Cypselurus hiraii Abe, 1953

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 : 6-33

Cypselurus hiraii Abe, 1953

Synonymy and bibliography.

Cypsilurus hirundo (non Steindachner). Jordan & Starks 1903: 542–543 (description of juveniles; waters of Japan).

Cypselurus agoo (non Temminck & Schlegel). Jordan & Hubbs 1925: 204 (short description of juveniles; Japan).

Cypselurus opisthopus hiraii Abe, 1953: 962–968 , pl. 191, figs.523–524 (original description; Japan). Imai 1955: 99–101, 103– 104, fig. 5 (comparison with C. naresii ). Matsubara 1955: 400 (in key). Tomiyama et al. 1958: 244, fig. (short description; Japan). Imai 1958: 40–41, pl. 35 fig. 4, pl. 38 (early life history stages; Japan). Imai 1959: 65–72, pls. 1d, 2, 29, 30, 31a–b, 32, 33 (description, distribution, early life history stages; Japan; in part). Tsukahara 1959: 177–180, figs. 27–33 (description, early life history stages; Japan, Amakusa Is.). Abe 1960: 149 (listed; Japan, Kuroshio waters). Honma 1963: 17 (listed; Japan, Sado I.). Shojima & Ueki 1964: 253 (listed; Tsuyazaki, Japan). Shiokawa 1967: 1–12, figs. 1–3 (biology; Japan). Kojima 1969a: 284–288 (spawning behaviour; Sea of Japan: Hamada, Shimane Pref.). Kojima 1969b: 1055–1059 (spawning behaviour; Japan, Oki Is.). Nishimura 1969: 79 (temperature optimum; Sea of Japan). Kojima 1971: 284–288 (distribution of eggs; Japan, Oki I.). Masuda et al. 1975: 180 (short description; Japan). Inoue et al. 1986: 55–60 (diurnal migrations; Goto Is., Japan).

Cypselurus hiraii . Parin 1958: 121 (distribution). Parin 1960a: 223, 248–251, 279, 281 (description; Japan). Parin 1960b: 156– 157, 159 (distribution; north-western Pacific). Parin 1961b: 107, 117, 118, 129, 137, 140, 165 (morphology, systematics). Parin 1962: 224–229 (distribution; Sea of Japan and adjacent waters). Lindberg & Legeza 1965: 222, 228–229, fig. 215 (short description, distribution; Japan and Yellow seas). Nishimura 1965: 66 (listed; Sea of Japan). Parin 1967: 44, 46–47, 50–52, 54 (distribution, biology). Ueno 1971: 77 (listed; Hokkaido and adjacent waters). Kovalevskaya 1980: 224 (listed). Kovalevskaya 1982: 117–118, figs. 5, 8 (early life history stages; Japan). Kovalevskaya 1983c: 1–2 (early life history stages). Chen 1987: 19, 20, 23, 26, 55–57, 152, figs. 3-33H, 4-10, 6-10, 6-20, Tabs. 2-1, 3-1, 4-10 (description, distribution, early life history stages; north-western Pacific). Chen 1988: 280–281, 1028 (early life history stages; figures; distribution; Japan). Nagasawa & Torisawa 1991: 365 (listed; Hokkaido). Abe et al. 1993: 67–80, figs. 1–9 (reproductive biology; Sea of Japan, Fukawa Bay). Kawano et al. 1995a: 123–125 (fishery; Japan, Yamaguchi Pref.). Kawano et al. 1995b: 257–263, figs. 1–5 (reproductive biology; Japan, Yamaguchi Pref.). Okabe 1996: 81 (listed; Boso Peninsula, Japan). Burgess et al. 2000: 99, pl. 55A (keeping in aquariums). Kawano 2005: 75–77, figs. 1–2 (capture by set net; Japan, Yamaguchi Pref.). Nagase et al. 2005: 914–922, figs. 1–3 (complete mitogenome; Japan). Senou et al. 2006: 431 (listed; Sagami Sea). Ichimaru 2007: 7–110, figs. 2-13—5-4-4 (biology, fisheries; Japan). Nishida et al. 2008: 287, 290 (listed as associated with drifting seaweeds; Northern Kyushu, Japan). Nagase et al. 2009: 812 (listed; Tanegashima, Japan). Kharin & Saveliev 2011: 572, 576 [551, 554–555]. (in key; Russia).? Chang et al. 2012: 543, 547 (Kee-Lung, Taiwan). Parin et al. 2014: 194 (listed; Russian waters). Saveliev et al. 2014: 411–412 [405–406] (description and photographs of a juvenile; Sea of Japan: Russia, Serebrynka Bay). Saveliev et al. 2015: 24–30 [22–28], figs. 1a, 2a, 3a–b (description of a juvenile; SE of Southern Kuril Is., Russia).? Lee 2016: 901, fig. 1 (molecular phylogeny). Gordeeva & Shakhovskoy 2017: 215–216, fig. 1 [289, 293, fig.1] (DNA-barcoding). Iwatsuki et al. 2017: 34 (listed; Hyuga Nada, south-western Japan). Tanoue et al. 2017: 265 (listed; Futaoi-jima I., Japan). Ueda et al. 2017: 2 (karyotype; Oshima, Japan). Cui et al. 2018: 4, 11, figs. 7–8 (phylogenetic position based on whole mitogenome). Nagasawa & Isozaki 2019: 195–197, 199, fig. 1a,b (host of Nerocila trichiura (Miers) ; 34°13’33”N 136°29’00”E). Hata 2020: 157–158 (short description, photos, fishery; Osumi, Japan). Sonoyama et al. 2020: 40 ( Japan, Yamaguchi Pref.).

