Amphinemura retusilobata, Mo & Wang & Yang & Li & Murányi, 2020

Mo, Raorao, Wang, Guoquan, Yang, Ding, Li, Weihai & Murányi, Dávid, 2020, Two new species of the Amphinemura sinensis group (Plecoptera: Nemouridae) from southern China, Zootaxa 4820 (2), pp. 337-350 : 338-342

Amphinemura retusilobata sp. n.

( Figs. 1–4 )

Diagnosis. Male: tergum IX with short spines, tergum X with long spines, epiproct with apically notched lateral processes that are shorter than median process, paraproctal outer lobe slender, median lobe flat in lateral view and the tip strongly outcurved in dorsal view. Female: pregenital plate large and dark, subgenital plate bicolored and posteriorly bilobed with deep and wide medial indentation, inner genitalia with a pair of stripe-like medial sclerites.

Male habitus ( Figs. 1 a–1b). Body color brown to dark brown. Head and mouthparts dark brown; antennae brown, and palpi paler; compound eyes black; head wider than pronotum; pronotum brown, rectangular with obscure rugosities, but pronotum of older or well-sclerotized specimens, trapezoidal with distinct dark brown markings; legs brown. Wing membranes subhyaline, veins brown. Abdominal segments light brown with darker terminalia.

Male ( Figs. 1–3 ). Forewing length 5.2–5.4 mm, hind wing length 4.3–4.4 mm. Tergum IX sclerotized, rather constricted medially, with triangular anterior and posterior indentations, and with two groups of tiny black spines and several long bristles present along posterior margin ( Figs. 2a, 2c , 3a, 3c ). Slender vesicle of sternum IX claviform, length 4.2X maximum width, constricted basally and slightly constricted medially. Hypoproct rectangular basally, gradually narrowing toward nipple-like tip ( Figs. 2 b–2c, 3b–3c). Tergum X sclerotized, a membranous concavity present below the epiproct, bearing two groups of strong black spines on either sides of the epiproct. Cercus slightly sclerotized, cylindrical and weakly curved inward, as long as 2.5X width. Epiproct ( Figs. 2a, 2 c–2d, 3a, 3c–3d,) subrectangular, trifurcate with a slender median process and a pair of lateral processes, the median process much longer than bifid lateral processes. Dorsal sclerite with a broadly oval, membranous basal half; lateral processes strongly sclerotized, straight but apically slightly outcurved and downcurved, apex with several small denticles and an outer semicircular lobe, tip blunt. Ventral sclerite light colored but sclerotized, triangular, tapering toward tip; apical half up-curved but bent downward apically in lateral view; ventrally expanding into a triangular ridge with a row of small black spines. Paraproct trilobed ( Figs. 1 c–1d, 2, 3a–3c): inner lobe triangular, moderately long; median lobe long, the apical half strongly sclerotized in a triangular stripe ending in acute spine, apex strongly curved upwards, bear 0–2 black, long spines medially and numerous long spines along its membranous tip, seems rotated in dorsal view; outer lobe slender, sclerotized and slightly curved outward with a black, long spine at tip but the spine may lacking.

Female ( Fig. 4 ). Forewing length 6.0– 6.7 mm, hind wing length 5.1–5.8 mm. Sternum VII produced in a large, darkly sclerotized semicircular pregenital plate, covering anterior portion of subgenital plate. Sternum VIII forms bilobed subgenital plate with a deep medial indentation; the plate is lightly sclerotized medially, while lateral parts and the posterior lobes are dark. Paragenital plate paired, forming banded brownish lobe connected with posterolateral corner of subgenital plate. Sternum IX trapezoidal, full sclerotized. Paraprocts brown, wide triangular with blunt, rounded tip; cerci brownish, short. Inner genitalia ( Fig. 4d ) mostly membranous, inverted triangular, opening under the forked medial indention of the subgenital plate; a pair of stripe-like medial sclerites present beneath the apical tube that leads into oviductus; medial sclerites linked to medial portion of subgenital plate; apical tube distinctly sclerotized at base.

