Cephalodella gracilis (Ehrenberg, 1830)

Yang, Hee-Min & Min, Gi-Sik, 2023, A new species of the genus Cephalodella (Rotifera, Monogononta) from Korea, with reports of four additional cephalodellid species, ZooKeys 1141, pp. 185-199 : 185

Cephalodella gracilis (Ehrenberg, 1830)

Material examined.

Soil from Cheonan-si, Chungcheongnam-do, Republic of Korea (36°54.095'N, 127°12.380'E), 22 Jun. 2019, Hee-Min Yang leg. NIBRIV0000879592, 1 female, glycerol permanent slide .

Remarks.

The body size of the Korean specimens was 120-125 μm in length (Fig. 5B ). The soft body was elongated and compressed laterally. The head was clearly distinguished from the body by a neck fold. The foot was conical in shape, short, and half the length of the toes. The length of the toes was 20-25 μm, less than one-fifth of the total length. The two toes were equal in length and slightly curved dorsally. One red eye was located at the front of the head. The vitellarium was large and contained four nuclei. The large trophi was symmetrical, virgate type B, and had a length of 20 μm (Fig. 6B ). The fulcrum was long and straight without expansion at the end. The manubrium was long and crutched, with a bulge in the middle. The uncus had one tooth and was less than half the length of the manubrium. The rami were denticulated.

Cephalodella gracilis has been reported to have high morphological variation in the shape of the toes and trophi. The Korean specimen had dorsally curved toes that gradually tapered toward the end. The trophi shape of the Korean specimen did not correspond to a specific specimen but was most similar to that described by Jersabek et al. (2003) in that it had a straight, slender fulcrum without expansion and a crutched manubrium end. However, this species can be regarded as a species complex, based on its morphological diversity and cosmopolitan distribution. Therefore, it is necessary to re-examine it through morphological redescription and molecular analysis.

Molecular data.

Partial COI sequences were obtained from two Korean specimens (NIBR deposit numbers, NIBRGR0000649741, NIBRGR0000649742; GenBank accession numbers, ON898535, ON898536).

Figures

Figure 5. Line drawing of cephalodellid rotifers A Cephalodella tinca Wulfert, 1937 B C. gracilis (Ehrenberg, 1830) C C. auriculata (Mueller, 1773) D C. catellina (Mueller, 1786). Scale bars: 50 μm.

Figure 6. SEM image of the trophi of cephalodellid rotifers A Cephalodella auriculata (Mueller, 1773) B C. gracilis (Ehrenberg, 1830) C C. catellina (Mueller, 1786) D C. tinca Wulfert, 1937. Scale bars: 10 μm.