Diplectrona kibuneana Tsuda 1940

(Figs 1, 7)

Diplectrona kibuneana Tsuda 1940, 24−25, male; Inazu & Nishida 2011, 191, male, larva; Nozaki 2016, 75, 348, male; Tanaka 2016, 2, 5, male; Park et al. 2017, 5−6, male; Tanida 2018, 571, 577, larva.

Diplectrona sp. DB: Akagi 1956, 24−25, larva; Tsuda & Akagi 1962, 133−134, larva; Tanida 1985, 176−177, larva.

Hydropsyche difficultata Kobayashi 1984, 5−6, male. New synonym.

Diagnosis. The male of this species is similar to that of D. burha distributed in southeastern Asia and Japan in genitalic morphology, but is easily distinguishable from the latter by the pair of long lateral filament of the abdominal segment V, and the pair of large internal gland of the segment VIII: Each lateral filament is approximately 2 times as long as segment V in this species, but is about 1.3 times as long as the segment in D. burha; and each internal gland is longer than the segment VII in this species, but is lacking in D. burha .

Adult (Figs 1A–1L). Head and body (Fig. 1A) mostly dark brown, antennae with dark stripes; forewings black, with sparse white spots, spots around pterostigma larger (Fig. 1A), but indistinct for specimens preserved in alcohol. Head (Fig. 1B) with small round frontal setal wart (f.s.w.) and pairs of anterior and posterior setal warts; each anterior setal wart (a.s.w.) semicircular, mesal margin slightly concave; each posterior setal wart (p.s.w.) large, oval. Venation as in Figure 1C; forewings each 6.0–8.5 mm long in male (n = 10), 6.8–10.5 mm in female (n = 10), with postcostal region (posterior of looped anal veins) half as long as wing and wider than any wing cells; hind wings each with Sc and R1 veins bowed at pterostigma. Pair of lateral filaments (l.f.) of abdominal segment V (V) long, each approximately 2 times as long as segment V in male (Fig. 1D), 1.5 times in female. Segment V with small internal gland (i.g.) both in male and female. Segment VIII (VIII) with very large internal gland in male, apparently longer than segment VII (VII) (Fig. 1D), lacking in female.

Male genitalia (Figs 1E–1I). Segment IX (IX) triangular in lateral aspect (Fig. 1E). Segment X (X) with pair of mesocaudal lobes (m.c.l.), separated apically in dorsal aspect (Fig. 1F), each with round apex in dorsal and lateral aspects (Figs 1E, 1F), with stout clavate setae; pair of lateral lobes (l.l.) projected outward in dorsal aspect (Fig. 1F), appearing jagged posteriorly because of tiny marginal spines, with short stout setae ventrally, shape of posterior margin in lateral aspect variable (Figs 1E, 1I); pair of preanal appendages (p.a.) large oval in lateral aspect (Fig. 1E), weakly bulging, setose. Inferior appendages (i.a.) each with basal segment long, extending beyond apex of segment X, gradually thickened from base to apex; distal segment about 1/3 as long as basal segment, tapering to apex, curved mesad (Fig. 1F). Phallic apparatus thick basally, narrow in middle (Fig. 1G); apex weakly bulging laterally in dorsal aspect (Fig. 1H), with two pairs of endothecal processes (e.p.) dorsally, each process ovate, dorsal pair larger than ventral pair.

Female genitalia (Figs 1J–1L). Sternum VIII cleft from base, forming pair of lateral lobes (l.l.) widely separated from each other posteriorly in ventral aspect (Fig. 1L). Segment IX (IX) triangular in dorsal aspect (Fig. 1K), rhomboid in lateral aspect (Fig. 1J); with pair of long external sclerotized ribs (s.r.) ventrolaterally, weakly ridged (Figs 1J, 1L). Vulval scale (v.s.) tongue-like in ventral aspect (Fig. 1L), reinforced by sclerotized ribs basolaterally; apex membranous with small median bulge. Segment X (X) rhomboid in lateral aspect (Fig. 1J), anteroventral corner slightly protruding anteriorly.

Immature stage. Diplectrona sp. DB described by Akagi (1956) is the larval stage of this species (Kagaya et al. 1998; Inazu & Nishida 2011).

