Hemienchytraeus koreanus, 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 : 31-41

publication ID	https://doi.org/ 10.5281/zenodo.194222
DOI	https://doi.org/10.5281/zenodo.5669742
persistent identifier	https://treatment.plazi.org/id/65774246-B87E-9D0F-FF5B-3669FE642D6A
treatment provided by	Plazi
scientific name	Hemienchytraeus koreanus
status	sp. nov.

Treatment

Hemienchytraeus koreanus View in CoL sp. n.

( Figures 1–7 View FIGURE 1 View FIGURE 2 View FIGURE 3 View FIGURE 4 View FIGURE 5 View FIGURE 6 View FIGURE 7 )

Type material. Holotype: Clitellate (NIBRIV 0000138923). 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 borax-carmine, whole-mounted on slide (No. 178). Deposited in the National Institute of Biological Resources, Korea.

Paratypes: C litellate (NIBRIV 0000138924) one specimen on slide, stained with borax-carmine (No. 156) locality is the same as the locality of the holotype, collected on 0 3 0 9. 2007; NIBRIV 0 0 0 0 138925 one specimen on slide (No. 155) stained with paracarmine-bromophenol blue, locality: Soil and litter layers in maple trees cultivation of experimental farm, College of Agriculture & Life Science, Chonbuk National University, Jeonju-si, Jeollabuk-do, Korea (N 35˚50΄51.1ʺ, E 127˚08΄0.3ʺ), (site A), collected on 0 3. 0 9. 2007. Deposited in the National Institute of Biological Resources, Korea.

P. 85. 1–4 four specimens on four slides (No. 157, 180–182), stained with borax-carmine; P. 85. 5-7 three specimens on slides (No. 159, 215, 216) stained with paracarmine-bromophenol blue, collected on 0 3. 0 9. 2007; P. 85. 8 three specimens in 70 % ethanol, coll. 0 6.10.2008. The type locality of all paratypes of P. 85 is the same as the locality of the holotype. Deposited in the collection of K. Dózsa-Farkas at Department of Systematic Zoology and Ecology, Eötvös Loránd University, Budapest.

. Etymology: Named after the country where it was found.

Description. Holotype 8.2 mm long, 266 µm wide at VIII and 295 µm at the clitellum (fixed), segments 43. Body length of paratypes 7.5–12 mm, width 300–380 µm at VIII and 360–440 µm at the clitellum (in vivo), length of fixed specimens 6.4–9 mm, width 250–300 µm at VIII, 290–320 µm at the clitellum, segments 38–45. Chaetae 2 per bundle, absent in XII, slightly sigmoid without nodulus, pointed distally, blunt proximally. Chaetae in preclitellar bundles 35–38 µm long, diameter ca. 5 µm, gradually increasing in size posteriad, in terminal segments 63–71 µm long and 6 µm thick. Prostomium rounded, head pore on the prostomium, dorsal just subterminal ( Fig. 1 View FIGURE 1 A), dorsal pores absent. Epidermal gland cells three to four transverse rows per segments, inconspicuous but prostomium and the first segment densely covered with gland cells. Clitellum in XII–1 /3–1/4XIII girdle-shaped, hyalocytes and granulocytes arranged in dense rows dorsally ( Fig. 1 View FIGURE 1 D); mid-ventrally only granulocytes ( Fig. 1 View FIGURE 1 C) (occasionally with a few smaller hyalocytes). Body wall 18–20 µm thick, cuticle ca. 2–3 µm (fixed specimens).

All preclitellar septa well-developed. Brain ( Fig. 1 View FIGURE 1 B) about 1.5–1.7 times as long as wide incised anteriorly and posteriorly. Post-pharyngeal bulbs conspicuous. Ventral nerve cord perikarya concentrated in segmental ganglia, no perikarya in the region of the septa ( Fig. 2 View FIGURE 2 A), two or three pairs of lateral nerves, which enter the body wall, arising from ventral nerve cord in each segment ( Fig. 2 View FIGURE 2 B). Oesophageal appendage ( Fig. 7 View FIGURE 7 A) arises from mid dorsal region of pharynx, with a shorter unpaired root (60–80 µm long, 45–55 µm wide), two longer and thinner primary branches (95–130 x33 –38 µm) ( Fig. 2 View FIGURE 2 C) and five to six secondary branches (43– 47 x17–19 µm) on each side (in vivo) ( Fig. 2 View FIGURE 2 D). All three pairs of pharyngeal glands united dorsally with ventral lobes in V and VI. Three pairs of secondary ventral glands (lobes) in V, VI and VII but only the first pair is well-developed, the other two are rudimentary sometimes inconspicuous, smallest in VI ( Fig. 3 View FIGURE 3 A, Fig. 7 View FIGURE 7 B). Chloragocytes from V. Dorsal vessel from XIII–XIV, anterior bifurcation at 0/I ( Fig 3 View FIGURE 3 B), blood colourless. Inflated ventral gut epithelium from XXVI to XXXIII, extending over two segments, often not visible.

