Rhyacophila yamamotoi Nozaki & Park 2021, sp. nov.
Creators: name: Nozaki, Takao
name: Park, Sun-Jin
Publisher: name: Zenodo
Year: 2021
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Trichoptera
Rhyacophilidae
Rhyacophila
Rhyacophila yamamotoi

description: Rhyacophila yamamotoi Nozaki sp. nov.
(Figs 5, 8, 9)
Rhyacophila sp. B: Morita 2009, 6–7, list.
Rhyacophila sp. 4: Kawase & Morita 2010, 36, list
Rhyacophila sp. 3: Yamamoto & Ito 2014, 7, list.
Diagnosis. Male and female of this species are most similar to those of R. kangae sp. nov. but can be distinguished by characters of the genitalic morphology. In males, the apex of each preanal appendage of this species is weakly bilobed apically in lateral aspect (Fig. 8B) but is rounded in R. kangae (Fig. 1A). Each paramere is expanded subapically in this species (Fig. 8E) but is club-like in R. kangae (Fig. 1E). In the female, the posterior process of the vaginal apparatus of this species is broader and thicker than that of R. kangae (Figs 4E, 4F, 5E, 5F). In Japan, the male genitalia of this species are somewhat similar to that of Rhyacophila kawamurae in lateral aspect, especially in the shape of the inferior appendages, but can be easily distinguished by the shape of the complex of a pair of preanal appendages and the apicodorsal lobe of segment IX in dorsal aspect: These are bilobed from the basal 1/3–1/ 2 in this species but bearing only a minute apical notch in R. kawamurae (Tsuda 1940, fig. 17).
Adult. Specimens in alcohol mostly dark brown to black, but legs light brown. Forewings each 8.0– 11.5 mm in male (n = 10), 10.2–11.0 mm in female (n = 7). Ratio of width of eye to distance between eyes (a/b in Fig. 1F) 0.33–0.40 in male (n = 10) (Fig. 8A), 0.24–0.30 in female (n = 8).
Male genitalia. Segment IX longitudinally short in lateral aspect (Fig. 8B), ventral half longer than dorsum; membranous along midline in dorsal aspect (Fig. 8C). Complex of pair of preanal appendages and apicodorsal lobe of segment IX bilobed from basal 1/3–1/2, widely separated, large, U-shaped in dorsal aspect (Fig. 8C); in lateral aspect each lobe rectangular, apex slightly concave (Fig. 8B); with 2 teeth apicomesally, dorsal one small, ventral one tiny (inset of Fig. 8B). Anal sclerites fused basally, bilobed, each round apex with minute black denticles dorsally (Fig. 8C). Apical band long, curved posterad, ventral margin connected to sagittal appendage of tergal band (Fig. 8B); sagittal appendage round trapezoidal in dorsal and ventral aspects. Basal segment of each inferior appendage thick in lateral aspect (Figs 8B, 8D); mesal face with ridged tendon longitudinally, extending to phallotheca (Figs 8B, 8D); posteromesal angle acute, directed mesad in dorsal aspect (Fig. 8C). Distal segment of each inferior appendage bilobed (Figs. 8B, 8D); both lobes club-like in lateral aspect, with minute spines apicomesally (Fig. 8D). In phallic apparatus, aedeagus bottle-shaped in dorsal and ventral aspects (Fig. 8E); with pair of parameres, each broadened subapically, with tiny spines apically in dorsal aspect (Fig. 8E).
Female genitalia. Segment VIII annular, but semi-membranous along dorsal midline, with pair of dorsal weakly sclerotized extensions (Fig. 5C); pair of apodemal rods reaching posterior end of segment VI. Segment IX membranous, with pair of dorsolateral apodemal rods extending into segment VI; fused with segment X ventrally, with pair of ventrolateral sclerotized band extending to segment X. Segment X slender, with pair of strongly sclerotized bands dorsolaterally; fused with segment XI. In vaginal apparatus, processus spermathecae claw-like in lateral aspect (Fig. 5E), semicircular in ventral aspect (Fig. 5F); posterior process tongue-like in ventral aspect (Fig. 5F), not more than 3 times longer than anterior width, elliptical in lateral aspect.
Immature stages. Unknown.
Holotype. Male (in alcohol). Namakusa-dani, Odamiyama, Uchiko-cho, Ehime, Shikoku, Japan, 33.560°N, 132.918°E, alt. 1225 m, 11–20.v.2020, E. Yamamoto (Malaise trap) (CBM-ZI 0180217).
Paratypes. 10 males, 2 females, same data as the holotype (CBM-ZI 0180218–0180229), 6 males, same data as the holotype excepting the collection period 11–20.vi.2020 (CBM-ZI 0180230–0180235); 1 male, 1 female, Izugatani-yama, Nishidani, Kumakogen-cho, Ehime, Japan, 1–10.v.2018, E. Yamamoto (Malaise trap) (NIBR0000935602–0000935603); 5 males, 2 females, same locality, 11–20.v.2018, E. Yamamoto (Malaise trap) (KPM-NK); 4 males, same locality, 21–31.v.2018, E. Yamamoto (Malaise trap) (NIBR0000935604–0000935607).
Other specimens examined. JAPAN: Honshu: Shizuoka: 1 male, tributary of Nishigochi-gawa, Yokosawa, Aoi-ku, Shizuoka-shi, alt. 550 m, 5.v.2006, T. Nozaki (net sweeping) (TN). Mie: 4 males, Sakashita, Kameyamashi, 14.v.2006, N. Kawase (net sweeping) (MITR-20090042); 10 males, Ojigahata, Taga-cho, alt. 600 m, 19.v– 8.vi.2009, H. Morita (Malaise trap) (NK). Shiga: 2 males, Yuzurio, Eigenji, Higashi-omi, 12–31.v.2009, N. Kawase (Malaise trap) (MITR-20090419). Shikoku: Ehime: 2 males, same data as holotype (TN); 1 male, Izugatani-yama, Nishidani, Kumakogen-cho, 21.vi.2018, E. Yamamoto (light trap) (TN); 14 males, 1 female, same locality, 1– 30.vi.2018, E. Yamamoto (Malaise trap) (TN); 7 males, 1 female, same locality, 1.vii–10.viii.2018, E. Yamamoto (Malaise trap) (SJP). Kochi: 1 male, 1 female, Nishikuma-rindo, Monobe-cho, Kami-shi, M. Takai (TN); 1 male, Befu-kyo, Monobe-cho, Kami-shi, 24.iv.2004, M. Takai (TN).
Etymology. This species is dedicated to Mr. Eiji Yamamoto, who gifted us valuable specimens, including specimens of this species.
Distribution. Japan (Honshu, Shikoku).
Remarks. This species was found from two major islands, Honshu and Shikoku, in Japan (Fig. 9). The genitalic characteristics are consistent in both populations, and there are stable differences between this species and a Korean species, R. kangae sp. nov.
description: Published as part of Nozaki, Takao & Park, Sun-Jin, 2021, Two new species of the genus Rhyacophila Pictet (Trichoptera, Rhyacophilidae) from Korea and Japan, pp. 97-105 in Zootaxa 5067 (1) on pages 99-100, DOI: 10.11646/zootaxa.5067.1.5, http://zenodo.org/record/5656552