Cypselurus neglectus subsp. shcherbachevi Shakhovskoy & Parin 2022, subsp. nov.

Cypselurus neglectus shcherbachevi subsp. nov.

Synonymy and bibliography.

Cypselurus neglectus. Kovalevskaya 1980: 224 (listed; tropical waters of Indian Ocean).

Cypselurus oligolepis (non Bleeker). Fedoryako 1982: 111 (juveniles listed as associated with drifting objects; Indian Ocean; in part: only specimens from Station 4936). Parin 1984: EXOC Cyp 11 (description, figures, distribution; Western Indian Ocean; in part). Fedoryako 1989a: 234 (listed as associated with drifting objects; in part). Lakshminaraina 1993: 26–27, fig. 4a (short description, distribution; “Indian seas”; in part). Parin 1999: 2165, 2174 (distribution, diagnostic characters; western Pacific; in part). Barman & Mishra 2006: 3, 11, 13–14 (description; India; in part).

Material examined. Sixty-eight specimens 35–186 mm SL.

Bay of Bengal and Arabian Sea. Full morphological study. IORAS 04031 (paratype) (1, 138 mm SL), 6°33’N 82°18’E, 18.04.1977. IORAS 04032 (4, 35– 78 mm SL), 5°00’N 90°52’E, 11- 12.02.1961. IORAS 04033 (1, 105 mm SL), 9°36’N 90°53’E, 13- 14.02.1961. IORAS 04034 (16, 70– 122.5 mm SL), 13°37’N 86°53’E, 2- 3.02.1961. ZMMU 24453 (holotype) (1, 123 mm SL), 14°11’N 82°53’E, 28.01.1961. IORAS 04036 (paratype) (1, 115 mm SL), 14°11’N 82°53’E, 28.01.1961. IORAS 04037 (1, 74 mm SL), 13°37’N 86°53’E, 2- 3.02.1961.

Partial morphological study. IORAS 04038 (1, ~ 53 mm SL), 5°18’N 86°55’E, 5- 6.02.1961. IORAS 04039 (1, 81 mm SL), 9°22’N 92°43’E, 5.03.1961. CMFRI uncat* (6, 160– 186 mm SL), Cochin, India, 31.10.1972.

Andaman Sea. Full morphological study. IORAS 04040 (1, 80 mm SL), 5°27’N 97°34’E, 1- 2.11.1962. IORAS 04041 (3, 78– 112 mm SL), 6°04’N 98°29’E, 22.01.1979. IORAS 04042 (3, 90– 127 mm SL), 6°04’N 98°29’E, 22.01.1979. IORAS uncat.* (1, 60 mm SL), 5°37’N 94°46’E, 9.03.1961. SOSC Acc. No. 4 (3, 74– 80 mm SL), 7°27’N 94°21’E, 19.03.1963. ZMUC uncat. (6, 49.5–135 mm SL), 6°06’N 96°00’E, 10.05.1951.

Partial morphological study. IORAS 04043 (1, 79 mm SL), Andaman Sea, 19.03.1964. IORAS 04044 (2, 44– 46 mm SL), 2°48’N 101°06’E, 20.10.1964. ISH 10-1993 * (1, 131 mm SL), Ranong, Thailand, 10.12.1993. ISH 12-1993 * (1, 152 mm SL), Ranong, Thailand, 10.12.1993. URM P 9269 * (1, 137 mm SL), Phuket (Andaman Sea) USNM 193249 (1, 36 mm SL), 10°N 95°E, November–December 1961. USNM 193255 (1, 42.5 mm SL), 13°N 95°E, November–December 1961. USNM 198520 (338945) (1, 70 mm SL), 10°14’N 94°36’E, 15– 31.03.1964. USNM 321572 (removed from 193274) # (1, 75.5 mm SL), Strait of Malacca, November–December 1961. USNM 321575 (removed from 193241)* (1, 84.5 mm SL), 10°N 93°E, November–December 1961.

Indonesia. Full morphological study. IORAS 04045 (1, 109 mm SL), 7°49’S 120°09’E, 15.03.1975. IORAS 04046 (1, 47 mm SL), ~ 2°25’S 107°36’E, 25.03.1961. IORAS 04047 (1, 139 mm SL), Madura Strait, Situbondo abeam, 14.11.1962. ZMUC uncat. (3, 64– 71 mm SL), 5°18’S 131°18’E, 23.09.1951.

Partial morphological study. IORAS uncat.* (1, 85 mm SL), 7°17’S 105°07’E, 16.07.1962.

