Rhyacophila arakawa Ito 2021, sp. nov.

• Main Author: Ito, Tomiko
• Format: Other/Unknown Material
• Language: unknown
• Published: 2021
• Subjects: Biodiversity; Taxonomy; Animalia; Arthropoda; Insecta; Trichoptera; Rhyacophilidae; Rhyacophila; Rhyacophila arakawa; Morse; morse; Siberia
• Online Access: https://zenodo.org/record/5225412; https://doi.org/10.5281/zenodo.5225412

Rhyacophila arakawa sp. nov. (Figs 3, 6B) Rhyacophila sp. 1: Kuhara & Ito 2017, 16, Yakushima. Diagnosis. This new species belongs to the R. lieftincki Species Group, and the male is similar to those of R. kando Schmid 1970, found in Nepal and Bhutan (Schmid 1970; Morse 2021), R. claviforma Sun & Yang 1998, found in eastern and southwestern China (Sun & Yang 1998), and R. impar Martynov 1914, found in Japan (Honshu) and Russia (Siberia, Far East) (Hattori 2005; Ivanov 2011), in having a long triangular segment IX in lateral view, an ax-shaped segment X and a sock-like apical segment of each inferior appendage. However, the male of this new species is distinct from the three similar species in the combination of the following characteristics: Segment IX is triangular in dorsal view; apical parts of segment X are strongly broadened with irregularly serrated caudal margin and pair of lateral plates; and parameres are circular-saw-like apically. The female of R. arakawa is similar to that of R. impar (Arefina 2001; Hattori 2005) but is distinguished by the ratio of length to basal width of segment VIII, which is about 1.3 in R. arakawa but lower than 1.0 in R. impar. Adult. Lengths of forewings and hind wings: Each forewing 8.4–10.3 mm long (mean 9.6 mm, n = 7) and each hind wing 7.1–9.0 mm (mean 8.1 mm, n = 7) in males, 10.7–10.9 mm (mean 10.8 mm, n = 2) and 8.4–9.4 mm (mean 8.9 mm, n = 2) in females, respectively. Head brown, warts light brown with brown setae; antennae brown, scapes thicker and longer than other apical segments; palpi brown to light brown. Thorax brown dorsally. Legs brown, spurs dark brown. Wings brown with darker veins and whitish pterostigmas, light-colored dots scattered on apical 1/3 of forewings. Abdomen with brown tergites and sternites, darker pigments scattered dorsally; small mid-ventral process on sternite VII (or VI and VII) in male and on sternite VI in female, process on sternite VI of male often very small or completely absent. Male genitalia (Figs 3A–3D). Segment IX ...