Capnia yavorskayae Teslenko, 2022

Teslenko, Valentina A. & Semenchenko, Alexander A., 2022, Morphological description of a new species of Capnia (Plecoptera: Capniidae) with DNA barcoding of genus members from the Russian Far East, Zootaxa 5155 (1), pp. 133-141 : 135-138

Capnia yavorskayae Teslenko sp. nov.

( Figs. 1–7 )

Material examined. Holotype: female, Russia, Far East, Khabarovskiy Kray, Komsomolskiy State Nature Reserve , Khankuka Stream Basin , Gorin River Basin , Amur River Basin , 50º76.818 N, 137º42.157 E, 14.05.2020, coll. N. Yavorskaya. Paratypes: 2 females the same place and data as holotype ; 21 females, Khankuka Stream, low part, Gorin River Basin, Amur River Basin , 14.05.2020, coll. N. Yavorskaya ; 1 female, quarry on the road 50º75.695 N, 137º41.273 E, Amur R. Basin , 14.05.2020 ; 3 females (2 in slides) unnamed stream near Kamennaya Pad cordon, Amur River Basin , 50°41’ N, 137°14’ E, 14.05.2020, coll. N. Yavorskaya ; 2 females, Siutaru Stream, Gorin River Basin, Amur River Basin , 19.05.2020, coll. N. Yavorskaya.

Diagnosis. Female subgenital plate short, transverse, truncated posteriorly, occupies anterior half of the sternum 8; unevenly pigmented, anterolateral edges pale, posterior margin straight or slightly rounded medially, and strongly sclerotized; inner sclerite of vaginal complex small, tooth-shaped, and black. Two or three thin transverse shallow membranous folds and a pair of lateral sclerites located below posterolateral margin the subgenital plate. Genital opening of the vaginal complex is broad.

Description. Medium-sized species, body length 5.2–6.2 mm (n=7), darkly sclerotized, and overall brown color ( Figs. 1 , 4–6 ). Setation is dense and long, especially on abdomen and cerci ( Figs. 1 , 4–6 ). Antenna is moderately long, with 31 or more segments. Cercus slender and hairy, shorter than the abdomen length, with 11 or more club-shaped segments; third basal segment as long as wide, further ones are gradually elongated ( Figs. 5, 6 ); apical cercal segments are the longest with their length about three times of their width, intercalary setae are dense and short ( Fig. 1 ).

Wings shortened, forewing length 4.3 – 4.6 mm, wingspan 9.6‒10.2 mm; brownish along radial field, veins dark brown, margins with relatively long brown bristles ( Figs. 2, 3 ). R 1 of forewing typical of Capnia , bent upward at its origin, four cross veins between C and Sc. Rs bears two apical branches, two veins between М and Cu 2; anal veins two ( Fig. 2 ). Hindwing paler than forewing, veins brownish ( Fig. 3 ).

Mesothoracic sclerite ( Fig. 4 ) from ventral view features narrow spinasternum (Sс), not fused with prothoracic postfurcasternum (PPfs) and large basisternum (Bs); median-sized subtriangular presternum (Prs) not fused with basisternum; subtriangular furcasternum (Fs) fused with basisternum, furcasternal arms (Fsa), and furcasternal pit (Fsp); postfurcasternum (Pfs) divided into two lateral, suboval sclerites not fused with others; katepisternum (Kes) separated from basisternum and trochantin (Tn).

Abdominal terga 1−8 brown with broad longitudinal membranous areas along the midline, integument light, matte in appearance. Terga 9‒10 are fully sclerotized. Abdominal sterna 1 – 7 with paired unsclerotized paralateral bands, sternum 7 slightly longer than others ( Figs. 5, 6 ). Sternum 8 has a short, transverse subgenital plate, truncated posteriorly, length does not exceed ½ the length of the sternum 8 ( Figs. 5, 6 ). An oval, unevenly pigmented spot occupies most of the subgenital plate, with pale anterolateral edges. Posterior margin strongly sclerotized, straight or slightly rounded medially, covered posterolaterally with long setae, and overlapping a small tooth-shaped black inner sclerite ( Figs. 5, 6 ). Two or three thin transverse shallow membranous folds are below the subgenital plate. A pair of lateral sclerites located below posterolateral margins of subgenital plate at the membranous half of sternum 8 and do not exceed the length of sternum ( Figs. 5, 6 ). Vaginal complex with broad genital opening, membranous genital cavity reaches the middle of the segment 7 where it branches into the oviducts ( Fig. 7 ).

Affinities. Based on external female morphology, no closely related species are indicated. The noticeably short and truncated subgenital plate is not similar to other Capnia species, and only remotely resembles that of C. kurnakovi , from the Kolyma River Basin, North-East Russia ( Zhiltzova 1978). Сapnia kurnakovi has a shortened subgenital plate but posterior obtuse-angled margin, its base and medial parts are dark, thin and transverse; and membranous folds below the subgenital plate are absent.

Distribution and ecology. The Gorin River is a left tributary (facing downstream) of the Amur River (the Low Amur Basin) about 390 km long. It flows in the Komsomolskiy State Nature Reserve in the Khabarovskiy Kray, of the Russian Far East. The mountain ranges belong to the Sikhote-Alin folded region. Capnia yavorskayae sp. nov. was collected in tributaries of the Gorin River downstream: in the Khankuka Stream (13 km long, altitude 360 m above sea level), Siutaru Stream (13 km long, 480 m above sea level), and small unnamed stream in tract Kamennaya Pad, which flows down in Amur River independently ( Figs. 9–11 ). Stream water temperature did not exceed 5–7°C.

Capnia yavorskayae sp. nov. seems to be a cold stenothermal species occurring in small mountain streams at altitudes of 300–500 m above sea level. The flight period is difficult to understand from the collection method and narrow window of time it was in operation; all females were collected between 14–19 May, and at that time appeared to be nearing completion. The new species was collected along with females of C. khingana , Capniella nodosa Klapálek, 1920 , Paracapnia leisteri Zhiltzova and Potikha, 2005 , and males and females of Paraleuctra cercia ( Okamoto, 1922) ( Klapálek 1920, Potikha and Zhiltzova 2005, Okamoto 1922).

Etymology. The new species is named for Nadezhda Yavorskaya, a Russian chironomidologist, who actively collects stoneflies, including this interesting species.

Figures

FIGURES 1–3. Female of Capnia yavorskayae sp. nov. Paratype. 1. Habitus, dorsal. 2. Right forewing. 3. Right hindwing.

FIGURES 4–7. Female of Capnia yavorskayae sp. nov. Paratype. 4. Mesothoracic sclerite, ventral: Bs—basisternum; Fs— furcasternum; Fsa—furcasternal arm; Fsp—furcasternal pit; Kes—katepisternum; Pfs—postfurcasternum; Prs—presternum; PPfs—prothoracic postfurcasternum; Sc—spinasternum; Tn—trochantin. 5–6. Abdominal tip, variation of the subgenital plate. 7. Vaginal complex (cleared) with genital opening, membranous genital cavity, inner tooth-shaped black sclerite.

FIGURES 8–11. 8. Drift net for collecting stoneflies. 9–11. Holotype and paratype localities of Capnia yavorskayae sp. nov., the Komsomolskiy State Nature Reserve, Gorin River Basin, the Low Amur River Basin, Khabarovskiy Kray, Far East of Russia. 9. Paratype. The unnamed stream near Kamennaya Pad cordon. 10. Holotype. The unnamed stream, Khankuka Stream Basin. 11. Paratype. The Siutaru Stream.