Cypselurus clariangulatus, Shakhovskoy & Parin, 2022

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 : 47-64

Cypselurus clariangulatus sp. nov.

Synonymy and bibliography.

Cypselurus oligolepis (non Bleeker). Fedoryako 1982: 111 (juveniles listed as associated with drifting objects; Pacific Ocean; in part: only fish captured at Station 5028).? Dalzell 1993: 22, 27 (fishery; Camotes Sea, Philippines).

Material examined. Thirty-seven specimens 29.5–153 mm SL.

Full morphological study. ZMMU P-24452 (holotype) (1, 50 mm SL), 8°18’N 120°25’E, 21- 22.06.1971 . IORAS 03999 (1, 128.5 mm SL), Philippines (Camotes Sea?) . IORAS 04000 (2, 51– 55.5 mm SL), 7°45’N 120°25’E, 4- 5.04.1961 . IORAS 04002 (paratype) (1, 56 mm SL), 8°18’N 120°25’E, 21- 22.06.1971 . IORAS 04003 (1, 44 mm SL), ~ 7°N 135°31’E, 30.05.1971 . IORAS 04004 (1, 76 mm SL), 8°18’N 120°25’E, 26.06.1971 . CAS 81823 (2, 29.5–32 mm SL), 8°43’N 122°40’E, 17.06.1948 . CAS 81829 (16, 48.5–151 mm SL), 6°56’N 121°45’E, 6.05.1948 . CAS 81904 (2, 128– 129 mm SL), Zamboanga Del Sur, Pilas Group , Minis I., 7.05.1948 . CAS 81916 (1, 34 mm SL), Zamboanga del Sur, Sibugney Bay , 7.04.1948 . SOSC Ref.No. 190 (4, 133.5– 153 mm SL), 6°30’N 118°45’E, 27.01.1965 . ZMUC uncat (1, 61 mm SL), 2°54’N 120°04’E, 20.08.1951 .

Partial morphological study. CAS 81884* (1, 71 mm SL), 6°44’N 125°37’E, 13.05.1948 . CAS 81920* (1, 33 mm SL), 7°18’N 122°30’E, 9.05.1948 . CAS B-89* (1, 137 mm SL), 6°37’N 121°33’E, 13.01.1948 . USNM 435571 # (1, 108.5 mm SL), near Dauis, Panglao, 1.08.2016 .

As juveniles, Cypselurus clariangulatus is easily distinguished from C. oligolepis , but we did not find reliable diagnostic characters for adults. Thus, only juveniles are included in the type series.

Holotype ( Fig. 20 ). ZMMU P-24452, R / V Vityaz Cruise 50, Sta. 6490, sample 534, 8°18’N 120°25’E, 21–22 June 1971, dip-net, with night-light. Length 50 mm SL (juvenile). D 11, A 7, P I 14, Spred 24, Str 8½, Sp.br 23 (6 + 17), Vert 40(?). Measurements (in % SL): aA 76.4, aD 70.4, aV 54.6, cV 29.8, pV 42.6, c 25.4, po 11.8, o 10.4, ao 3.6, io 14.2, Hc 19.8, H 21.4, h 9.4, Dc 28.4, lP 58.0, lP 1 36.6, lV 46.2, lD 20.8, lA 11.4, HD 13.6?, HA 10.2, p 20.4. Body brown, ventral side somewhat darker than dorsal ( Fig. 20a ). Head dark brown, “lips” (mouth margin) and chin pale. Pectoral fins brown with three small pale areas near tips of 1 st –3 rd rays and pale lower edging ( Fig. 20b ). Tip of pectoral fin slightly protruding beyond 5 th dorsal-fin ray. Pelvic fins brown, their 1 st ray somewhat paler; inner fin corner without pigmentation ( Fig. 20c ). Tip of pelvic fin nearly reaching origin of middle rays of caudal fin. Dorsal fin pale with dark dots anteriorly and on upper part of fin to 7 th ray, and scarce dots near bases of rays. Tip of last dorsal-fin ray nearly reaching origin of caudal-fin upper lobe, penultimate rays shorter than last ray. Anal fin pale, with only solitary dots present near bases of rays. First anal-fin ray beneath 5 th dorsal-fin ray. The 2 nd ray of dorsal and anal fins longest. Caudal fin pale with brown base and large brown band on lower lobe distally. Lower and upper jaws equal. Jaw teeth very small, conical. Palatine teeth present (arranged in a row).

Paratypes. IORAS 04002 , 56 mm SL, 8°18’N 120°25’E, 21–22 June 1971 . CAS 81884, 71 mm SL, 6°44’N 125°37’E, 13 May 1948 .

