Rhyacophila acanthoida, Sun, Chang-Hai, 2016

Sun, Chang-Hai, 2016, New species, new records, and new collection data of Rhyacophila from China (Trichoptera: Rhyacophilidae), Zootaxa 4189 (1), pp. 134-144 : 135

Rhyacophila acanthoida n. sp.

( Fig. 1 A–1D)

Diagnosis. The new species is similar to R. annulicornis KIMMINS 1953 in male genitalia, especially in the shape of the ventral plate of the aedeagus, which is slender and deeply incised mesally into two branches in both species, but the new species can be readily diagnosed by the bulging horizontal part of segment X, strong parameres, and the trapezoidal apical segment of each inferior appendage when viewed laterally.

Description of male. Length of each forewing: 8.0-9.0 mm (n = 4). Body (in alcohol) brown. Head brown, antennae and palpi pale. Thorax brown dorsally, pale laterally and ventrally; wings brown; legs yellowish brown, with spurs dark brown. Abdomen brown.

Male genitalia. Segment IX (IX) in lateral view with anterior margin slightly sinuate, posterior margin strongly incised at middle, upper margin about 1/2 as long as ventral margin; in dorsal view, anterior margin slightly concave and posterior margin shallowly incised. The horizontal part of segment X (h.p.X) in lateral view large, with apex rounded, in dorsal view apex truncate; vertical part (v.p.X) slender, with apex slightly recurved posteroventrad. Anal sclerites (a.s.) small, roots short. Apical band in caudal view with straight bottom and paired curved lateral arms. Tergal band (t.b.) strong, in lateral view tapering from broad base to truncate apex. Inferior appendages strong; each with basal segment (b.i.a.) pentagonal in lateral view and somewhat triangular in ventral view; apical segment (a.i.a.) trapezoidal in lateral view and slender in ventral view. Phallic apparatus complicated: phallotheca (pht.) subrectangular; aedeagus (aed.) slender, tapering from base to acute apex, ventral plate (v.p.a.) very long, about 3 times as long as aedeagus, in ventral view with lateral margins parallel to each other, and apical 1/4 divided into 2 branches, each slender and heavily setose apically; parameres (par.) each very strong, setose apically and subapically, with narrow base, in lateral view basal 1/3 gradually enlarged from base, and remaining 2/ 3 somewhat rectangular, in ventral view each progressively enlarged from base to incised apex.

Holotype male. P.R. CHINA: Si-chuan Province , Kang-ding County, unnamed waterfall, tributary of Da-du River, 100 m upstream of G318 at 2824.9 km stone marker, 30.066°N, 102.117°E, elev . 1675 m, 29 June 2005, collected by John C. MORSE.

Paratypes. P.R. CHINA, Si-chuan Province : Lu-ding County, Da-ba Village , La-zi-gou stream, tributary of Da-du River, 100 m upstream of G318 at 2788.7 km stone marker, 29.861°N, 102.223°E, elev . 1515 m, 29 June 2005, collected by Chang-hai SUN, 2 males; Bao-xing County, Da-shui-gou Stream, Feng-tong-zhai National Nature Preserve, Da-shui-gou Station, Route S 210 at 257.7 km marker, 30.579°N, 102.875°E, elev . 1580 m, 27 June 2005, collected by Chang-hai SUN, 2 males, 1 female.

Etymology. The species is named R. acanthoida from the Latin adjective acanthoidus, -a, -um, meaning “like a spine,” in reference to each branch of the ventral plate of the aedeagus with the subapical portion having many spine-like hairs.

Distribution. China (Si-chuan).

Remarks. ROSS (1956) created the R. truncata Group in his Branch 8 to house R. annulicornis and R. truncata KIMMINS 1953, both from Myanmar . SCHMID (1970) created the R. annulicornis Species Group with 12 species, including the only two members of ROSS’ R. truncata Group, and expanded the group by reporting 7 species from India and 1 from Malaysia, and by moving R. marcida BANKS 1947 from ROSS’ R. pepingensis Group and R. dilatata MARTYNOV 1935 from “unplaced species” into the group. Then , SUN & YANG (1995), SUN (1997), and MALICKY & SUN (2002) reported 5 additional species for the group. Rhyacophila brachyblasta MALICKY & SUN 2002 was original assigned to the group, but it should be included in the R. wangpo Species Group instead, thus it is not included among the members of the R. annulicornis Species Group. Therefore, the total number of species in the group is 17. With the description of the new species, the number is brought to 18, of which 7 species are now reported from China .

Figures

FIGURE 1. Rhyacophila acanthoida n. sp., male genitalia. 1 A, left lateral; 1 B, dorsal; 1 C, ventral; 1 D, segment X and anal sclerites and apical band, caudal; 1 E, phallic apparatus, left lateral; 1 F, phallic apparatus, ventral, left paramere omitted. Abbreviations: aed. = aedeagus; a. i. a = apical segment of an inferior appendage (paired); a. s. = anal sclerites; b. i. a. = basal segment of an inferior appendage; h. p. X = horizontal part of segment X; IX = segment IX; par. = paramere (paired); pht. = phallotheca; t. b. = tergal band; u. = apical band; v. p. a = ventral plate of aedeagus; v. p. X = vertical part of segment X; X = segment X.