The genus Labiobaetis (Ephemeroptera: Baetidae) in China, with description of a new species Author Shi, Weifang Author Tong, Xiaoli text Zootaxa 2014 3815 3 397 408 journal article 45477 10.11646/zootaxa.3815.3.5 a135a590-a8a5-4fc1-bb2f-925d6920e48b 1175-5326 225975 CBBEC600-252A-4591-BD83-C754948ED3A3 Labiobaetis mustus ( Kang & Yang, 1996 ) n. comb. ( Figs. 20–23 ) Baetis (Labiobaetis) mustus : Kang & Yang, 1996 : 63 ; Pseudocloeon mustum : Soldán & Yang, 2003 : 415 Specimens examined (in ethanol). China , Guangdong Province: 4 nymphs, Yingde City, Shimentai Nature Reserve ( 24.40°N , 113.31°E ), 7-vi-2011 , and 2 nymphs on slides and 7 nymphs, the same locality but collected on 5-xi-2011 , coll. Shi Weifang; Hong Kong : 9 nymphs, Lantau Is., Ling Yan Temple, near Tai O Road, 21-xi-1998 , 1 male imago (emerged on 27-xi- 1998 in the lab), coll. Tong Xiaoli; 8 nymphs, Tan Shan River, near Tan Chuk Hanm ( 22.51°N , 114.18°E ), 18-iii-1998 , coll. Tong Xiaoli; 10 nymphs and 7 female imagoes (reared from nymphs), Lantou Is., Pui O, the Pumpig Station ( 22.23°N , 113.96°E , 7m ), 22-vi-1999 , coll. Tong Xiaoli; Hainan Province : 9 nymphs, Baisha County, Yinggeling National Nature Reserve, Daoyin ( 18.99°N , 109.58°E ), 22-xi- 2005 , coll. Yao Haiyuan; 2 nymphs, Wanning City, Nanqiao Town ( 18.68°N , 110.15°E , alt. 40m ), 22-iv-2011 , coll. Shi Weifang. Nymph was adequately described and illustrated by Kang & Yang (1996) . The imago stage is described for the first time as follows. Male imago (in ethanol, genitalia on slide, reared specimen). Body length 4.8 mm . Forewing 4.4 mm . Cerci 8.5 mm . Turbinate eyes orange to orange-red dorsally and well developed; ocelli off-white with red-brown basal rings. Antennae longer than head capsule; flagella grey with off-white basally; pedicels red-brown; and scapes offwhite or cream. Pronotum yellow-brown with purple-brown markings; mesonotum light yellow-brown with brown markings medially and laterally; metanotum yellow-brown; thorax yellow-brown laterally. Forewing hyaline, longitudinal veins and paired marginal intercalaries light yellow; costa with serration; pterostigmal areas with 4-5 slanting veinlets; hind wings hyaline with 2 longitudinal veins and a tiny vestigial costal process ( Fig. 21 ). Legs off-white to cream. Abdominal segment I red-brown, segments II–V (VI) off-white and translucent; segments (VI) VII–X cream to grey-white; terga I–VIII with single purple-brown transverse streak ( Fig. 20 ); terga II–IV with light brown oblique streak laterally. Genital forceps ( Fig. 22 ) off-white, three-segmented; first segment of forceps broad with a small protuberance on inner apical margin, 2nd segment long and slightly expanded on basal half; 3rd segment short and oval; segments 2–3 covered with wrinkles densely; subgenital projection short and prominent medially. Cerci off-white. Female imago (in alcohol, reared specimen). Body 4.5–5.0 mm. Forewing 4.7–5.5 mm . Cerci 8.8 mm . Female is similar to male except the following characteristics: vertex off-white with 2 longitudinal red-brown streaks submedially; compound eyes black; abdominal segments I–X red-brown, terga II–VIII with two small yellow or pale submedial oblique dashes anteriorly, and two small yellow or pale submedial dots in mid-region; cerci light yellow-brown with red-brown basally. Distribution. China (Guangdong, Hong Kong , Taiwan ). Remarks. Nymphs of this species are similar to those of Labiobaetis atrebatinus orientalis (Kluge) in color pattern of abdomen, but can be differentiated by abdominal segment I lacking a pair of gills. The male imagoes of L. mustus (Kang & Yang) can be separated from that of L. a. orientalis by (1) the abdominal terga VII–X cream to grey-white; (2) terga I–VIII with single purple-brown transverse streak posteriorly; (3) terga II–IV with light brown oblique streak laterally and (4) unlike the known imagoes of genus Labiobaetis whose hind wing without costal process, this species having a tiny vestigial costal process on costal margin of hind wing ( Fig. 21 ). Both species live among marginal vegetation, but the nymphs of L. mustus are most common in slow-flowing or still water.