Tubifex tubifex (Müller, 1774), tubifex (Muller, 1774

Cui, Yongde, 2017, Four species of Tubifex Lamarck (Annelida: Oligochaeta: Naididae) from Tibet, China, Zootaxa 4320 (2), pp. 366-378 : 373-377

Tubifex tubifex (Müller, 1774)

( Figs 9–10 , table 1)

Lumbricus tubifex Müller, 1774: 27 .

Tubifex tubifex Müller : Liang 1962: 20 –22; Brinkhurst 1965: 123 –124; Brinkhurst 1966: 145; Brinkhurst & Jamieson 1971: 453 –456; Brinkhurst & Marchese 1987: 3154 –3155; Holmquist 1983: 189 –192; Timm 2006: 32 –37; Marotta et al. 2009: 181 –187.

For further synonymies and citations of the name see Brinkhurst & Jamieson (1971).

New material. IHB XZ 20130630 m–r, 6 mature specimens, whole-mounted in Canada balsam. 1 mature specimen, processed for Scanning Electron Microscopy. Collected from one river in Cuomujiri Mountain (29°45'54" N, 94°24′25″ E) of southern Tibet , China., ca. 3,537 m asl. Substrate type silt, hydrophytes abundant. Water depth 30–100 cm, water temperature 11.1°C, pH 7.0, dissolved oxygen 9.0 mg/L, conductivity 16.5 µs/cm. Collected on 30 June 2013 by the authors.

Description. Length 14–21 mm, width at genital segments X–XI 1.0– 1.2 mm. Segments 76–84. Prostomium obtuse ( Fig. 9A ). Clitellum inconspicuous. No coelomocytes. Dorsal chaetae 1–2 hairs and 2–3 bifids per bundle. Hairs slightly hirsute, 250–550 µm long, 2–4 µm thick ( Fig. 9C ). Dorsal bifids pectinate, 100–150 µm long, 2–4 µm thick, two short outer teeth nearly equal, 7.5 µm long, with 1–4 fine intermediate teeth, nodulus distal ( Fig. 9D ). Ventral chaetae bifid, anteriorly 3–5 per bundle, posteriorly 2–3 per bundle, 55–150 µm long, 3–5 µm thick, anterior upper tooth slightly thinner than and nearly 2 times as long as lower (10 µm/6 µm), posterior upper tooth as long as lower (7 µm/6 µm), with (0) 1–3 fine intermediate teeth, nodulus distal ( Fig. 9E–F ). Ventral chaetae in X and XI present, unmodified. Spermathecal pores paired in line with lateral line, in anterior of X ( Figs. 9B : spp). Male pores paired in line with ventral chaetae, middle to posterior of XI ( Fig. 9B : mp).

Chloragogen cells beginning in VI onwards. Male genitalia generally paired in X–XI, in one specimen shifted to VI–VII. Sperm funnel cup-shaped. Vas deferens long and irregularly coiled, anteriorly 30 µm wide, posteriorly 50 µm wide, ciliated throughout and entering atrium subapically ( Fig. 10B : vd). Atrium comma-shaped, 500–600 µm long, maximally 120–125 µm wide, with long ejaculatory duct gradually becoming narrower toward the ectal end, and enlarged into a characteristic subspherical widening at the base of penis ( Fig. 10B : at). Large compact prostate gland with stalk-like attachment connected to ental atrium subapically near the vas deferens, 150–200 µm long, 200–250 µm wide ( Fig. 10B : pr). Penis cylindrical ( Fig. 10B : pe), 150–175 µm long, covered with a short, tub-shaped, flexible (= non-chitinous), cuticle ring. Testes paired in X, immediately behind septum 9/10. Ovaries paired in XI, immediately behind septum 10/11. Spermathecae generally paired in X (One specimen shifted to VI), with ampullae partially pressed into XI, 500–625 µm long, 250–330 µm wide; duct 150–225 µm long; sperm not observed in lumina ( Fig. 10A : spa).

Remarks. T. tubifex is one of the most widely distributed species in the world, and has been redescribed over and over again ( Liang 1962; Brinkhurst & Jamieson 1971; Brinkhurst & Marchese 1987; Hrabě 1981; Holmquist 1983; Timm 2006; Marotta et al. 2009). The morphological accounts of this cosmopolitan species show some differences, mainly in the hair chaetae, the penial sheath and the spermatheca (Table 1). Some of these differences, however, may be due to different observation techniques or modes of interpretation: Under SEM-observation, the hair chaetae of T. tubifex from Tibet are slightly hirsute. Other authors, using light-microscopy, could not determine whether the hair chaetae of T. tubifex from other areas were serrate or not ( Liang 1962; Brinkhurst & Jamieson 1971; Brinkhurst & Marchese 1987; Hrabě 1981). Furthermore, we identified a cuticle ring around the penis of T. tubifex from Tibet, whereas other authors, referring to the same structure, describe a penial sheath ( Brinkhurst 1965; Brinkhurst & Jamieson 1971; Brinkhurst & Marchese 1987; Hrabě 1981). The cuticle ring in specimens from Tibet is flexible and non-chitinous—we observed contractions in living specimens—and it shows clearly in vivo but is difficult to see or seemingly absent in material that has been stained with borax carmine and mounted whole in Canada balsam. We therefore agree with Holmquist (1983) and Timm (2006) that T. tubifex has no penial sheaths proper.

sheath al. 2009 Italy serrate muscular description no et Marotta

Netherlands smooth cuticle ring present absent or with spermatozeugmata Timm 2006 Denmark serrate

not

or cuticle ring present absent or with spermatozeugmata Holmquist 1983 areas

Slovakia serrate sheath penial or present absent with spermatozeugmata Hrabě 1981 other and

Tibet North

America not serrate or penial sheath or present absent with spermatozeugmata Brinkhurst & 1971 Jamieson

from southern, China River serrate description without present Sungari no spermatozeugmata 1962 Liang

tubifex

of Tubifex China Tibet, slightly hirsute cuticle ring present without spermatozeugmata research present

Comparison

cuticle 1. Area Hair Penial Spermatheca Reference Table

Table 2. Comparison of Tubifex species with funnel-shaped penial sheaths

Species Tubifex laxus n. sp. Tubifex gracilentus n. sp. Tubifex montanus Tubifex conicus He, Cui & Tubifex newfei Pickavance Kowalewski, 1919 Wang, 2012 & Cook, 1971 In the material of T. tubifex from Tibet, spermathecae are generally paired in X with no sperm observed in lumina, which is different from T. tubifex from other areas that usually have paired spermathecae with spermatozeugmata, or only one spermatheca with spermatozeugmata, or no spermatheca at all ( Brinkhurst & Jamieson 1971; Hrabě 1981; Holmquist 1983; Timm 2006).

Distribution and habitat. Cosmopolitan. Freshwater.

Figures

FIGURE 9. Tubifex tubifex (Müller, 1774), specimens from Tibet, SEM micrographs. A. Lateral view of anterior body. B. Spermathecal pore in X and male pore in XI. C. Hairs and pectinate chaetae in V. D. Dorsal pectinate chaeta in XII. E. Ventral chaetae in III. F. Ventral chaetae in XVI. Scale bars: A. 1000 µm; B. 500 µm; D. 10 µm; C, E, F. 20 µm.

FIGURE 10. Tubifex tubifex (Müller, 1774), specimens from Tibet. A. Spermatheca. B – C. Lateral view of male genitalia in segment XI. Scale bar: A – C. 100 µm.