Tanytarsus dawai Lin, 2025

Tanytarsus dawai Lin , sp. nov.

urn:lsid:zoobank.org:act:031BCB5A-D91A-4C28-B79F-06BB3D4FA5FE

( Figs 2–10 View FIGURE 2 View FIGURE 3 View FIGURE 4 View FIGURE 5 View FIGURE 6 View FIGURE 7 View FIGURE 8 View FIGURE 9 View FIGURE 10 )

Type material. Holotype: male (SHOU & BOLD sample ID: XL157), China, Xizang, Xigaze City, Nilun Village , 29.31684°N, 88.93410°E, 3798 m a.s.l., sweep net, 22.VII.2014, leg. X.L. Lin. GoogleMaps Paratypes: female (SHOU & BOLD sample ID: XL50), China, Xizang, Chamdo City, Ranwu Town, Ranwu Lake , 29.50581°N, 96.76048°E, 3963 m a.s.1., sweep net, 10.VII.2014, leg. X.L. Lin; GoogleMaps 2 males (SHOU & BOLD sample ID: XL117, XL118), China, Xizang, Shannan City, Gongga County, Gangdui Town , 29.27888°N, 90.82323°E, 3586 m a.s.1., sweep net, 18.VII.2014, leg. X.L. Lin; GoogleMaps 4 males (SHOU: XL8, XL10, XL11; SHOU & BOLD sample ID: XL9), China, Xizang, Shannan City, Yamzho Yumco , 29.18879°N, 90.56003°E, 4458 m a.s.l., sweep net, 18.VII.2014, leg. X.L. Lin; GoogleMaps 5 males (SHOU & BOLD sample ID: XL48; SHOU: XL49, XL51, XL52, XL53), China, Xizang, Chamdo City, Ranwu Town, Ranwu Lake , 29.50581°N, 96.76048°E, 3963 m a.s.l., sweep net, 10.VII.2014, leg. X.L. Lin; GoogleMaps 6 larvae (SHOU & BOLD sample ID: XL431, XL432, XL434, XL435, XL437, XL440), China, Xizang, Chamdo City, Ranwu Town, Ruanwu Lake , 29.50581°N, 96.76048°E, 3963 m a.s.l., 10.VII.2014, leg. X.L. Lin. GoogleMaps

Etymology. The specific epithet is dedicated to Associate Professor Dawa from the Tibet Plateau Institute of Biology in Lhasa, Xizang, China, for his outstanding contribution to the knowledge of insects in Xizang; noun in genitive case.

Diagnostic characters. The adult male of the new species can be distinguished from known species of the Tanytarsus norvegicus species group by the following combination of characters: Tergite I-V with horizontal dark brown bands at the posterior quarter. AR 0.86–1.10. Ac absent. LR 1 1.55–1.71. Tarsomere l of mid leg with sensilla chaetica distally. Anal point slender triangular, with six lateral setae on each side, 8–11 spinulae evenly placed at 2/3 length of anal point. Superior volsella sub-rectangular with ventral, small patch of microtrichia. Digitus bent downwards. Stem of median volsella long, with six setiform lamellae and one distal, spatulate lamella. The larva of the new species can be distinguished from known species of the T. norvegicus species group by the following combination of characters: AHR 0.15–0.21. LOR 1.92–2.63. Mandible with one ventral apical tooth, three ventral inner teeth, four dorsal teeth. Mentum with 11 teeth; median tooth with small lateral notches. Premandible with five teeth in addition to lateral spine; premandibular brush well-developed.

Description. Adult male (n = 13).

Total length 3.68–4.08, 3.84 mm; wing length 2.25–2.93, 2.46 mm; total length/wing length 1.39–1.66, 1.56.

Colouration ( Figs 2B View FIGURE 2 ; 3A–B View FIGURE 3 ). Head and legs brown. Thorax and abdomen with pale brown ground colour. Ventral part of parapsidal suture, postnotum, preepisternum and median anepisternum II dark brown, scutum and epimeron II light brown. Tergite I–V with horizontal dark brown bands at the posterior quarter. Tergite VI with horizontal light brown band at the posterior seventh.

