Marionina seminuda Xie & Rota, 2001

Felföldi, Tamás, Dózsa-Farkas, Klára, Nagy, Hajnalka & Hong, Yong, 2020, Three new enchytraeid species (Enchytraeidae, Annelida) from mountain soils of Korea and ten species new for the country, Zootaxa 4896 (1), pp. 1-45 : 33-36

Marionina seminuda Xie & Rota, 2001

( Figure 20 )

Material examined. 9 specimens (four specimens were deposited in the National Institute of Biological Resources , Korea; NIBRIV0000860939, slide No. 2734, NIBRIV0000860940, slide No. 2735, NIBRIV0000860941, slide No. 2743) .

Our observations mainly agree with the original description by Xie & Rota (2001), based on Chinese worms, but some dimensional traits were closer to the variation reported by Rota & Manconi (2004) in worms from New Zealand. Small worms (2–3 mm long, 110–145 μm wide at XII in vivo, 1.7–2 mm long and 70–130 μm wide at XII, fixed), segments 17–24. Chaetae straight with distinct ental hook, sharply pointed ectally, present only ventrally from segment III, 2 per bundle ( Fig. 20B ). 18–30 μm long preclitellarly and longer postclitellarly, 30–40 μm ( Fig. 20C ) [It differs from the Chinese specimens, where the chaetae of the postclitellar bundles are the smallest. In the specimens from New Zealand ( Rota & Manconi, 2004), similarly to the Korean specimens, these are longer postclitellarly, but smaller than in the Korean species (31 μm long ( Xie & Rota 2001)]. Clitellar glands large, somewhat squared about in 18–22 transverse rows. Between the male pores glands are absent or 1–2 smaller cells can be found ( Fig. 20E ). Brain incised posteriorly and convex anteriorly ( Fig. 20A ) [different from Chinese and New Zealand specimens (vs. concave anteriorly)]. The anterior two pairs of pharyngeal glands merging dorsally, with ventral lobes (small in IV and larger in V), the posterior one in VI elongate and separate ( Fig. 20G ). Coelomocytes oval, 16–24 μm long with coarse granules, dark in vivo in transmitted light ( Fig. 20H ) or filled with shining granules when fixed. Dorsal blood vessel from XII or XIII, blood colourless, anterior bifurcation in III ( Fig. 20D ). Three pairs of nephridia preclitellarly (7/8–9/10). In one specimen, only 2 pairs in 7/8 and 9/10. Sometimes unpaired. Pars tumida of midgut at 1/2 XVII–XIX (occupying 2 segments) (in the Chinese specimens it was found in XVI). Seminal vesicle absent or small. Sperm funnels small, 31–41 μm long, 1.6–2.6 times longer than wide in vivo (31–37 μm long, 1.5– 2.2 times longer than wide, fixed). Collar high and narrower than funnel ( Fig. 20I ). Sperm ducts irregularly coiled, 4–5 μm wide (in Chinese and New Zealand specimens, regularly coiled). Penial bulbs small, compact, diameter 20–21 μm ( Fig. 20E ). Spermathecae confined to V, attached to the oesophagus.Ampullae globular 14–17.5 μm wide with spermatozoa in lumen. Ectal ducts 15–20 μm long and 7–8 μm wide, with small gland cells along their whole length and at the orifice one larger gland, 7–10 μm long, fixed ( Fig. 20J ). One mature egg at a time.

Distribution and habitat in Korea. Mt. Hallasan, Jeju city, Jeju-do, soil and litter layers of Q. serrata coppice forests, wetland, South-East slope of Mt. Hallasan, N 33°19’23.88”, E 126°33’29.90”, 777 m asl. The Korean record confirms the associaton of this species with wet habitats.

Figures

FIGURE 20. Micrographs of Marionina seminuda Xie & Rota, 2001. A. Brain. B. Preclitellar chaetae, present only ventrally (upside down). C. Chaetae posteriorly. D. Anterior bifurcation of dorsal blood vessel in III. E. Clitellar glands, ventral view (penial bulbs marked with arrows). F. Segments 0–VII, lateral view (pharyngeal glands marked with short arrows, head pore with protruded coelomocytes marked with long arrow). G. Pharyngeal glands, dorsal view. H. Dark coelomocytes. I. Sperm funnel. J. Spermatheca. B–E, G–I in vivo, A, F, J. fixed, stained. Scale bars 50 μm, C, E, I–J 20 μm.