Description. Meristic and morphometric characters are given in Tables 1–6 and 10. D 11–12, A 7–9 (usually 8), P I 13–16 (usually I 14–15), Spred 23–27 (usually 24–26), Str 7½–9½ (usually 8½), Sp.br 22–25 (6–8 + 16–19), usually 24–25 (6–7 + 17–18), Vert 39–42 (25–27 + 14–15), usually 40–41 (25–26 +14–15). Snout short and blunt, upper jaw not pointed anteriorly ( Fig. 21 ), lower jaw shorter than upper or of equal length (rarely lower jaw may be slightly longer, especially in juveniles). Jaw teeth small (usually not visible with naked eyes), mainly tricuspid (some specimens also have conical teeth or teeth with additional cusps). Juveniles <100 mm mainly with conical teeth. Teeth arranged in 2–4 rows; in juveniles <100 mm SL in 1–2 rows. Palatine teeth always present, numerous in adults and sparse in juveniles <60 mm SL.

Body rather deep; greatest body depth not changing with growth, 4.3–5.4 in SL. Body width decreasing with growth: in juveniles 30–95 mm SL it fits 4.5–6.6 in SL and 0.91–1.27 in greatest body depth, in fish 128–153 mm SL, 6.1–6.7 and 1.37–1.78, respectively. Caudal peduncle depth slightly decreasing with growth: in juveniles 30–95 mm SL it fits 10.2–13.3 in SL and 2.10–2.64 in greatest body depth, in fish 128–153 mm SL, 12.05–13.9 and 2.46–2.71, respectively. Greatest head depth and head length hardly changing with growth, 4.5–5.7 and 3.7–4.6 in SL, respectively. Head length 0.99–1.31 in dorso-caudal distance. Eyes relatively large, eye diameter decreasing strongly with growth ( Fig. 6a ): in juveniles 30–95 mm SL eye diameter 7.6–13.0 in SL, 2.00– 2.97 in head length, 1.17–1.60 in interorbital width and 0.76–1.39 in postorbital distance ( Fig. 6e ); in fish 128–153 mm SL, 11.8–13.15 in SL, 2.92–3.30 in с, 1.08–1.26 times in io and 1.27–1.53 in po.

Pectoral fins relatively short, their length increasing with growth ( Fig. 6c ): in juveniles 30–95 mm SL it fits 1.5–2.0 in SL and in fish 128–153 mm SL, 1.55–1.65 in SL. Tip of pectoral fin reaching from middle to end of dorsal-fin base, occasionally extending beyond it; in juveniles <60 mm SL from origin to middle of dorsal-fin base. First pectoral-fin ray unbranched, its length increasing slightly with growth: in juveniles 30–95 mm SL it fits 2.7–3.4 in SL and 1.58–2.01 in lP; in fish 128–153 mm SL, 2.60–2.95 in SL and 1.59–1.77 in lP. Pelvic fin base much closer to posterior edge of head than to origin of caudal-fin lower lobe (cV / pV = 0.48–0.85); pelvic fins shift slightly posteriorly as fish grows. Pelvic-fin length decreasing strongly from juveniles to adults ( Fig. 6d ): in juveniles 30–95 mm SL it fits 2.1–2.9 in SL and 1.01–1.67 in lP ( Fig. 6f ); in fish 128–153 mm SL, 3.3–3.6 in SL and 1.99–2.26 in lP. Tip of pelvic fin in small juveniles 30–60 mm SL reaching (or nearly reaching) origin of caudal-fin lower lobe or protruding slightly beyond; in juveniles 60–80 mm SL, protruding beyond middle of caudal peduncle but not reaching origin of caudal-fin lower lobe; in fish 80–92 mm SL, reaching from end of anal-fin base to middle of caudal peduncle, and in fish> 128 mm SL, from middle (or nearly so) to end of anal-fin base.

Anal-fin origin far behind dorsal-fin origin, 1st anal-fin ray beneath 5 th –7 th (very rarely 4 th) dorsal-fin ray. Dorsal fin with 2–4 rays more than anal fin. Height of dorsal and, especially, anal fins decreasing with growth. In juveniles 30–95 mm SL, HD 7.1–8.7 and HA 9.2–12.65 in SL; in fish 128–153 mm SL, HD 9.7–10.85 and HA 13.9–15.15 in SL. Longest ray of dorsal and anal fins 2 nd or 3 rd. Tip of last dorsal-fin ray protruding behind middle of caudal peduncle but never reaching origin of caudal-fin lower lobe. Middle and posterior rays of dorsal fin not elongate, penultimate rays not extending behind tip of last ray.

