Rhyacophila geranos, Kawase, 2025

Rhyacophila geranos sp. nov.

( Figs 1A, 1B View FIGURE 1 , 2A–2H View FIGURE 2 , 3A–3E View FIGURE 3 , 16C View FIGURE 16 )

Rhyacophila sp. 15: Yamamoto et al. 2021, 70, list.

Diagnosis. Male and female genitalia of this species are very distinctive among the R. retracta Species Group. The male genitalia are distinguishable from those of other species by the following two remarkable characters: The apicodorsal lobe of segment IX bears two pairs of stout and acute projections and segment X curves sharply posteroventrally ( Figs 2A, 2C View FIGURE 2 ). In females, a pair of lateral clefts of segment VIII are situated rather ventrally and these clefts can be seen in ventral view ( Fig. 3C View FIGURE 3 ). Moreover, the apical half of the posterior process of the vaginal apparatus is acicular in this species ( Figs 3D, 3E View FIGURE 3 ).

Adult ( Figs 1A, 1B View FIGURE 1 ). Length of each forewing: male 9.0–11.4 mm (mean = 10.4, SD = 0.70, n = 20), female 9.5–13.5 mm (mean =11.9, SD = 0.94, n = 16). Forewings pale yellowish brown in male, yellowish brown in female, with irregular brown reticulation as in Figs 1A, 1B View FIGURE 1 ; assembly of rather clear pale patches at middle of hind margin in male and female ( Figs 1A, 1B View FIGURE 1 ). Abdomen with small midventral process on posterior margin of sternites VI and VII in male, on that of sternite VI in female.

Male genitalia ( Figs 2A–2H View FIGURE 2 ). Segment IX (IX) very short ventrally and long dorsally in lateral view ( Fig. 2C View FIGURE 2 ), rectangular in dorsal view ( Fig. 2A View FIGURE 2 ). Apicodorsal lobe (adl) large, widely spread and covered basal part of segment X, with two pairs of acute, finger-like projections, middle pair longer than lateral one ( Figs 2A, 2C View FIGURE 2 ). Segment X (X) long, extending posteroventrad, bend 90 degrees in middle, like crane neck in lateral view ( Fig. 2E View FIGURE 2 ); with pair of dorsolateral ridges forming longitudinal deep groove, ridges bearing raw of setae ( Fig. 2F View FIGURE 2 ); apex dark pigmented, with median incision, each posterolateral process (plp) slightly expanded posterolaterad ( Fig. 2F View FIGURE 2 ). Pair of anal sclerites (as) fused together, bean shaped in ventral view, dark pigmented, with long common root ( Figs 2E–2G View FIGURE 2 ). Apical band (ab) sclerotized, u-shaped in ventral view, and fused with tergal band basally; tergal band (tb) well sclerotized apically, connecting to dorsum of phallotheca (pht) anteriorly ( Fig. 2E View FIGURE 2 ). Basal segment of each inferior appendage (bsia) setose, elongate, basal half slightly thicker in lateral view ( Figs 2C, 2D View FIGURE 2 ). Apical segment of each inferior appendage (asia) subtriangular, posterodorsal margin weakly concaved in lateral view ( Figs 2C, 2D View FIGURE 2 ), bearing spinules mesally ( Fig. 2D View FIGURE 2 ). In phallic apparatus, phallotheca cup-shaped in lateral view ( Fig. 2E View FIGURE 2 ); aedeagus (aed) long, almost cylindrical tapering to apex ( Figs 2B, 2E, 2H View FIGURE 2 ); dorsal appendage of phallic apparatus (dap) sclerotized, slightly shorter than aedeagus, basal 3/4 fused with aedeagus, apex truncated in dorsal view ( Figs 2E, 2H View FIGURE 2 ). Pair of parameres (par) long, basal half thick in lateral view ( Fig. 2E View FIGURE 2 ), apical half thin, directed posterodorsad with acute apex ( Figs 2B, 2E View FIGURE 2 ).

