Pempheris sasakii Jordan & Hubbs 1925

Pempheris sasakii Jordan & Hubbs, 1925 Figs 8, 11, Suppl. material 2 Standard Japanese name: Mie-hatampo Liopempheris sasakii Jordan & Hubbs, 1925: 228, pl. 10, fig. 1 (type locality: Toba, Mie Prefecture, Japan); Tanaka 1931: 25. Pempheris sasakii: Uchida 1933: 217; Okada 1938: 179; Okada and Matsubara 1938: 180; Matsubara 1955: 590; Tominaga 1963: 283, fig. 10; Koeda et al. 2013 a: 231; Koeda et al. 2014: 327. Pempheris nyctereutes (not Jordan & Evermann, 1903): Hayashi 1984 (in part): 160, pl. 350 - G; Hatooka 2002 (in part): 879; Senou et al. 2006 b: 463; Koeda et al. 2010 a: 75; Koeda et al. 2010 b: 81; Hatooka and Yagishita 2013 (in part): 984; Koeda and Motomura 2015: 139; Koeda et al. 2015: 275; Ikeda and Nakabo 2015: 160, figs 4–6; Kaburagi 2016: 99, upper fig. (without scientific name; shown as “ Mie-hatampo ”); Kimura et al. 2017: 119, fig. 6; Kagoshima City Aquarium Foundation 2018: 210, unnumbered fig.; Koeda 2018 b: 298, unnumbered fig.; Koeda 2018 c: 342, unnumbered figs; Murase et al. 2019: 132, fig. 285; Koeda 2020 a: 409, unnumbered figs; Murase et al. 2021: 166, fig. 341; Koeda 2022: 158, unnumbered fig.; Koeda et al. 2022: 9; Motomura 2023: 128. Diagnosis. Counts of holotype and non-types are given in Table 1. Dorsal-fin rays VI – VII, 9–10; anal-fin rays III, 40–46; pectoral-fin rays 17–20; pored lateral-line scales 67–78, usually fewer than 73; scale rows above lateral line 8 ½ – 10 ½; scale rows below lateral line 19–22; circumpeduncular scales 24; gill rakers 7–9 + 19 – 22 = 28–30; head length 28.1–29.7 %; body depth 40.6–44.6 %; eye diameter 38.9–43.2 %; upper jaw length 50.0–55.6 %; maximum 170 mm SL; snout sharp; scales weakly ctenoid, deciduous, thin, semicircular in shape, far wider than long (see Koeda et al. 2013 a: fig. 2 a); dorsal half of body brown, with golden reflection in fresh specimen; ventral half golden; tip and anterior margin of dorsal fin zonally blackish; faint blackish band on anal-fin base; dusky band on outer edge of anal fin; paired fins pink; posterior half of caudal fin dusky; body pale brown in fixed specimen; black pigmentation on each fins usually persistent, but not in holotype; no blackish blotch on pectoral-fin base; narrow band of villiform teeth in jaws; abdomen cross-sectional outline V-shaped. Distribution. Endemic to southern Japan known from Tateyama at Boso Peninsular in Chiba Prefecture, Misaki and Manazuru in Kanagawa Prefecture, Nishi-izu at Izu Peninsular in Shizuoka Prefecture, Toba and Shima in Mie Prefecture, Muroto, Susaki, Tosashimizu, Iburi, and Otsuki in Kochi Prefecture, Nobeoka and Nango in Miyazaki Prefecture, Uchinoura Bay, Kagoshima Bay, Ibusuki, and Minami-satsuma in Kagoshima Prefecture, Miyake-jima Island in Izu Islands, Tanega-shima, Yaku-shima, and Kuchinoerabu-jima islands in the northern Ryukyu Archipelago (Fig. 8). Remarks. Pempheris sasakii has been commonly confused with P. nyctereutes and has been presumed to be the junior synonym (e. g., Hayashi 1984), even though both species were described by the same first author. Only Tominaga (1963) showed the difference in anal fin coloration (P. sasakii: margin of anal fin fuscous vs P. nyctereutes: margin of anal fin pale) between these two species and described the details of both as valid species. In our morphological observations, however, several P. nyctereutes specimens have dusky margins on the anal fin; thus, this character was not diagnostic for identifying those species. The present comparison based on both species indicated that these two species can be distinguished by the counts of scale rows below lateral line (19–22 in P. sasakii vs 25–27 in P. nyctereutes) with modal difference of pored lateral-line scales (72–81 usually> 79 vs 67–78 usually fewer than 73). The coloration of the species slightly differs in that the former has golden body (sometimes silverish) in fresh condition, but the latter has copper to silver coloration: compare Figs 7, 11). Although the morphological differences between the two species are very few, the molecular analyses strongly supported the intraspecific difference which revealed that sequences of P. nyctereutes and P. sasakii differed by more than 3.1 % over mitochondrial 16 S ribosomal DNA and COI, comprising different monophyletic groups (Fig. 3). Pempheris sasakii is widely distributed in the Pacific coast of southern Japan, and commonly collected by set nets (but not abundant compared to P. xanthoptera). However, no specimens of this species have ever been collected from the Japan Sea coast, East China Sea coast, and the Ryukyu Archipelago. The distributions of both P. sasakii and P. nyctereutes are clearly isolated from each other (Fig. 8).