Cypselurus poecilopterus (non Valenciennes).? Chyung 1977: plate 169 (7, 8) ( Korea; in part).

Prognichthys agoo (non Temminck & Schlegel).? Park & Kim 1987a: 308–316, pls. 1–2 (early life history stages; Korea, U-do Island).? Park & Kim 1987b: 447–456, pls. 1–7 (osteology of larvae and juveniles; Korea).

Cypselurus hirai . Sokolovsky et al. 2004: 45 (listed; NW Sea of Japan, Russia).

Probable misidentifications. Park et al. (2016: 110–114) described larvae and juveniles of C. hiraii 9.6–23.0 mm TL; however their material was a mix of Hirundichthys sp. (fish in figs. 2, 3c) and Cheilopogon sp. ( doederleinii ?) (fish in fig. 3d–e).

Material examined. One hundred and eighty-six specimens 15–221 mm SL.

Sea of Japan. Full morphological study. IORAS 04117 (1, 79 mm SL), 39°22’N 133°55’E, 23.08.1967 . IORAS 04122 (1, 92 mm SL), 39°31’N 135°21’E, 25.08.1967 . IORAS 04123 (1, 121 mm SL), 37°37’N 134°25’E, 11.09.1967 . IORAS 04129 (5, 79–94.5 mm), 37°32’N 133°24’E, 16.08.1967 . IORAS 04133 (9, 46–71 mm SL), 41°35–58’N 138°28’E, 3.08.1967 .

Partial morphological study. FRSKU 16670 * (1, 188 mm SL), Miyazu, Kyoto Pref., 11.07.1951 . FRSKU 16671 * (1, 190 mm SL), same data . FRSKU 16672 * (1, 195 mm SL), same data . FRSKU 21622 * (1, 214 mm SL), same place, 1.03.1952 . FRSKU 21624 * (1, 214 mm SL), same data . FRSKU 21625 * (1, 201 mm SL), same data . FRSKU 21626 * (1, 216 mm SL), same data . FRSKU 21627 * (1, 198 mm SL), same data . FRSKU 21630 * (1, 202 mm SL), same data . FRSKU 21637 * (1, 219 mm SL), same data . FRSKU 23131 * (13, 113– 189 mm SL), Oky Is., Shimane Pref., March 1958 . FRSKU 25778 * (1, 201 mm SL), Maizuru Fish Market, May 1955 . FRSKU 28220 * (1, 145 mm SL), same place, 18.10.1958 . FRSKU 28221 * (1, 141 mm SL), same data . FRSKU 101899 * (1, 188 mm SL), Tsushima Is., Kyushu , 31.07.1973 . FRSKU 101900 * (1, 199.5 mm SL), same data . FRSKU W365 * (1, 111 mm SL), Maizuru fish Market , 24.08.1978 . FRSKU W370 * (2, 75–100 mm SL), same data . FRSKU W385 * (3, 116– 123 mm SL), same data . FRSKU W553 * (2, 131 mm SL), same data . FRSKU W603 * (2, 124.5– 125 mm SL), same place, 16.09.1976 . FRSKU W780 * (2, 123– 128 mm SL), same place, 11.10.1981 . HUMZ 3018 * (1, 198 mm SL), Oshoro , Hokkaido . HUMZ 3019 * (1, 207 mm SL), same place . HUMZ 3020 * (1, 187 mm SL), same place . HUMZ 3021 * (1, 218 mm SL), same place . NSMT P6371 * (1, 190 mm SL), 34°46’N 129°28’E, 25.08.1968 . NSMT P6372 * (1, 182 mm SL), 34°20’N 129°13’E, 13.07.1968 . NSMT P6373 * (1, 188 mm SL), 34°39’N 129°29’E, 16- 17.07.1968 . NSMT P12696 * (1, 189 mm SL), Tsuruga Bay, July–August 1969 . NSMT P12697 * (1, 192 mm SL), same data . NSMT P12698 * (1, 207 mm SL), same data . NSMT P35786 * (1, 205 mm SL), 35°38’N 134°46’E, 25.05.1990 . NSMT P35787 * (1, 95 mm SL), same place, 12.08.1991 . NSMT P35791 * (1, 88 mm SL), same place, 30.08.1991 . NSMT P35795 * (1, 207 mm SL), same place, 25.05.1990 . NSMT P44457 * (2, 113– 115 mm SL), 37°22’N 136°53’E, 9.09.1985 . Tokiharu Abe’s collection, No. 34.916 (1, 35 mm SL), Niigata Prefecture. Unknown collection, uncat* (1, 87 mm SL), Amur Bay, Vladivostok , 16.08.1967 .