Specimens examined. Holotype male, paratype male of Hydropsyche difficultata Kobayashi 1984 (in alcohol): Konomazawa, Aone, Tsukui-machi, Kanagawa, 13.vii.1983, M. Kobayashi (KPM-NK). Hokkaido: 1 female, Akanko-Takiguchi, Akan-cho, Kushiro-shi, 1.vii.1991, Y. Hirama; 4 males, 2 females, Ken’ichi River, Yakumocho, 26.vi.–20.vii.1995, Y. Ito & T. Ito (TI). Honshu, Iwate, 1 female, Omori, Koromogawa-ku, Oshu-shi, 19– 20.vi.2017, T. Ito. Akita: 1 male, Otaki-yama, Akita-shi, 6.vii.2004, M. Tanaka (MT); 1 female, Kasukose, Sannai, Yokote-shi, 30.viii.2011, M. Tanaka. Fukushima: 5 males, 2 females, Shio-zawa, Kanozu, Tadami-machi, alt. 430 m, 2–3.viii.2014, S. Inaba. Gunma: 1 male, Funako, Kanna-machi, 28.vii.1998, T. Hattori (SPMN-IS). Ibaraki: 1 male, Uwaso, Ishioka-shi, 4.vi.2011, N. Katsuma. Tokyo: 1 male, Una-zawa, Okutama-machi, 10.vii.1991, T. Nozaki; 4 males, 1 female, Mitsu-sawa, Hinode-machi, 9.vii.1991, T. Nozaki & T. Kagaya; 5 males, Takimoto-sawa, Oguno, Hinode-machi, alt. 430 m, 21.vii.2010, T. Nozaki. Kanagawa: 2 males, Sawai-gawa, Fujino, Midori-ku, Sagamihara-shi, 11.vii.1984, T. Nozaki; 2 males, 2 females, Sakai-gawa, Shiroyama-cho, Sagamihara-shi, larvae collected on 7.vi.1984, adults emerged on 9.vii–12.viii.1984, T. Nozaki; 7 males, Jindai-sawa, Yamakita-machi, 5.vii.1984, T. Nozaki. Niigata: Higashimata-gawa, Oishi, Sekikawa-mura, 31.viii–1.ix.2014, S. Inaba. Toyama: 1 female, Kotani-gawa, Nanto-shi, alt. 450 m, 30.vii.1995, T. Hattori (SPMN-IS). Yamanashi: 1 male, Akasawa, Hayakawa-cho, 3.viii.2008, T. Nozaki. Nagano: 1 male, Shira-kawa, Mitake, Kiso-machi, alt. 1060 m, 4.viii.1998, T. Nozaki; 1 male, Oonagare-sawa, Tohyama-gawai, Iida-shi, 8.viii.2008, T. Torii (TT). Gifu: 1 male, Tsukechikyo, Nakatsugawa-shi, 22.viii.2008, T. Torii (TT); 1 female, Ten-no-taki, Mikawa, Shirakawa-cho, 12.vi.2010, T. Nozaki. Shizuoka: 1 male, 1 female, Jizodo-gawa, Izu-shi, 2.vi.2009, T. Hattori (SPMN-IS); 3 males, same locality, 16.ix.2009 (SPMN-IS); 1 male, 1 female, Kurobe-sawa, Hirano, Aoi-ku, Shizuoka-shi, 20.viii.2009, T. Hattori (SPMN-IS); 1 male, 1 female, Hirano, Aoi-ku, Shizuoka-shi, 25.v.1995, T. Hattori (SPMN-IS). Mie: 1 male, Yunoyama, Komono-cho, 30.v.1997, H. Morita; 2 males, Minamiise-cho, 2.x.2008, H. Morita (NK); 3 males, Kakiuchi, Hakusan-cho, Tsu-shi, 31.v.2009, H. Morita (NK); 1 male, Hirakura, Misugi-cho, Tsu-shi, 14.viii.2011, H. Morita (NK); 3 males, Kammuri-yama, Mizusawa-cho, Yokkaichi-shi, 6–16.iv.2009, H. Morita (NK); 6 males, Kikaji, Iitaka-cho, Matsusaka-shi, 4.viii.2019, H. Morita (NK). Shiga: 2 males, 2 females, Yuzurio, Eigenji-cho, Higashi-omi-shi, alt. 380 m, 6.ix.2013, T. Ito. Hyogo: 3 males, Omen-no-taki, Shinonsen-cho, 12.viii.1989, C. Kugo. Hiroshima: 1 male, Ohta-gawa, Doi, Akiota-cho, 26.vii.2003, S. Nakamura; 1 male, 1 femal, Hosomi-dani, Yoshiwa, Hatsukaichi-shi, alt. 820 m, 19.vii–13.ix.2005, I. Mori. Shikoku, Ehime: 1 male, Ono-ga-hara, Seiyoshi, 7.viii.2018, E. Yamamoto; 2 males, 3 females, Izugatani-yama, Nishidani, Kumakogen-cho, 1–10.viii.2018, E. Yamamoto; 7 males, 6 females, Honomata, Odamiyama, Nakagawa, Uchiko-cho, 11.ix.2018, E. Yamamoto; 10 males, 2 females, Namakusa-dani, Odamiyama, Nakagawa, Uchiko-cho, 16.vii.2000, E. Yamamoto; 1 male, 1 female, same locality, 11–20.vii.2020, E. Yamamoto. Kochi: 1 male, Yosakoi-toge, Teragawa, Ino-cho, 3.viii.2000, I. Yamashita; 1 male, Kuwaze, Ino-cho, alt. 618 m, 2.vii.2003, K. Nio; 2 males, Befu-kyo, Monobe-cho, Kami-shi, 18.ix.2003, K. Nio; 1 male, Tengu-ike, Tsuno-cho, 13.viii.2005, M. Takai; 1 male, 1 female, Kuishi-yama, Kochishi, 8.vii.2005, M. Takai; 1 male, Kitao, Hane, Muroto-shi, 3.vi.2006, M. Takai; 2 males, Kanaezaki, Tosashimizushi, 30.ix.2006, M. Takai; 2 males, 2 females, near Ashizuri-misaki, Tosashimizu-shi, 21.v.1999, A. Ohkawa & T. Ito. Kyushu, Fukuoka: 1 male, Mt. Hiko, Soeda-machi, alt. 650 m, 10.ix.1996, T. Nozaki. Nagasaki: 4 males, 3 females, Todoroki-keikoku, Takaki-cho, Isahaya-shi, 18.ix.2000, T. Nozaki. Kumamoto: 2 males, Kakizako, Izumi-machi, Yatsushiro-shi, 24.v.1998, T. Hattori (SPMN-IS). Miyazaki: 3 males, 2 females, Kawanaka, Aya-cho, 9.xi.2012, Y. Hayashi. Kagoshima: 2 males, 2 females, Tashirofumoto, Kinko-cho, 28.vi.2014, S. Inaba.