Head ( Fig. 3A View FIGURE 3 ). AR 0.86–1.10, 0.94. Antenna with 13 flagellomeres, ultimate flagellomere 500–619, 564 μm long. Frontal tubercles 25–38, 31 μm long, 8–13, 10 μm wide at base. Temporal setae 8–12, 10. Clypeus with 10–15, 13 setae. Tentorium 145–176, 156 μm long, 33–50, 39 μm wide. Palpomere lengths (μm): 35–40, 39; 38–63, 51; 102–140, 122; 118–145, 129; 200–237, 218.

Thorax ( Fig. 3B View FIGURE 3 ). Ac absent; Dc 7–10, 8; Pa 1; Scts 5–8, 6. Haltere with 4–5, 4 setae.

Wing ( Fig. 3C View FIGURE 3 ). VR 1.08–1.18, 1.11. Brachiolum with l seta, R with 8–21, 15 setae, R 1 with 6–15, 10 setae, R 4+5 with 7–28, 16 setae, M 1+2 with 3–57, 28 setae, M 3+4 with 1–11, 5 setae, false vein with 0–3 setae (usually 0), Cu with 0–6, 1 seta, Cu 1 with 0–3, 1 seta, r 4+5 with 79–115, 96 setae, m 1+2 with 14–117, 60 setae, m 3+4 with 0–17, 3 setae, remaining veins and cells bare.

Legs. Fore leg bearing single tibial spur 26–43, 34 μm long. Combs of mid tibia 11–21, 16 μm wide with 25–33, 30 μm long spur, and 10–20, 15 μm wide with 23–30, 27 μm long spur; combs of hind tibia 15–28, 22 μm wide with 28–38, 33 μm long spur, 17–27, 22 μm wide with 23–35, 31 μm long spur. Tarsomere l of mid leg with 4–7, 5 sensilla chaetica distally. Lengths and proportions of legs as in Table 1 View TABLE 1 .

Hypopygium ( Figs 4–5 View FIGURE 4 View FIGURE 5 ). Tergite IX 100–125, 113 μm long. Anal tergite bands V-shaped, well separated, ending at mid-length of tergite. Anal point ( Fig. 5 View FIGURE 5 ) 48–67, 56 μm long, slender triangular, tapering near the apex, with six lateral setae on each side, 8–11, 9 spinulae evenly placed at 2/3 length of anal point. Transverse sternapodeme 62–91, 78 μm long, with oral projections. Phallapodeme 90–125, 101 μm long. Gonocoxite 152–177, 165 μm long. Gonostylus 140–173, 159 μm long. Superior volsella ( Fig. 4D View FIGURE 4 ) sub-rectangular, with concave inner margin, bearing seven dorsal setae and two ventral setae, ventral surface with small patch of microtrichia at posterior margin. Digitus long and bent downwards, curved, with swollen blunt apex, extending beyond the inner margin of superior volsella. Stem of median volsella 20–25, 23 μm long, with 6 setiform lamellae and one distal spatulate lamella ( Fig. 4E View FIGURE 4 ). Inferior volsella weakly curved, 100–128, 111 μm long, with 11–23, 19 strong setae. HR 0.94–1.18, 1.04; HV 2.36–2.66, 2.51.

Adult female (n = 1)

Total length 4.29 mm. Wing length 2.98 mm. Total length/wing length 1.44.

Colouration. As in male, the colour of scutum, parapsidal suture and median anepisternum II lighter. Tergite I–II light brown with horizontal dark brown bands at the posterior quarter.

Head ( Fig. 6A View FIGURE 6 ). Antenna ( Fig. 6B View FIGURE 6 ) with four flagellomeres, flagellomere length (in μm): 117, 75, 79, 214. AR 0.79. Frontal tubercles 14 μm long, 18 μm wide at base. Temporal setae 8. Clypeus with 17 setae. Tentorium 141 μm long, 26 μm wide. Palpomere lengths (in μm): 261, 144, 134, 62, 42.

Thorax ( Fig. 6C View FIGURE 6 ). Ac absent; Dc 15; Pa 1; Scts 3. Halteres with 1 seta.

Wing ( Fig. 6D View FIGURE 6 ). VR 1.28. Brachiolum with one seta, R with 11 setae, R 1 with 32 setae, R 4+5 with 64 setae, M 1+2 with 38 setae, M 3+4 with 41 setae, Cu with 20 setae, Cu 1 with 24 setae, false vein with 50 setae, An with 17 setae, remaining veins bare. Cell r 4+5 with 180 setae, m 1+2 with 88 setae, m 3+4 with 150 setae, cu + an with 61 setae, remaining cells bare. Anal lobe strongly reduced.

