Cypselurus oligolepis (Bleeker, 1865)

Shakhovskoy, Ilia B. & Parin, Nikolay V., 2022, A review of the flying fish genus Cypselurus (Beloniformes: Exocoetidae). Part 2. Revision of the subgenus Poecilocypselurus Bruun, 1935 with descriptions of three new species and five new subspecies and reinstatement of Exocoetus apus Valenciennes and E. neglectus Bleeker, Zootaxa 5117 (1), pp. 1-109 : 13-14

Cypselurus oligolepis species group

The history of the Cypselurus “ oligolepis ” species group began with the work of Valenciennes (1847), who described a new species of flying fish from waters of China as Exocoetus apus . Subsequently, this name was not used in the literature for almost a century, until Bruun (1937) redescribed the type of Exocoetus apus . Bruun only mentioned that this species is a member of the genus Cypselurus Swainson. In 1997 , Collette et al. re-examined the type and determine that E. apus is a senior synonym of E. oligolepis Bleeker, 1865 , but the former name has not been used as valid since the original description while the latter was widely used. Therefore, following the Code ( ICZN 1999), E. apus should be regarded as nomen oblitum and E. oligolepis as nomen protectum.

In 1865, Bleeker described three similar species: Exocoetus oligolepis , E. brachysoma and E. neglectus ( Fig. 4 ). According to Bleeker (1865, 1866 –1872), E. oligolepis differs from the other two species in fewer scales in a row along side of body, a stockier body and a blunt and convex snout. Exocoetus brachysoma differs from other two species in a more pointed snout, and also from E. neglectus in a deeper body, larger head and fewer dorsal-fin rays (10–11 vs. 12–13). Subsequently, however, the validity of E. brachysoma and E. neglectus was questioned. As early as 1866, Günther suggested that E. brachysoma and E. neglectus may be synonymous (noting, however, that the latter species has a slightly more elongate body). Günther considered E. brachysoma as a valid species and stated that it differs from E. oligolepis in shorter pelvic fins that reach only to the middle of the anal-fin base (vs. to the end of the anal-fin base in E. oligolepis ). However, later Weber & de Beaufort (1922) placed both E. brachysoma and E. neglectus in synonymy with E. oligolepis , and placed this species into the genus Cypselurus . Subsequently, E. brachysoma and E. neglectus were placed in synonymy with C. oligolepis by Herre (1953) and Parin ( Parin 1960a; Parin & Besednov 1965), though the latter author noted that C. oligolepis is likely a composite species. Fowler & Steinitz (1956) also regarded that E. neglectus Bleeker (as well as E. socotranus Steindachner ) is a junior synonym of Exocoetus oligolepis Bleeker. Since then, E. brachysoma and E. neglectus firmly remained in the lists of synonyms for C. oligolepis , where they are at present ( Fricke et al. 2021). However, Parin (1967) and Kovalevskaya (1980) listed C. neglectus among valid species of the genus Cypselurus , without explanation.

Our examination of specimens previously identified as C. oligolepis showed that six species (two of them also include subspecies) had been lumped under this name. These species and subspecies are very difficult to distinguish as adults but much easier to distinguish as juveniles. Four of these, C. oligolepis , C. izumii sp. nov., C. clariangulatus sp. nov. and C. neglectus , we place in the C. “ oligolepis ” species group. The other species, C. nossibe sp. nov. and Cypselurus sp. , are more distant relatives; we place the former in the subgenus Cypselurus s. str. and the latter is probably synonymous with C. poecilopterus .

Figures

FIGURE 4. Flying fish drawings from Bleeker 1866-1872: (A)—Exocoetus oligolepis; (B)—E. brachysoma; (C)—E. neglectus.