Nemoura nankinensis Wu, 1926

Chen, Zhi-Teng, 2020, Plecoptera larvae of China: larval descriptions of two stonefly species (Capniidae, Nemouridae) from Jiangsu Province, Zootaxa 4759 (2), pp. 223-236 : 230-233

Nemoura nankinensis Wu, 1926

Figs. 11–20 .

Nemoura nankinensis Wu, 1926 . J. Sci. Arts., 5: 332; Wu, 1938. Plecopt. Sin., 182; Illies, 1966. Das Tierreich, 82: 208. Baumann, 1975. Smithson. Contrib. Zool., 211: 21; Yang, Li & Zhu, 2015. Fauna Sinica Insecta , 58: 376; Chen & Du, 2017. Zootaxa, 4254(2): 298; Chen & Du, 2017. Illiesia, 13(10): 102; Yang & Li, 2018. Species Catalogue of China. Vol. 2. Animals, Insecta (III), Plecoptera 20.

Material examined. Four male larvae, China: Jiangsu Province, Nanjing City, Mt. Zijinshan ( Fig. 1 ), 32°03′20″N, 118°51′15″E, 50m, Jan. 5, 2020, leg. Zhi-Teng Chen (ICJUST); one male larva, same locality, Jan. 23, 2019, leg. Zhi-Teng Chen (ICJUST).

Mature larva. Body length ca. 5.0 mm. General color light brown, appendages pale ( Fig. 11 ). Head oblong and covered by pale, short hairs; three ocelli indistinct, compound eyes dark and glabrous; anterior half of head dark brown, clypeus contoured by a narrow dark band with mesal notch ( Fig. 12A, B ). Epicranial suture pale; a small dark patch beyond epicranial suture, between lateral ocellus and each compound eye; posterior half of head covered with net-shaped rugosities ( Fig. 12A ). Antennae subequal in length to abdomen, each segment with an apical fringe of equally short, cylindrical bristles ( Figs. 11 , 13 ). Mouthparts typical euholognathan as in Figs. 12B , 14 and 15 , glossa and paraglossa of labium knob-shaped, subequal in length ( Fig. 12B ); labial palp short, three-segmented with longest apical segment, maxillary palp five segmented ( Fig. 14 ); cardo of maxilla weakly sclerotized, outer margin of apical half with a row of moderate bristles; stipes of maxilla short, outer margin and ventroapical area with several moderate bristles; galea long and hook-shaped, apex with a bunch of short bristles, outer margin of apical half fringed with a row of long bristles, inner margin slightly serrate; lacinia long triangular and sclerotized, with four major apical teeth, dorsal and ventral combs with about 12 long bristles. Mandible with six major unserrated, sclerotized apical teeth, near the apical teeth with a marginal comb of about 20 moderate bristles and another several (about six) isolated bristles; molar area glabrous ( Fig. 15 ). Cervix elongated and membranous, ventrally with paired lateral cervical sclerites ( Fig. 12A, B ). Thoracic terga with irregular brown pattern ( Fig. 12A, C ). Pronotum subquadrate, light brown with pale diffuse X-shaped pattern, corners obtuse, margins with moderate spines, the marginal spines reduced near median line of pronotum ( Fig. 12A ). Mesonotum anterolaterally fringed with moderate spines which joint and extend backwards along the median suture; wing pads long elliptical, posterolateral margins with several short spines but inner margins glabrous, surface covered with sparse short spines ( Fig. 12C ). Metanotum anterolaterally with moderate spines which joint and extend backwards along the median suture; wing pads subtriangular, posterolaterally fringed with several short spines, surface with much fewer short spines than forewing pads ( Fig. 12C ). Legs pale. Coxae and trochanters mostly glabrous ventrally, with short spines dorsally ( Figs. 12 , 16 ). Femora with patches of short and long thick spines on outer 2/3 of dorsal surface and along outer margin, and with a dorsal row of moderate spines near inner margin, but mostly glabrous ventrally; inner margin of femora fringed with a sparse row of short spines ( Fig. 16 ). Tibiae dorsally with two divided longitudinal stripes of long spines, and ventrally with a longitudinal patch of moderate spines; inner and outer margins of tibia with moderate and long spines; two large tibial spurs present ventrally ( Fig. 16 ). Outer margin of femora and tibia covered with sparse swimming hairs ( Fig. 16 ). Tarsal segments mostly glabrous; mid tarsal segment shortest; each segment with an inner row of short hairs; apical tarsal segment with sparse swimming hairs along outer margin ( Fig. 16 ). Claws sharp, apically weakly sclerotized ( Fig. 16 ).

