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Hydroptila hahajima Ito & Sasaki sp. nov. (Figs 11A–11G, 12A, 12B) Diagnosis. The male of this species resembles that of Hydroptila ishiura sp. nov. in having a narrow transverse tergal bridge of segment IX, semi-membranous lateral processes, and a subtriangular subgenital plate, but it is clearly distinguished from the latter by the forms of inferior appendages: The inferior appendages are narrowly triangular without any basoventral hooks in H. ishiura (Figs 6B, 6D), but the inferior appendages are subquadrate, each with a short, curled, basoventral hook in this species (Fig. 11D) Adult (Figs 11A–11G). Head, thorax, wing color, tibial spurs, processes of sternites V and VII same as for H. ishiura. Forewings each 2.0 mm in length and hind wings each 1.8 mm in male (n = 1); forewings each 2.1–2.2 mm in length and hind wings each 1.9–2.0 mm in female (n = 2). Antennae each 29-segmented, length 1.2 mm in male (n = 1); each 24–25-segmented, length 0.8–1.0 mm in female (n = 2). Male genitalia (Figs 11A–11E). Segment IX (IX) annular, rather long, transverse tergal bridge narrow, together with subrectangular dorsal setose plate of segment IX (dsp IX) about 1/4 as long as segment, with deep and wide subquadrate excision at anterior margin dorsally and subtriangular excision anteroventrally. Dorsal plate (dp) semimembranous, subtriangular in dorsal view. Lateral processes (lp) semi-membranous, thick, subquadrate in lateral and ventral views. Subgenital plate (sp) thin, triangular, curved ventrad apically, slightly longer than inferior appendages (ia) in lateral and ventral views. Inferior appendages broad in basal 2/3, abruptly narrowed in apical 1/3, with pair of small, curled hooks (ch) basoventrally curved caudad and laterad apically in ventral view. Phallic apparatus (pa) long, almost straight, anterior end extending from anterior margin of segment V when retracted, without titillator. Female genitalia (Figs 11F, 11G). Segment VIII relatively short, with no distinct tergite or sternite: 2–3 pairs of marginal setae on each of dorsum and venter, pair of transverse bands near ventral margin; ventral margin slightly projecting caudad at middle. Vaginal apparatus depressed, thin in lateral view, elongate-oval in ventral view. Final instar larva and case (Fig. 12B). The final instar larva and case are very similar to those of H. ishiura and H. ogasawaraensis, and could not be discriminated from those of the latter two species. Holotype. Male, Japan, Ogasawara Islands, Haha-jima: Uch ̊-zawa (N26.6526, E142.1508, 35 m above sea level), 12–13.iv.2022, TI & TS, L (CBM-ZI 0184763). Paratypes. 2 females, same data as holotype (CBM-ZI 0184764–0184765). Other specimens. Haha-jima: 1 female, same data as holotype; 3 prepupae, 9 larvae, type locality, 1.iii.2020, TI et al., H; 1 larva, Iguma-dani, 29.ii.2020, TI et al., H (Table 1). Distribution (Fig. 1D). Japan (Ogasawara Islands: Haha-jima). Habitat (Fig. 12A). Larvae of this species were found in hygropetric habitat of small mountain streams. Etymology. The species epithet refers to the name of the type locality. Japanese name. Hahajima-hime-tobikera. |
