Mystacides moritai Kuhara & Nozaki & Zhang & Zhou 2023, n. sp

Mystacides moritai n. sp. Figs 1, 4A–4I Mystacides sp. (af. superatus): Morita 2011, 217. Diagnosis. Among species of the M. azureus Species Group, the male of this species shares an unusually large caudal projection of the each inferior appendage with that of M. superatus from China, but can be distinguished from it by lack of the lower projection of the appendage. Female of this species is similar to that of M. azureus but can be distinguished from it by the shape of the lamellae; in lateral aspect, each is parallel sided or slightly tapered in the apical half in the present species but broadest with a dorsal expansion at midpoint in M. azureus. It also somewhat resembles that of M. rivularis n. sp. but can be distinguished from it by the subtriangular plate of the spermathecal sclerite. Adult. Forewing length: male 6.1–8.1 mm (mean = 7.5 mm, n = 10); female 6.8–8.5 mm (mean = 7.5 mm, n = 8). Vertex, thorax, and wings in ethanol brownish black. General morphology typical for the genus. Relative eye size smaller than that in M. azureus for both male and female (Fig. 1). Male genitalia (Figs 4A–4E). Segment IX 1/8 as long dorsally as tall laterally, 1 1/4 times as long ventrally as tall laterally; in ventral view apicoventral process of sternum 2/3 as long as rest of sternum, with stout base and slender V-shaped lateral arms. Preanal appendages very long and slender. Tergum X antisymmetrical, produced into two spines; longer spine bent inward at one-third from base in dorsal aspect, extending beyond apical process of sternum IX; other spine half as long as longer one, nearly straight in dorsal aspect with acute apex. Inferior appendages each clavate in lateral view with slender base 1/3 as thick as broad apex; upper caudal projection directed dorsad, as long as wide; middle caudal projection unusually large, curved dorsomesad, tapering to acute apex; lower caudal projection lacking. Phallus without evident paramere spines or phallicata, with ventromedian spine directed anteroventrad at one third distance from apex and pair of sharp, triangular flanges subapically, apicoventral lip of phallobase constricted subapically in ventral aspect. Female genitalia (Figs 4F–4H). Segment IX short. Segment X shorter than preanal appendages, narrowly incised ventromedially in dorsal view. Preanal appendages slender, straight, and setose. Lamellae very long; in lateral aspect each with apical half twice as broad as basal half, somewhat curved downward, parallel sided or slightly tapered in apical half, with round apex; dorsal margin inflated; outer surface slightly concave. Gonopod plates triangular in ventral aspect with short, rounded pair of posterolateral processes; apex extending far beyond apex of segment X. Spermathecal sclerite rhomboid, rounded anteriorly. Holotype: ³, Honshû, Mie, Shima-shi, Isobe-chô, Natsukusa, 34.359°N, 136.766°E, alt. 20 m, 5.vii.2008, H. Morita. Paratypes: 1³, same data as holotype; 7³, Honshû, Hyôgo, Asago-shi, Wadayama, Kudawa, Ishibe-jinjya, 3.xi.2006, K. Inazu & TI. Other specimens examined. HONSHÛ: Fukui: 5³ 9♀, Tsuruga-shi, Ikenokôchi-shitsugen, 1.x.2013, TI; 3³ 11♀, same location, 30.v.2015, TI; 8³ 7♀, same location, 24.vi.2015, TI; 5³ 4♀, same location, 21.vii.2015, TI; 4♀, same location, 11.vi.2016, TI. Hyôgo: 3³, Asago-shi, Wadayama, Kudawa, Ishibe-jinjya, 19.v.2009, R.B. Kuranishi. Etymology. Named moritai after Mr. H. Morita, who first provided us the examined specimens of this species, including the holotype. Distribution. Japan (western Honshû). Habitat. Adults of this species have been collected at three sites: beside a small stream with low gradient, from a stream flowing through a small marsh, and from a pond recharged by spring water. Adults of M. azureus also have been collected at all these sites sympatrically.