Five pairs of preclitellar nephridia from 5/6 to 9/10, (in one case there was only a single nephridium at 9/ 10). One or two pairs of nephridia are present at 13/14, 14/15 or sometimes only at 15/16, then missing in the next few segments, and posterior to this present in all segments until the end of worm. Efferent ducts arise mid-ventrally on the nephridia in preclitellar segments ( Fig. 4 View FIGURE 4 B) and sub-terminally ( Fig. 4 View FIGURE 4 A) on those of posterior segments; no terminal vesicle. Anteseptal with brownish granules ( Fig. 3 View FIGURE 3 C, 3D). Anterior nephridia 130–180 µm long (in vivo) ( Fig 4 View FIGURE 4 B), gradually increasing to a maximum at the first pairs posterior to the clitellum (187–210 µm), then gradually decreasing ( Fig. 3 View FIGURE 3 C) to only 95–130 µm ( Fig. 4 View FIGURE 4 A) in posteriormost segments. Ratio of lengths of anteseptal: postseptal 1:1.3–1.5 for most segments but 1:1 for the posteriormost segments. Nephridia often narrow at the septa ( Fig. 3 View FIGURE 3 D). Coelomocytes broadly oval yellowish with clearly visible nucleus and finely granular matrix, 20–33 x 15–17 µm (in vivo) ( Fig. 4 View FIGURE 4 C).

Seminal vesicles large (in well developed adults) in XII–XIII. Sperm funnels ( Fig. 5 View FIGURE 5 A, B and 7C) welldeveloped, length about equal body diameter, 5–6 times as long as wide tapering distally (340–380 µm long proximally 60–70 µm wide, distally only 20–24 µm, in vivo). In fixed specimens the length of funnels are 176–230 µm. Collar bending out, wider than the funnel body. Spermatozoa ca. 100 µm (in vivo), 75 µm (fixed); head 13 µm in vivo and 8–10 µm fixed specimens. Sperm ducts ( Fig. 5 View FIGURE 5 C, D) long in loose or tight coils in XII–XIII, diameter 7–8 µm (fixed). Male copulatory organs ( Fig. 5 View FIGURE 5 C, D and 6A) with distinct musculature, male glandular body globular, diameter ca 45–57 µm (fixed). No accessory copulatory glands.

Spermathecae ( Fig. 7 View FIGURE 7 D) paired, free, not attached to oesophagus. Ectal duct 100–160 µm long and 11–13 µm wide (fixed), with a short dilation in V (diameter 22–30 µm) ( Fig. 6 View FIGURE 6 B), and then continuing as a smooth tube (ca 220–230 µm long); terminating in a thin-walled, cylindrical ampulla in VIII–X. Size of ampulla varying according to the amount of sperm contained, sperm not arranged in packages ( Fig. 6 View FIGURE 6 C, D). One mature egg at a time.

Distribution and habitat: Soil and litter layers in maple trees cultivation of experimental farm of Agriculture Life Science, Chonbuk National University (site A), soil and litter layers in mountain forest nearby the experimental farm (site C) and soil of earthworm breeding experimental box (site E).

Diagnosis. The new species can be recognized by the following combination of characters: (1) the size of worms: 7.5–12 mm long, width 300–380 µm in vivo, 38–45 segments; (2) all pairs of pharyngeal glands united dorsally, among the three pairs of secondary ventral glands only the first pair is well developed; (3) five pairs of preclitellar nephridia; (4) nephridia in the posteriormost segments are half the size of the first postclitellar ones; (5) primary branches of oesophageal appendages are longer and thinner than the unpaired trunk, with five–six secondary branches; (6) oval, yellowish, faintly granular coelomocytes with nucleus; (7) girdle-shaped clitellum, ventrally only granulocytes; (8) dorsal vessel from XIII–XIV; (9) large seminal vesicle; (10); large sperm funnel regularly tapering distad, approximately 6 times as long as wide, collar bending out; (11) spermathecae are free, extending into VIII–X, consisting of relatively long ectal ducts, dilations in V and connecting tubes with large cylindrical ampullae.

