Sphaeronemoura separata, Li, Weihai, Murányi, Dávid & Yang, Ding, 2014

Li, Weihai, Murányi, Dávid & Yang, Ding, 2014, A new species of Sphaeronemoura (Plecoptera: Nemouridae) from Henan Province of China, with additions to generic characters of the female and larva, Zootaxa 3793 (3), pp. 371-378 : 372-377

Sphaeronemoura separata sp. n.

( Figs. 1–16 )

Diagnosis. Male tergite VIII with a large, bilobed plate. Male paraproct: inner lobe longer than the projection of median lobe, both darkly sclerotized. Male epiproct: flagellum double curved in lateral view, apex acute. Male cercus slightly bent inwards, tip stout and indented. Female with very large pregenital plate, with widely separated triangular lateral lobes. Female subgenital plate with two large lateral lobes. Larval cercus 10 segmented, lightly colored. Larval setation generally short and relatively indistinct, legs lack swimming hairs.

Type material. Holotype ♂: CHINA: Henan Province, Luanchuan County, Chongdugou Village, Chongdugou scenic area, upper tributary of Jinji River, 1,100–1,300 m a.s.l., N 33°94.08’ E 111°72.78’, 20.VIII.2013, leg. W.H. Li ( HIST); paratypes: 1♂ 1♀, 1♂ larva ( HNHM), 1♂ ( CAU), 1♀ ( HIST).

Description. Large sized species, macropterous. Forewing length: males: 11.0– 11.2 mm; paratype females: 13.0– 13.3 mm. Head uniformly dark brown; palpi and antennae dark brown. Pronotum slightly lighter, trapezoid, wider than long; rugosities scattered. Legs uniformly dark brown; wings dark brown, venation brown. Abdomen brownish but with transverse, sclerotized dark bands on male terga, terminal segments dark brown. Pilosity generally short but with some long hairs on terminal segments.

Male terminalia ( Figs. 1–4 ): Hypoproct small and rounded, apical projection tapering with slightly upcurved, blunt tip; vesicle elliptical, more than 2X longer than wide. Paraproct inner lobe finger-like and dark colored, slightly longer than projection of the median lobe, apex blunt. Median lobe with short, rounded projection of the same dark color as the longer inner lobe; outer portion of the lobe entirely sclerotized, membranous part with conspicuous, short hairs. Outer lobe forming a slender strip curved from the cercal base to the median lobe, apex not forked. Cerci stout, with a dorso-basal lobe in lateral view; slightly bent inwards, tip indented, with an apical nipple. Tergite VIII with very large, dark brown median plate overhanging nearly all of tergite IX, distinctly bilobed in its posterior half; protruding lobe as wide as long. Tergite IX partly sclerotized, antecosta medially thickened before a wide, posteriomedial membranous field that is delimited and partly covered with strong hairs. Tergite X with entire antecosta, medial fifth of the segment completely membranous with a few very short hairs only; well sclerotized lateral areas bear moderately long hairs. Tergal projections situated beneath the apex of epiproct, single at each sides, acute but moderatelly prominent. Epiproct usual for the genus, tongue-shaped in dorsal view, flagellum double curved in lateral view. Dorsal sclerite forked after a strong, trapezoid base; branches short and terminating well before the epiproct’s apex, running laterally and lightly bent downwards, delimiting a large, membranous dorsal area. Ventral sclerite trapezoid, apically slightly bilobed, bears several short teeth in the apical half. Membranous apex tapering in dorsal view, covered base of the flagellum well transparent and attached to the ventral sclerite. Protruding part of the flagellum double curved in lateral view, while curved only once in the apical part in dorsal view; the acute apex slightly bent downwards above the antecosta of tergite X. Basal ⅔ of the flagellum dark brown but gradually lightened towards the pale brown apex; a conspicuous central filament terminates before the apex.

Female terminalia ( Figs. 5–7 ): Pregenital plate very large and dark brown, covering most of sternite VII and overhanging anterior half of sternite VIII; anterior margin rounded, posteriorly with bears two, relatively short, triangular lateral lobes, but concave between the widely separated lobes. Subgenital plate small and trapezoid, basal half hidden beneath the pregenital plate; two, relatively large lateral lobes are attached to its posterolateral corners. Surface of the median subgenital plate bald but wrinkled, while the lateral lobes are covered with short hairs; lateral lobes are dark brown, median plate lighter but with dark lateral margins. Two small, unpigmented vaginal lobes protruding between the lateral lobes of the subgenital plate. Sternite IX dark brown but with a small membranous indentation on the anterior edge medially. Paraprocts with moderately acute tip, epiproct simple; cerci stout with slightly bilobed tip.

