Hydroptila ogasawaraensis Ito

Ito, Tomiko, Ohkawa, Ayuko & Hattori, Toshio, 2011, The genus Hydroptila Dalman (Trichoptera, Hydroptilidae) in Japan, Zootaxa 2801, pp. 1-26 : 7-8

Hydroptila ogasawaraensis Ito , sp. nov.

( Figs. 4 , 14 B)

Hydroptila sp. Satake & Kuranishi, 2007, 283, Japan (Ogasawara Islands).

Adult. Wings dark brown with several small lighter markings. Antennae brown to light brown with darker markings at about half length and at apices.

Male. Lengths of forewing, hindwing and body 2.0– 2.5 mm, 1.8–2.1 mm and 1.8–2.2 mm (n=5), respectively. Antennae 28–31-segmented; length 1.1–1.3 mm (n=5). Ventral process of sternite VII short, subacute apically. Segment IX with rounded apico-lateral apodemes; a short, wide darkly sclerotized rectangular sclerite present at dorsoposterior margin, in lateral view directed slightly dorso-caudad. Dorsal plate membranous with sclerotized lateral edges, short and rectangular in dorsal view, in lateral view thin, rod-shaped. Subgenital plate semi-membranous with strongly sclerotized lateral edges, apically acute or subacute, twice as long as dorsal plate, triangular in lateral view. Phallic apparatus slender with narrow flanges at basal 3/5–4/5. Inferior appendages sub-triangular in ventral and lateral views, angled ventrad for proximal 4/5 and curved dorso-laterad at distal 1/6, almost as long as subgenital plate; ventrally, flared outward at apices.

Female. Lengths of forewing, hindwing and body 2.1–2.7 mm, 1.8–2.3 mm and 2.0– 2.5 mm, respectively (n=5). Antennae 24–26-segmented; length 0.8–1.0 mm (n=5). Segment VIII relatively short, with no distinct tergite or sternite; 3 pairs of marginal setae on each of dorsum and venter, thin transverse bands at base of ventral marginal setae; ventral margin distinctly protruded caudally at middle in ventral and lateral views. Bursa copulatrix thin, lozenge-shaped.

Holotype: Japan, Ogasawara Islands: 1 male, Chichi-jima, Ogasawara-mura, a headwater of Yasse-gawa (27˚03’55” N, 142˚13’08” E, 210 m), 19.II.2006, K. Satake, L (CBM-ZI 145405).

Paratypes: 3 males, same data as holotype (CBM-ZI 145406–145408); 3 females, type locality, 9.XII.2005, K. Satake (CBM-ZI 145409–145411).

Other specimens examined. Ogasawara Islands, Chichi-jima: 13 females, type locality, 28.X.2005, K. Satake, L (RBK); 9 females, ibid., 9.XII.2005, K. Satake, L (RBK); 8 males, ibid., 9.II.2006, K. Satake, L (RBK); 2 females, upper reaches of Okumura-gawa, 1.VII.2005, K. Satake, L (RBK); 1 male, 2 females, Ogasawara-mura, Okumura-gawa, Tokyo Fall, 27.X.2005, K. Satake, L.

Diagnosis. The male of this species is similar to that of H. chinensis in having the dorsal plate membranous and rectangular and subgenital plate triangular, but is clearly distinguishable from that species as follows: The dorsal and subgenital plates are slender and the proximal 5/6 of the inferior appendages are parallel-sided in lateral view in H. chinensis ; whereas in H. ogasawaraensis the 2 plates are short and stout, and the inferior appendages are gradually tapered. The female of this species is clearly distinguished from those of other congeneric Japanese species by having an apico-mesal projection on segment VIII.

Etymology. The specific name refers to the name of the islands where this species was collected.

Distribution. Japan (Ogasawara Islands). Endemic to Ogasawara Islands.

Habitat. Adults were collected from upper reaches of small streams (K. Satake, personal communication).

Japanese name. Ogasawara-hime-tobikera.

Figures

FIGURE 14. Distributions of 12 species of Hydroptila in Japan and adjacent areas. For clarity, nearby collection sites in Japan are grouped together as a single point and the sites are roughly plotted in adjacent, non-Japanese areas.

FIGURES 3 – 4. 3, H. chinensis: A – C, male; A—abdominal segments VII – X, lateral; B—genitalia, dorsal; C—same, ventral; D-F, female; D—abdominal segments VIII, lateral; E—same, dorsal; F—abdominal segments VII – X, ventral. 4, H. ogasawaraensis: A – E, male; A—abdominal segments VIII – X, lateral; B—genitalia, dorsal; C—apex of subgenital plate, variation, dorsal; D—genitalia, ventral; E—phallic apparatus, lateral; F – H, female; F—abdominal segments VII – X, lateral; G—same, ventral; H—abdominal segment VIII, dorsal.