Distribution. Japan: Hokkaido, Honshu, Shikoku, Kyushu, Tsushima, Yaku-shima. South Korea.

Japanese name. Kibune-miyama-shima-tobikera.

Remarks. Tsuda (1940) described this species based on two males collected from Kyoto, central Japan. Although I could not examine the type series materials of this species, which are likely lost, the male characteristics in the original description agree well with those of the male described above, especially the length of lateral filaments of abdominal segment V, and the shapes of mesocaudal lobes of segment X and inferior appendages.After comparative study of the type series males of Hydropsyche difficultata with specimens collected widely from Japanese main islands, I recognized that H. difficultata is the same species as D. kibuneana . Although the posterior margin of each lateral lobe of H. difficultata bears a ventral projection directed posterodorsad in lateral aspect (Kobayashi 1984, fig. 12; Fig. 1I), the shape is variable in D. kibuneana even in the same locality.

In the collection of the late Mr. Kobayashi deposited in the Kanagawa Prefectural Museum of Natural History, the holotype and paratype males of H. difficultata were preserved together in the same vial with two handwritten labels reading “7262 ♂.” A male without abdomen and a cleared abdomen in the vial must have been used in the original description by Kobayashi (1984). I added a label “ HOLOTYPE labeled by T. Nozaki, 2021” into this vial and another male was moved into a different small vial with labels, “7262 ♂ ” and “ PARATYPE labeled by T. Nozaki, 2021.”