Female inner genitalia ( Fig. 8 ): Vaginal lobes small, partly hidden beneath the lateral lobes of the subgenital plate and bearing a few sensilla-like short hairs apically. The lobes are continued in a very long ductus that extends forward beyond the pregenital plate, probably to the spermatheca that should be placed dorsal from sternite VI; near opening section of the ductus is wrinkled inside. The ductus is invaginated into the body from a wide opening between segments VII and VIII, beneath the posterior edge of the pregenital plate. Membranous parts of sternite VII form a large pocket beneath the pregenital plate, where a bulbous body surrounds the ductus. Inner part of this bulbous body is well delimited and with some conspicuous horizontal lines, further thin membranes surround it like onion-skins.

Mature larva ( Figs. 9–16 ): Body relatively slender, body length without antennae and cerci 11.0 mm. General color dark brown, with some hardly visible pattern on the head and prothorax, cerci light brown. Setation short and not so distinct. Legs long, tibiae longer than femora; width of hind femora less than ⅓ of their length. Head dark brown with paler occiput, tentorial callosities well visible. The pronotum is trapezoidal, laterally indented in its posterior third; rugosities indistinct but lateral margins are paler, its length is more than half its maximum width. Cervical gills simple, bald and short. Wing pads less than half as long as the corresponding segments, meso- and metanota without distinct pattern. Abdomen relatively slender and uniformly dark brown colored, integument light matt brown, first 4 abdominal segments fully, 5th partly divided by pleura. Posterior margin of sternite IX of the mature male larva triangular, slightly protruding and not pointed; paraprocts blunt. Terminalia of the mature female larva unknown. Cerci short, with 10 segments. Segments 1–6 not modified and with parallel sides, segments 7–10 bulb shaped and increasing in length, while the widest is the 9th; its width is 0.7 mm; length of the 10th segment is 1.0 mm.

Setation: Head with dense but inconspicuous, stout setae and thin hairs; antennal segments with short setation. Pronotum with dense, short setae and thin hairs; margin of the pronotum bearing acute setae, length of the longest ones is less than 1/20 of pronotum width. Setae on anterior corners of meso and metanota are longer than the marginal setae of pronotum, but still not so distinct. The setae placed in lines on wing pads are short and blunt. Legs with dense setation. All femora bear both short and long, acute setae and a few thin hairs. Long setae are most frequent on the outer and dorsal surface, but not in a regular arrangement; longest ones reach ½ of femur width on first pair, ⅓ on hind legs. A bald median line is conspicuous on the outer surface of all femora. Tibiae bear conspicuous, acute setae arranged in lines, these are erect on dorsal surface; apical spines of tibiae relatively short. Tarsi covered with thin hairs and very short setae, claws normal. Tergal segments with blunt setae and thin hairs, acute spines occur only in the row of the posterior margin. Paired setae are laterally followed by one or two thinner, but sometimes even longer pairs, on tergite V the main pair reaches less than one fourth of segment length. Cercal segments are mostly bald besides their apical whorls. The apical whorl is a set of strong, acute setae (7–9 setae can be seen from dorsal view), with tufts of short setae between them. Setae are of the same length on all fully separated segments but are lacking on terminal segment.

Affinities: The new species is apparently closely related to S. plutonis ( Banks, 1937) from Taiwan, but the male differs with a distinctly bilobed plate on tergite VIII and having the epiproctal flagellum with an acute tip, and the female has a much larger pregenital plate than S. plutonis . It also shares some similarities with S. songshana Li & Yang, 2009 known from Beijing, but the unique plate on the male tergite VIII easily distinguishes it, and additionally having differently shaped cerci and epiproctal flagellum. The larva differs from the known Sphaeronemoura larvae by having fewer segments of the cerci, however, only the larva of S. paraproctalis ( Aubert, 1967) has been described in detail. Larva of the new species differs from this species by having generally much shorter setation and lacking swimming hairs on the legs.

