Hemienchytraeus jeonjuensis, Dózsa-Farkas, Klára & Hong, Yong, 2010

Dózsa-Farkas, Klára & Hong, Yong, 2010, Three new Hemienchytraeus species (Enchytraeidae, Oligochaeta, Annelida) from Korea, with first records of other enchytraeids and terrestrial polychaetes (Annelida), Zootaxa 2406, pp. 29-56 : 41-48

publication ID	https://doi.org/ 10.5281/zenodo.194222
DOI	https://doi.org/10.5281/zenodo.5669745
persistent identifier	https://treatment.plazi.org/id/65774246-B870-9D10-FF5B-33EBFDD52D3F
treatment provided by	Plazi
scientific name	Hemienchytraeus jeonjuensis
status	sp. nov.

Treatment

Hemienchytraeus jeonjuensis View in CoL sp.n.

( Fig. 8–12 View FIGURE 8 View FIGURE 9 View FIGURE 10 View FIGURE 11 View FIGURE 12 )

Type material. Holotype: Clitellate (NIBRIV 0 0 0 0 138926): Type locality: Korea, Soil and litter layers in mountain forest nearby experimental farm, College of Agriculture & Life Science, Chonbuk National University, Jeonju-si, Jeollabuk-do, (N 35˚50΄50.2ʺ, E 127˚08΄0 1.8ʺ) (site C), collected on 0 3. 0 9. 2007. Stained with paracarmine-bromophenol blue, whole-mounted on slide (No. 154). Deposited in the National Institute of Biological Resources, Korea.

Paratypes: C litellate (NIBRIV 0000138927) one specimen on slide (No. 132), stained with borax carmine, collected 0 3. 0 9. 2007, locality is the same as the holotype; (NIBRIV 0000138928) one specimen in 70 % ethanol from the same locality as holotype, coll. 18.09.2008. Deposited in the National Institute of Biological Resources, Korea.

P. 86. 1-5 five specimens on five slides (No. 134–137, 152), stained with borax carmine coll. 0 3. 0 9. 2007; P. 86. 7 one specimen on slide (No. 153) coloured paracarmine-bromophenol blue, coll. 0 3. 0 9. 2007; P.86. 8 one specimen on slides (No. 202), stained with borax-carmine, coll. 18. 0 9. 2008. All specimens collected from locality C: soil and litter layers in mountain forest nearby experimental farm, College of Agriculture & Life Science, Chonbuk National University, Jeonju-si, Jeollabuk-do, (N 35˚50΄50.2ʺ, E 127˚08΄0 1.8ʺ), Korea; P.86. 9 four specimens in 70% ethanol, from locality J: Litter layers in deciduous forest, Bamsagol Valley (deciduous forest), Mt. Jiri, Unbong-myon, Namwon-si, Jeollabuk-do, Korea (N 35º22΄0 4.3ʺ, E 127º34’51.9”), Korea, 18 0 9. 2008; P.86. 10 one specimen in 70 % ethanol from locality I: Litter layers in deciduous forest, Dalgoung Valley (deciduous forest), Mt. Jiri, Unbong-myon, Namwon-si, Jeollabuk-do, Korea (N 35º20΄56.4ʺ, E 127º33’03.9”, 569 m) 18. 0 9. 2008. Deposited in the collection of K. Dózsa-Farkas at Department of Systematic Zoology and Ecology, Eötvös Loránd University, Budapest.

Etymology: Named after the type locality, the city of Jeonju.

