Osakatheta yasukoae Maruyama, Klimaszewski & Gusarov

Maruyama, Munetoshi, Klimaszewski, Jan & Gusarov, Vladimir, 2008, Osakatheta yasukoae, a new intertidal genus and species of athetine rove beetles (Coleoptera, Staphylinidae, Aleocharinae) from Japan, Zootaxa 1683, pp. 39-50 : 41-47

Osakatheta yasukoae Maruyama, Klimaszewski & Gusarov , sp. nov.

( Figs. 1–37 )

Type material. Holotype ɗ: JAPAN: Ôsaka-fu, Ôsaka-shi, Suminoe-ku, Nankô-yachôen, 11 IV 2002, Y. Kawakami ( NSMT). Paratypes (all collected by Y. Kawakami): JAPAN: 7 ex., same data as holotype but, 27 III 2002 ( OMNH, cMM); 1 ex., ditto, 28 III 2002 (cMM); 2 exs., ditto, 12 IV 2002 (cMM); 2 exs. (teneral), ditto, 19 III 2003 (cMM); 24 exs., ditto, 16 IV 2003 ( FMNH, LFC, CNC, NHMO); 7 exs., ditto, 21 V 2003 (cMM); 2 exs., ditto, 25 VI 2003 (cMM); 3 exs., Suminoe-ku, Nankô-kita Sakishima, 22 V 2003 (cMM); 1 ex., Nishiyodogawa-ku, Hanakawa, Yodo-gawa, 28 III 2002 (cMM); 3 exs., Nishiyodogawa-ku, Himeshima, Yodo-gawa, 12 IV 2003 (cMM); [Mie-ken (Ise-wan)]: 1 ex., Matsuzaka-shi, Kushida-gawa, 28 IV 2002 (cMM).

Diagnosis. This is the only species of the genus currently known. If additional species of Osakatheta are discovered, they are likely to differ in the shape of the median lobe of the aedeagus and spermatheca.

Description. Reddish brown in ground colour; antennae, mouthparts and legs paler. Head ( Figs. 3–5 ) wider than long (head width/head length ratio ca. 1.09); apical margin of clypeus truncate; surface smooth, moderately covered with setae, which are somewhat shorter than those on pronotum and elytra; length of eyes 0.39–0.40 times as long as head width. Antennae ( Figs. 1, 2 ) almost as long as head and pronotum combined; antennomere I long, slightly longer than II; antennomere II almost as long as III; antennomeres 4–10 moniliform, each almost as long as wide; antennomere XI slightly shorter than 1st; approximate relative lengths of segments from basal to apex: 5.0:4.0:4.0:2.0:2.0:2.0:2.0:2.5:2.5:2.5:4.0. Pronotum slightly transverse, about 1.2 times as wide as long, widest around anterior 2/5, narrowed posteriorly; postero-lateral corner rounded; surface finely punctured, densely covered with setae, with 6 macrosetae along lateral margin. Scutellum with integument smooth and sparsely covered with setae. Elytra slightly wider than long (length measured at humeral level), slightly broadened posteriorly; surface finely punctured, densely covered with setae, with 4 or 5 small macrosetae laterally. Legs long, mesotibia 0.9 times shorter than elytra; approximate relative lengths of tarsal segments from basal to apical: 9.0:9.0:8.0:14.5 (protarsus); 15.0:10.0:8.0:7.0:12.0 (mesotarsus); 14.5:12.5:10.0:8.0:15.0 (metatarsus). Abdomen oblong, wider than elytra, widest around segments V and VI; surface smooth; tergites III–VII densely covered with setae; tergite VIII ( Fig. 24 ) broadly rounded on posterior margin, densely covered with setae, with 4 macrosetae on each side; sternite VIII ( Fig. 25 ) rounded on posterior margin, with 6 macrosetae on each side.

Male. Median lobe of aedeagus as in Figs. 28–29 ; in lateral view ( Fig. 28 ) apical lobe slightly bent paramerally, much narrowed subapically, sinuate abparamerally and rounded at apex; basal ridge weakly convex; copulatory piece of inner sac as in Figs. 30, 31 . Paramere ( Figs. 32–33 ) with apical lobe of paramerite dilated apically, with basal two setae about 4 times as long as apical two setae.

Female. Spermatheca ( Figs. 34–35 ) with basal part of stem twice curved around base; capsule dilated apically, about 1/5 as long as stem, densely covered with wrinkles on internal side of apical 2/5–1/2.

Measurements. Body length, ca. 2.3–2.5 mm; fore body length, ca. 1.3–1.4 mm; head width, 0.45–0.46 mm; pronotal length, 0.43–0.45; pronotal width, 0.50–0.52 mm.

Biology. The adult beetles were found under stones on mudflats at river mouths, which are located under the high water line ( Fig. 36 ). The beetles were observed from the beginning of March to the end of June, and in March were all teneral. Immature stages have not been found.

Distribution. Japan: Honshû (Ôsaka-wan, Ise-wan) ( Fig. 37 ).

Etymology. Dedicated to Mrs. Yasuko Kawakami, Ôsaka-fu, collector of the type series, for her contribution to the knowledge of the coastal beetle fauna of the Ôsaka-wan and adjacent areas.

Figures

FIGURE 36. The type locality of Osakatheta yasukoae, a tidal flat at Nankô-yachôen, Ôsaka-fu, Japan. The beetles were found under the stones in the bottom of this photograph. Photographed by Rikio Matsumoto.

FIGURE 37. Known localities of Osakatheta yasukoae (black stars).

FIGURES 1 – 5. Osakatheta yasukoae, SEM photographs. 1 — habitus, dorsal view; 1 a—pronotum, dorsal view; 2 — facies, antero-dorsolateral view; 3 — head, antero-dorsal view; 4 — head, lateral view; 5 — head, ventro-lateral view.

FIGURES 6 – 10. Osakatheta yasukoae, mouthparts. 6 — labrum, dorsal view; 7 — epipharynx, adoral view; 8 — left mandible, dorsal view; 9 — left mandible, ventral view; 10 — right mandible, ventral view.

FIGURES 11 – 18. Osakatheta yasukoae, mouthparts. 11 — prementum; 12 — hypopharynx, adoral view; 1 — right maxilla, ventral view; 14 — right lacinia, ventral view; 15 — right lacinia, dorsal view; 16 — right galea, ventral view; 17 — right galea, dorsal view; 18 — mentum.

FIGURES 19 – 23. Osakatheta yasukoae, SEM photographs. 19 — pronotum, dorso-lateral view; 20 — prosternite, ventral view; 21 — meso- and metathorax, ventral view; 22 — elytra, dorso-lateral view; 23 — claws, right mid leg.

FIGURES 24 – 27. Osakatheta yasukoae, abdominal segment VIII. 24 — male tergite VIII; 25 — male sternite VIII; 26 — apex of male sternite VIII; 27 — apex of female sternite VIII.

FIGURES 28 – 35. Osakatheta yasukoae, male genitalia and spermatheca. 28 — median lobe of aedeagus, lateral view; 29 — median lobe of aedeagus, parameral view; 30 — everted internal sac, lateral view; 31 — everted internal sac, parameral view; 32 — paramere, lateral view; 33 — apical lobe of paramerite, lateral view; 34, 35 — spermatheca.