Cypselurus neglectus ( 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 : 64-67

Cypselurus neglectus ( Bleeker, 1865)

This species ( Fig. 23 ) is very similar to Cypselurus oligolepis and has been considered synonymous with it for a long time (since Weber & de Beaufort 1922). Here we resurrect C. neglectus based mainly on differences in position of pelvic-fin origin, length of head, depth of body ( Fig. 24 ) and pigmentation of juveniles.

Synonymy and bibliography.

Exocoetus neglectus Bleeker, 1865: 107 , 112–113 (original description; Indonesia, Singapore; in part?). Günther 1866: 296 (listed as a probable synonym of Exocoetus brachysoma ). Bleeker 1866 –1872: 68, 71, Tab. CCXLVII Pl. Scombres I fig. 2 (description; Indonesia, Singapore; in part?). Weber 1913: 125 (conspecific with E. brachysoma ). Weber & de Beaufort 1922: 189–190 (synonym of C. oligolepis ). Fowler & Steinitz 1956: 271–272 (mentioned as a synonym of Exocoetus oligolepis Bleeker ). Parin 1960a: 254 (listed as synonym of C. oligolepis ).

Cypsilurus oligolepis (non Bleeker). Weber & de Beaufort 1922: 180, 189–190 (description; Indo-Australian Archipelago; in part).

Cypselurus oligolepis (non Bleeker).? Woods & Schultz 1953: 184–185, 187 (morphometry; Siam; in part: USNM 103338). Parin 1960a: 222, 254, 255, 279 (description (after Weber & de Beaufort 1922 and Woods & Schultz 1953); western Pacific; in part). Parin 1960b: 156 (distribution; western Pacific; in part).? Kovalevskaya 1965: 124, 143, 145 (a juvenile listed; Tonkin Bay). Parin & Besednov 1965: 106–109, fig. 1 (description; Tonkin Bay; in part: except specimen 107 mm SL). Shuntov 1965: 119–122 (distribution; Tonkin Bay; in part?).? Mai & Bui 1978: 251, 261 (listed; Vietnam; in part?). Parin 1984: EXOC Cyp 11 (in part: figure).? Nguyen & Nguyen 1994: 150 ( Tonkin Bay). Sommer et al. 1996: 164 (in part: figure (from Parin & Besednov 1965)). Parin 1999: 2165, 2174 (distribution, diagnostic characters, figure; western Pacific; in part). Barman & Mishra 2006: 14 (in part: figure (after Parin & Besednov 1965)). Matsunuma 2018: 67 (short description; Vietnam, Ha Long Bay; in part).

Cypselurus neglectus . Parin 1967: 52, 54 (distribution).

? Cheilopogon katoptron (non Bleeker). Matsunuma 2011: 53 (in part: only specimen KAUM-I. 17095 161 mm SL; Terengganu ( Malaysia)) .

See further bibliography below in the account for C. neglectus shcherbachevi .

Material examined. One hundred and thirty-nine specimens 24–187 mm SL (see details below in the subspecies descriptions).

Types. The three syntypes of Exocoetus neglectus Bleeker were examined by the second author; the type status of two of them (from Bleeker’s collection in RMNH) is doubtful. In this work we designate the syntype BMNH 1866.5.2.34 as the lectotype to clarify the application of the name to the taxon.

Lectotype (ex syntype) of Exocoetus neglectus Bleeker ( BMNH 1866.5.2.34 , no label data). Length 165 mm SL (female). D 11, A 8, P I 14, Spred 28, Str 8, Sp.br 21 (4 + 17), Vert 40 (25 + 15). Measurements (in % SL): aA 81.2, aD 72.0, aV 58.6, cV 1 36.0, pV 39.6, c 24.5, o 8.4, ao 1 5.9, H 17.8, Dc 24.6, lP 62.7, lV 28.8, lD 16.9, lA 8.7, HD 11.9 , HA -, p 15.2. Pectoral fins gray to the membrane between 7 th and 8 th rays. First anal-fin ray beneath 5 th dorsal-fin ray. The 2 nd ray in dorsal fin longest. Lower jaw shorter than upper jaw; teeth rather large (visible with a naked eye), tricuspid teeth not found. Palatine teeth present.

