Pteroidichthys Bleeker, 1856

Motomura, Hiroyuki & Kanade, Yuka, 2015, Review of the scorpionfish genus Pteroidichthys (Scorpaenidae), with descriptions of two new species, Zootaxa 4057 (4), pp. 490-510 : 491

Genus Pteroidichthys Bleeker, 1856

Pteroidichthys Bleeker, 1856: 33 (type species: Pteroidichthys amboinensis Bleeker, 1856 ; type by original description, monotypic; gender: masculine).

Pteropelor Fowler, 1938: 77 (type species: Pteropelor noronhai Fowler, 1938 ; type by original description; monotypic; gender: neuter).

Diagnosis. A genus of the family Scorpaenidae with the following combination of characters: body strongly compressed, body width 10–24% of SL, and elongated, body depth 28–40% of SL; 12 dorsal-fin spines; no palatine teeth; tympanic spines present; upper posttemporal spines absent; body scales cycloid; lower pectoral-fin rays not strongly notched, not filamentous; no black blotches on lower caudal fin.

Remarks. The scorpionfish genera, Pteroidichthys , Hipposcorpaena Fowler 1938 , and Rhinopias Gill, 1905 , are closely related to each other ( Motomura & Senou, 2005; Motomura & Johnson, 2006); Pogonoscorpius Regan, 1908 is a junior synonym of Rhinopias (Motomura unpub. data). These genera are distinguished from all other genera of the family Scorpaenidae by having 12 dorsal-fin spines, a strongly compressed body, cycloid body scales, and no teeth on the palatines ( Poss, 1999; this study). Pteroidichthys differs from Hipposcorpaena and Rhinopias in having a shallower body depth [28–40% of SL vs. 40–53% of SL in the latter two genera, data from Motomura & Senou (2005) and Motomura & Johnson (2006); 38–54% of SL from Poss (1999)], tympanic spines present (vs. spines absent in Rhinopias ), and the lower pectoral-fin rays not strongly notched (vs. strongly notched, forming filaments in Hipposcorpaena ), and in lacking upper posttemporal spines (spines present in Rhinopias ) and lacking black blotches on the lower caudal fin (1–4 distinct blotches present in Hipposcorpaena ) ( Motomura & Senou, 2005; Motomura & Johnson, 2006).

The genus Pteropelor was originally described by Fowler (1938) for his new species, Pteropelor noronhai , from off Hong Kong, China. Although Chen & Liu (1984) and Mandrytsa (2001, 2002) treated it as a valid species of Pteropelor, Poss (1999) and Motomura et al. (2011a) regarded it as a species of Pteroidichthys . Fowler (1938) stated that Pteropelor is similar to Pteroidichthys but differs in “its incised spinous dorsal membranes, absence of barbels, and large scales”. However, these general characters usually represent species-level differences in the family Scorpaenidae . In addition, differences in the number of anal-fin spines (2 vs. 3) and the condition of the dorsal-fin spines (flexible vs. rigid) found between P. amboinensis and P. noronhai might be thought equal to generic features, but characters of a newly described species in this study, P. caussei , represent an intermediate condition between the two species, i.e., having 3 anal-fin spines and rigid dorsal-fin spines. Thus, Pteropelor is herein regarded as a junior synonym of Pteroidichthys , and P. noronhai is treated as a valid species of Pteroidichthys .