Stactobiella mutica, Zhou, Lei, Yang, Lian-Fang & Morse, John C., 2016

Zhou, Lei, Yang, Lian-Fang & Morse, John C., 2016, New species of microcaddisflies from China (Trichoptera: Hydroptilidae), Zootaxa 4097 (2), pp. 203-219 : 211

Stactobiella mutica n. sp.

( Fig. 4 )

Diagnosis. The male of the new species is somewhat similar to that of Stactobiella alasignata BOTOSANEANU 1993 (Far East Russia) in having a deep posterior concavity on dorsum IX, a subgenital plate with a long stem, and inferior appendages bearing long setae. But S. mutica n. sp. differs from S. alasignata in having 1) the posteroventral corners of pleura IX forming slender projections with acute tips ( S. alasignata is without projections on the posteroventral corners of pleura IX); 2) inferior appendages positioned underneath segment IX (in S. alasignata they are positioned posterior to segment IX); and 3) the long setae occur only on the anterior portions of the inferior appendages and the posterior portions of the appendages are thumb-like, each with a truncate apex bearing one setae (in S. alasignata the long setae are set all along the posterior margins of the inferior appendages and the posterior 1/3 portion of each inferior appendage is elongated with a rounded apex bearing at least 3 setae).

Male. Length of each forewing 1.8–1.9 mm (n=8). Antennae each 18-segmented (n=8). Ventral process on sternum VII small, short, triangular in lateral view ( Fig. 4 E).

Male genitalia. Anterolateral apodemes of segment IX set on dorsal half, extending to middle of segment VII; posteroventral corners of pleura IX forming slender hooks with acute tips tilted upward in lateral view ( Fig. 4 A) and strongly curved mesad with tips almost meeting each other in ventral view ( Fig. 4 C); posterior dorsum of segment IX forming deep trapezoidal concavity ( Fig. 4 B). Tergum X membranous, trapezoidal with anterior margin about 3 times as broad as posterior margin and with shallow emargination on posterior margin in dorsal view ( Fig. 4 B); in lateral view, apical portion of segment X forming triangular lobe with blunt apex extending beyond segment IX. Inferior appendages partly exposed from beneath segment IX with their posterior ends not extending beyond hooked tips of segment IX in lateral view ( Fig. 4 A); in ventral view, anteroventral 2/3 of inferior appendages thick and semicircular, together outlining open oval with many long setae on inner surfaces of anterior ends and with single pair of short setae submesally; posterior 1/3 of each inferior appendage thumb-like, with apex obliquely truncated and bearing one setae on apicomesal corner. Subgenital plate only about 2/3 as long as inferior appendages in ventral view, anteriorly forming long stem covered with tiny setae, posterior half fan-like, with apical region 8 times as broad as stem in ventral view ( Fig. 4 C). Aedeagus long, simple tube, broadest in basal 1/4, slightly thicker in third 1/4, apical portion slightly curved ( Fig. 4 D).

Holotype. Male; CHINA: Si-chuan Province, Ma-bian County, Tian-xing village, Zhong-shan-gou stream, 4.9 km W of bridge in Ma-bian N28.8492°, E103.5091°, alt. 597 m, 7 Jul 2005. Coll. ZHOU X., SUN C-h., ZHOU C-f., and J. MORSE, CN05070701 ( Fig. 9 ). Paratype. Same data as holotype, 7 males.

Etymology. Latin, mutica = shortened, with reference to the truncate ends of the thumb-like posterior portions of inferior appendages.

Distribution. Oriental region of S.W. China: Southern Si-chuan.

Figures

FIGURE 4. Stactobiella mutica n. sp. male genitalia. A, left lateral; B, dorsal; C, ventral; D, aedeagus; E, ventral process of segment VII, left lateral. a. l. ap. = anterolateral apodeme of segment IX; inf. app. = inferior appendage; sub. g. pl. = subgenital plate; t. X = tergum X; IX = segment IX.

FIGURE 9. Type locality for Stactobiella mutica n. sp.: CHINA: Si-chuan Province, Ma-bian County, Tian-xing village, Zhong-shan-gou stream, 4.9 km W of bridge in Ma-bian N 28.8492 °, E 103.5091 °, alt. 597 m, collection number CN 05070701.