Holotype (Fig. 29). ZMMU 24453, R / V Vityaz Cr. 33, Sta. 4927, Sample 589, 14°11’N 82°53’E, 28 January 1961, depth 3200 m, captured at surface with dip-net and night-light, time of capture: 19.10–04.25. Length 123 mm SL (immature female). D 11, A 8, P I 14, Spred 28, Str 9, Sp.br 22 (6 + 16), Vert 41 (27 + 14). Measurements (in % SL): aA 79.2, aD 72.2, aV 57.8, cV 35.1, pV 39.0, c 23.0, po 10.9, o 7.3, ao 3.9, io 9.8, Hc 17.0, H 17.9, h 7.9, Dc 26.0, lP 69.1, lP 1 40.0, lV 38.2, lD 18.8, lA 9.7, HD -, HA -, p 15.3. Body and head brown, ventral side slightly paler than dorsal one (Fig. 29a). Lower surface of head pale, covered with numerous dark dots; “lips” and lower and posterior margins of gill covers entirely pale. Pectoral fins dark brown to 8 th ray with pale tip (Fig. 29b). Tip of pectoral fin nearly reaching middle of caudal peduncle. Pelvic fins dark brown between 1 st –5 th rays, paler near fin base (Fig. 29c). Tip of pelvic fin nearly reaching origin of caudal-fin lower lobe. Dorsal fin gray with dusky upper margin, tip of its last ray nearly reaching origin of caudal-fin upper lobe, penultimate ray broken. Anal fin pale with dark dots between 4 th –7 th rays distally. First anal-fin ray beneath 5 th –6 th dorsal-fin rays. Caudal fin pale brown (brown at fin base) with three brown bands on lower lobe and two bands on upper lobe (both lobes broken at tip). Lower jaw slightly longer than upper jaw. Jaw teeth small, mainly tricuspid and with additional cusps, some teeth conical. Teeth arranged in two rows (in three rows near lower jaw symphysis). Palatine teeth present.

Paratypes. IORAS 04036, 115 mm SL, 14°11’N 82°53’E, 28 January 1961. IORAS 04031, 138 mm SL, 6°33’N 82°18’E, 18 April 1977. USNM 198520 (USNM 338945), 70 mm SL, 10°14’N 94°36’E, 15–31 March 1964.

Description. Meristic and morphometric characters are given in Tables 1–5 and 9–10. D 11–12, A 7–9 (usually 8), P I 13–15 (usually I 14), Spred 25–29 (usually 26–28), Str 7½–9 (usually 8½), Sp.br 20–25 (5–8 + 14–18), usually 22–24 (6–7 + 16–17), Vert 39–42 (26–28 + 13–15), usually 41–42 (26–27 + 14–15). Snout short (Fig. 30), lower jaw shorter than upper or of equal size (some fish with lower jaw slightly longer). Upper jaw not pointed anteriorly. Jaw teeth small to medium (not visible or barely visible with naked eyes), mainly tricuspid and (or) with additional cusps (some fishes also with conical teeth). Juveniles <90 mm with mainly conical teeth. Teeth arranged in 2–4 rows, in juveniles in 1–3 rows. Palatine teeth always present, usually numerous (sparse in juveniles <40 mm SL).

Body elongate (Fig. 30), greatest body depth not changing with growth, 5.05–6.0 in SL. Body width 1.0–1.3 and caudal peduncle depth 2.0– 2.7 in greatest body depth. Greatest head depth and head length not changing with growth, 5.35–6.1 and 3.75–4.5 in SL, respectively. Head length 0.97–1.23 in dorso-caudal distance. Eyes large, eye diameter decreasing strongly with growth (Fig. 26a): in juveniles 35–90 mm SL eye 8.8–12.35 in SL, 2.1–2.9 in head length, 1.05–1.4 in interorbital width and 0.9–1.4 in postorbital distance; in fish 105–155 mm SL, 10.75–13.7 in SL, 2.75–3.15 in с, 1.05–1.35 times in io and 1.2–1.5 in po.

