Stactobiella kumejima, Ito, 2020

Ito, Tomiko, 2020, The genus Stactobiella Martynov (Trichoptera, Hydroptilidae) in Japan, Zootaxa 4748 (3), pp. 561-571 : 567-568

Stactobiella kumejima sp. nov. ( Figs 5 , 6 )

Diagnosis. The male of this species resembles that of Stactobiella amami sp. nov., described from Amami-o-shima, in having long ventro-lateral appendages and well-developed inferior appendages, but it is clearly distinguished from the latter by the form of the ventro-lateral appendages in ventral and dorsal views: slender, strongly curved mesad at half way with strongly pronounced, sharply curved apices in S. kumejima in contrast to the gently curved, short apical section in S. amami .

Adult. Wings brown, some light brown patterning in forewings, but often indistinct in alcohol; light brown dots absent in hind wings. Wing length: males (n=4), forewings each 1.6–1.7 mm and hind wings each 1.3–1.4 mm; females (n=3), forewings each 1.8–1.9 mm and hind wings each 1.6–1.7 mm. Antennae brown; in male (n=3), each 18-segmented, 0.6 mm long; in female (n=3), each 18-segmented, 0.4–0.5 mm long. Short ventral process on abdominal segment VII in male and on VI in female.

Male ( Figs 5 A–5C). Segment IX shorter than segment VIII, with pair of long anterior apodemes and round ventral sclerite mesally. Segment X membranous, subrectangular. Subgenital plate heavily sclerotized, thick, strongly curved ventrad. Ventro-lateral appendages long, directed latero-posterad at first, curved ventro-mesad medially, strongly curved apicad in lateral and ventral views. Inferior appendages in lateral view expanded and rounded in distal half, irregular in shape in ventral view; with few long and many short setae marginally. Aedeagus almost straight, tapered from apical 2/3.

Female ( Figs 5D, 5E ). Tergite and sternite of segment VII fused laterally. Segments VIII–X without any surface sclerites. Segment VIII with about 10 marginal setae. Vaginal apparatus lozenge-shaped, in ventral view with long caudal tube, in lateral view comb-shaped extending into posterior tube.

Holotype. Male , Japan, Ryukyu , Kume-jima , Kumejima-cho, Shirase-gawa, middle reach (28.351667 N, 129.766944 E, 32 m above sea level), 23.iii.2018, N. Shimura, light pan trap. (CBM-ZI 0178576).

Paratypes. 2 males, 5 females, same data as holotype (CBM-ZI 0178577–0178583) .

Other specimens. Ryukyu: 5 females, same data as holotype ; 1 male, Kume-jima, Kumejima-cho, Shirase-

dam-shita, 24.iii.2018, N. Shimura, light pan trap; 1 male, Okinawa-jima, Nago-shi, Genka, Genka-gawa, Hogenhashi, 22-24.xi.2010, T. Ito, light pan trap .

Distribution ( Fig. 6 ). Japan (Ryukyu: Kume-jima, Okinawa-jima).

Habitat. Adults of this species were collected near small stony rapid streams.

Etymology. The name “ kumajima ” is a noun in apposition, coined from the type locality.

Japanese name. Kumejima-sawa-himetobikera.

Figures

FIGURE 5. Stactobiella kumejima sp. nov. 5A–5C, male: 5A, genitalia, left lateral; 5B, same, dorsal; 5C, same, ventral. 5D–5E, female: 5D, abdominal segments VII–X, left lateral; 5E, vaginal apparatus, ventral. Abbreviations: VII–X=abdominal segments VII–X; ae=aedeagus; ia=inferior appendage (paired); lp=lateral process (paired); sp=subgenital plate; vla=ventro-lateral appendage (paired); vs=ventral sclerite. Scale bars, 0.1 mm.

FIGURE 6. Distributions of five species of the genus Stactobiella in Japan and neighboring countries. Symbols in Russia, Mongolia and China are cited from references.