Hydnobius akitsuensis Hoshina & Sunada, 2003

Hoshina, Hideto, 2012, Review of the tribes Sogdini and Leiodini from Japan and North Chishima Islands. Part II. Genera Hydnobius and Leiodes (Coleoptera: Leiodidae), Acta Entomologica Musei Nationalis Pragae (suppl. 1) 52, pp. 1-168 : 9-10

1. Hydnobius akitsuensis Hoshina & Sunada, 2003

Japanese name: Akitsu-chadutsu-tamakinokomushi ( Figs. 1–3 )

Hydnobius akitsuensis Hoshina & Sunada, 2003: 107 .

Type locality. Japan, Honshu, Yamanashi Pref., Mt. Hôô, Hôô-goya.

Type material examined. JAPAN: HOLOTYPE: ♂, HONSHU: Yamanashi Pref., Mt. Hôô, Hôô-goya , 28.viii.1989, K. Hosoda leg. ( MNHAH).

Additional material examined. JAPAN: HONSHU: 1 ♀, Yamanashi Pref., Mt. Fuji, Aokigahara, 23.viii.1982, S. Naomi leg. ( FUFJ). NORTH CHISHIMA ISLANDS: 1 ♂, Usishir Is., Kraternaya Bay, Yankicha, 20.viii.1995, M. Ôhara leg. ( HUMS).

Diagnosis. Coloration. Pronotum and elytra brown to dark brown; head a little darker than pronotum; coxae and trochanters reddish brown; femora, tibiae, and tarsi brown; antennomeres 3–6 brown; antennomeres 1–2 slightly paler than 3–6; antennomere 8 slightly darker than 3–6; antennomeres 7 and 9–11 dark brown.

Body length 2.5–3.0 mm, ca. 1.9× as long as wide ( Figs. 1A , 2A ), relatively flat ( Fig. 2B ), and almost glabrous on dorsum except for very fine, short, and sparse pubescence along lateral margins and near apex of elytra. Head minutely punctate; right mandible bidentate apically; left mandible with a tooth in apical fourth of inner margin ( Fig. 2C ); antennomeres 1–3 longer than wide; antennomere 4 almost as long as wide; remaining antennomeres each wider than long ( Fig. 2D ); antennomere 11 transversely oval. Pronotum densely punctate, with a fine transverse basal groove. Elytra transversely strigose; punctures of elytra dense, and slightly larger than those on pronotum ( Fig. 2A ); sutural stria distinct, arising from apex to ca. apical 2/3 of elytral length. Metathoracic wings fully developed.

Male. Metafemur relatively slender, almost straight at anterior margin, and with an internally curved tooth in distal fifth on posterior margin ( Fig. 2E ); aedeagus as shown in Figs. 3A, 3B .

Female. Metafemur relatively slender, almost straight at anterior margin, feebly curved posteriorly along posterior margin ( Fig. 2F ); abdominal sternite 8 bearing a robust spiculum ventrale at anterior margin ( Fig. 3C ); coxites and stylus as shown in Fig. 3D .

Differential diagnosis. Hydnobius akitsuensis is similar to H. tibialis Sahlberg, 1903 in dorsal appearance, but may be separated from it by having the slender hind femora and short aedeagus. In contrast, H. tibialis has the relatively robust hind femora and slender aedeagus.

Distribution. Japan: Honshu (Yamanashi Prefecture) and North Chishima Islands (Usishir Island). New to North Chishima Islands.

Note. The species was described on the basis of the only male specimen examined by HOSHINA & SUNADA (2003). Here, we record two additional specimens, including the first record for the North Chishima Islands. Female morphological features are described for the first time in this study.

Figures

Fig. 1. Habitus. A – Hydnobius akitsuensis Hoshina & Sunada, 2003 (from HOSHINA & SUNADA 2003); B – Leiodes kiuchii sp. nov.; C – L. osawai Nakane, 1963; D – L. kamezawai sp. nov. Scale bars: 1 mm.

Fig. 2. Hydnobius akitsuensis Hoshina & Sunada, 2003.A – body, dorsal view; B – ditto, lateral view; C – head; D – antenna; E – male hind leg; F – female hind leg. Scale I: 1 mm for A and B; II: 0.5 mm for C; III: 0.5 mm for D; IV: 0.5 mm for E and F.

Fig.3.Hydnobius akitsuensis Hoshina & Sunada, 2003.A – aedeagus, dorsal view; B – ditto, lateral view; C – female abdominal sternite 8; D – coxite and stylus. Scale I: 0.5 mm for A and B; II: 0.2 mm for C and 0.1 mm for D.