Pectoral fins relatively long, their length increasing strongly as fish grows: in juveniles 35–90 mm SL pectoral fin 1.45–1.8 in SL; in fish 105–155 mm SL, 1.4–1.6 in SL. Tip of pectoral fin reaching from end of dorsal-fin base to middle of caudal peduncle; in juveniles <90 mm SL from middle to end of dorsal-fin base (rarely beyond). First pectoral-fin ray unbranched, its length increasing with growth: in juveniles 35–90 mm SL it fits 2.6–3.15 in SL and 1.66–1.95 in lP; in fish 105–155 mm SL, 2.4–2.75 in SL and 1.60–1.83 in lP. Pelvic-fin base slightly closer to posterior edge of head than to origin of caudal-fin lower lobe (cV / pV = 0.80–0.96); pelvic fins not appreciably changing position as fish grows (Fig. 26e). Pelvic fin length decreasing strongly from juveniles to adults (Fig. 26c): in juveniles 35–90 mm SL pelvic fin 2.15–2.6 in SL and 1.29–1.73 in lP; in fish 105–155 mm SL, 2.6–3.25 in SL and 1.74–2.14 in lP. Tip of pelvic fin of small juveniles 35–105 mm SL protruding beyond origin of caudal-fin lower lobe; in fish 105–125 mm SL reaching from middle of caudal peduncle to origin of caudal-fin lower lobe (sometimes slightly beyond); in fish> 90 mm SL reaching to end of anal-fin base or slightly beyond.

Anal-fin origin far behind dorsal-fin origin, 1st anal-fin ray beneath 4 th –7 th dorsal-fin ray (usually beneath 5 th –6 th). Dorsal fin with 2–5 rays more than anal fin. Dorsal and anal fin height decreasing strongly with growth (Fig. 26d): in juveniles 45–90 mm SL, HD 5.85–8.6 and HA 9.8–12.35 in SL; in fish 105–135 mm SL, HD 8.55–10.1 and HA 11.35–14.7 in SL. Longest ray in dorsal and anal fins—2 nd or 3 rd. In juveniles 35–90 mm SL the longest rays in dorsal fin usually 6 th –9 th (though a few juveniles with 2 nd or 3 rd ray of equal length to 6 th –9 th, or even longest). Tip of last dorsal-fin ray in juveniles 35–105 mm SL reaching (nearly reaching) origin of caudal-fin upper lobe or, more often, slightly beyond. In fish ≥ 110 mm SL, it protrudes far beyond middle of caudal peduncle but not reaching origin of caudal-fin upper lobe. In juveniles 35–85 (115) mm SL, middle and posterior dorsal-fin rays elongated, tip of penultimate ray (rays) protruding beyond tip of last ray. In fish> 85 mm SL dorsal-fin rays of usual length.

Pigmentation. Body of juveniles 35–85 mm SL (Fig. 30a–c) brown or dark brown, the ventral side darker than dorsal one. Body bands usually absent, but some juveniles with 3 or 4 distinct dark bands posteriorly: between bases of pectoral and pelvic fins, above pelvic-fin base, under dorsal-fin origin and under posterior part of dorsal-fin base (Fig. 30b). In fish> 100 mm SL ventral side of the body paler than dorsal one, dark body bands absent (Fig. 30d–f).

Lower surface of head in juveniles 35–90 mm SL brown to dark brown, usually with paler chin, “lips” and distal parts of branchiostegal rays. In fish> 100 mm SL lower surface of head mainly pale (in fish 100–125 mm SL usually with rather dense aggregations of melanophores). Adults with a few small dark specks (Fig. 30f) on gill covers and under eyes.

Pectoral fins in juveniles 35–90 mm SL (Fig. 31a–b) brown or dark brown with pale lower edging, and, usually, with pale tip and two small to fairly large pale spots near tips of 2 nd and 3 rd rays; always without a pale transverse band or a row of pale spots. In fish> 90 mm SL (Fig. 31c–d) pectoral fins pale brown to dark brown to 8 th –9 th (rarely to 7 th) ray with pale tip and, sometimes, with very narrow posterior pale edging. Distally pigmentation usually extending one ray lower than proximally or a small flat “mirror” present (Fig. 31c–d).

Pelvic fins in juveniles 35–90 mm SL (Fig. 32a) entirely brown or dark brown (sometimes slightly paler at tips of 1 st –2 nd rays and (or) along 6 th ray). In fish 90–120 mm SL, pigmentation begins to disappear starting with proximal part of the fin, along 1 st ray and between 5 th –6 th rays (Fig. 32b). In fish> 120 mm SL pelvic fins pale (Fig. 32c), sometimes with few dots or a dark streak between some rays. However, in fish from the Bay of Bengal, pelvic fins become pale at larger sizes: a specimen 123 mm SL (the holotype of C. n. shcherbachevi) with fairly large dark spot and a specimen 138 mm SL (IORAS 04031) with entire fin pale (see Figs. 29c and 32c).

Dorsal fin in juveniles 35–90 mm SL covered with brown melanophores, denser near bases of anterior rays and along upper margin of fin; posterior edge usually paler. In fish> 90 mm SL dorsal fin gray to pale brownish, in fish 90–125 mm SL with darker upper margin.

