Indonemoura quadrispina, Mo, Raorao, Wang, Guoquan, Yang, Ding, Li, Weihai & uranyi, David, 2019

Mo, Raorao, Wang, Guoquan, Yang, Ding, Li, Weihai & uranyi, David, 2019, Two new species and one new regional record of Indonemoura from Guangxi, China, with additions to larval characters (Plecoptera, Nemouridae), ZooKeys 825, pp. 25-42 : 29-34

Indonemoura quadrispina sp. n. Figs 5, 6, 7, 8, 10c

Indonemoura sp. n.: Gamboa et al. 2019: S1 Table, using the sequence of the present specimens in phylogeny analysis.

Adult habitus

(Fig. 5a). Medium sized species, forewing length in males 5.6-6.2 mm, females 6.5 mm. General colour brown. Head, mouth parts and legs dark brown; antennae brown; compound eyes dark. Thorax including pronotum dark brown; pronotum (Fig. 5a) nearly trapezoidal, corners bluntly round, lateral margins light brown, midlateral portion with dark rugosity. Wings brownish, subhyaline with dark veins. Abdominal segments brownish but terminalia darker with hairs light brown.

Male terminalia.

Tergum IX (Fig. 6a) distinctly sclerotised anteriorly, with a large triangular mid-posterior incision. Sternum IX (Fig. 6b, c) with claviform vesicle; vesicle mostly membranous except anterior and lateral margins sclerotised, with an oval mid-anterior membrane, length greater than 4 × width; hypoproct broad and nearly rectangular at basal half, then gradually tapering to a nipple-like tip. Tergum X distinctly sclerotised, with a deep median concavity present beneath epiproct, and a pair of upraised triangular process present mesolaterally. Cercus slightly sclerotised and nearly cylindrical, with many clothing hairs, length ca. 2.5 × width. Epiproct (Figs 5 b–d, 6a, c) recurved and long; dorsal sclerite nearly gourd-shaped and basal half roughly circular, slightly constricted medially, rectangular subapically, then distinctly tapering toward sharp tip; ventral sclerite strongly sclerotised, broad at base and becoming narrower toward apex, expanded ventrally into a straight ridge with rows of spines before fusing with dorsal sclerite; bearing a pair of dark thorn-like subapical structures. Paraproct (Figs 5b, e, f, 6 a–d) divided into three lobes: inner lobe sclerotised, slender and rectangular basally, with an acute tip; median lobe mostly sclerotised and broad at base with a large triangular distal denticle at inner portion and a large, forked spine subapically, distinctly curved inward apically at outer margin; outer lobe strongly sclerotised, horn-shaped with a small projection near mid-point.

Female

(Fig. 7). Sternum VII membranous, with two dark markings at its inner and median portion, as inner genitalia structures appear by transparency. Sternum VIII with wide, bicolored subgenital plate covering two third of length and slightly overhanging, its width is more than two thirds of segment’s width; paired paragenital plate small and rounded, indistinct, attached to posterolateral sides of the subgenital plate. Lateral portions of the subgenital plate dark brown, medial area light and posteriorly narrowing; posterior margin laterally rounded and medially slightly concave. Sternum IX lightly sclerotised, anterior margin overlapped by the subgenital plate. Sternum X and paraproct typical. Inner genitalia mostly membranous, with two small lateral sclerites attached to the anterolateral edges of the subgenital plate, and a large, bulbous structure beneath spermathecal ductus, involving a pair of small central sclerite; genital opening narrow.

Mature larva

(Fig. 8): Body relatively slender, body length without antennae and cerci 4.8-5.2 mm. General colour brown, with indistinct dark brown pattern on thorax and slightly darker apical third on femora. Antennae, mouth parts and cerci pale, as well as ventral aspect of the body. Setation short and indistinct on the body but legs and cerci armed with longer setae. Legs moderately long, width of hind femora more than 1/3 of their length. The pronotum is trapezoidal with rounded corners, wider than long, as wide as head. Cervical gills shorter than the length of cervical sclerite where the gill is attached. Wing pads twice as long as the corresponding segments. Abdomen slender, integument yellowish matt brown, first six abdominal segments completely, tergum VII partly divided by pleura. Posterior margin of sternum IX of the male larva sharply triangular in the middle, sternum VIII of female larva slightly incised; paraprocts slightly elongated but apex blunt. Cerci long, with 29-32 cylindrical segments; length of the 15th segment is ca. two times of its width.

