Tubifex gracilentus, Cui, Yongde, 2017
publication ID |
https://doi.org/ 10.11646/zootaxa.4320.2.10 |
publication LSID |
lsid:zoobank.org:pub:961A9Ba8-98D5-4395-Be2A-892Fbe2Ffa70 |
DOI |
https://doi.org/10.5281/zenodo.5256388 |
persistent identifier |
https://treatment.plazi.org/id/03A48793-081D-FF83-0AC5-FDD5FAC2CA9B |
treatment provided by |
Plazi |
scientific name |
Tubifex gracilentus |
status |
sp. nov. |
Tubifex gracilentus n. sp.
( Figs. 4–6 View FIGURE 4 View FIGURE 5 View FIGURE 6 )
Holotype. IHB XZ20150511 About IHB a, mature specimen, stained and whole-mounted in Canada balsam.
Type locality. Juemu River (29°39'23″N, 94°17′12″E), southeast Tibet of China, ca. 3,290 m asl. Sediment silt. Water depth 40–60 cm, water temperature 6.4°C, pH 6.2, dissolved oxygen 8.8 mg /L, and conductivity 12.3 µs/cm. Collected on 11 May 2015 by the authors. GoogleMaps
Paratype. IHB XZ20150511 About IHB b, 1 mature specimen, stained and whole-mounted in Canada balsam, from the type locality.
Other material. 1 specimen for SEM, from the type locality; 1 mature specimen whole-mounted in Canada balsam, from Trigu Co ( Co means lake in Tibet).
Etymology. The epithet “ gracilentus ” is Latin for “slender and thin”, and refers to the thin and long penial sheath of this species.
Description. Length 6.4–6.7 mm (Holotype: 6.7 mm), width at genital segments X–XI 0.5–0.6 mm (holotype: 0.6 mm). Segments 32–34 (holotype: 32). Prostomium obtuse or conical ( Fig. 4A View FIGURE 4 ). Clitellum inconspicuous. No coelomocytes.
Dorsal chaetae (0) 1–2 hairs and 1–4 bifids per bundle. Hairs smooth anteriorly ( Fig. 4B View FIGURE 4 ), serrate posteriorly ( Fig. 4C View FIGURE 4 ), 120–300 µm long, 2–3 µm thick. Dorsal bifids pectinate, 50–100 µm long, 1.5–2.5 µm thick, upper and lower tooth subequal, 6–8 µm long, with 2–3 (4) fine intermediate teeth, nodulus distal ( Figs. 4D View FIGURE 4 , 5D View FIGURE 5 ). Ventral chaetae bifid, (2) 4–6 per bundle anteriorly, 2–3 per bundle posteriorly, 60–160 µm long, 2–3 µm thick, upper tooth twice as long as lower (4 µm/2 µm), with (0) 1–2 fine intermediate teeth, nodulus distal ( Figs. 4E,F View FIGURE 4 , 5A–C View FIGURE 5 ). Ventral chaetae in X–XI present, unmodified. Male pores ( Figs. 5G View FIGURE 5 , 6C View FIGURE 6 : mp) paired in line with ventral chaetae in anterior of X. Spermathecal pores ( Fig. 5E View FIGURE 5 : spp) paired in line with ventral chaetae, middle to posterior of XI.
Chloragogen cells from VI onwards. Male genitalia paired in X–XII. Sperm funnel cup-shaped, 30–40 µm long, 40–60 µm wide ( Fig. 5G, H View FIGURE 5 : sf). Vas deferens long and irregularly coiled, 1800–2000 µm long, at least 3 times as long as atrium, anteriorly 14–16 µm wide, posteriorly 28 µm wide, ciliated throughout and entering atrium apically ( Figs. 5G, H View FIGURE 5 , 6A View FIGURE 6 : vd). Atrium spindle-shaped, 560–640 µm long, maximally 80–100 µm wide ( Figs. 5G, H View FIGURE 5 , 6A View FIGURE 6 : at). Ejaculatory duct 100–120 µm long, 20–32 µm wide, entering muscular bulb ( Fig. 5G, H View FIGURE 5 , 6A View FIGURE 6 : ed; Fig. 5G View FIGURE 5 : mb). Prostate gland large, attached to ental portion of atrium, 120–140 µm long, 80–100 µm wide ( Fig. 5G, H View FIGURE 5 , 6A View FIGURE 6 : pr). Penis inconspicuous, surrounded by cuticular, symmetrical and funnel-shaped penial sheath. Penial sheath extremely thin, long and sinuous, 32–36 µm wide at ental end, 3–5 µm wide at thin and prolonged ectal portions, 520–540 µm long, length to width ratio nearly 15–16 ( Figs. 5G, H View FIGURE 5 , 6B View FIGURE 6 : ps). Testes paired in X, immediately behind septum 9/10. Ovaries paired in XI, immediately behind septum 10/11. Spermathecae paired in X, ampullae oblong, 200–280 µm long, 140–250 µm wide; duct 100–120 µm long, 24–28 µm wide; sperm random in lumina, no spermatozeugmata ( Figs. 5E View FIGURE 5 , 6C View FIGURE 6 : sp).
Remarks. The main identification characteristics of long and winding vas deferens divided into thin and thick sections, long atrium gradually tapering towards distal portion, large prostate gland and elongate penial sheath suggest that the present species belongs to the genus Tubifex ( Brinkhurst & Jamieson 1971; Holmquist 1985; Juget et al. 2006). Tubifex tubifex (Müller, 1774) resembles this species in pectinate dorsal chaetae, long and winding vas deferens divided into thin and thick sections, large prostates, and in atria with a long ejaculatory duct, but differs from it in a cylindrical penis covered with a short and tub-shaped cuticle ring. Furthermore, spermathecae are absent, or present with spermatozeugmata, or present with empty ampullae. T. gracilentus n. sp. is easily distinguished from its congeners by the extremely thin and long funnel-shaped penial sheath (Table 2).
Distribution and habitat. Known from the type locality, Cuomujiri Lake and Trigu Co. Freshwater.
IHB |
Institute of Hydrobiology, Chinese Academy of Sciences |
No known copyright restrictions apply. See Agosti, D., Egloff, W., 2009. Taxonomic information exchange and copyright: the Plazi approach. BMC Research Notes 2009, 2:53 for further explanation.
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SubClass |
Oligochaeta |
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SubFamily |
Tubificinae |
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