Cypselurus naresii septentrionalis, Shakhovskoy & Parin, 2024

Shakhovskoy, Ilia B. & Parin, Nikolay V., 2024, A review of the flying fish genus Cypselurus (Beloniformes: Exocoetidae). Part 3. Revision of the subgenus Cypselurus sensu stricto with descriptions of one new species and four new subspecies and reinstatement of Cypselurus crockeri Seale and Exocoetus socotranus Steindachner, Zootaxa 5473 (1), pp. 1-125 : 64-66

Cypselurus naresii septentrionalis subsp. nov.

Synonymy and bibliography.

Cypselurus naresii . Imai 1955: 97–104, figs. 2–3 (description, juveniles; Japan; in part: except specimens 53.0 and 231 mm SL). Imai 1959: 72–75, pl. 34b–d (description, distribution, early life history stages; Kyushu, Japan; in part: except specimens 53.0 and 231 mm SL). Tsukahara 1959: 180–181, figs. 34–36 (juveniles; Amakusa Is.). Chen 1987: 16, 18, 20, 25, 54, 55, 151, figs. 3-33E, 3-34C, 4-9, 6-10, 6-20, Tabs. 2-1, 3-1, 4-9 (description, distribution, early life history stages; north-western Pacific; in part: specimen 112.0 mm SL is probably C. n. ordinarius). Chen 1988: 282–283 (early life history stages, figures, distribution; Japan). Parin 1999: 2166, 2174 (distribution, in part: north-western Pacific).? Senou et al. 2006: 431 (listed; Sagami Sea). Arao et al. 2020: 63–64, fig. 2H (a juvenile 23.2 mm; Tokyo Bay).

Cypselurus opisthopus hiraii (non Abe).? Imai 1959: pl. 31c–e (juveniles; Japan; in part).

Cypselurus angusticeps (non Nichols & Breder).? Chen 1993: 189 (in part: only a figure of juvenile; Taiwan).

Material examined. Two specimens 33–44 mm SL.

Full morphological study. ZMMU P-24608 (holotype, 44 mm SL), 29°51’N 131°10’E, 9.07.1971 .

Partial morphological study. IORAS 04251 (paratype) (1, 33 mm SL), 29°51’N 131°10’E, 9.07.1971 .

Holotype ( Fig. 26 ). ZMMU P-24608, R / V Vityaz, Cruise 50, Sta. 6496, sample 622, 29°51’N 131°10’E, 9 July 1971. Length 44 mm SL (juvenile). D 13, A 8, P I 14, Spred 33, Str 9½, Sp.br 23 (6 + 17), Vert 45 (29 + 16). Measurements (in % SL): aA 79.7, aD 70.4, aV 57.9, cV 32.2, pV 39.7, c 26.8, po 11.5, o 9.3, ao 5.0, io 10.0, Hc 17.9, H 17.9, h 7.5, Dc 27.2, lP 63.1, lP1 -, lV -, lD 20.0, lA 10.9, HD -, HA -, p 16.3, Lcir 17.9. Body with typical adult “pelagic” pigmentation, ventral side of head pale with pigmented chin. Chin barbel short (only slightly protruding beyond eye), dark brown on both sides, paler near base, with a dark median keel along the full length; basal triangular lobes absent. Pectoral fins reaching last dorsal-fin ray, dark brown to 9th ray with a pale tip. Pelvic

8 For photo of such a specimen from the North-West Pacific, see Imai (1959: Pl. 35).

9 Imai (1959) also reported a juvenile 53 mm SL of C. naresii captured 11.08.1952 off Yaku Island. Judging by characters provided (long chin barbel, posterior position of pelvic-fin base, 11 dorsal-fin rays), this juvenile should be identified not as C. n. septentrionalis, but rather as C. n. ordinarius or, considering barbel pigmentation, even as C. n. albitaenia (if mislabeling were the case).

fins damaged, appears to be brown with paler 6th ray. Dorsal and anal fins heavily damaged and pigmentation not possible to observe. First anal-fin ray beneath 6th–7th dorsal-fin ray. Caudal fin pale with brown base and brown pigmentation along rays of lower lobe (both lobes damaged). Jaw teeth small, conical. Palatine teeth present.

Paratype. IORAS 04251 , 33 mm SL, 29°51’N 131°10’E, 9 July 1971 .

