madison, USA), AV Kovalev (Zoological Institute of the Russian Academy of Sciences), and H Douglas (Agriculture and Agri–Food Canada) for valuable comments of the paper. We acknowledge to BH Jung (Korean Entomological Institute, Korea University, Korea), SJ Lee (Seoul National University Forest), SH Lee, and MS Oh for assistance to collect samples for this study. The research on the species newly recorded in Korea was supported by a grant from the National Institute of Biological Resources (NIBR), funded by the Ministry of Environment (MOE) of the Republic of Korea (NIBR201601203).