Zosterodasys minutus Gong et al., 2007

Vďačný, Peter & Tirjaková, Eva, 2012, Taxonomic revision of the ciliate genus Zosterodasys Deroux, 1978 (Protista: Ciliophora: Synhymeniida), Zootaxa 3345, pp. 34-58 : 50-51

Zosterodasys minutus Gong et al., 2007

( Figs 8 A–F, I)

Chilodontopsis vorax (?) – Burkovsky 1970a: 54, fig. 9; Burkovsky 1970b: 187 (very likely a distinct species; see remarks). Zosterodasys minuta Gong et al., 2007: 307 , figs 38–52.

Diagnosis. Size about 50–100 × 20–40 µm in vivo. Body shape obovate with left margin anteriorly indistinctly projecting. Macronucleus ellipsoidal to bowknot-shaped with three comparatively large (4–10 µm) globular micronuclei. Many scattered contractile vacuoles. About 34–55 ciliary rows; ventral kineties form a suture in meridional and posterior body half. Synhymenium completely encircles body. On average 11 (10–12) nematodesmal rods. Marine.

Type locality. Intertidal muddy sediments of Ganghwa Island, Incheon, Korea, E126°32' N37°35'.

Type material. One holotype slide with protargol-impregnated specimens was deposited in the Natural History Museum, London, UK (registration number 2007:03:09:3). One paratype slide with protargol-impregnated specimens was deposited in the Regional Research Center for Coast Environments of Yellow Sea, Inha University, Incheon, Korea (registration number G 06052003).

Etymology. The Latin adjective minut · us, - a, - um ([m, f, n]; minute) refers to the small size of the species.

Remarks. Under the Articles 30.2.4, 31.2 and 34.2 of the ICZN (1999) we mandatorily change the species group-name from minuta to minutus because Zosterodasys is masculine gender. Zosterodasys minutus is outstanding among marine congeners in having a suture formed by the ventral ciliary rows in the meridional and posterior body half. This peculiar feature was also found in the marine “ Chilodontopsis vorax (?)” of Burkovsky (1970a). However, Burkovsky’s species is much larger (130–160 × 46–50 µm vs. 50–100 × 20–40 µm) and has a higher number of the ciliary rows (50–80 vs. 34–55) as well as of the nematodesmal rods (16–18 vs. 10–12). Further, it displays only a single micronucleus with a size of 6 × 4 µm (vs. three micronuclei 4–10 µm in diameter).

Thus, Burkovsky’s species, which was found in the Kandalakša [Kandalaksha] Gulf in the White Sea, very likely represents a distinct species and is therefore not incorporated into the diagnosis of Z. minutus .

Figures

FIGURE 8. Var i ou s Zosterodasys species and their supposed synonyms from life (A), after Heidenhain’s haematoxylin stain (J), and after protargol impregnation (B – I). (A – F) Zosterodasys minutus, ventral view of a representative specimen (A), variability of body shape and size as well as of the nuclear apparatus (B – D), ventral (E) and dorsal (F) view of ciliary pattern and nuclear apparatus. Note the S-shaped pattern of the synhymenium which completely encircles the cell (C – F). From Gong et al. (2007). (G, H) Zosterodasys minor, total ventral view of ciliary pattern (G) and dorsal view of ciliary pattern in anterior body region (H). From Alekperov et al. (2007 / 8). Reprinted by permission from “ Protistology ”, 2007 / 2008, 5 (2 / 3): 101 – 130. (I) Chilodontopsis vorax (?), total ventral view of ciliary pattern and nuclear apparatus. From Burkovsky (1970 a). (J) Zosterodasys numerosus, ventral view of a representative specimen showing many scattered contractile vacuoles. From Ozaki & Yagiu (1941).