Dasycerus occultus Hashizume & Maruyama, 2022

Hashizume, Takuto & Maruyama, Munetoshi, 2022, Taxonomy and phylogeny of the Japanese species of the genus Dasycerus Brongniart (Coleoptera: Staphylinidae: Dasycerinae) with description of a new species and notes on D. poseidon Hu & Liang, Zootaxa 5174 (3), pp. 233-246 : 234-237

Dasycerus occultus Hashizume & Maruyama sp. nov.

( Fig. 1 )

[Japanese name: Yotsumon-itohige-nisemakimushi]

Dasycerus japonicus: Löbl & Calame, 1996: 278 (in part).

Specimen examined. Type series. Holotype: male ( CBM-ZI), JAPAN: Honshu : “Honzawa Rindo / Sakamoto / Kamogawa-shi / Chiba Pref., 18.VI.2020 / Akiko Saito leg. // CBM-ZI / 224407 // HOLOTYPE / Dasycerus / occultus sp. n / det. Hashizume & Maruyama 2022” (recorded as Dasycerus japonicus in Saitô & Murakawa (2020)) . Paratypes: Honshu: Chiba-ken: 8 exs., same data as holotype. ( CBM-ZI: 224405–224406, 224408– 224413) (recorded as D. japonicus in Saitô & Murakawa (2020)); Aichi-ken : 1 ex., Mennoki-tôge, Toyota-shi , 2 V 1989 , N. Kanie leg. (KUM); 1 ex., alt. 930 m, Dandouradani , Tamine, Shitara-chô, 7 VIII 2020 , F. Nakano leg. (KUM); Tottori-ken : 1 ex., Dai-sen, 6 VII 2008, I. Tanaka leg. ( KUM); Kyushu: Fukuoka-ken : 2 exs., Shaka-dake , Yabemura, Yame-shi , 23 VI 2017 , S. Imasaka leg. (KUM); 1 ex., same data, but 26 VII 2017 ( KUM); Saga-ken: 7 exs., Hiroseyama - Kô , Arita-chô , 29 V 2021, T. Hashizume leg. ( KUM); 2 exs., Kurokami-yama , Takeo-shi , 21 IX 2016, M. Nishida leg. ( KUM); 1 ex., Kurokami-yama , Arita-chô , 5 V 2016 , M. Nishida leg. (KUM); 2 exs., Kurokami-yama , Arita-chô, 29 V 2021 , Y. Hisasue leg. (KUM); 1 ex., Tôsen-zan , Ureshino-shi, 26 V 2016 , M. Nishida leg. (KUM); 2 exs., same data, but 13 VII 2017 ( KUM); Nagasaki-ken: 2 exs., Unzen-dake , 24 X 1978, S. Imasaka leg. ( KUM); 1 ex., Gokahara-dake , Tara-dake , 11 VII 1978, S. Imasaka leg. ( KUM); 2 exs., Ônobarukôgen , Higashisonogi-chô , 17 XI 2002, M. Nishida leg. ( KUM); 1 ex., same data, but 7 XII 2002 ( KUM); Ôita-ken: 4 exs., Shaka-dake , Maetsue, Hita-shi , 23 VI 2017 , S. Imasaka leg. (KUM); 2 exs., same data, but 14 VII 2017 ( KUM); 2 exs., same data, but 2 VIII 2017 (KUM); 3 exs., same data, but 23 VIII 2017 (KUM); 2 exs., same data, but 13 VI 2018 (KUM); 1 ex., same data, but 10 VII 2018 ( KUM); 1 ex., same data, but 21 VII 2018 ( KUM); 1 ex., same data, but 11 VIII 2018 (KUM); 1 ex., Zenigame-tôge , Takasaki-yama, Beppu-shi, 26 VII 2015, T . Miyake leg. ( KUM); Miyazaki-ken: 6 exs., alt. 385 m, Miike , Natsuo-chô, Miyakonojô-shi , 17 VIII 2019 , F. Nakano leg. (KUM); 1 ex., Gokasho , Takachiho-chô, 25 VII 2020, T . Hashizume leg. ( KUM); Kagoshima-ken: 2 exs., Maruo Scenic Nature Path , Makizono, Kirishima-shi , 9–10 X 2021, N. Tsuji & T . Nozaki leg. ( KUM); 1 ex., Izashiki , Sata, Minamiôsumi-chô , 22 VI 2021 , S. Inoue leg. (KUM); 1 ex., Teuchi , Shimokoshiki-shima, Satsumasendai-shi, 22 VII 2020, R . Ito leg. ( KUM); 1 ex., Shimokoshiki-shima , Satsumasendai-shi , 25 VII 2020, R . Ito leg. (KUM).

Diagnosis. This species is similar to D. fasciatus Löbl, 1977 from India. However, this species can be distinguished from D. fasciatus by its larger body, and by the shape of the median lobe of the aedeagus. The number of rows of punctures between first and second internal discal costae is also different ( D. occultus sp. nov. with two rows of punctures; D. fasciatus with two rows of punctures and additional short row). In contrast to another Japanese species, D. japonicus , D. occultus sp. nov. has two pairs of dark brown spots on their elytra, and the female genital chamber of D. occultus sp. nov. ( Fig. 1H ) is weakly sclerotized and has a number of fine spines on its surface. The median groove of the pronotum is relatively long ( D. occultus sp. nov.: 0.52–0.54 times as long as pronotum; D. japonicus : 0.42–0.43 times as long as pronotum) ( Fig. 1B ). The punctures of elytron are relatively large and circular ( Fig. 1F ).

