Lepidostoma hattorii sp. nov.

(Figs. 12–17, 21)

Dinarthrum coreanum: Ito 1998, male, Japan (Honshu: Yamanashi, Shizuoka), in part, misidentification. Morita 2002, 37, Japan (Honshu: Mie). Morita 2003, 26, Japan (Honshu: Mie), misidentification.

Lepidostoma coreanum: Morita 2009, 140, Japan (Honshu: Mie), misidentification.

Lepidostoma sp.: Kawase & Hayashi 2010, 86, Japan (Honshu: Shimane).

Diagnosis. Males of this species are similar to those of Lepidostoma niigataense sp. nov., but clearly discriminated from the later by triangular mesal arms and reduced lateral and ventral arms of tergum X. Females of this species are also similar to those of L. niigataense and difficult to discriminate.

Male (Figs. 12–17). Type specimens (Fig. 12). Antennal length indeterminate due to specimen condition, each scape setose, thick and long, 1.5 times as long as head, with short mesal process near middle of scape. Maxillary palps very setose, unsegmented, comb-like, 0.6 mm long. Labial palps each 3-segmented, slender, 1.0 mm long in total.

Wings covered with fine setae, short scales, and spindle-like setae; spindle-like setae lining cubital area; forewings each with apical forks 1 and 2 and discoidal cell, Cu1 fused to Mp at apical 1/4; hind wings each with apical fork 1, Cu1 fused to Mp at apical 1/5, Cu2 short and strongly curved caudally, and vein A lacking; forewings and hind wings each 6.2–6.5 mm long and 5.0– 5.6 mm long, respectively (n=2).

Genitalia. Abdominal segment IX short, dorsum longer than venter. Segment X composed of mesal arms and lateral arms; mesal arms long, triangular in lateral and dorsal views with subacute apices; lateral arms absent or reduced to low lobes; ventral arms completely absent. Inferior appendages each composed of main article, dorsal hook, and inner hook; basal half of main article broad in lateral and ventral views with serrate mesal and posterior margins; apical half of main article comb-like, directed mesocaudad; dorsal hook bar-like, directed caudad, slightly curved mesad, slightly shorter than main article; inner hook much shorter than dorsal hook, bar-like, curved mesad. Phallic apparatus thick, membranous in apical half with inner U-shaped sclerite, paramere absent.

Variation (Figs. 13–17). Specimens collected from all 5 Japanese localities show some variations. In the males from Ishikawa (Fig. 13) and Shizuoka (Fig. 14), the genitalia and maxillary palps are almost identical to those of males from the type locality (Fig. 12), but wing venation is different from that of the later, with the thyridial cell present in each forewing and Cu2 gently curved to marginal vein in hind wings.

In the males from Aichi (Fig. 15) and Mie (Fig. 16), lateral arms are almost completely absent (Fig. 15 F) or represented by short slender lobes (Fig. 15 D, E, Fig. 16 C), and Cu2 and A are absent in hind wings.

In a male from Shimane (Fig. 17), lateral and ventral arms are completely absent; cross vein m-cu present in each forewing.

Female (Fig. 12 H–J). Type specimens (Fig. 12 H–J): Antennal length indeterminate due to specimen condition, each scape setose, thick, long and 2 times as long as head, mesal process absent. Maxillary palps each 5-segmented and about 0.8 mm long, labial palps each 3-segmented and 0.6 mm long, all palps slender.

Wings covered with short fine setae, venation typical of other species of Lepidostomatidae; forewings and hind wings each 6.0– 6.2 mm long and 5.0– 5.3 mm long, respectively (n=2).

Lateral ends of tergite VIII broad. Lateral plates indistinct. Subgenital plate subquadrate with convex posterior margin and slightly concave anterior margin. Vaginal apparatus oval and slightly sclerotized.

Immature stages. Unknown.

Holotype: Japan, Honshu, Yamanashi: 1 male, Fujikawa-machi, Kajikazawa, Oyama-gawa, hygropetric zone, 35˚31’00”N, 138˚22’50”E, 750 m, 9.vi.1996, T. Hattori (CBM-ZI 151255).

Paratypes. 2 males, 2 females, same data as holotype (CBM-ZI 151256 – 151259).

Other specimens examined. Japan, Honshu, Yamanashi: 1 male, 7 females, same data as holotype; 6 males, 3 females, Hokuto-shi, Hakushu-cho, Ojiro-gawa, 800– 100 m, 13.vi.1992, T. Hattori; 1 male, 2 females, Hokutoshi, Hakushu-cho, Shirasu, 1170 m, 10.vi.2010, T. Hattori. Shizuoka: 1 male, 2 females, Izu-shi, Jizodo, Mt. Amagi-san, 825 m, 16.vi.1996, T. Hattori; 1 male, Yokozawa, 550 m, 4.vi.2001, T. Hattori; 1 male, Yokozawa, Mizumine, small water flow, 1100 m, 6.vi.2003, T. Hattori; 1 male, 2 females, Kawane-honcho, Senzu, Sumatakyo, 550 m, 4.vi.2007, T. Hattori. Ishikawa: 7 males, 10 females, Kashima-cho, Kogane-dani, 16.v.2000, H. Kawase. Aichi: 3 males, Shinshiro-shi, Shimoyoshida, Adera, hygropetric zone on walking trail to Adera-no-taki Fall, 7.v.2010, H. Nishimoto. Mie: 4 males, Daian-cho, Ishigure, 8–12.vi.2001, H. Morita; 1 male, Yokkaichi-shi, Mizusawa, Kanmuri-yama, 5.vii.2009, H. Morita (deposited in the personal collection of H. Morita). Shimane: 1 male, Okuizumo-cho, Mt. Sentsu-zan, Karasuyama-tozanguchi, 16–28.v.2007, M. Hayashi.

Etymology. The species is dedicated to Mr. Toshio Hattori, Shizuoka, who gifted me many valuable specimens, including specimens of this species.

Distribution (Fig. 21). Japan (central and western Honshu).

Habitat. Adults were collected from beside small streams and hygropetric zones in forests.

Japanese name. Hattori-sunatsutsu-tobikera.