Enchytraeus irregularis Nielsen and Christensen,

Torii, Takaaki, Akagi, Tomohiro, Uchino, Toru & Kobayashi, Tohru, 2018, New descriptions of enchytraeid species (Clitellata: Enchytraeidae) from Korea, Journal of Species Research 7 (1), pp. 80-91 : 81-85

publication ID	https://doi.org/ 10.12651/JSR.2018.7.1.080
persistent identifier	https://treatment.plazi.org/id/038AA90E-FFFF-FFCE-BC04-F90BFB09FCC5
treatment provided by	Felipe
scientific name	Enchytraeus irregularis Nielsen and Christensen,
status

Treatment

2. Enchytraeus irregularis Nielsen and Christensen,

1961 ( Figs. 2-4 View Fig View Fig View Fig )

Enchytraeus irregularis Nielsen & Christensen, 1961: 13-14 View in CoL , Figs. 7 View Fig -10; Dózsa-Farkas and Hong, 2010: 173, Table 1.

New Korean name: Yangsik-ae-jireongi (ỌṆOiNjffiḍ)

Material examined. Korea, Jeollabuk-do, Jeonju-si, Songcheon-dong, Earthworm breeding box in house (food-waste), 3 September 2007, Y. Hong coll.

Schmelz and Collado (2010) synonymized this species with E. capitatus v. Bülow, 1957, however there are some differences between the two species and unfortunately the type specimens are lost. We give a more detailed description of E. irregularis on the basis of the specimens from Korea illustrated with micrographs.

Description. Medium-sized whitish worms, 14-20 mm long, width 400-500 μm at VIII and 550-650 μm at clitellum (in vivo), length of fixed specimens 10-13 mm, width 400-440 (600) μm at VIII, 550-680 (800) μm at clitellum, segments 47-66 (segments 41-49 in Nielsen & Christensen, 1961). Chaetae straight or slightly curved, formula of 3-2,3: 3-2,3,(4). Many small epidermal glands irregularly in first five segments ventrally ( Fig. 2A View Fig ). Clitellum saddle-shaped, extending mostly over XII- XIII, sometimes longer for XII-XIV, gland cells small (22-28 by 14-23 μm) with darker or lighter granules, irregularly scattered ( Fig. 2B View Fig ). Oesophageal appendages short, irregular outline, thin-walled with a single central lumen, communicate with oesophagus dorsally, immediately behind pharynx. Three pairs of pharyngeal glands all with a connection dorsally and ventral lobes, especially for posterior pair ( Fig. 2I View Fig ). Brain ( Fig. 2D, E View Fig ) about 145 μm long, about 1.7 times as long as width (in vivo), straight posteriorly, both postero-lateral region usually with two or one pairs of aggregation of refractile globules ( Fig. 2D View Fig ). Head pore at 0/1 ( Fig. 2C View Fig ). Four pairs of nephridia, anteseptale consisting of funnel only, postseptale oval, efferent duct originating postero-ventrally. Coelomocytes one type, only mucocytes, small, oval or olongate pear-shaped, about 20- 29 μm long (in vivo), filled with light granules ( Fig. 2F, G View Fig ). Chloragogen cells (20-39 μm long in vivo) from VII containing brownish globules ( Fig. 2H View Fig ). Dorsal vessel originates in XV-XVI, blood faintly red ( Fig. 2C View Fig ). Paired testis sacs (seminal vesicles), well developed and lobed in IX-XI. Sperm funnels ( Fig. 2J View Fig ) 400-600 μm long, 5-8 times longer than width, longer than body diameter, collars slightly wider than funnel. Spermatozoa about 85- 100 μm long, heads about 30 μm, sperm ducts about 20 μm wide in vivo and irregularly coiled in XII ( Fig. 3A View Fig ). Male copulatory organs ( Fig. 3B View Fig ) with a glandular bulb and 6-8 narrower long glandular bodies around male pores ( Fig. 3 View Fig A-F). Laterally bent bursal slits longitudinal ( Fig. 3C View Fig ). Whole male copulatory organ 130-150 μm long and 120-130 μm wide in vivo. After male copulatory organs, a pair of oval or square glandular structure with subdivision (‘accessory sexual glands’) (130-260 μm long, 90-180 μm wide, about 100 μm high) ( Fig. 3F, H, I View Fig ) without external orifice. These organs mostly larger than male copulations organ. In Nielsen & Christensen (1961), these glands ventrally in XII in front of male copulatory organs. These glands in collected specimens from Korea always only in XIII. In one case (slide No. 573), clitellum extended over XII-XV and accessory sexual gland found in XIV, but one side only ( Fig. 3G View Fig ).

Spermathecae ( Fig. 4A, B View Fig ) with have medial length of ectal ducts (ca. 100 μm long with distinct canals and a ring of glands around ectal orifices). Length of glands about 50-60 μm (fixed). Ducts widen into ampullae proximally (diameter of ampullae about 90 μm), which again gradually tapers into short ental ducts, communicating separately with oesophagus. From ampullae anteriorly or laterally arises one large diverticula filled with spermatozoa, 2- 8 eggs mature at a time.

Remarks. E. irregularis differs from E. capitatus by accessory sexual glands which are absent in E. capitatus . In the brain of E. capitatus there are no refractile droples in the postero-lateral region ( Nielsen & Christensen, 1961). There are 4 chaetae in bundles praeclitellarly of E. capitatus , whereas there are maximum of 3 chaetae in these bundles and postclitellarly of E. irregularis (very rarely 4 chaetae). In addition, there is no enlarged posterior chaetae as in E. irregularis ( Schmelz and Collado, 2010) .

Habitat and distribution. Compost of botanical gardens in Denmark. Vermicompost in Hungary (1987) and

Korea (2007). Possibly an introduced species. Deposition. NIBRIV0000544611.