Description. Holotype 5.7 mm long, 181 µm wide at VIII and 243 µm at the clitellum (fixed), segments 32. Body length of paratypes 6.9–7.5 mm, width 200–280 µm at VIII and 250–290 µm at the clitellum (in vivo), length of fixed specimens 4.8–6.1 mm, width at VIII 180–270 µm, 200–340 µm at the clitellum, segments 29–39. Chaetae 2 per each bundle, absent in XII (in one of the paratype specimens [No. 152] the lateral chaetae in II–IV absent), slightly sigmoid without nodulus, pointed distally, blunt proximally. Chaetae in ventral preclitellar bundles 28–35 µm long and ca. 3–3.5 µm thick, lateral chaetae smaller (22–25x 2.7 µm), all chaetae gradually increasing in size posteriad, in terminal segments 50x 4.5 µm ventrally and 35– 45 x 4 µm laterally. Head pore on the prostomium dorsal, subterminal ( Fig. 8 View FIGURE 8 A), dorsal pores absent. Epidermal gland cells one or two transverse rows per segments, inconspicuous. Clitellum in XII extending over a little more than one segment, girdle-shaped, hyalocytes and granulocytes arranged net-like dorsally ( Fig. 9 View FIGURE 9 A); size of hyalocytes 17x12 µm, of granulocytes 12.5 x 6–7 µm (fixed), ventrally only granulocytes ( Fig. 9 View FIGURE 9 B). The height of clitellum 20 µm dorsally only 10 µm ventrally. Body wall ca. 15 µm, cuticle <1 µm thick (fixed). All septa well-developed, only in the terminal segments less developed. Brain ( Fig. 8 View FIGURE 8 B) about twice as long as wide deep incised anteriorly and more or less straight posteriorly. Post-pharyngeal bulbs conspicuous. Ventral nerve cord perikarya concentrated in segmental ganglia, no perikarya in the region of the septa. Two or three pairs of lateral nerve arising from ventral nerve cord per segment ( Fig. 10 View FIGURE 10 C).

Oesophageal appendage (peptonephridia) ( Fig. 12 View FIGURE 12 A) with an unpaired root 20–21 µm wide and 30–40 µm long and two longer and thinner primary branches (52– 60 x17–20 µm) ( Fig. 8 View FIGURE 8 C). Primary branches terminate in two longer (52–60 µm) and thinner (15–16 µm) (in vivo) secondary branches on each side ( Fig. 8 View FIGURE 8 D). Trunk and primary branches with distinct winding canal, secondary branches compact. All three pairs of pharyngeal glands united dorsally with ventral lobes in V and VI. Two pairs of secondary glands in V, VI ( Fig. 10 View FIGURE 10 A).

Chloragocytes from V, well-developed (20–25 µm long in vivo) filled with dark brown granules. Dorsal vessel from XII–XIII, blood colourless. Inflated ventral gut epithelium from ½ XIX to XX or XXI–XXII extending over two segments.

Three pairs of preclitellar nephridia from 6/7 to 8/9 ( Fig. 10 View FIGURE 10 B) (sometimes only single). In postclitellar segments usually from 13/14 to 19/20 often missing in some segments, then present again in all segments to the end of worms. Rarely, nephridia absent in the terminal segments. In preclitellar segments efferent duct arising medially, in posterior segments sub-terminally; no terminal vesicle. Anterior nephridial lengths 85–95 µm, increasing to their longest just posterior to clitellum (119 µm), then decreasing gradually to half that size (59–55 µm long) in posteriormost segments (fixed). Length ratio anteseptal: postseptal 1: 1.2 in anterior segments, in the terminal segments 1:1. Coelomocytes oval with obvious nucleus and finely granular matrix, 20–25x 5–8 µm (in vivo) ( Fig. 10 View FIGURE 10 D).

Seminal vesicle absent. Sperm funnels ( Fig. 11 View FIGURE 11 A, 12B) elongate pear-shaped, about ¼ as long as body diameter, 2–3 times as long as wide (62–80 µm long, fixed). Collar slightly wider than the funnel body. Spermatozoa ca. 30 µm, head 15 µm (fixed.). Sperm ducts not long, more or less coiled in XII, diameter 5 µm (fixed). Male copulatory organs ( Fig. 9 View FIGURE 9 B) with distinct musculature; male glandular body globular, diameter ca. 28–38 µm height 50 µm (fixed). No accessory copulatory glands.

Spermathecae ( Fig. 12 View FIGURE 12 C) free, not attached to oesophagus. Ectal ducts long ca. 250–300 µm long and 6– 7.5 µm wide (fixed) only very small dilation in V but often absent, and ectal duct at the ectal opening slightly wider (about 10 µm wide) ( Fig. 11 View FIGURE 11 B); spermathecae terminate in small ampullae (25–32 µm long and 11-12 µm wide) in VI–VII. Ampullae thin-walled, empty or with a few sperm in them ( Fig. 11 View FIGURE 11 C). One or two mature eggs at a time.