Pigmentation. Body of juveniles 30–80 mm SL ( Fig. 21a–b ) pale brown to dark brown, usually darker ventrally and paler dorsally. Body bands usually absent, but a dark band between origins of pectoral and pelvic fins present in occasional specimens. Body of fish ≥ 80 mm SL pale brown or brown, dorsally darker than ventrally.

Lower surface of head in juveniles 30–80 mm SL brown or dark brown with pale chin and distal parts of branchiostegal rays (in few fish rather pale with pigmentation mainly under eyes). In fish 80–90 mm SL, lower surface of head pale with weak dotted pigmentation on bases of branchiostegal rays and near lower jaw symphysis. Fish> 125 mm SL with a few small dark specks on gill covers and (or) under eyes ( Fig. 21e ) or without specks.

Pectoral fins ( Figs. 20b , 22a ) of juveniles 30–80 mm SL brown or dark brown with pale tip and lower edging and, in some fish, with two small pale areas near tips of 1 st –2 nd rays; pale transverse band or spots always absent. In fish 80–110 mm SL, a small “mirror” reaching 8 th ray appears. In fish 128–153 mm SL, pectoral fins pale brown to dark brown to 8 th –9 th ray with broad pale tip and very narrow posterior pale edging. Distally fin pigmentation usually extends one ray lower than proximally ( Fig. 22b ) or a small “mirror” present.

Pelvic fins of juveniles 30–80 mm SL ( Figs. 20c , 22c ) brown or dark brown (1 st and 2 nd rays sometimes paler) with unpigmented inner corner. In fish 80 mm SL pigmentation begins to disappear, and in fish 85–95 mm SL pelvic fin pale with residual pigmentation (dots and streaks) along some rays in central and posterior parts ( Fig. 22d ). In fish ≥ 105 mm SL pelvic fins pale ( Fig. 22e ).

Dorsal fin of juveniles 30–95 mm SL covered with brown melanophores, denser near bases of anterior rays and along upper margin, sparser posteriorly (or entirely pale). In fish 128–153 mm SL, dorsal fin gray or pale brownish.

Anal fin of juveniles 30–90 mm SL transparent, sometimes with few dots near base of some rays. Occasionally, pigmentation also present distally between penultimate rays. In fish ≥ 90 mm SL, anal fin translucent (rarely grayish near base).

Caudal fin of fish 30–35 mm SL pale with dots on fin base, along lower lobe rays (sometimes aggregated in a dark band distally) and, in some cases, on tip of upper lobe ( Fig. 21a ). In fish 40–55 mm SL, caudal fin pale, but fin base and distal half of lower lobe densely covered with brown melanophores. In fish 55–75 mm SL, fin base and lower lobe brown or dark brown (sometimes with a paler zone on lower lobe proximally), upper lobe (except pigmented tip) and fork pale ( Fig. 21b ). In fish 75–95 mm SL, caudal fin brown or dark brown with a pale band passing through upper lobe and fork ( Fig. 21c ). In fish 125–155 mm SL ( Fig. 21d–e ), caudal fin brown or pale brown, sometimes upper lobe darker distally.

Coloration in life. The holotype and a paratype ( IORAS 04002 , 56 mm SL) of C. clariangulatus exhibited much yellow and red pigmentation: lower surface of body blackish-yellow; pectoral fins dark brown, nearly black, anteriorly and orange-red posteriorly; pelvic fins with yellow, red and black pigmentation; band on lower lobe of caudal fin red.

Maximum size. The maximum length of adults of C. clariangulatus was 153 mm SL ( SOSC Ref.No. 190, 6°30’N 118°45’E, not dissected for sex). The largest female was 151 mm SL, and the only male was 128 mm SL.

Intraspecific variation. No data.

Etymology. The species name reflects its main diagnostic character—unpigmented inner corner of pelvic fins in juveniles (from Latin clarus —clear and angulus —corner).

Common names. The name “Clear-corner flying fish” (Russian: “уголковый стрижехвост”) is proposed here for C. clariangulatus .