Abdominal terga mostly brown ( Figs. 17 , 18 ); abdominal sterna mostly pale ( Fig. 19 ). Posterior margins of abdominal segments fringed with thick spines ( Figs. 17 , 18 ); less distinct, sparse spines present on posterior 2/3 of each segment; boundaries of terga and sterna indistinct ( Fig. 19 ). Terga 6–7 each with two pale triangular spots on posterior margins ( Figs. 17A , 18A ). Posterior of tergum 10 with a membranous median process, which covered by short spines ( Figs. 17B , 18B ). Paraprocts subtriangular and covered with sparse long spines ( Fig. 19B, C ). Cerci pale, longer than abdomen, each segment apically fringed with long bristles and short cylindrical bristles, length of which increases from basal to distal segments ( Figs. 11 , 20 ).

Remarks. The positive association of larvae and adults of N. nankinensis was confirmed by fact only two stonefly species occurred in the sampled stream. General larval morphology of N. nankinensis is consistent with the generic definition of Stewart & Stark (2002) except for the mandible and maxilla, which are apparently diagnostic characters between species of Nemoura . Additional description of larvae will allow for future comparative morphological studies.

Figures

FIGURE 1. Habitat and habitus of Capnia zijinshana Du & Chen, 2016 and Nemoura nankinensis Wu, 1926. A. habitat of adults in Mt. Zijinshan; B. habitat of larvae in fallen leaves of an unnamed stream; C–E. habitus of C. zijinshana when alive; F. habitus of N. nankinensis when alive.

FIGURE 11. Male larva of Nemoura nankinensis Wu, 1926. A–B. larval habitus, dorsal view; C. larval habitus, ventral view.

FIGURE 12. Male larva of Nemoura nankinensis Wu, 1926.A. head and pronotum, dorsal view; B. head and pronotum, ventral view; C. mesothorax and metathorax, dorsal view; D. mesothorax and metathorax, ventral view.

FIGURE 13. Male larva of Nemoura nankinensis Wu, 1926. A. basal segments of antenna, lateral view; B–C. apical segments of antenna, lateral view.

FIGURE 14. Male larva of Nemoura nankinensis Wu, 1926. A. left maxilla, dorsal view; B. left mandible, ventral view.

FIGURE 15. Male larva of Nemoura nankinensis Wu, 1926. A–B. left mandible, dorsal view; C. left mandible, ventral view.

FIGURE 16. Male larva of Nemoura nankinensis Wu, 1926. A. left hind leg, dorsal view; B. left hind leg, ventral view.

FIGURE 17. Male larva of Nemoura nankinensis Wu, 1926. A–B. abdominal segments, dorsal view. Abbreviation: T = tergum.

FIGURE 18. Male larva of Nemoura nankinensis Wu, 1926. A–B. detail of abdominal segments, dorsal view. Abbreviation: T = tergum.

FIGURE 19. Male larva of Nemoura nankinensis Wu, 1926. A–B. abdominal segments, ventral view; C. terminal abdominal segments and cerci, ventral view. Abbreviation: ST = sternum.

FIGURE 20. Male larva of Nemoura nankinensis Wu, 1926. A–B. basal segments of cerci, lateral view; C–D. apical segments of cerci, lateral view.