Cypselurus, Swainson, 1838

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 : 99-100

Genus Cypselurus

Subgenus Poecilocypselurus

Cypselurus bosha

Cypselurus olpar

Cypselurus poecilopterus

C. poecilopterus poecilopterus

C. poecilopterus arabicus

C. poecilopterus crassus

Cypselurus simus

Cypselurus callopterus

Cypselurus starksi

Cypselurus oligolepis

C. oligolepis oligolepis

C. oligolepis apus

C. oligolepis georgii

C. oligolepis persicus

Cypselurus clariangulatus

Cypselurus izumii

Cypselurus neglectus

C. neglectus neglectus

C. neglectus shcherbachevi

Subgenus Cypselurus s. str.

Cypselurus nossibe

Cypselurus opisthopus

Cypselurus naresii

Cypselurus comatus (Mitchill)

Cypselurus angusticeps

Cypselurus hiraii Abe

The genus Cypselurus includes two subgenera, sixteen species and nine subspecies. Some subspecies, such as C. oligolepis apus and C. neglectus shcherbachevi , might merit full species rank, but we refrain from such a taxonomical decision until a more comprehensive study of ontogeny of C. o. apus and finding more reliable distinguishing features or other corroborating evidence that these taxa are distinct species. We agree with statement of Hillis et al. (2021: 898): “Taxonomic change without solid supporting evidence is a disservice to science and society because it causes confusion and taxonomic instability”. Further study is needed.

Cypselurus nossibe sp. nov. is intermediate in external morphology between C. neglectus and C. opisthopus . We place C. nossibe into the subgenus Cypselurus s.str. based on presence of a chin barbel in small juveniles.

For identification of species and subspecies of Poecilocypselurus and C. nossibe the following provisional key is provided.

1. Pelvic fins of adults pigmented distally. Juveniles with a short chin barbel.............. Cypselurus (Cypselurus) nossibe

- Pelvic fins of adults usually unpigmented. Juveniles without a chin barbel............... subgenus Poecilocypselurus (2)

2. Anal fin rays usually 10 or more. In adults pelvic fin length usually <28% SL and index lP/lV> 2.35. Jaw teeth usually unicuspid................................................................................................. 3

- Anal fin rays usually 9 or fewer. In adults pelvic fin length usually> 28% SL and index lP/lV usually <2.35. Jaw teeth usually tricuspid or with additional cusps........................................................................ 4

3. Palatine teeth usually present. Transverse scales usually 8 or fewer. Pelvic fins short (in fish ≥ 130 mm SL index lP/lV usually> 2.75). Juveniles (45–55 mm SL) without an oblique pale stripe on pectoral fins............................ С. olpar

- Palatine teeth usually absent. Transverse scales usually 8½ or more. Pelvic fins long (in fish ≥ 130 mm SL index lP/lV usually <2.75). Juveniles (45–55 mm SL) with an oblique pale stripe on pectoral fins.............................. C. bosha

4. Pectoral fins spotted................................................................................... 5

- Pectoral fins not spotted................................................................................ 9

5. Greatest body depth in juveniles (<100 mm SL) 17–20% SL, in adults 18–21% SL. Predorsal scales 30–38 (usually 32–36). Gill rakers 18–22 (usually 19–20).............................................................. C. callopterus

- Greatest body depth of juveniles (<100 mm SL) 20–25% SL, in adults 17–25% SL. Predorsal scales 23–35 (usually 24–32). Gill rakers 19–28 (usually 21–24)........................................................................ 6

6. Predorsal scales 27–35 (usually 29 or more). Pectoral fins usually with relatively small black spots not arranged in oblique transverse rows (occasionally without spots)........................................................ C. simus

- Predorsal scales 23–32 (usually 24–28). Pectoral fins with large black spots arranged in oblique transverse rows................................................................................................ C. poecilopterus

7. Pelvic fins in adults with dark background pigmentation distally. Predorsal scales 27–32, vertebrae 41–44, usually 42–43.................................................................................. C. poecilopterus arabicus

