Rhyacophila lambakanta Schmid 1970

Rhyacophila lambakanta Schmid 1970 View in CoL

( Figs 10A–10C View FIGURES 8–11 , 14A–14D View FIGURES 12–15 , 16C View FIGURE 16 )

Rhyacophila lambakanta Schmid 1970 View in CoL , 209, pl. 41, male, Honshu ( Nagano); Tani 1978, 7–8, male; Emoto 1979, 556–560, 562–565, wings, male, female; Hattori 2005, 422, 430, male, female.

Rhyacophila imagamiensis Kobayashi 1973 , 22–23, pl. 3, male. Synonymized by Tani (1978) and Emoto (1979).

Diagnosis. The male genitalia of R. lambakanta are very distinctive among the R. retracta Species Group in the shape of the apicodorsal lobe of segment IX: Narrow, long, and arcuately curving posteroventrally in apical half ( Figs 10A, 10B View FIGURES 8–11 ). The female genitalia of R. lambakanta are similar to those of R. motakanta and R. humerigera sp. nov. in having a medium-sized dorsal cleft and a pair of lateral clefts in segment VIII ( Figs 5A–5C View FIGURE 5 , 13A–13B, 14A–14B View FIGURES 12–15 ), but can be distinguished from them by the characters given in the diagnosis of R. humerigera sp. nov.

Specimens examined. Honshu: Miyagi: 1 male, Natori-gawa, Futakuchi Onsen, Akiu-machi , Sendai-shi, 8.vi.1974, T . Hattori ( SPMN) . Yamagata: 1 male, 1 female, Shizu, Nishikawa-machi , 18–19.ix.2004, H. Nishimoto ( SPMN) . Tochigi: 1 male, Daiya-gawa, Nikko-shi , 6.x.2002, H. Nishimoto ( SPMN) . Tokyo: 6 males, 1 female, Ôkumotori-dani, Nippara-gawa, Okutama-machi , alt. 1300 m, 5.vi.1991, T . Nozaki (Nka) . Kanagawa: 3 males ,

Shiraishizawa, Yamakita-machi , 12–13.v.1982, T . Nozaki ( Nka ). Niigata: 8 males, 5 females, Wasabi-zawa, Ôtokoro, Itoigawa-shi, alt. 1150 m, 14.viii.1998, T . Hattori ( SPMN); 1 male, Yahei-gawa, Ôtokoro, Itoigawa-shi, alt. 1600 m, 31.viii.2023, D. Kato (NKa) . Ishikawa: 1 male, Chûgu, Hakusan-shi, 29.ix.2001, H. Nishimoto ( SPMN) . Yamanashi: 1 pupa (male), Sakuba-daira-bashi, Ichinose-takahashi, Enzan, Kôshu-shi, alt. 1300 m, T . Hattori ( SPMN); 3 males, 2 females, Hirogawara, Ashiyasu-ashikura, Minami-arupusu-shi, 13.viii.1973, T . Hattori ( SPMN); 1 male, Kamanashi-gawa, Hakushu-cho, Hokuto-shi, alt. 900 m, 1.vi.1997, T . Hattori ( SPMN) . Nagano: 2 males, Kuro-sawa, Yokokawa, Tatsuno-machi, alt. 1050 m, 17.viii.1996, T . Hattori ( SPMN); 1 male, Oguro-gawa, Ina-shi, alt. 1400 m, 17.viii.1996, T . Hattori ( SPMN); 10 males, 1 female, Shio-kawa, Kashio, Ôshika-mura, alt. 1400 m, T . Hattori ( SPMN) . Gifu: 1 male, Namai, Taki-machi, Takayama-shi , 9.vi.2003, H. Nishimoto ( SPMN); 5 males, same locality, 24.vi.2004, H. Nishimoto ( SPMN); 4 males, 1 female, same locality, 18.vi.2005, H. Nishimoto ( SPMN); 1 male (pinned), 2 females (pinned), Iwai-machi, Takayama-shi, 9.vi.2011, T . Hattori ( SPMN); 1 female, Otome-keikoku, Kashimo , Nakatsugawa-shi , 8.vi.2003, H. Nishimoto ( SPMN); 1 male (pinned), 1 female (pinned), Hora, Miyagawa-cho, Hida-shi, 9.vi.2011, T . Hattori ( SPMN); 1 male, Tsurumi, Fujihashi, Ibigawa-cho , 29.v.2002, N. Kawase (NKa) . Shizuoka: 3 males, 5 females, Nishihikage-zawa, Umegashima, alt. 900 m, Shizuoka-shi, 5.vi.1999, T . Hattori ( SPMN); 10 males, 2 females, same locality, 28.v.2014, T . Hattori & T . Nozaki ( SPMN); 4 males, 6 females, Higashi-zawa-deai, Umegashima, Shizuoka-shi, alt. 900 m, 23.vii.1994, T . Hattori ( SPMN); 2 females, Abe-kawa, Nyû-jima, Shizuoka-shi, alt. 375 m, T . Hattori ( SPMN) . Shiga: 1 male, Takatoki-gawa, Yogo-cho, Nagahama-shi, 28.v.2008, T . Ushijima (NKa); 1 male, Intani, Kitahira, Ôtsu-shi , 30.iv.2014, S. Takeda (NKa); 1 male, Katsuragawa-sakashita-cho, Ôtsu-shi, 20.v.2013, S. Takeda (NKa) . Kyoto: 1 pupa (male), Kurama, Kyotoshi, 19.v.1974, T . Hattori ( SPMN) .

Distribution and biology. Rhyacophila lambakanta is distributed from northeastern to central Honshu, Japan ( Fig. 16C View FIGURE 16 : Taira et al. 2025). Adults of this species were collected near streams in late April to early October. Hattori (2005) indicated that this species was found in rather higher altitude than R. motakanta and R. orthacantha .

Japanese name. Yumi-nagare-tobikera.

Remarks. Kobayashi (1984) recorded a male collected from Sado Island (Sadogashima) as R. lambakanta . I examined his specimen (KPM-NKMK72950) and found that the apicodorsal lobe of segment IX of his male is clearly shorter than that of R. lambakanta described above. Further research is needed to confirm the specific identity of this male.