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Anal fin in juveniles 35–90 mm SL brown or dark brown (usually paler near fin base) with pale area between 1 st –3 rd (4 th) rays distally. Some fish with almost entirely brown anal fin. In fish 90–105 mm SL pigmentation starts to disappear and in fish> 105 mm SL anal fin pale. However, fish from the Bay of Bengal retain pigmentation on the posterior part of anal fin at least up to 125 mm SL.

Caudal fin in fish 35–50 mm SL (Fig. 30a–b) pale, with pale brown to brown base and dots along lower lobe rays (except uppermost rays). In fish 50–110 mm SL (Fig. 30c–d), caudal fin usually with (1)2–3 dark bands on lower lobe and, by about 70–80 mm SL, 1–2 dark bands also on upper lobe. In fish 110–125 mm SL, the dark bands coalesce, making the fin brown with 2-3 paler bands on lower lobe and 1–2 on upper lobe (Figs. 29a, 30e). In fish> 125 mm SL, caudal fin pale brown to brown, usually with darker fin-base and distal part of upper lobe (Fig. 30f).

Coloration in life. The second author observed at time of capture that the main background pigmentation of pectoral fins in juvenile C. n. shcherbachevi (IORAS 04032, 4 specimens of 35–78 mm SL) is red with dark dots (giving an overall impression of brown); dorsal fin with red bands and black dots.

Maximum size. The maximum length of C. n. shcherbachevi in our material was 186 mm SL (CMFRI uncat., Cochin). The largest female and male were 127 and 138 mm SL, respectively (only five specimens 112–138 mm SL were dissected for sex identification).

Intrasubspecies variation. Populations from different regions may be isolated to some extent. Fish from Bay of Bengal differ from fish of other regions in longer pelvic fins and shorter snout (Fig. 26b–c, f), a higher dorsal fin in juveniles (Fig. 26d), larger index po/o (> 1.30 vs. usually <1.30) and delayed disappearance of dark pigmentation from pelvic, anal and caudal fins (see above). Fish from Indonesia have fewer predorsal scales (Table 3), shorter postorbital (usually <10.4 vs. usually> 10.4 % SL) and postventral (≤ 38.2 vs. usually> 38.2) distances and more elongate body (lower average values of H, Hc and h, see Table 9), but the sample from that region is too small for any taxonomic conclusions. Fish from Andaman Sea have on average a larger head (usually ≥ 24 vs. usually <24% SL). The above differences are probably of no taxonomic significance.

Etymology. The subspecies named in honor of our dear colleague, the late Yurij Nikolaevitch Shcherbachev to recognize his many years studying of fishes at IORAS.

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

Comparative remarks. Cypselurus n. shcherbachevi differs most strikingly from C. n. neglectus in the dorsalfin morphology of juveniles: in C. n. shcherbachevi middle and posterior dorsal-fin rays elongated (longest rays usually 6 th –9 th vs. 2 nd –3 rd in C. n. neglectus), tip of penultimate ray protrudes farther back than tip of the last ray (while in C. n. neglectus this is usually not the case). Also, C. n. shcherbachevi differs in more posterior pelvic-fin origin (index cV/pV usually> 0.85 vs. usually <0.85, see Fig. 26e), and in delayed disappearance of dark pigmentation from the underside of head, anal fin, and caudal fin (see above). It is possible that these two subspecies merit full species rank, further research is needed.

Biology. No mature fish were found (due to low number and small size of fish dissected for sex identification). Small juveniles of 35–50 mm SL were captured in the Bay of Bengal in February (IORAS 04032), in the Andaman Sea in May (ZMUC uncat.) in the Malacca Strait in October (IORAS 04044) and near Banca and Belitung Islands in March (IORAS 04046). These data suggest only that spawning period of C. n. shcherbachevi is protracted.

Distribution. Cypselurus n. shcherbachevi is distributed (Fig. 28) from Cochin (CMFRI uncat.) through the Bay of Bengal, Andaman Sea, Strait of Malacca and south Indonesian islands eastwards to the Banda Sea (ZMUC uncat., 5°18’S 131°18’E). The northernmost occurrence at 14°11’N 82°53’E (ZMMU 24453, IORAS 04036) and the southernmost at 7°49S 120°09’E (IORAS 04045). The distribution ranges of C. n. shcherbachevi and C. n. neglectus overlap slightly in waters of the southern Indonesian islands. The boundary between ranges of the subspecies coarsely corresponds to Indo-Pacific Barrier (Bowen et al. 2016: fig. 1a).