Setation of the larva (Fig. 8): Head, antennae, and palpi with moderately dense, short setae. Pronotum covered with very short and scarce setae; marginal setae very short and blunt, of which bases are narrower than the rounded apices, row interrupted in anteromedial and posteromedial fifth, corners have the longest setae that are as long as one 35th of pronotum width (Fig. 8a). Setae on meso- and metanotum slightly longer than marginal setae on pronotum; wing pads with very short, blunt setae. Legs with scarce setation, all tibia bears indistinct, scarce swimming hairs as long as half of femur width (Fig. 8e, f). Longest acute setae on fore femora as long as half of femur width, while on hind femora only as one third of femur width; long setae not arranged in line, restricted to mediodorsal area. Tarsi and claws relatively long. Tergal segments covered with very short setae; row of posterior margin with slightly longer, blunt paired setae reaching ca. one seventh of segment length, but on posterior terga more, similar long setae occur (Fig. 8c, d). Cercal segments with sparse but relatively long intercalary setation, apical setae dense and relatively long; cercomeres 14-16 with an apical whorl of 9-11 acute setae that are longer than half of segment length (Fig. 8b).

Type material.

Holotype: 1 male (HIST), China: Guangxi Zhuang Autonomous Region, Shangsi County, Shiwandashan National Natural Reserve, forest seep by the Pearl River, 265 m, 21°54.216'N, 107°54.240'E, 2015.Ⅲ.27-29, leg. J Kontschán, JN Li, S Li, WH Li, D Murányi, GQ Wang. Paratypes: 2 males and 1 female, 2 pharate male larvae, 3 ultimate instar larvae (HNHM), same data as holotype.

Etymology.

The specific name is a noun in apposition, referring to four apical spines on the median lobe and outer lobe of the paraproct.

Distribution.

China (Guangxi).

Ecology.

The species was found only in a small forest seep by the Pearl River in the Shiwandashan National Natural Reserve (Fig. 10c). The seep is having sandy or fine gravel substrate with plenty of organic materials like fallen leaves. Besides the new species, adults of Rhopalopsole cestroidea Li, Murányi & Gamboa, 2017 (in: Li et al. 2017c), Amphinemura hainana Li & Yang, 2008d and A. hamiornata Li & Yang, 2008c were also collected beaten from the riparian plants around the seep. However, only larvae of the new species were found in the water, and other adult stoneflies probably emerged from the Pearl River flowing only a few meters far from the seep. March seems to be the main season of its emergence, since more adults than larvae were found.

Remarks.

The new species seems to be most similar to I. curvicornia Wang & Du, 2009 described from Zhejiang in the dorsal aspect of the long and narrow epiproct and similar outer lobe of paraprocts, especially the horn-shape of outer lobe with a small projection at apical half. However, the new species may be separated from I. curvicornia by its dorsal sclerite gourd-shaped in dorsal view and ventral sclerite of epiproct with straight ridge in lateral aspect; median lobe with a subtriangular denticle at apical inner portion and its outer portion is forked subapically. In I. curvicornia , the ventral sclerite of slim epiproct with narrow keel; median lobe membranous at inner portion and its outer portion slim and unforked apically (figs 15-19, 21 in Wang and Du 2009). Similar bifurcate median paraproctal lobes also occur in I. trichotoma Li & Yang, 2008b from Yunnan Province, but it is easily separated from that species by the forked outer paraproctal lobe and the spineless hypoproctal apex (comparing Figs 6-7 in Li and Yang 2008b and Figs 3b, e, f, 4 a–d). The female of I. quadrispina is less distinctive, simple subgenital plate is similar to several congeners, e.g I. clavata Sivec & Stark, 2010 or the I. scalprata female described below. It can be distinguished from the latter on the basis of bicolored, wider, and less concave subgenital plate. The larva can be easily distinguished from known larvae of congeners on the basis of its very short tergal setation.