Differential diagnosis. The new species is most similar to Hemienchytraeus loksai Dózsa-Farkas, 1989 ( Dózsa-Farkas 1989) from Ecuador, because both have 5 pairs of preclitellar nephridia and a similar form of spermathaecae but in H. koreanus sperm in the spermathecal ampulla is not arranged in packages, in contrast with H. loksai . The size of both species is about the same but H. loksai has more segments (48–55). Further differences include: (1) the terminal chaetae are about twice as large as the largest chaetae near the clitellum in the new species, while only slightly larger in H. loksai . (2) all three pairs of secondary pharyngeal glands are well developed in the H loksai , but only the first pair in H. koreanus . (3) the dorsal vessel origin is farther back (in XIV–XVI) in H. loksai , (4) the sperm ducts extend into XIV–XVII and the male copulatory organs are larger in H. loksai , (6). the sperm funnels are shorter and the sperm duct occurs only in XII–XIII in the new species.

Hemienchytraeus loksai View in CoL has been reported in China ( Xie et al 1999), but the Chinese specimens differ somewhat from the original description of H. loksai View in CoL . The new species is also different from the Chinese worms. Foremost, the Chinese worms are larger (51–55 segments, 14 mm long when fixed), the origin of dorsal vessel is more anterior in XII–XIII, the spermathecal ampullae are situated in XI–XII, and the spermathecal ectal ducts are much longer, 770 µm. In the new species, and also in H. loksai View in CoL from Ecuador, these ducts are only 100–160 µm long. The Chinese specimens described by Xie et al (1999) also have sperm in packages in the spermathecal ampullae and the sperm ducts extend back as far as XVI, which are both similar to H. loksai View in CoL from Ecuador. Even given these last two similarities, the number differences between the Chinese specimens and the originally described specimens of H. loksai View in CoL , are numerous so that it is unlikely they represent the same species. Although the number of pairs of preclitellar nephridia is not noted for the Chinese specimens, as the first nephridia occur in 6/7 it seems likely there are no more than four pair, moreover, the Chinese worms had only primary lobes of pharyngeal glands, as illustrated by Xie et al (1999, Fig. 3 View FIGURE 3 B) (although in the description there is no comment on secondary lobes of pharyngeal glands).

All other species of Hemienchytraeus View in CoL having large spermathecal ampullae appear to be distinct from the new species. H. guineanus Omodeo View in CoL has more segments (52–55), the sperm funnels are very long and the sperm duct extends as far backwards as segment XV, the sperm in the spermathecal ampulla is arranged in regularly oval packages, and the glandular body of male copulatory organ is very small (25 µm). H. inversus Omodeo, 1958 View in CoL differs from the new species because nephridia are present from 4/5 ( Omodeo 1958) (in H. koreanus View in CoL only from 5/6) and the sperm funnel is only twice as long as wide (in the new species this ratio is 4– 6:1). H. cipoensis Righi, 1973 View in CoL again, has more segments (50–53), the oesophageal appendages have no secondary branches and the pharyngeal glands have no secondary lobes, the dorsal vessel origin is anterior to the clitellum in X, the sperm funnels are short, only 1½ times as long as wide, and the male copulatory organ is absent ( Righi 1973). H. makusi Righi, 1988 View in CoL has sperm-rings in a wide spermathecal ampulla and the spermathecal ectal ducts are relatively short, moreover, this worm is far larger (15–17 mm, with 53–67 segments) and the pharyngeal glands have only one pair of secondary lobes ( Righi 1988). H. africanus Černosvitov View in CoL , again, is much larger (17 mm long, more than 50 segments) and has a unique character: the postseptal part of a nephridium is bilobed, the ampullae of spermathecae are even larger than in H. koreanus View in CoL , extending into X–XI, and seminal vesicle is very large filling up segments XV–XXI ( Černosvitov 1935).

Finally it is necessary to compare the new species to H. siljae Schmelz and Römbke, 2005 . These two species are very similar in size, chaetal size distribution patterns (in posterior segments these are two times as large as in preclitellar segments), form of oesophageal appendage although there may be slightly fewer secondary branches in H. siljae (4–5) ( Schmelz & Römbke 2005). H. siljae differs from the new species further, by having well-developed secondary lobes of the pharyngeal glands and primary lobes at 6/7 that are not connected dorsally, only four pairs of nephridia in preclitellar segments, and slightly more posterior dorsal vessel origin, in XIV–XV.