Legs. Foreleg bearing single tibial spur 38 μm long. Combs of mid tibia 13 μm wide with 34 μm long spur, and 14 μm wide with 36 μm long spur; combs of hind tibia 16 μm wide with 42 μm long spur, 20 μm wide with 38 μm long spur. Tarsomere l of mid leg with 28 sensilla chaetica distally. Lengths and proportions of legs as in Table 2 View TABLE 2 .

Genitalia ( Fig. 7 View FIGURE 7 ). Tergite IX semicircular with 22 setae; sternite VIII with 36 setae; gonapophysis VIII single lobe with long posteromedially directed microtrichia; gonocoxapodeme 124 μm wide, slightly curved; coxosternapodeme well-developed with distinct anterior and posterior lobes. Notum including rami 134 μm long, notum alone 36 μm long. Seminal capsules semi-circular, 63 μm long, 47 μm wide. Postgenital plate triangular. Cercus 96 μm long, with 29 setae.

Pupa. Unknown.

Larva (n = 4)

Total length 5.5–7.2, 6.5 mm.

Head Capsule ( Fig. 8 View FIGURE 8 ). Length 346–396, 376 μm, width 341–370, 355 μm, length/width 0.99–1.16, 1.06; mental and mandibular teeth dark brown. Antennal pedestal 54–78, 68 μm long ( Fig. 9A View FIGURE 9 ). AHR 0.15–0.21, 0.18; AAR 0.53–0.74, 0.64. Antenna shorter than head length, 5-segmented, only first and second antennal segments well sclerotized. Antennal segment length (in μm): 101–106, 104; 20–25, 23; 9–13, 12; 4–7, 6; 3–5, 4. AR 2.06–2.81, 2.34. Antennal blade 14 μm long. LO stems + stylus 42–51, 47 μm long; LOR 1.92–2.63, 2.19. Mandible ( Fig. 9 View FIGURE 9 B-C) 149–153, 151 μm long, 43–50, 47 μm wide, 1 ventral apical tooth, 3 ventral inner teeth, 4 dorsal teeth and one robust dorsal plate; seta subdentalis thick and curved, 44–55, 50 μm long, reaching beyond apex of dorsal tooth; seta interna well–developed with 4 main branches. Mentum ( Fig. 9 View FIGURE 9 D-E) 98–115, 107 μm wide, with 11 teeth; median tooth with small lateral notches or absent; ventromental plate 122–128, 126 μm wide, 22–28, 26 μm long, MVR 0.80–0.91, 0.85. Premandible ( Fig. 10 View FIGURE 10 A-B) 78–81, 80 μm long, with 5 teeth in addition to lateral spine; premandibular brush well-developed. Labrum ( Fig. 10C View FIGURE 10 ) with S I pectinate and chaetae plumose; S II long, simple; clypeal seta S3 long, simple. Labral lamella pectinate. Pecten epipharyngis consisting of three plumose lobes. Maxilla ( Fig. 10D View FIGURE 10 ) with two long and one short lacinial chaetae, palp normally developed, postoccipital margin darkly pigmented. Postmentum 156–165, 162 μm long.

Abdomen. Procercus 40–54, 47 μm high, with 8 anal setae, 551–569, 560 μm long. Anal tubules two pairs,156– 180, 168 μm and 108–110, 109 μm long.

Remarks. The new species is closely related to Tanytarsus sinuatus in the shape of hypopygium, but can be separated from the latter species by the following characters of adult males: LR 1 1.55–1.71, frontal tubercles longer, tarsomere l of mid leg with sensilla chaetica distally, superior volsella more rectangular, digitus curved and without a protuberance at mid length, median volsella has one distal spatulate lamella, and anal point has more spines in the new species. The larvae of the new species exhibit a Tanytarsus glabrescens - type mandible, characterized by the presence of 2+2 dorsal teeth ( Eggermont 2008), similar to the mandible morphology observed in the larvae of T. gracilentus and T. lapponicus ( Stur & Ekrem 2011) . However, the dorsal plate is smaller compared to those of these latter two species.

Ecological notes. The larvae of the new species were found in glacier lakes of Qinghai-Tibet Plateau.

Distribution. China (Xizang).