Brachionus kostei Shiel 1983

Brachionus kostei Shiel, 1983 (Fig. 2) ȓċ테DŔḆệ (ljạ) Brachionus kostei Shiel, 1983: p. 33, fig. 2. Material examined. Female, glycerol permanent slide (NIBRIV0000919538, NIBRIV0000919542). Reservoir in Wanju-gun, Korea (35°50 ʹ 10.6 ʺ N, 127°00 ʹ 57.2 ʺ E), 20 Sep. 2021. Collected by Hee-Min Yang. Diagnosis. Lorica stiff, with six anterior spines on dorsal plate. Anterolateral spines and median spines long, submedian spines short. Foot opening terminally, with two spines. Lorica 110 - 135 μm in length, including anterior spine and spines on foot opening. Lorica 80 - 96 μm in width. Pattern of dorsal plate symmetrical. A triangular plate between median plate, following a pair of rectangular plates. Pentagonal median plate and heptagonal median plates subsequently located. Ventral plate with two small median spines and median elongated U-shaped sinus. Foot opening round in ventral view. Trophi malleate type. Fulcrum very short. Rami triangular shape and symmetrical. Five teeth on each uncus. Distribution. Australia (Shiel, 1983), China, India (Sharma, 2004), Papua New Guinea (Segers and De Meester, 1994), Thailand (Sanoamuang et al., 1995), Korea (This study). Remarks. Since this species possesses an oval-shaped body, six anterior spines, and narrow bases of the anterior spines, it is most similar to B. urceolaris Müller, 1773. However, it can be distinguished from B. urceolaris by its unique foot opening spines and distinctive patterns on the dorsal and ventral plates. Initially recorded in Australia, this species has subsequently been recorded in the Australasian, Indomalayan, and Palearctic regions (Shiel, 1983; Segers and De Meester, 1994; Sanoamuang et al., 1995; Sharma, 2004; Jin et al., 2013). This study represents the second report of this species in the Palearctic region, following its discovery in China, and the first to provide whole-body SEM images. Molecular analysis. Genomic DNA was extracted from a single specimen, and a partial COI sequence was obtained (759 bp, PQ594385). A total of 3,957 COI sequences from 27 Brachionus species were obtained from GenBank. Among the Brachionus sequences in GenBank, the genetic distance between B. kostei and B. urceolaris from China (MZ438220) was found to be the closest, with a difference of 12.9%. Family Lepadellidae Harring, 1913 ṘḂḆệ⁂ Genus Squatinella Bory de St. Vincent, 1822 ffiṻĒḆệẃ