Comparative remarks. Cypselurus clariangulatus is very similar to C. oligolepis , differing most noticeably in pigmentation of pelvic and anal fins of juveniles (up to 80 mm SL). The juveniles of C. clariangulatus also have a wider interorbital space (12.5–16.3 vs. 10.0–14.0, see Fig. 6b ). However, we did not find reliable diagnostic characters for adults. The only differences noted were that the adults of C. clariangulatus tend to have more gill rakers (usually 24–25 vs. usually <24), lower height of dorsal and anal (except C. o. persicus) fins (HD 9.2–10.3 vs. 9.2–13.8, usually> 10.5% SL; HA 6.6–7.2 vs. 6.8–9.3, usually> 7.5% SL), shorter pectoral fins and their first ray (lP 60.2–64.1 vs. 60.3–71.2% SL, lP 1 34.0–37.9 vs. 32.0–45.3% SL) and smaller eye (except persicus and georgii) (7.6–8.5 vs. 7.0–10.7% SL) (see Tables 4, 6–8 ); also, pelvic fins are shorter than in C. o. oligolepis and C. o. persicus ( Fig. 6d ). However, nearly all these differences have much overlap. Thus, further research is needed to find reliable characters for identification of adults of this species. Cypselurus clariangulatus differs from C. izumii in shorter pelvic (≤ 32.2 vs. ≥ 32.9% SL) and pectoral (lP ≤ 63.8 vs. ≥ 66.0% SL, lP 1 ≤ 37.9 vs. ≥40.1% SL) fins, lower dorsal and anal fins (HD ≤ 10.3 vs. ≥10.6% SL, HA ≤ 7.2 vs. ≥ 7.3% SL), larger head (≥ 24.5 vs. ≤ 24.4% SL), fewer vertebrae (39–42, usually <42 vs. 42–44) and in other characters (see Tables 1 , 6 and 10 ).

Note: Here and elsewhere the mean is given above the line, the range of variation—under the line.

Biology. Females mature at 128 mm SL. Close to mature or mature fish were captured near Pilas Is. in May ( CAS 81829) and in Camotes Sea ( IORAS 03999 , date unknown). Small juveniles of 30–35 mm SL were captured on 7 April 1948 in Sibugney Bay ( CAS 81916), on 9 May 1948 at 7°18’N 122°30’E ( CAS 81920), and on 17 June 1948 at 8°43’N 122°40’E ( CAS 81823). These data suggest that C. clariangulatus spawns in waters of the Philippines at least from March to May .

Distribution. Cypselurus clariangulatus occurs ( Fig. 18 ) mainly in the Sulu Sea, but has also been collected in the Celebes (ZMUC uncat, 2°54’N 120°04’E) and Camotes (IORAS 03999) seas, Davao Gulf (CAS 81884) and, its easternmost occurrence, the Caroline Islands (IORAS 04003, ~ 7°N 135°31’E). This species is sympatric with C. oligolepis and, probably, with C. neglectus .

Figures

FIGURE 6. Size variation of morphometric characters (in % SL) in Cypselurus oligolepis (□— C. o. oligolepis, ○— C. o. apus, ∆— C. o. persicus, +—C. o. georgii), C. clariangulatus (◊) and C. izumii (x): (A)—diameter of eye (o); (B)—width of interorbital space (io); (C)—length of pectoral fin (lP); (D)—length of pelvic fin (lV); (E)—postorbital distance divided by diameter of eye (index po/o); (F)—pectoral fin length divided by pelvic fin length (index lP/lV).

FIGURE 18. Distribution of Cypselurus oligolepis apus (○) and C. clariangulatus (◊). Filled symbols indicate capture loca- tion for fish ≤ 100 mm SL, open symbols indicate capture location for fish> 100 mm SL. Positions of holotypes marked with asterisk.

FIGURE 20. Holotype of Cypselurus clariangulatus (50 mm SL, ZMMU P-24452, 8°18’N 120°25’E): (A)—side view; (B)— pectoral fin; (C)—pelvic fin.

FIGURE 21. Cypselurus clariangulatus: (A)—32 mm SL, CAS 81823, 8°43’N 122°40’E; (B)—61 mm SL, ZMUC uncat., 2°54’N 120°04’E; (C)—92 mm SL, CAS 81829, 6°56’N 121°45’E; (D)—128.5 mm SL, IORAS 03999, Philippines (Camotes Sea?); (E)—147 mm SL, CAS 81829, 6°56’N 121°45’E.

FIGURE 22. Pectoral (A–B) and pelvic (C–E) fins in Cypselurus clariangulatus: (A)—55.5 mm SL, IORAS 04000, 7°45’N 120°25’E; (B)—147 mm SL, CAS 81829, 6°56’N 121°45’E; (C)—44 mm SL, IORAS 04003, ~ 7°N 135°31’E; (D)—89 mm SL, CAS 81829, 6°56’N 121°45’E; (E)—128 mm SL, CAS 81904, Minis I.