Description. Measurements. (n=8): BL: 1.82 (1.72–1.92); HL: 0.34 (0.33–0.36); HW: 0.46 (0.45–0.48); EL: 0.14 (0.13–0.14); PL: 0.42 (0.41–0.44); PW: 0.56 (0.54–0.58).

Coloration. Body, legs, and antennae reddish brown, with two pairs of dark brown spots on elytra.

Head. Apex of frontoclypeus arcuate; vertexal grooves indistinct; pair of rows of tubercles present on mesal vertex extending to frontoclypeus, each row with 8–9 tubercles each with one microseta on apex; group of tubercles present on external margin of frontoclypeus beside the mesal vertex row of tubercles on each side. Antenna 11- segmented, inserted above anterior part of eye; long and slender, sparsely setose on antennomeres III–VII, densely setose on antennomeres I–II and VIII–XI; antennomere I and II globular, enlarged, with dorsal setiferous tubercles; antennomere II slightly smaller than I; antennomeres III–VII extremely slender, filiform, slightly dilated at the apex; antennomeres VIII–XI globular; antennomere XI wider than all other antennomeres. Eyes large; eye pedestal present.

Thorax. Pronotum hexagonal ( Fig. 1B ), with rows of tubercles on the lateral margin and disc, each tubercle with one microseta on apex. Apicolateral angle distinct, not prominent. Disc with a pair of swellings in front of antebasal transverse groove. Median groove distinct, 0.52–0.54 times as long as length of pronotum, extending from antebasal transverse groove. Oblique tubercle row absent. Lateral tubercle row parallel to margin. Middle of antebasal transverse groove strongly arcuate; basal area with five groups of irregular foveae separated by tubercles. Hypomeron with anterior transverse groove. Protergosternal keel entire ( Fig. 1D ). Keel of procoxal process weekly arcuate; some prosternal foveae on prosternum of each side. Elytra rounded laterally and posterolaterally, widest near middle, covering whole abdomen; rows of microsetae along sutural margin and costae; elytra humeral area rounded and raised. Elytral disc with three costae on each elytron, two internal discal costae extending from base to apex of elytron; one external discal costa shorter than internal discal costae, extending from base to 4/5 point of elytron; posterior-lateral margin of elytron with few tubercles which are similar to those on costae. Each elytron with ten rows of circular punctures ( Fig. 1E ): two rows between sutural margin and first internal discal costa; two rows between first and second internal discal costae; two rows between second and external discal costae; three rows between external discal costa and the edge of elytron (punctures strongly reduced on humeral area, the three rows gradually fused to one toward apex), and one row between marginal costa and margin of elytron. Each discal row with 20–28 punctures; rows 1–4 each with about 26 punctures, rows 5–10 with fewer. Hind wings well developed. Scutellum glossy, oblique. Mesoventral median keel extending from anterior margin of prepectus to apex of internal process. Prepectus as long as distance from its posterior margin to procoxae. Posterior margin of mesovaxal cavity with a distinct projection on each side.

Abdomen gradually narrowed apically, not visible in dorsal view. Abdominal tergites V–VIII sclerotized, IV– VI with median furrows. Sternite III with three pairs of coxal foveae and five pairs of microsetae on basal margin; intercoxal process depressed at anterior end.

Male. Aedeagus ( Fig. 1G ) symmetrical. Median lobe with basal bulb moderately large, about as long as apical portion. Apical portion strongly arcuate. Paramere weakly arcuate, narrow in middle, widened at apex; base of paramere triangular; four setae on apex of apex of each paramere.

Female. Female genital chamber ( Fig. 1H ) weakly sclerotized and has a number of fine spines on its surface. Distal gonocoxite has about 10 preapical setae. Gonostylus has one seta slightly shorter than gonostylus at the apex and shorter preapical setae.

Bionomics. They appeared to be feed on fruiting bodies of basidiomcetous fungi that arose on the surfaces of dead trees.

Distribution. Japan (Honshu, Kyushu (incl. Shimo-Koshiki-shima)).

Etymology. The epithet of this new species is derived from the Latin adjective “ occultus ”, which means “hidden”, because this species was previously confused with D. japonicus .

Remarks. Löbl & Calame (1996) redescribed “ D. japonicus ” based on the paratype and additional specimens in the revision of Dasycerus but illustrated the male genitalia of this species. Because it was initially believed that there was only one species of D. japonicus in Japan, all previous records of D. japonicus should be reviewed. This species has been collected from lowland laurel forest to the montane zone at elevations of up to 1,200 m.

Figures

FIGURE 1. Dasycerus occultus sp. nov. (A) Habitus in dorsal view. (B) SEM image of pronotum in dorsal view. (C–D) Prothorax in ventral view (black triangles indicate the protergosternal keel). (E–F) Right elytron in dorsolateral view. (G) Aedeagus in lateral view. (H) Female genital chamber in ventral view. Scale bars: 1.0 mm for A; 0.5 mm for C & E; 0.2 mm for G–H.