Distribution and habitat: Soil and litter layers in mountain forest nearby the experimental farm of Agriculture & Life Science, Chonbuk National University, Jeonju-si (site C) and litter layers in decidouos forests in Dalgoung Valley (site I) and in Baemsagol Valley, Mt. Jiri (site J).

Diagnosis. The new species can be recognized by the following combination of characters: (1) the size of worms (6.9–7.5 mm, width 200–280 µm in vivo, segment number 29–39); (2) all pairs of pharyngeal glands united dorsally with ventral lobes in V and VI, secondary ventral lobes in V and VI; (3) three pairs of preclitellar nephridia; (4) nephridia in the terminal segments half size of the first postclitellar ones; (5) primary branches of oesophageal appendages are longer and thinner than the unpaired trunk with two longer compact secondary branches on each side; (6) oval, faintly granular coelomocytes with well visible nucleus; (7) clitellum girdle-shaped, ventrally only granulocytes; (8) Dorsal vessel from XII–XIII; (9) seminal vesicle absent; (10) sperm funnel small, elongate pear-shaped approximately 2–3 times as long as wide, collar slightly wider than the funnel body; (11) spermathecae free, extending into VI–VII, consisting of long ducts, mostly no dilations and terminate in a small thin-walled ampullae.

Differential diagnosis. Previously, only four species were described in which the primary branches of the oesophageal appendage divided into just two secondary branches. Among them H. tanjae Schmelz and Römbke (2005) is similar to the new species in regard to the number of segments and the length of worms, (but probably H. tanjae is slightly thinner: 120–150 µm in vivo), absence of a seminal vesicle, the structure of the clitellum, the form and location of the spermathecae, and the length of the terminal chaetae (but these are only 33 µm in H. tanjae and 45–50 µm in H. jeonjuensis ). There are notable differences between the species, however: H. tanjae has four pairs of nephridia preclitellarly (from 5/6), but H. jeonjuensis only three (from 6/ 7); in H. tanjae the dorsal vessel origin is further back, from XIV; in H. tanjae there is only one pair of secondary pharyngeal glands (in V), but two pairs in the new species (in V and VI); and in H. tanjae the attached spermatozoa are longer than the length of the sperm funnels ( Schmelz & Römbke 2005), whereas in H. jeonjuensis the spermatozoa are half as long as the length of the funnels, although the sperm funnels are slightly longer.

The new species also is comparable to H. bifurcatus Nielsen and Christensen, 1959 in structure of spermathecae and oesophageal appendages, but H. bifurcatus species is larger (10 mm), the nephridia have large terminal vesicles and the coelomocytes contain small refractive granules ( Nielsen & Christensen 1959). As noted earlier, H. bifurcatus species is of a doubtful status. Healy (1996) described a worm as H. bifurcatus from Florida, but this differs from H. jeonjuensis , because it has a seminal vesicle, nephridia at 4/5 or 5/6, and thin-walled secondary branches of oesophageal appendage with a wide lumen. H. bifurcatus was described from Japan by Nakamura (1984) and, although some characters are not mentioned, the form of the spermathecae illustrated for the Japanese specimens ( Nakamura 1984 p. 32. Fig. 1 View FIGURE 1 D) is different.

The principal differences between H. jeonjuensis and H. solimoensis Righ, 1978 are: the spermathecae of the latter are much shorter, only in V, the third pair of pharyngeal glands are separate dorsally and the coelomocytes are smaller (9 µm) ( Righi 1978). Finally, H planisetosus Xie, Wang and Liang 1999 also has a number of distinctive characteristics compared to the new species: anteriorly the chaetae have flattened and widened distal tips, there are five pairs of preclitellar nephrida, more segments (up to 45), the spermathecae can reach the segment IX, and the male glandular bulb are large (the size is not given but according to the text “the penial bulb large” [ Xie et al. 1999]).