Rhyacophila hamata Hattori & Ohkawa 2007

Rhyacophila hamata Hattori & Ohkawa 2007 (Fig. 1D) Rhyacophila hamata Hattori & Ohkawa, in Ohkawa & Hattori 2007, pp. 270–274, male, female, larva, Hokkaido (Soya, Okhotsuk, Tokachi, Sorachi, Hidaka, Ishikari). Records in references. Kuhara 2011, pp. 52, 61, Hokkaido (Sorachi, Hidaka); Ito & Kuhara 2023, p. 63, Hokkaido (Soya, Okhotsuk, Kamikawa). Material examined. Hokkaido, Kamikawa: Horokanai-chô, Sounnai-gawa, upper reach, 1 male, 7.vii.2007, leg. TI, S (SPMN-IS); 1 larva, 28.x.2007, leg. TI (SPMN-IS). Ishikari: Ishikari-shi, Hamamasu-ku, Ofuyu, Shiragane-no-taki (type localty), 20 males, 5 females, 9.vi.2007, leg. TI, S (TI); 1 male, 3 females, 7.vii.2007, TI, S (TI); 10 males, 3 females, 11.vi.2008, leg. TI, S (TI); 4 males, 1 female, 7.vii.2009, leg. TI, S (TI); 1 male, 1 female, 29.ix.2016, TI, S (TI). Distribution (Fig. 1D, black squares). Hokkaido (northern and central areas). Habitat. The adults of this species were collected in mountain areas near waterfalls and small rapid streams up to several meters wide. Species group. This species was placed in the Rhyacophila kalkatica Species Group (Ohkawa & Hattori 2007). The species group was first recognized by Arefina (2001) and followed by Hattori (2005) with seven East Palearctic species; a Siberian (R. kalkatica Levanidova & Schmid 1977), two Russia Far Eastern (R. sutchanica Schimid & Levanidova 1986, R. silinka Arefina 1994), a North Korean (R. szeptyckii Malicky 1993) and three Japanese [R. azumaensis Kobayashi 1973, R. asahiensis Kobayashi 1976, and R. hayachinensis Kobayashi 1976 (the two later species synonymized with R. azumaensis by Kuranishi 2016)]. Arefina (2001) and Hattori (2005) did not provide a definite diagnosis for males of the group, but the following characteristics of the R. kalkatica Species Group can be used to diagnose males of the included species: Dorsoposterior margin of segment IX protruding caudad with several spiny processes, long depressed segment X, large anal sclerite and thick inferior appendages with long basal and short apical segments. Rhyacophila hamata is the only species whose larva is known in the species group (Ohkawa & Hattori 2007). Japanese name. Magari-nagare-tobikera.