Differential diagnosis and comparative remarks. Imai (1955) has noted that specimens of C. naresii from the waters of Japan have more dorsal-fin rays and predorsal scales than tropical conspecifics from Melanesia and Indo-Australia. Kovalevskaya (1982), based on the higher number of dorsal-fin rays (11–13 vs. 10–12 elsewhere) in fish described by Imai (1955, 1959), suggested that Imai had dealt not with pure C. naresii , but with material contaminated with C. angusticeps and C. hiraii . Our data agree with that of Imai and indicate that C. naresii from waters of Japan and Taiwan do differ from conspecifics of other populations, and the difference is strong enough to separate at least a subspecies.

Cypselurus n. septentrionalis differs from other subspecies in chin barbel morphology and pigmentation (short, <20% SL (see Fig. 20d ), without basal lobes and not widened terminally; pigmentation dark with paler base and a dark median keel), more dorsal-fin rays (12–13 vs. 9–13, usually <12), more anterior position of pelvic-fin base (index cV/pV 0.81–0.89 vs. 0.88–1.22, cV 32.2–33.1 vs. 34.1–41.8% SL, aV 56.3–58.0 vs. 58.8–65.4% SL) and dorsal-fin origin (aD 69.1–70.6 vs. 68.8–75.7, usually> 71.0% SL), shorter pelvic fins (in fish <70 mm SL, lV 35.9–37.4 vs. 37.5–44.1% SL, see Fig. 20c ) and some other characters (see Table 10).

Adults of C. n. septentrionalis are still not known. The only large specimen reported to be C. naresii (231 mm SL) from the waters of Japan was described by Imai (1955, 1959), but we cannot agree with his species identification as this specimen has unusual pectoral-fin pigmentation (pigmented to 10th ray with a pale “mirror” to 5th ray) and pelvic fins too long (33.7% SL) for C. naresii . It seems that adults of C. n. septentrionalis may be hard to distinguish from C. hiraii and C. angusticeps (see below for description of this species). However, C. n. septentrionalis differs from C. hiraii in fewer vertebrae and gill rakers (Tables 4–6), smaller head (c 23.7–26.8 vs. 21.2–24.7% SL, index Dc/c 1.01–1.04 vs. 1.07–1.33), more anterior position of pelvic-fin base (aV 56.3–58.0 vs. 56.0–62.3, usually> 58.0% SL; cV 32.2–33.1 vs. 32.8–40.6, usually> 34.0% SL), and some other characters ( Tables 7, 10, 14).

Etymology. The subspecies’ name reflects its distribution in the northernmost latitudes as compared with other subspecies of C. naresii (from Latin “ septentrionalis ”—northern).

Common name. The name “northern pharao flying fish” (Russian: “северный стрижехвост-фараон”) is proposed here for C. n. septentrionalis.

Distribution. Cypselurus n. septentrionalis occurs from off southern Taiwan (9 mm SL, 21°20’N 121°55’E, after Chen 1987) to Boso Peninsula (48.9 mm SL, Amatsu, Chiba, after Chen 1987), the majority of occurrences is in the East China Sea ( Fig. 24 ). Judging by data of Kovalevskaya (1982: fig. 5), larvae and juveniles may drift with currents eastwards to about 150°E.

Figures

FIGURE 24.Distribution of Cypselurus naresii (∆—C.n.naresii, —C.n. septentrionalis (our data), —C. n. septentrionalis (data of Imai 1959, Tsukahara 1959 and Chen 1987), ○—C. n. ordinarius, ◊—C. n. albitaenia, □—C. n. socotranus). Filled symbols indicate capture location for fishes ≤ 100 mm SL, open symbols indicate capture location for fishes> 100 mm SL; holotype position marked with asterisk.

FIGURE 26. Holotype of Cypselurus naresii septentrionalis, 44 mm SL, ZMMU P-24608, 29°51’N 131°10’E. (A)—side view; (B)—ventral view.

FIGURE20.Sizevariationofmorphometriccharacters(in%SL)inCypselurusnaresii:x—C.n.naresii;◊—C.n.septentrionalis; □—C. n. socotranus; Δ—C. n. ordinarius (lilac—western Pacific Ocean, red—eastern Indian Ocean, orange—Bay of Bengal and Andaman Sea); ○—C. n. albitaenia (dark blue—Indian Ocean, light blue—Arabian Sea). (A)—preventral distance (aV); (B)—greatest body depth (H); (C)—pelvic-fin length (lV); (D)—length of chin barbel (Lcir).