Distribution and ecology. The species was collected from a stream upstream from the Xiefenya Waterfall of the Jinji River scenic area in Chongdugou Village in Luanchuan County, western Henan Province ( Fig. 17 ). No other stoneflies were collected with the new species despite light trapping downstream where electricity was available.

Etymology. The name separata (from the Latin word separatus, means divided, separated) refers to the bilobed plate on tergite VIII. Considered as an adjective, gender feminine.

Remarks on the female inner genitalia. The long ductus that originates from the vaginal lobes is probably forming a “lock-and-key structure” with the male epiproctal flagellum. It is uncertain if its original form is similar to the flagellum or changed into a simple straight ductus during KOH treatment. In all probability it leads to the spermatheca that should be placed unusually far from the genital opening but we were not able to detect it in the specimen after KOH treatment. The function of the bulbous body is also not clear, but seems to have some muscular connection and possibly acts as a contractor during mating.

Remarks on generic characters of the larvae. Among the thirteen known species of the genus, only four are known in the larval stage. In S. plutonis and S. formosana Shimizu & Sivec, 2001 only the cerci were figured ( Shimizu & Sivec 2001), whereas S. paraproctalis was described and figured by Sivec (1980, 1981), and Zwick & Sivec (1980). Sphaeronemoura separata has the typical form of the cervical gills and cerci, but the generic description of the cerci can be complemented by the lack of long setae on last segment. Presence of prominent paired setae on tergal segments seems also a useful generic character. Other larval setation features seem rather different between the two larvae described in detail, the most conspicuous difference is the presence of swimming hairs on the legs of S. paraproctalis , whereas these are lacking in S. separata .

Distribution of the Sphaeronemoura species. The genus exhibits an extensive Oriental distribution. Despite the relatively poor knowledge of the distribution of Sphaeronemoura , the known occurrences of the genus are depicted in Fig. 17 . The type species, S. plutonis is endemic to Taiwan, together with S. formosana and S. elephas ( Zwick, 1974) . Additional six species are known from Indochina: S. inthanonica Shimizu & Sivec, 2001 , S. malickyi Sivec & Stark, 2010 , S. poda Sivec & Stark, 2010 and S. spinacercia Sivec & Stark, 2010 are from northern Thailand, whereas S. shimizui Sivec & Stark, 2010 and two unnamed species ( Sphaeronemoura Vn A and Vn B sensu Sivec & Stark 2010 ) are from northern Vietnam. There are two species known from the central-western part of the Oriental region: S. paraproctalis is widely distributed in the Central and Eastern Himalayas and the Meghalaya Plateau. The recently described S. siveci Murányi & Li, 2013 is presently known only from the latter range. In continental China, S. hamistyla ( Wu, 1962) and an unnamed species ( Sphaeronemoura Cn-Y sensu Li & Yang 2009) are known from the Oriental Region in Yunnan Province, while S. songshana is the only known Palearctic member of the genus known from Beijing, and S. separata was found in Henan Province, on the border of the two biogeographic regions.

Figures

FIGURE 9. Habitus of mature larva of Sphaeronemoura separata sp. n.; paratype, China, Henan Province—scale 1 mm.

FIGURES 10 – 16. Mature larva of Sphaeronemoura separata sp. n.; paratype, China, Henan Province— 10: left hind leg, outer face; 11: left fore femur, outer face; 12: left fore femur, inner face; 13: tergite V, dorsal view; 14: cervical gills, ventral view; 15: right lateral edge of pronotum, dorsal view; 16: right cercus, dorsal view—scale 1 mm.

FIGURE 17. Known distribution of Sphaeronemoura Shimizu & Sivec, 2001 species—grey areas are above 2000 m.

FIGURES 1 – 4. Male terminalia of Sphaeronemoura separata sp. n.; paratype, China, Henan Province— 1: dorsal view; 2: laterodorsal view; 3: lateral view; 4: ventral view—scale 1 mm.

FIGURES 5 – 8. Female genitalia of Sphaeronemoura separata sp. n.; paratype, China, Henan Province— 5: terminalia, ventral view; 6: terminalia, lateral view; 7: pilosity around the genital opening, ventral view; 8: inner genitalia, dorsal view—scales 1 mm.