Psilotreta voluta, Kawase, 2021

Kawase, Naoki, 2021, Description of three new species of Psilotreta (Trichoptera: Odontoceridae) from Japan, Zootaxa 4980 (3), pp. 589-598 : 590-593

Psilotreta voluta sp. nov.

( Figs 1A–1H , 2A–2V )

Psilotreta kisoensis Kuwada 1965: 164 , pl. 82, male; Tanida 2008: 254, pl. 94, male; misidentification.

Psilotreta sp. Kawase & Hayashi 2010: 86.

Psilotreta sp. Nojima 2017: 127 .

Diagnosis. This species is easily distinguished from the previously known Japanese species by the shapes of the male genitalia. Although the male genitalia of this species are very similar to those of Psilotreta excavata Yuan et al. 2008 described from the Chinese mainland, Psilotreta clyssan Malicky 2014 from Taiwan, and Psilotreta moritai sp. nov., the male of P. voluta can be distinguished from latter three species by the shape of the ventral projection of the lateral processes and intermediate appendages of the male genitalia. The male of P. voluta is distinguishable from P. excavata by following structures: (1) the intermediate appendages of P. voluta are strongly curved, usually forming a C-shaped structure in lateral view, but those of P. excavata are more strongly curled, almost circular in shape; (2) ventral projections of the lateral processes are extended more anteriorly in P. voluta , but directed right ventrad in P. excavata ; (3) the pair of parameres in the phallus are positioned near the center in P. voluta , but are positioned outside along the outer edges in P. excavata in ventral view. The male of P. voluta is distinguished from P. clyssan by following structures: (1) the median dorsal process of segment X is slightly clavate in P. voluta , but tapering to a weakly acuminate apex in P. clyssan ; (2) the intermediate appendages of P. voluta are strongly curved, usually forming a C-shaped structure in lateral view, but those of P. c lyssan are more strongly curled, almost circular in shape; (3) with one or two spines along the outer edge of each intermediate appendage in P. voluta , but lacking spines in P. clyssan . Diagnosis of P. voluta and P. moritai is discussed in the description of the next following species, P. moritai .

Adult Male and Female. ( Figs 1A, 1B ). General coloration brown for body, antennae, and wings. First and second segments of maxillary palps about same length. Head in dorsal view typical for genus ( Parker & Wiggins 1987): anteromesal warts between bases of antennal sockets; pair of small oval anterior warts and larger oval posterior warts present; elongate, narrow posterolateral warts extending ventrad along posterior margins of eyes ( Fig. 1A ). Length of each forewing: male 7.6–9.7 mm (mean = 8.9 ± 0.68, n = 7), female 9.2–10.3 mm (mean = 9.83 ± 0.36, n = 6). In venation ( Fig. 1B ), discoidal cell present in each fore- and hind wing; male forewings each with apical forks I, II, and V (M1+2, M3+4 undivided); fork I rooted on discoidal cell about 1/3 its length, Cu1a fused with M3+4; and Cu1a and Cu1b separate, Cu2 apparently absent, row of setae parallel with posterior margin suggesting wing coupling mechanism; male hind wings each with apical forks I and II (M1+2, M3+4, and Cu1 undivided), fork I rooted on discoidal cell about 2/3 its length, crossvein between M3+4 and Cu1 absent.

Male Genitalia ( Figs 1C–1F , 2A–2V ). Tergum IX elongate, subtriangular in dorsal view, with finely granular surface and steep sides above basal setal warts. Basal segment of each inferior appendage shorter than preanal appendages, cylindrical and slightly tapered near apex, covered with setae; apical segment about 0.4X as long as basal segment, cylindrical with many small brown teeth on apical half. Preanal appendages elongate, compressed (flattened, about 4 times as long as thick in dorsal view), parallel-sided in lateral and dorsal views, extending beyond posterior margins of lateral processes in lateral view. Tergum X forming median dorsal process slightly clavate apically, posterior margin usually rounded but sometimes shallowly notched ( Figs 1D, 1E ); lateral processes each forming subtriangular or oval plate with ventral projection heavily sclerotized and variously shaped (even at same localities), usually curved anteroventrad and acutely pointed at apex ( Figs 2A–2H ); intermediate appendages dark brown, heavily sclerotized, strongly curved, usually forming C-shaped structure in lateral view, each with 1 or 2 spines along outer edge, ending in acute apex directed ventrad (or rarely posteroventrad).

Phallus with phallotheca long, cylindrical; endotheca ventrally with pair of parameres variously prolonged among localities: in Shikoku (Kochi, Ehime, and Tokushima), its length about 4 to 5 times its basal width; in Honshu (Okayama and Shimane) and northern Kyushu (Nagasaki), the length about 5 to 6 times; and in southern Kyushu (Kagoshima), the length more than 6 times as long; aedeagus with ventral plate slightly sclerotized, membranous apex rounded and slightly enlarged, internal phallotremal sclerite V-shaped in ventral view, strongly curved dorsad in lateral view ( Figs 2S–2V ).

Female Genitalia ( Figs 1G–1H ). Length of segment IX about as long as wide in ventral view. Vaginal chamber within segment IX; anterior vaginal sclerite weakly sclerotized; posterior vaginal sclerites heavily sclerotized distally.

Larva, Pupa. Unknown.

Holotype. male (in alcohol), Japan, Shikoku , Kochi, Ino-cho, Teragawa (Yosakoi pass), 33°45'N, 133°11'E, alt. 1350 m, 3.viii.2001, I. Yamashita [Izumi Yamashita] ( LBM141001205 ).

