Squatinella lamellaris (Müller, 1786)

Min, Hee-Min Yang and Gi-Sik, 2025, Seven monogonont rotifers newly recorded in Korea (Rotifera: Monogononta), Journal of Species Research 14 (1), pp. 106-115 : 109-110

Squatinella lamellaris (Müller, 1786) ( Fig. 4A )

ġêẨffiṻĒḆệ ( ljạ)

Brachionus lamellaris Müller, 1786: p. 340 , pl. XLVII, figs. 8 - 11.

Stephanops muticus Ehrenberg, 1832: p. 138 .

Stephanops tridentatus Fresenius, 1858: p. 216 , pl. 10, fig. 11.

Stephanops dichthaspis Anderson, 1889: p. 353 , pl. 20, fig. 7.

Stephanops intermedium Burn, 1889: p. 179 , fig. 119.

Stephanops emarginatus Bilfinger, 1894: p. 52 , pl. 3, fig. 12.

Squatinella scutellata Hauer, 1936: p. 147 , pl. 2, figs. 14a - d.

Squatinella aurita Wulfert, 1951: p. 464 , fig. 12.

Squatinella donneri Wulfert, 1956: p. 485 , fig. 39.

Squatinella similis Wulfert, 1960: p. 327 , fig. 55.

Squatinella minor Wulfert, 1961: p. 95 , fig. 33.

Material examined. Female , glycerol permanent slide ( NIBRIV0000909856 ). Temporary pond in Incheon, Korea ( 37°23 ʹ 19.1 ʺ N, 126°25 ʹ 34.7 ʺ E), 24 Apr. 2023. Collect- ed by Hee-Min Yang .

Diagnosis. Body oval shape, with three short spines on posterior margin of dorsal lorica. Head shield hyaline, large and semicircular. Two red eyespots and corona beneath head shield. Body 130 - 135 μm in length, head shield 45 μm in width. Foot three pseudosegments, distal two segments almost equal in length. Two toes symmetrical, slim and long, 25 μm in length, with acute point. Vitellarium with eight nuclei.

Distribution. Cosmopolitan ( Segers, 2007).

Remarks. Among the 11 valid species of Squatinella , four species, S. geleii Varga, 1933 , S. lamellaris , S. lunata Segers, 1993 , and S. rostrum (Schmarda, 1846) , lack dorsal spines. Squatinella lamellaris is morphologically similar to S. rostrum in terms of head shield shape, body shape, and foot and toe characteristics. However, S. lamellaris can be distinguished by the absence of a spine between the toes, while S. rostrum has a short spine in this part. Squatinella geleii and S. lunata are easily distinguished from S. lamellaris by their unique characteristics in the head shield and lorica. The head shield of S. lamellaris is semicircular, while that of S. lunata is crescent-shaped. Additionally, S. geleii bears two short spines on the ventral side of lorica, while S. lamellaris lacks this characteristic. Previous studies have reported variation in the shape of the posterior margin of the dorsal lorica, which includes circular, tongue-shaped, truncated, and with spines ( Koste and Shiel, 1989). The Korean specimens examined exhibit three short spines on the posterior margin. Prior to this study, only one species of Squatinella , S. rostrum , had been recorded in Korea ( Chung et al., 1991).

Molecular analysis. Genomic DNA was extracted from each of the two specimens, and partial COI sequences were obtained (759 bp, PQ594389, PQ594390). No intraspecific variation was found. Interspecific variation was calculated using the partial COI sequences of S. rostrum ( EU499867 , EU499868 ) and S. longispinata (PQ594391), with variation ranged from 19.7 to 20.5% ( Table 2).

Figures

Fig. 4. Line drawing of habitus. A. Squatinella lamellaris (Müller, 1786), dorsal view; B. Notommata copeus Ehrenberg, 1834, dorsal view. The mark indicates the conical tail.