Henlea perpusilla Friend 1911

Henlea perpusilla Friend, 1911

(Figure 17)

Henlea perpusilla Friend, 1911. Černosvitov 1937; Nielsen and Christensen 1959; Chalupský 1986; Kasprzak 1986; Rota and Healy 1994; Rota 1995; Rota et al. 1998; Wang et al. 1999; Schmelz and Collado 2010; Lu et al. 2018.

Henlea brucei Stephenson, 1922.

Henlea balcanica Černosvitov, 1930.

Material investigated

GZO202007008–GZO202007009, stained and whole-mounted, two mature specimens from site H. CJJ 87, one mature specimen from site 1, whole worm used for DNA extraction, preserved as total DNA.

Further material investigated

Six mature specimens and one immature specimen from site H, one mature specimen from site B, seven mature specimens from site 1, two mature specimens from site 7 and one mature specimen from site 12, 18 in total, preserved in 75% ethanol.

Description

Small worms. Length 5.7–10.4 mm (in vivo), diameter 0.32–0.43 mm at VII, 0.35–0.5 mm at clitellum (in vivo). Number of segments 26–39. Chaetae without inner hook, straight distally, slightly bent proximally, fan-shaped, short in the middle and long on the side. Chaetae formula 3–6 – (2)3–5: 4–6 (7,8) – 3–6. Body wall 12.5–25 μm thick, cuticle very thin (<1 μm). Epidermal gland cells rectangular, 2–3 rows per segment (Figure 17c). Clitellum at XII–1/2XIII, girdle-shaped, developed well, thickened both dorsally and ventrally, gland cells reticulate, hyalocytes in contact with each other (Figure 17h). Brain flat anteriorly and weakly concave posteriorly, ca. 130 μm long, 107 μm wide (in vivo) (Figure 17a). Pharyngeal glands 3 pairs in IV–VI, all separate dorsally (Figure 17d). Preclitellar nephridia 5 pairs, 6/7–10/11. Gut abruptly widened at 7/8, no intestine diverticulum (Figure 17e). Dorsal vessel rising in VIII, pulsating and conspicuous, blood pale (Figure 17e). Coelomocytes only mucocytes, finely and regularly vesicular, diameter 40–47 μm (in vivo). Chloragocytes yellowish, forming a thin layer on the intestine from VII. Seminal vesicle absent. Sperm funnel cylindrical, small, collar distinct, nearly as wide as funnel body. Length and width varies among specimens, 49–108 μm long, 35–50 μm wide (in vivo), ca 1.4–2.1 × as long as wide (Figure 17g, i). Vas deferens long, coiled irregular, diameter 6.5 μm (in vivo). Spermathecae without ectal gland. Ectal pores lateral at 4/5; ectal ducts muscular, short, 55.3 μm long, 24.5 μm wide; ampullae spindle-shaped, thiner than ectal ducts, 110.9 μm long, 18.6 μm wide (in vivo); ental ducts narrower than ampullae, united before attachment to oesophagus in V (Figure 17b). 1–2 mature eggs at a time, occupying 1–3 segments (Figure 17f).

Remarks

This species is common and widespread around the world. In China, the worms have been found in Hunan, Jilin, Gansu, Yunnan, Xinjiang, Guizhou Provinces and Tibet (J.J. Chen, unpublished data).

K2P distances were calculated based on COI sequences: high genetic distances were shown between our species and H. perpusilla from Sweden (Erséus et al. 2010) (18.2%), H. perpusilla from Svalbard (Dózsa-Farkas et al. 2015) (16.0%) and H. perpusilla from Switzerland (Vivien et al. 2015) (18.2%). Henlea perpusilla is probably a species complex, containing several species.