Cinygmula longissima sp. nov.

Holotype: male imago, China, Qinghai Province, Menyuan County, Laohugou, 37°46′44″ N, 101°20′11″ E, 3620 m a.s.l., 25. VII. 2023, leg. De – Wen Gong . Paratypes: 1 male imago, 1 male subimago, 1 female subimago, 7 nymphs, same as the holotype.

Mature nymph (Figs. 1–3): body 9.0–10.0 mm, caudal filaments 7.5–8.0 mm; body slim, grey to pale brown (Fig. 1). Anterior half of head extended forward, median notch shallow “v” shaped (Figs 2A–B). Labium and maxillary palp partially visible in dorsal view. Antennae 2.5 mm, slightly longer than head width, with very tiny almost invisible setae (Figs 2A–B). Posterior margin of head almost straight (Figs 2A–B).

Mouthparts (Fig. 3): labrum semi-circular, with hair-like setae on dorsal and ventral surfaces, and margins, those setae on dorsal surface longer but fewer (Fig. 3A). Structures of left and right mandibles similar, both outer and inner incisors serrated, prostheca presented by row of setae, a few spine-like setae on mesal margin near molar (Figs 3B–C); right mola with distinct denticle on mesal corner (Fig. 3C). Maxillae with row of spine-like setae on mesal margin and another row on ventral surface; line of comb-shaped spines on crown. Apical segment of maxillary palp ca. 1.5× basal one, apex narrowed and pointed; row of setae brush on ventral surface (Fig. 3E). Lingua larger than superlinguae, with hair-like setae on margins and tips (Fig. 3D). Glossae of labium oval, paraglossae heart-shaped, slightly wider than the former; both of them with hair-like setae on margins and dense setae on dorsal surfaces; two segments of labial palpi subequal in length and width; basal segment with several hair-like setae near apex, apical segment with row of setae on outer margin, and with two setae brushes on both dorsal and ventral surfaces, ventral ones larger (Fig. 3F).

Thorax: Pronotum slightly extended laterally (Fig. 1A). Three pairs of legs similar to each other; foretibiae subequal to forefemora; tibiae of mid- and hindlegs shorter than their femora. Median portion of femora paler than surrounding area; tibiae and tarsi uniformly pale to grey, with apex slightly darker (Fig. 1A). Femora with a row of setae on posterior margin and some scattered spine-like setae on dorsal surface. Tibiae with some spine-like setae on anterior margin and some setae on dorsal margin, these setae much shorter than those of femora. Tarsi with setae on dorsal and apical margins (Fig. 2C). Claws of all legs deep brown to dark, with 5 subapical denticles (Fig. 8A).

Abdomen: glabrous, with pair of submedian pale stripes and pair of pale dots, sometimes merged together (Fig. 1A); middle portions of abdominal sterna blacker than lateral portions. (Fig. 1B). Gill plates semi-hyaline with clear brown to dark tracheae. Gills I heart shaped, with single filament; gills II– V similar to each other, plate oval, with single filament; gills VI –VII with plate only (Fig. 2D). Cerci with very tiny setae on articulations, nearly glabrous (Fig. 1).

Male imago (Figs 4–6): body length 11.0–12.0 mm, forewing 11.5 mm, hindwing 4.0 mm, foreleg 9.0 mm, cerci 20.0–21.0 mm. Head and thorax brown to chocolate, abdomen whitish to grey (Fig. 4A). Tergites with a pair of submedian pale stripes and a pair of pale dots but most of them unclear; each sternite with brown to black dot near anterior margin; cerci grey (Fig. 4A).

Frontal fold distinct, anterior margin with a shallow “ V ” shaped notch (Figs 4C–D). Distance between two compound eyes subequal to width of median ocellus (Fig. 4C). Wings transparent (Figs 4A, 5), veins brown, tinged with brown clouds; forewings with pigmented base, Rs and MP forked subequally to wingbase and symmetrically (Fig. 5A). Basal pigmentation of hindwings wider and darker than forewings, MA and MP forked symmetrically, costal projection nearly acute (Fig. 5B). Legs uniformly grey to dark brown, femora darker. Length ratio of forefemora: tibiae: tarsi 10.0: 9.0: 12.0; tarsal segments 2.5: 3.0: 2.5: 2.0: 1.5. Mid- and hindlegs, with femora slightly longer than tibiae, tibiae longer than tarsi; all tarsal segments subequal in length but apical one usually longer than others (Fig. 4B). Articulation between tibia and first tarsal segment distinct. Two claws of all legs similar, acute (Fig. 4B).

Genitalia (Fig. 6): Posterior margin of styliger convex, posterolateral angles of styliger projected (Figs 6A–B). Gonostyli with combined length of segments III and IV slightly shorter than segment II, segment III slightly longer than segment IV (Figs 6A–B). Penes fused at basal 2/3 and separated at apical 1/3, apex round (Figs 6C–D); each penis with pointed median titillators (Figs 6A–E) and lateral spine with 3–4 tiny protuberances on apex (Figs 6A–D, F).

Male subimago (Fig. 7A): body length 9.0 mm, cerci 9.0 mm, forewings 10.5 mm, hindwings 4.0 mm. Similar to male imago but abdomen darker, pale stripes and dots on abdominal tergites clearer. Frontal fold of head and pointed claws of legs as in imago (Fig. 7A).

Female imago (unknown).

Female subimago (Fig. 7B): body length 13.0 mm, forewings 13.0 mm, hindwings 5.0 mm, similar to male subimago but slightly larger and darker. Veins of wings clearer and darker. Frontal fold and claws same as the male (Fig. 7B).

Egg: about 0.2 mm length. One pole flat, other convex. Convex pole with KCTs, flat pole covered with fine protuberances, median portion with both KCTs and protuberances but fewer than on two poles (Fig. 8B).