- Pelvic fins in adults usually without dark background pigmentation distally. Predorsal scales 23–32, usually 24–28, vertebrae 40–43, usually 41–42.................................................................................. 8

8. Juveniles (25–80 mm SL) with body width 20.0–22.4% SL, interorbital width 12.8–16.6, usually> 14.5% SL............................................................................................. C. poecilopterus crassus

- Juveniles (25–80 mm SL) with body width 17.2–21.0, usually <20% SL, interorbital width 11.7–15.6, usually <14.5% SL............................................................................. C. poecilopterus poecilopterus

9. Pectoral fins of adults pigmented to (9 th)10 th –13 th ray. Precaudal vertebrae 27–29, usually 28–29. Dorsal-fin rays 12–14, usually 13. Predorsal scales 26–33, usually 28 or more...................................................... C. starksi

- Pectoral fins of adults pigmented to 7 th –11 th, usually to 7 th –9 th ray. Precaudal vertebrae 24–28, usually 27 or fewer. Dorsal-fin rays 10–14, usually 11–12. Predorsal scales 21–30, usually 24–28.............................................. 10

10. Pelvic-fin origin slightly closer to posterior margin of head than to origin of caudal-fin lower lobe (cV/pV 0.71–0.96, usually> 0.80). Body elongate (H 16.6–21.9, usually <20% SL, Hc 16.4–19.7, usually <19% SL)............... C. neglectus (11)

- Pelvic-fin origin much closer to posterior margin of head than to origin of caudal-fin lower lobe (cV/pV, 0.49–0.88 usually <0.80). Body rather deep (H 16.1–25.0, usually> 20% SL, Hc 16.9–22.2, usually> 19% SL)......................... 12

11. Middle and posterior dorsal-fin rays of juveniles not elongated. Pelvic-fin origin more anterior (index cV/pV 0.71–0.91, usually <0.85)............................................................................. C. neglectus neglectus

- Middle and posterior dorsal-fin rays of juveniles elongated. Pelvic-fin origin more posterior (index cV/pV 0.80–0.96, usually> 0.85).......................................................................... C. neglectus shcherbachevi

12. Pelvic-fin length in adults (> 145 mm SL) 32.9–37.1% SL............................................... C. izumii

- Pelvic-fin length in adults (> 145 mm SL) 27.8–32.8% SL.................................................... 13

13. In juveniles ≤ 80 mm SL pelvic fins with pale inner corner. Gill rakers 22–25, usually 24–25............ C. clariangulatus

- In juveniles ≤ 80 mm SL pelvic fins without pale inner corner. Gill rakers 19–26, usually <24........... C. oligolepis (14)

14. Pectoral fins of adults pigmented to 9 th –11 th ray. Transverse scales 8½–10½, usually 9½ or more; predorsal scales 26–30, usually 27 or more....................................................................... C. oligolepis persicus

- Pectoral fins of adults pigmented to 7 th –11 th, usually to 7 th –9 th ray. Transverse scales 6½–9½, usually 8½ or fewer; predorsal scales 21–28, usually 26 or fewer........................................................................ 15

15. Pelvic-fin length in adults 25.7–31.4, usually <30% SL. In juveniles, pectoral and pelvic fins without pale band or a row of pale spots................................................................................. C. oligolepis apus

- Pelvic-fin length in adults 29.2–35.7, usually> 30% SL. In juveniles pectoral and pelvic fins usually with pale band or a row of pale spots........................................................................................ 16

16. Vertebrae 39–41, usually 40; dorsal-fin rays 11–12, usually 11. In adults index po/o 1.36–1.61; greatest body depth 17.5–20.7, usually <19.7% SL.................................................................... C. oligolepis georgii

- Vertebrae 39–43, usually 41; dorsal-fin rays 10–13, usually 12–13. In adults index po/o 1.13–1.45, usually <1.36; greatest body depth 18.3–25.0, usually> 19.7% SL................................................... C. oligolepis oligolepis