Aspidisca dentata Kahl, 1928

Choi, Ji Hye & Jung, Atef Omar and Jae-Ho, 2023, New record of three Aspidisca species (Protozoa, Ciliophora) from South Korea, Journal of Species Research 12 (1), pp. 90-94 : 91

1. Aspidisca dentata Kahl, 1928 ( Fig. 1 )

Material examined. Marine water (salinity 34.8‰, temperature 9.7℃) collected from Anin Beach , Gangdong-myeon , Gangneung-si, Gangwon-do, Korea (37°44 ʹ 2 ʺ N, 128° 59 ʹ 26 ʺ E) on January 3, 2022 .

Diagnosis. Size 33 - 39 × 29 - 34 μm in vivo and 26 - 28 × 21 - 27 μm after protargol impregnation (n = 3); body broadly rotund; cortex rigid, with a single conspicuous peristomial spur along left margin, dorsal side ornament- ed with distinct ridges along dorsal kineties and a single thorn about 18 μm in vivo and about 10 μm after protargol impregnation ( Fig. 1B, D ); anterior adoral zone of membranelles (AZM1) about 4 μm long with 4 membranelles, posterior adoral zone of membranelles (AZM2) about 10 μm long after protargol impregnation and with 10 - 12 membranelles; 7 frontoventral cirri in “ polystyla -arrangement”; 5 transverse cirri, only the leftmost cirrus splits into 2 parts ( Fig. 1A, C ); 4 dorsal kineties with 4 - 6, 6 - 9, 5 - 8, and 6 dikinetids in dorsal kineties 1 - 4, respectively; cytoplasm colorless; 1 horseshoe-shaped macronucleus, micronucleus not observed.

Distribution. Germany, North Sea, South Korea.

Remarks. Aspidisca dentata is a poorly known species and lacks sufficient morphological data. The Korean population of A. dentata is similar to the type population described by Kahl (1928) in all available aspects except the number of transverse cirri. Kahl (1928) reported that A. dentata has six transverse cirri, however, the Korean population usually has five transverse cirri, of which two parts are distinguishable in vivo and after protargol impregnation from the leftmost cirrus ( Fig. 1A, C ), giving the impression that it has six transverse cirri. Considering the presence of a distinct thorn on the dorsal side, three species namely A. aculeata , A. herbicola Kahl, 1932 , and A. turrita should be compared to A. dentata . Both A. herbicola and A. turrita differ from A. dentata in having ‘ lynceus -arrangement’ (vs. ‘ polystyla -arrangement’) of frontoventral cirri ( Wu and Curds, 1979; Foissner, 1994). Also, A. herbicola , which has both peristomial spur and dorsal thorn, is a freshwater species, while A. dentata is a marine species ( Wu and Curds, 1979). Aspidisca dentata can be easily distinguished from both A. aculeata and A. turrita by the presence (vs. absence) of a peristomial spur ( Kahl, 1928; 1932; Wu and Curds, 1979; Li et al., 2008).

Voucher slides. One slide with protargol-impregnated specimens was deposited at the National Marine Biodiversity Institute of Korean (MABIK PR00044190).

Figures

Fig. 1. Aspidisca dentata in life (A, B) and after protargol impregnation (C, D). A, B, Ventral (A) and dorsal (B) view, showing the body shape, the prominent peristomial spur (arrow), and the dorsal thorn (arrowhead). C, D, Ventral (C) and dorsal (D) view, showing the anterior and posterior portion of adoral zone of membranelles, the transverse cirri, and the frontoventral cirri in “polystyla-arrangement”. The arrow marks the peristomial spur and the arrowhead denotes the dorsal thorn.AZM1, adoral zone of membranells 1; AZM2, adoral zone of membranelles 2; DK1-4, dorsal kineties; FVC, frontoventral cirri; TC, transverse cirri;. Scale bars=10μm.