Paratypes. Japan, Shikoku, Kochi: 1 male, 1 female, same locality as holotype, 7.vii.2001, M. Takai [Mikio Takai] ( LBM141001206–141001207 ) ; 1 male, same locality as holotype, 16.vii.2000, I. Yamashita ( LBM141001208 ) ; 1 female, same locality as holotype, 18.vii.2005, M. Takai ( LBM141001209 ) ; 1 male, same locality as holotype, 14.vii.2006, M. Takai ( MKNC2021001 ) ; 1 female, same locality as holotype, 14.vii.2001, I. Yamashita ( MKNC2021002 ) ; 1 female, same locality as holotype, 9.vii.2004, M. Takai ( MKNC2021003 ) ; 1 female, same locality as holotype, 17.vii.2004, M. Takai ( MKNC2021004 ) ; 1 male and 1 female, Kami-shi, Monobe-son, Kubokage , 33°48'N, 133°59'E, 25.vi.2006, M. Takai ( CBM0180204–0180205 ) ; 1 male, Kami-shi, Monobe-son, Sasa , 33°47'N, 133°53'E, 3.vii.2004, M. Takai ( CBN0180206 ) . Ehime: 1 male (pinned), Saijyo-shi, Komatsu-cho, Ishizuchi , Ishizuchi Shrine Jojusha , 33°47'N, 133°07'E, 26.vii.1952, “J.I. & T.I.” ( EUM) . Tokushima: 1 male, Mima-shi, Minokoshi , 33°52’N, 134°05’E, 4.viii.2003, Kaori Nio ( MKNC2021005 ) . Honshu, Okayama: 2 males, Kagamino-cho, Hadenishitani , 35°13'N, 133°49'E, 12.vii.2013, Koichi Nojima ( MKNC2021006–2021007 ) . Shimane: 1 female, Okuizumo-cho, takezaki ( Mt. Sentsu ), 35°10'N 133°10'E, 26.vi–5.vii.2007, Masakazu Hayashi ( MKNC2021008 ) ; 2 females, ibid., 5–22.vii.2007, Masakazu Hayashi ( MKNC2021009–2021010 ) ; 1 male, ibid., 6–7.vii.2019, N. Kawase & H. Morita [Hisayuki Morita] ( MKNC2021011 ) . Kyushu, Nagasaki: 1 male, Goto-shi, Tomie-machi, Shigejiki , 32°39'N, 128°45'E, larva collected on 28.viii.2018, adult emerged on iii.2019 by Noriyoshi Shimura ( MKNC2021012 ) ; 2 females, ibid., larvae collected on 28.viii.2018, adult emerged on 16.v.2020 by Noriyoshi Shimura ( MKNC2021013–2021014 ) . Kagoshima: 2 males, Yakushima-cho, Kurio , 30°18‘N, 130°24‘E, 10–11.v.2006, Tomiko Ito ( MKNC2021015–2021016 ) .

Etymology. The Latin specific epithet voluta , “volute” in English, is derived from the sharply curved intermediate appendages in the male genitalia.

Distribution. Western Honshu (Okayama, Shimane), Shikoku (Ehime, Kochi, Tokushima), and Kyushu (Kagoshima-Yakushima, Nagasaki-Fukue) Islands.

Habitat and biology. Adults collected near small mountain streams by net sweeping or light traps in late June to August.

Japanese name. Uzu-kiso-tobikera.

Remarks. Kuwada (1965) and Tanida (2008) recorded P. kisoensis from Shikoku based on a male specimen. I examined the specimen deposited in Ehime University Museum and determined it as P. voluta sp. nov. There is no reliable record of P. kisoensis from Shikoku at present.

Figures

FIGURE 1. Psilotreta voluta sp. nov. 1A, male head and pro- and mesothoraces, dorsal; 1B, male right wings, dorsal. 1C–1F, male genitalia: 1C, left lateral; 1D, dorsal (1E, variation); 1F, ventral. 1G–1H, female genitalia: 1G, dorsal; 1H, ventral.Abbreviations: I, II, V = apical forks I, II, V; amw. = anteromesal warts; avs. = anterior vaginal sclerite; a.w. = anterior warts; bsw = basal setal wart (paired); Cu1, Cu1a, Cu1b, Cu2 = cubital veins 1, 1a, 1b and 2; dc = discoidal cell; inf.app. = inferior appendage (paired); int.app. = intermediate appendage (paired); lat.pr. = lateral process (paired); M1, M2, M3, M4 = median veins 1–4; mdp.tX = median dorsal process of tergum X; plw. = posterolateral warts; pr.app. = preanal appendage (paired); pvs. = posterior vaginal sclerite; p.w. = posterior warts; sIX = sternum IX; t.IX = tergum IX; v.pr. = ventral projection (paired).

FIGURE 2. Psilotreta voluta sp. nov., the variations of male genitalia: 2A–2H, left lateral process & intermediate appendage of segment X, left lateral; 2I, 2K, 2M, 2O, 2Q, 2S & 2U, phallus, left lateral; 2J, 2L, 2N, 2P, 2R, 2T & 2V, phallus, ventral. Abbreviations: aed. = aedeagus; end. = endotheca; int.app. = intermediate appendage (paired); lat.pr. = lateral process (paired); par. = paramere (paired); phall. = phallotheca; v.pr. = ventral projection (paired).