Female genitalia ( Figs 3A–3E View FIGURE 3 ). Segment VIII (VIII) with dorsal cleft (dc) extremely wide and deep, reaching approximately 2/3 of segment in dorsal view ( Fig. 3A View FIGURE 3 ); with pair of deep lateral clefts (lc) lateroventrally, each extending to middle part of segment ( Figs 3B, 3C View FIGURE 3 ); pair of apodemal rods (ar) slightly longer than segment VIII in lateral view ( Fig. 3B View FIGURE 3 ). Intersegmental membrane of segment VIII–X (ismVIII–X) deeply invaginated into segment VIII, slightly sclerotized, anterior part fixed to interior wall of segment VIII ( Figs 3A–3C View FIGURE 3 ). In vaginal apparatus, posterior process (pp) long, sclerotized, apical half extremely thin ( Figs 3D, 3E View FIGURE 3 ), basal half thick, subtriangular in lateral view, slightly curved anteroventrad ( Fig. 3D View FIGURE 3 ); processus spermathecae (ps) small, subrectangular in lateral view, covered by basal part of posterior process ( Fig. 3D View FIGURE 3 ).

Immature stage. Unknown.

Holotype. Male (in alcohol): Namakusa-dani , Odamiyama , Uchiko-cho, Ehime Prefecture, Shikoku, Japan, 33°33’37” N 132°55’04” E, alt. 1225 m, 11–20.vi.2020, E. Yamamoto ( LBM1410012659 View Materials ). GoogleMaps

Paratypes. Shikoku : Ehime : 1 female (pinned), Yonaru-kawa, Yanaigawa, Kuma-kôgen-cho, 25.v.2011, T. Hattori ( SPMN) ; 1 female, same data as the holotype ( LBM1410012660 View Materials ) GoogleMaps ; 2 males, 4 females, type locality, 21.vi.1999, E. Yamamoto ( SPMN) ; 6 males, 3 females, type locality, 5.vi.2000, E. Yamamoto ( SPMN) ; 1 female, type locality, 8.viii.2000, E. Yamamoto ( SPMN) ; 2 males, 1 female, type locality, 20.ix.2000, E. Yamamoto ( SPMN) ; 1 female, Honomata, Odamiyama, Uchiko-cho, 1–10.vi.2018, E. Yamamoto ( LBM1410012661 View Materials ) ; 1 male, same locality, 11–20.vi.2018, E. Yamamoto ( LBM1410012662 View Materials ) ; 1 male (pinned, fig. 1A), 1 female (pinned, fig. 1B), Mitaki-keikoku, Kubono, Shirokawa-cho, Seiyo-shi, 22.v.2011, T. Hattori ( SPMN) .

Other specimens examined. Shikoku: Ehime: 2 females, Kanmon , Omogo, Kuma-kôgen-cho, 23–25.v.1999, A. Ohkawa & T. Ito ( SPMN) ; 4 males, 6 females, same data as the holotype, 11–20.vi.2020, E. Yamamoto ( Nka) GoogleMaps ; 1 male, Hontani , Odamiyama, Uchiko-cho, 5–8.v.2000, E. Yamamoto ( SPMN) ; 1 female, same locality, 19.v.2000, E. Yamamoto ( SPMN) ; 1 female, Tarôdani , Odamiyama, Uchiko-cho, 20.vi.2000, E. Yamamoto ( SPMN) . Kochi: 1 male, Sakihama-gawa , Muroto-shi, 29.iv.2004, M. Takai ( SPMN) ; 2 males, Ioki-gawa , Bettyaku, Aki-shi, 25.iv.2004, K. Nio ( SPMN) ; 1 female, Nishikuma-keikoku , Kubo-wakubo , Monobe-cho, Kami-shi, 25.vi.2003, K. Nio ( SPMN) ; 1 male, Befu-kyo , Monobe-cho, Kami-shi, 28.v.2004, M. Takai ( SPMN) .

Distribution and biology. Rhyacophila geranos sp. nov. is distributed only in Shikoku, one of Japanese main islands ( Fig. 16C View FIGURE 16 ). The adults were collected near mountain streams in late April to September by sweeping, Malaise traps or light traps.

Etymology. The species epithet “ geranos ” (= crane) is a Greek noun derived from the crane neck-like segment X in lateral view, and crane wing-like apicodorsal lobe of segment IX in dorsal view.

Japanese name. Tsuruo-nagare-tobikera.