Paralectotype (ex syntype?) of Exocoetus neglectus Bleeker ( RMNH 6975 , no label data). Length 187 mm SL. D 12, A 8, P I 14, Spred 30, Str 9, Sp.br 21 (5 + 16). Measurements (in % SL): cV 1 35.5, pV 38.7, c 23.4, o 8.0, io 1 8.0, H 17.5, h 7.0, Dc 27.8, lP 59.8+, lV 28.6(+?), HD -, p 12.9. Fins discoloured, probably as a result of poor preservation (anal fin black anteriorly?). First anal-fin ray beneath 6 th dorsal-fin ray. Jaw teeth tricuspid (unicuspid teeth present only in posterior part of upper jaw). Palatine teeth present (arranged in 2–3 rows?).

Paralectotype (ex syntype?) of Exocoetus neglectus Bleeker ( RMNH 6975 , no label data). Length 143 mm SL. D 12, A 9, P I 14, Spred 28, Str 8, Sp.br 21 (5 + 16). Measurements (in % SL): cV 1 37.4, pV 39.7, c 23.9, o 8.5, io 1 8.5, H 18.3, h 6.4, Dc 25.8, lP -, lV 26.9, HD -, p 14.6. A discoloured specimen with fins cut off. Palatine teeth present. We identify this specimen as C. neglectus , but with some reservation, as it may also be C. oligolepis apus .

Description. Meristic and morphometric characters are given in Tables 1–6 , 9–10. D 10 –13 (usually 11–12), A 7–9 (usually 8), P I 13–15 (usually I 14), Spred 23–29 (usually 26–28), Str 7½–9½ (usually 8½), Sp.br 20–25 (5–8 + 14–19), usually 22–24 (6–7 + 16–17), Vert 39–42 (25–28 + 13–15), usually 41–42 (26–27+14–15). Snout short ( Fig. 23 ), lower jaw shorter than upper jaw or of equal size (some fish with lower jaw slightly longer). Upper jaw not pointed anteriorly. Jaw teeth small to medium-sized (not visible or barely visible to the naked eye), mainly tricuspid and (or) with additional cusps (some fish also with conical teeth). Juveniles under 90 mm with mainly conical teeth. Teeth arranged in 2–5 rows, in juveniles in 1–3 rows. Palatine teeth always present, usually numerous (sparse in juveniles <40 mm SL). For further description see below in the subspecies accounts.

Intraspecific variation. We discern two subspecies within C. neglectus , which differ mainly in morphology of dorsal fin in juveniles, position of pelvic-fin origin and pigmentation of juveniles.

Common names. The name “neglected flying fish” (Russian: “ПриЗрачный стрижехвост”) is proposed here.

Comparative remarks. Cypselurus neglectus differs most notably from C. poecilopterus , C. simus and C. callopterus in the absence of dark spots on pectoral fins (however, see below for various patterns among juveniles of C. poecilopterus ). From C. bosha and C. olpar , it differs in longer pelvic and shorter pectoral fins (index lP/lV in juveniles 1.29–1.76 vs. usually> 1.80, in large fish 1.74–2.21 vs.> 2.40), fewer vertebrae (Vert.c 13–15 vs. 16–18) and rays in dorsal (usually 11–12 vs. usually 13–14) and anal (7–9 vs. usually 10–11) fins, in pectoral fin pigmentation (in adults dark to 7 th –9 th vs. 10 th –13 th ray) and morphology of jaw teeth (in adults mainly tricuspid vs. mainly conical). From C. starksi it differs in fewer dorsal (usually 11–12 vs. usually 13–14) and pectoral (usually 15 vs. usually 16) fin rays, vertebrae (39–42 vs. 42–44, usually 43–44), transverse (usually ≤ 8½ vs. usually ≥ 9) and predorsal (23–29 vs. 26–33) scales, in more posterior pelvic-fin origin (pV usually <40 vs. usually> 40% SL, see Fig. 24b ), shorter pelvic fins (in fish> 130 mm SL pelvic-fin length usually <32 vs. usually> 32% SL) and dorsal-fin base (usually <19 vs. usually> 19% SL), smaller Dc (usually <27 vs. usually> 27% SL) and larger aD (usually> 71 vs. <71% SL).

