Chamaedrilus cf. ozensis Torii, 2015

Chen, Jing, Jiang, Wanxiang & Xie, Zhicai, 2016, First records of Enchytraeidae (Annelida, Clitellata) from the Three Parallel Rivers region, Zootaxa 4093 (2), pp. 275-284 : 276-277

Chamaedrilus cf. ozensis Torii, 2015

( Figure 1 A–D)

Chamaedrilus ozensis Torii, 2015: 477 –479, Fig. 2 .

Material examined. 10 fully mature specimens examined in vivo and 10 whole-mounted specimens; Mt. Laojun, Yunnan Province (99° 43.185E, 26° 37.956N, 3958 m asl), under snow, dark sandy soil under roots of Abies spp. and moss. Coll. J. Chen and W.X. Jiang on 27 April 2014.

Description. Small species, body length 9–12 mm in vivo, body width 0.35–0.42 mm at V, 0.38–0.53 mm at clitellum. Segment number 39–42. Head pore at 0/I, longitudinal slit. Only few conspicuous epidermal gland cells present. Chaetal formula: 3–3: 3–3. Three chaetae per bundle throughout. Chaetae of XII lacking in mature specimens. Clitellum elevated inconspicuously, in XII–1 /2XIII. Hyalocytes and granulocytes irregularly arranged; granulocytes often in contact with each other. Two separate male pores, ventrally in the middle of XII. Spermathecal pores paired in 4/5, in lateral position.

Brain ( Fig. 1 A) in I–II, trapezoidal, deeply concave anteriorly and slightly incised posteriorly, 100–110 µm wide in maximum and 150–200 µm long in vivo. Dorsal vessel arising from XII–XIII. Blood colorless. Three pairs of well-developed primary pharyngeal glands attached to septa at 4/5–6/7, all without dorsal connection. Additionally, two pairs of secondary glands in segments V and VI. Gradual transition between oesophagus and intestine. No oesophageal appendages. No intestinal diverticula. Chloragogen cells yellowish, granulated, beginning from V backwards. Coelomocytes ( Fig. 1 B) round or ellipse-shaped, scarce, 26–41 µm long and 14–30 µm wide. Three pairs preclitellar nephridia in 6/7, 7/8 and 8/9. Anteseptale containing nephrostome only, about 25– 30 µm long, postseptale stout, almost spherical, with an efferent duct arising from the middle of postseptale.

Sperm funnels cylindrical ( Fig. 1 D), length 1/3–1/2 of body diameter, 2.5–3 times longer than wide (length 150–200 µm, width 40–50 µm). Sperm ducts long, narrow (width 8 µm) and irregularly coiled in segments XII– XIII. Small penial bulbs (width 60–100 µm) situated ventrally in the middle of XII. Seminal vesicle absent. 2– 4 eggs mature at a time, and several immature eggs present in XII. Spermathecae one pair in V (occasionally extending into VI), length 200–250 µm, slightly shorter than body diameter. Each ectal duct possessing two distinct parts ( Fig. 1 C); a large bulbous, asymmetrical mass of fused elongate cells (resembling a large gland at the ectal duct orifice when observed in vivo) surrounding a narrow canal that opens to the orifice through a straight or curved slit at 4/5, and a thick-walled section (ca. 20–25 µm in width) entally gradually widened into the ampulla. Ampulla simple, elongate, slightly wider than ectal duct, and not attached to oesophagus. Sperm present in all parts of the ampulla, usually concentrated in the terminal part.

Remarks. Among the 17 described species of Cognettia that have recently been included in the revalidated genus Chamaedrilus Friend, 1913 (Martinsson et al. 2015) , our specimens are most similar to Ch. lapponicus (Nurminen, 1965) and Ch. ozensis Torii, 2015 .

Ch. lapponicus (formerly Cognettia lapponica ) is similar in body size, chaetal number, pattern of pharyngeal glands, male pore positon, length-width ratio of sperm funnel (ca. 2.5–3:1) and the length ratio of spermathecal ectal duct and ampulla (ca. 2:1) (Nurminen 1965; Christensen & Dózsa-Farkas 1999; Schmelz & Collado 2010). However, Ch. lapponicus differs from our specimens in distinctly bipartite spermathecal ampullae.

Ch. ozensis is similar as regards the chaetal number, pattern of pharyngeal glands, male pore positon, lengthwidth ratio of sperm funnel (ca. 2.5–3:1), spermathecal shape and the length ratio of spermathecal ectal duct and ampulla (ca. 2–2.5:1). However the origin of dorsal blood vessel is in XV, occasionally in XIV (vs. XII–XIII in our specimens), and there are two types of coelomocytes, ca. 15–17 Μm long (vs. only one type, 26–41 Μm long), indicating that our worms may represent an undescribed species.

For the time being, and in view of the many similarities, especially the identical spermathecal shape, we identify our specimens as Ch. cf. ozensis , pending further taxonomical investigations.

Distribution and habitat. Mt. Laojun in Yunnan Province; Chaun Bay (Piper et al. 1982); Palearctic tundra: Pechora Bay, N. Yamal peninsula, Lopatka Peninsula, NE. Kolyma Delta, Wrangel Island (Christensen & Dózsa- Farkas 1999).

Figures

FIGURE 1. Chamaedrilus cf. lapponicus (A – D): A. Brain. B. Coelomocytes. C. Spermathecae. D. Sperm funnel. Scale bar: 50 Μm.

FIGURE 2. Mesenchytraeus laojunensis sp. nov. (A – I): A. Ventral chaetae in II. B. Ventral chaetae in V. C. Ventral chaetae in VII. D. Sperm funnel (in vivo). E. Pattern of clitellar glands. F. Coelomocyte. G. Sperm bundle. H. Spermatheca. I. Male organ in clitellar region. Scale bars: A, B, C, E, F, G 25 Μm; D, I 100 Μm; H, 50 Μm. Abbreviations: acg, accessory copulatory glands; at, atrium; bsf, body of sperm funnel; dt, diverticulum; ecd, spermathecal ectal duct; gr, granulocyte; hs, heads of spermatozoa; hy, hyalocyte; s, spermatozoa; sa, spermathecal ampulla; sp, spermathecal pore; vd, vas deferens.