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Hydroptila nagahama Ito & Sasaki sp. nov. (Figs 11H–11N, 12C–12H) Diagnosis. The male of this species resembles that of Hydroptila ishiura sp. nov. in having a narrow transverse tergal bridge of segment IX and an almost straight phallic apparatus, but it is clearly distinguished from the latter by the forms of inferior appendages and absence of a subgenital plate or lateral processes: The inferior appendages are narrowly triangular in H. ishiura (Figs 6B, 6D), but the inferior appendages are each subquadrate with a strongly sclerotized, large claw and three stout spines on its caudodorsal margin in this species (Figs 11I, 11K). Adult (Figs 11H–11N, 12E). 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 = 2); forewings each 2.0 mm in length and hind wings each 1.8–1.9 mm in female (n = 2). Antennae each 28-segmented, length 1.1 mm in male (n = 2); each 25-segmented, length 0.9–1.0 mm in female (n = 2). Male genitalia (Figs 11H–11L). Segment IX (IX) annular, rather long, about 2.2 times longer than height, transverse tergal bridge narrow, on midline about 1/6 as long as segment, with transverse dark and setose plate (dsp IX) not projecting and with deep and wide circular excisions at anterior margins dorsally and ventrally. Dorsal plate (dp) semi-membranous, trapezoidal with mesal concavity at caudal margin in dorsal view; thick and triangular with subacute apex, longer than inferior appendages and curved ventrad in lateral view. Inferior appendages (ia) subquadrate with strongly sclerotized, large claw ventromesally, thick spine caudoventrally, and three thick spines caudodorsally. Phallic apparatus long, almost straight, anterior end extending from middle of segment VI when retracted, without titillator. Lateral processes and subgenital plate absent. Female genitalia (Figs 11M, 11N). 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 (Figs 12G, 12H). The final instar larva and case of this species are very similar to those of H. ishiura, H. ogasawaraensis, and H. hahajima, and could not be discriminated from those of the latter three species. Holotype. Male, Japan, Ogasawara Islands, Haha-jima: Nagahama (N26.6736, E142.1502, 130 m above sea level), 12.iv.2022, TI & TS, L (CBM-ZI 0184766). Paratypes. 1 male, 2 females, same data as holotype (CBM-ZI 0184767–0184769). Other specimens. Haha-jima: 8 females, 4 pupae (1 male, 3 females), 81 larvae, type locality, 28.ii.2020, TI et al., L & H; 1 male, type locality, 21.xii.2021, TS & Y. Kaga, L; 1 larva, Iguma-dani, 29.ii.2020, TI et al., H (Table 1). Distribution (Fig. 1D). Japan (Ogasawara Islands: Haha-jima). Habitat (Figs 12C, 12D, 12F). Larvae and pupae were found on surfaces of hard rocks and in small concavities of hygropetric habitat in small mountain streams, respectively. Etymology. The species epithet refers to the name of the type locality. Japanese name. Nagahama-hime-tobikera. |