Cypselurus neglectus differs from C. oligolepis , C. izumii and C. clariangulatus in more posterior pelvic-fin origin (index cV/pV usually> 0.80 vs. usually <0.80), shorter head (except C. izumii ) and more elongate body ( Fig. 24 ), slightly more predorsal scales (usually 26–28 vs. usually 24–26) and, from C. oligolepis (except C. o. apus ) and C. clariangulatus , in pigmentation of juveniles (pectoral and pelvic fins uniformly pigmented vs. pectoral and pelvic fins with pale band or a row of pale spots in C. oligolepis and pelvic fins with a pale inner corner in C. clariangulatus ). Also, C. neglectus differs from C. izumii in shorter pelvic fins (usually <33 vs. usually> 33% SL), smaller predorsal distance (usually <71 vs. usually> 71% SL) and fewer vertebrae (39–42, usually ≤ 41 vs. 42–44) and from C. clariangulatus in longer pectoral fins of adults (usually> 64 vs. usually <64% SL), smaller interorbital distance in juveniles (usually <12.5 vs. usually> 12.5% SL) and some other characters (see Tables 5–6).

Cypselurus neglectus is most similar to C. o. apus and their differentiation is challenging, especially as juveniles. However, C. neglectus has slightly more predorsal scales (23–29, usually 26–28 vs. 21–28, usually 24–26) and vertebrae (Vert. 39–42, usually 41–42 vs. 38–41, usually 40; Vert.pc 25–28, usually 27 vs. 24–26, usually 25), more posterior pelvic-fin origin (cV usually> 32.3 vs. usually <32.3% SL; index cV/pV usually> 0.80 vs. usually <0.80), shallower body and head (in juveniles 30-55 mm SL H usually <18.3 vs.> 18.3% SL and in fish> 110 mm SL H usually <19.5 vs. usually> 19.5% SL; in fish> 110 mm SL Hc usually <18.5 vs. usually> 18.5% SL), longer pelvic fins (in fish> 110 mm SL lV usually> 30 vs. usually <30% SL), smaller head (in fish> 110 mm SL c usually <25.5 vs. usually> 25.5 % SL), eyes (in fish> 110–140 mm SL o usually <9 vs. usually> 9% SL and index po/o usually <1.20 vs. usually> 1.20) and snout (in juveniles 30-50 mm SL ao usually <3.4 vs. ≥ 3.4% SL), and darker pigmentation of pelvic, anal and caudal fins in large juveniles (85–120 mm SL). It cannot be excluded that C. neglectus neglectus and C. o. apus may interbreed, binding C. neglectus and C. oligolepis into a single complex species (see above), thus further research is needed.

Distribution. This species occurs in neritic waters from western coast of India to Melanesia and from Tonkin Bay to southern Indonesia. It has sympatric distribution with C. oligolepis . See the below subspecies accounts for more details.

Figures

FIGURE 23. Cypselurus neglectus neglectus: (A)—160.5 mm SL, IORAS 04007, Tonkin Bay; (B)—83 mm SL, IORAS 04013, Tonkin Bay. After Parin and Besednov 1965.

FIGURE 24. Size variation of morphometric characters (in % SL) in Cypselurus oligolepis (□), C. clariangulatus (♦), C. izumii (x), C. neglectus (○), C. starksi (◊) and C. nossibe (▲): (A)—cephalo-ventral (head to pelvic-fin origin) distance (cV); (B)—postventral distance (pV), (C)—cephalo-ventral distance divided by postventral distance (index cV/pV); (D)—head length (c); (E)—greatest body depth (H); (F)—greatest head depth (Hc).