Rhyacophila kuranishii Torii, 2021

Torii, Takaaki & Kobayashi, Tohru, 2021, Redescription of Rhyacophila yukii Tsuda 1942 and description of three new Rhyacophila species from Japan (Trichoptera: Rhyacophilidae), Zootaxa 4995 (3), pp. 537-550 : 545-548

Rhyacophila kuranishii Torii n. sp.

Figs 4A–4J

Rhyacophila sp. I : Kuranishi & Yamamoto 2000, p. 63, list.

Rhyacophila sp. 8 : Yamamoto & Ito 2014, p. 7, list.

Diagnosis. This species is generally similar to other members of the Japanese R. anatina Group: R. bilobata Ulmer 1907 (= R. niwae Iwata 1927b ); R. itoi Tsuda & Kawai 1967 ; R. brevicephala Iwata 1927a (= R. lacrimae Tsuda 1940 , = R. nakagawai Kobayashi 1969 ); R. pacata Tsuda 1940 , and R. verecunda Tsuda 1940 . Among them, the male genitalia of the new species are most similar to those of R. pacata . The male differs from R. pacata by the following characters: (1) The apex of segment IX in dorsal view extends slightly distad, but not as far distally as in R. pacata ; (2) the paired preanal appendages (pr.a.) are cylindrical, with short setae, extending distad, and are about 2/3 as long as the basal segments of the inferior appendages (b.i.a.), but paired preanal appendages (pr.a.) of R. pacata are about 4/5 or more as long as the basal segments of the inferior appendages.

The female vaginal apparatus of this species is similar to that of R. pacata . However, it can be distinguished by the posterior process of the vaginal apparatus, which is wider than in R. pacata .

Male. Length of each forewing 7.8–9.3 mm (n = 9). Specimens in alcohol with head, thorax, and wings light brown; legs and spurs yellowish brown.

Male genitalia ( Figs 4A–4G ). Segment IX in lateral view short ventrally, long dorsally, dorsal margin about 4 times as long as ventral margin; in dorsal view center of posterior margin extending distad. Pair of preanal appendages (pr.a.) in dorsal view extending posterad, about 1/3 as long as basal segments of inferior appendages (b.i.a.), cylindrical with short setae, somewhat H-shaped with expanded base in dorsal view. Segment X between segment IX and preanal appendages, not visible in dorsal view. Anal sclerites (a.s.) in lateral view bar-shaped, posteroventral margins slightly concave; in caudal view subquadrate. Basal segment of each inferior appendage (b.i.a) long, in lateral view dorsal and ventral margins approximately parallel to each other, basal portion slightly thicker than distal portion, anterior and posterior margins oblique; each apical segment (a.i.a.) in lateral view subquadrate.Apical band (a.b.) in lateral view long and narrow, bar-shaped, in dorsal view ligulate, aedeagus (aed.) in lateral view slender, tubular, curved slightly upward; parameres (par.) elongate, distally thinner and with strong mesal bristles.

Female. Length of each forewing 8.3–9.1 mm (n = 3).

Female genitalia ( Figs 4H–4J ). Segments IX, X, XI often pulled into segment VIII. Segment VI with small thin spur mesoventrally. Segment VIII cone shaped. Segment IX membranous and trapezoidal, dorsal and ventral margins parallel. Segment X membranous and trapezoidal. Segment XI with pair of cerci (c.). Apodemal rods from segment VIII (ap.r.VIII) elongate in anterior direction in segment VII. Apodemal rods from segment XI (ap.r.XI) elongate in anterior direction through segment VI. Posterior process of vaginal apparatus (p. pr.) heavily sclerotized, in dorsal view long oval, in lateral view boat shaped.

Immature stages. Unknown.

Holotype. Male, Semidani, Kitô-chiku , Naka-machi , Tokushima (33.7958°N, 134.2072°E, 380 m a.s.l.), 5.v.2009, T. Torii, sweep ( SEHU).

Paratypes. 1 male and 3 females, same date as holotype ( SEHU) ; 1 male, Izugatani, Kuma-kogen , Ehime, 1–5.vi.2013, E. Yamamoto ( CBM) ; 3 males, Higashi-iya-sueoi, Miyoshi-shi , Tokushima (1410–1430 m a.s.l.), 8.vi.2011, T . Nozaki ( CBM) ; 1 male, Namakusa-dani, Uchiko-cho , Ehime (33.5616°N, 132.9033°E, 1000 m a.s.l.), 28.v.1994, R . B. Kuranishi ( CBM) .

Other material examined. 2 females, Akaragi-toge , Jizouji , Tosa-machi, Tosa-gun, Kochi, 21.v.2008, T . Ito ( SPMN) ; 3 males, Shiraga-toge , Monobe-cho, Komi-shi, Kochi (1400 m a.s.l.), 22.v.2008, M. Takai & T . Ito ( SPMN) .

Etymology. The new species is named in honor of Dr. Ryoichi B. Kuranishi, who first collected this species and sent us the specimens.

Distribution. Japan (Shikoku).

Habitat. The type locality was a small, 10-m-wide, mountain stream with bottom consisting of boulders of different sizes, pebbles, and leaf litter, and with steep banks. Water was clear, colorless, transparent, and odorless.

Remarks. Thirty-six species are included in the R. anatina Group ( Sun 2016), most of which are Holarctic, and 6 species are recorded in Japan ( Hattori 2018). This species is currently distributed only in Shikoku, Japan.

Japanese name. Kuranishi-nagare-tobikera.

Figures

FIGURE 4A−4J. Rhyacophila kuranishii new species. 4A−4G, male genitalia: 4A, left lateral; 4B, dorsal; 4C, ventral; 4D, segment IX and anal preanal appendages, dorsal; 4E, segment IX and preanal appendages, caudal; 4F, left paramere, left lateral, inset; 4G, apex of aedeagus, left lateral, inset. 4H−4J, female genitalia: 4H, segments VI−XI, left lateral; 4I, vaginal apparatus, ventral; 4J, vaginal apparatus, left lateral. Abbreviations: a.b. = apical band; aed. = aedeagus; a.i.a = apical segment of an inferior appendage (paired); a.s. = anal sclerite (paired); ap.r.VIII = apodemal rod from segment VIII (paired); ap.r.XI = apodemal rod from segment XI (paired); b.i.a. = basal segment of an inferior appendage (paired); c. = cercus (paired); par. = paramere; p.pr = posterior process of vaginal apparatus; pr.a. = preanal appendage (paired); pr.sp. = processus spermathecae of vaginal apparatus.