Type Material. Holotype: male ( HIST), China: Guangdong Province, Maoming City, Xinyi City, Dacheng Town , Yunkaishan National Natural Reserve , the bridge next to the security office at the entrance to the reserve, 966 m, 22º16'34" N, 111º11'43" E, 2018.X.4, light trap, Raorao Mo, Fengping Qin, Wei Liu, Shuai Tang . Paratypes: 2 males, 2 females ( HIST), same locality and date as holotype ; 10 males, 2 females ( HIST), Yunkaishan National Natural Reserve , the river at the gate of the reserve, 987 m, 22º16’34”N, 111º11’43”E, 2018.X.5, Raorao Mo, Fengping Qin, Wei Liu, Shuai Tang ; 4 males ( GXU) , 2 males ( HNHM) , 8 females ( HIST), same locality, 2018. X.4, Raorao Mo, Fengping Qin, Wei Liu, Shuai Tang ; 1 teneral male with weakly developed paraproct, Guangxi Zhuang Autonomous Region, Nanning City , Wuming County, Liangjiang Town , Neichao , Longmugou River , 220 m, 23°29′40”N, 108°21′37”E, 2015.III.24, Junyi Li, Shan Li, Weihai Li, Dávid Murányi ; same section of Long-mugou River , 198 m, 23°29′39”N, 108°21′36”E, 2020.V.18, Raorao Mo, Yan Lai, Yingying Mo ; 1 female, lower section of Longmugou River , 194 m, 23°29′33”N, 108°21′29”E, 2020.V.19, Raorao Mo, Yan Lai, Yingying Mo ; 1 female, lower section of Longmugou River , 186 m, 23°29′57”N, 108°21′21”E, 2020.V.21, Raorao Mo, Yan Lai, Yingying Mo .

Etymology. The name refers to the lateral processes of the male epiproct with an apical notch. Latin “retusus” means notch, and “lobus” means projection.

Distribution and ecology. The new species is known from southern China, the type series was collected from low and medium elevations of two isolated mountain systems of Guangdong and Guangxi Provinces. The two mountain ranges are separated nearly by 300 km. Collected in foothill and medium elevation habitats, A. retusilobata is expected occur more widely in southern China. The type locality in Guangdong is a variable stony stream with dense riparian vegetation ( Figs. 9 a–c). In Guangxi, the specimens were collected from the Longmugou River, a small foothill stream ( Fig. 9d ). Its upper section habitat was described and illustrated in Mo et al. (2019b: Fig. 10d ), under the name Neichao River.

Remarks. The new species is a distinctive member of the A. sinensis group, only resembling A. viet Stark & Sivec, 2010 , a species described from northern Vietnam. The two species share a similar tergum X, inner paraproct lobe, ventral sclerite of epiproct, and dorsal sclerite of epiproct that is armed with an outer apical notch on the lateral processes. However, A. retusilobata can be easily separated from A. viet by the median lobe of paraproct which is flat in lateral view and the tip strongly outcurved in dorsal view, the median process of epiproct is much longer than lateral processes and the bifid lateral processes are having blunt apex ( Figs. 1 c–1d, 2–3). In A. viet , the median lobe of paraproct is slightly club-shaped in lateral view, and swollen outside of the tip in dorsal view; median process and lateral processes subequal in length, and the lateral processes with an acute apex (figs. 24–26, Stark & Sivec 2010). In addition, outer paraproctal lobes of A. viet may be obscure, not mentioned or figured in the original description by Stark & Sivec (2010). The outer paraproct lobes of A. retusilobata are slender, distinctly sclerotized, usually with a black apical spine. The female is less distinctive, but can be identified by the combination of presence of large and dark pregenital plate, bicolored and posteriorly widely bilobed subgenital plate, and a pair of stripe–like medial sclerites of the inner genitalia.

Figures

FIGURE 1. Amphinemura retusilobata sp. n. (male). a. Head and pronotum, dorsal view. b. Head and pronotum, dorsal view. c. Left paraproct, ventral view. d. Left paraproct, ventral view.

FIGURE 2. Amphinemura retusilobata sp. n. (male). a. Terminalia, dorsal view. b. Terminalia, ventral view. c. Terminalia, lateral view. d. Epiproct and apex of the median left paraproct lobe, oblique caudal view.

FIGURE 3. Amphinemura retusilobata sp. n. (male). a. Terminalia, dorsal view. b. Terminalia, ventral view. c. Terminalia, lateral view. d. Epiproct, dorsal view.

FIGURE 4. Amphinemura retusilobata sp. n. (female). a. Terminalia, ventral view. b. Terminalia after being cleared, ventral view. c. Vaginal complex after being cleared, dorsal view. d. Vaginal complex after being cleared, dorsal view.

FIGURE 9. a–c. Type locality habitat of Amphinemura retusilobata sp. n. and A. simifleurdelia sp. n. in Yunkaishan National Natural Reserve, Guangdong Province, China. d. Habitat of paratypes of A. retusilobata sp. n. in lower section of Longmugou River, Guangxi Zhuang Autonomous Region, China.

FIGURE 10. Distribution of the Amphinemura sinensis species group. Grey areas are above 2000 m s.l., dark line delimits known distribution of the group, dark grey areas are with more than one species known.