Pacific Ocean. Full morphological study. IORAS 04119 (2, 120.5– 142 mm SL), 34°04’N 137°09’E, 1– 2.09.1970 . IORAS 04120 (2, 144– 166.5 mm SL), 30°57’N 142°17’E, 2.10.1955 . IORAS 04121 (1, 160 mm SL), 27°35’N 133°44E, 30.10.1955 . IORAS 04124 (2, 73 mm SL), 38°19’N 145°36’E, 30.08.1959 . IORAS 04125 (3, 68–80 mm SL), 39°50’N 144°00’E, 15–16.08.69 . IORAS 04126 (1, 69 mm SL), 40°59’N 153°30’E, 30.08.1958 . IORAS 04127 (1, 61.5 mm SL), 37°N 160°E, 14.08.1974 . IORAS 04128 (4, 49.5–64 mm SL), 41°23’N 142°19’E, 11.08.1969 . IORAS 04130 (5, 59.5–71.5), 40°07’N 144°21’E, 17.08.1969 . IORAS 04131 (5, 43–54 mm SL), same place, 16.08.1969 . IORAS 04132 (7, 47–66 mm SL), 41°31’N 142°17’E, 2.08.1959 . IORAS 04134 (8, 52–68 mm SL), 41°23’N 142°19’E, 11.08.1969 . Tokiharu Abe’s collection, No. 20.687 (1, 64 mm SL), Misaki. Tokiharu Abe’s collection, No. 20.793 (1, 89 mm SL), Misaki. Tokiharu Abe’s collection, No. 20.923 (1, 117 mm SL), Misaki. ZIN 7475 * (2, 209– 221 mm SL), Yokohama, 1884 .

Partial morphological study. IORAS 04118 (2, 83–93 mm SL), 36°25’N 147°27’E, 28– 29.08.1959 . IORAS 04128 (1, 50 mm SL), 41°23’N 142°19’E, 11.08.1969 . IORAS 04131 (1, 22 mm SL), 40°07’N 144°21’E, 16.08.1969 . AMS I.6907* (1, 198 mm SL), Hiroshima . CAS 107329 ( SU 7329 )* (paratype) (1, 200 mm SL), Honshu , Tokyo Bay . HUMZ 3022 * (1, 217 mm SL), Asamushi , Aomori Pref. HUMZ 13179 * (1, 197 mm SL), Kamiiso, Hakodate , July 1955 . HUMZ 13480 * (1, 192 mm SL), Hakodate Bay, Hokkaido, July 1956 . HUMZ 50216 * (1, 206 mm SL), Usujiri, Minamikayabe , Hokkaido, July 1975 . HUMZ 57014 * (1, 82 mm SL), same place, 26.08.1971 . HUMZ 65137 * (1, 205 mm SL), Oshironai , Hokkaido, August 1951 . HUMZ 65246 * (1, 216 mm SL), Usujiri , Hokkaido, August 1951 . HUMZ 65333 * (1, 112 mm SL), Yusangata , Aomori . HUMZ 69312 * (1, 219 mm SL), Kamiashi Fish Market , Iwate . HUMZ 70875 * (1, 80 mm SL), Usujiri, Minamikayabe , Hokkaido, 22.08.1977 . HUMZ 75750 * (1, 206 mm SL), same place, 20.07.1978 . HUMZ 76139 * (1, 187 mm SL), Ofune, Minamikayabe , Hokkaido, 23.08.1978 . HUMZ 80869 * (1, 96 mm SL), Usujiri , Hokkaido . HUMZ 88002 * (1, 212 mm SL), same place, 14.07.1980 . HUMZ 105230 * (1, 179 mm SL), same place, 18.07.1985 . HUMZ 105232 * (1, 186 mm SL), Usujiri , 18.07.1985 . HUMZ 105239 * (1, 187 mm SL), Usujiri , 19.07.1985 . HUMZ 105240 * (1, 185 mm SL), same data . HUMZ 105296 * (1, 187 mm SL), Usujiri , 16.08.1985 . HUMZ 260 (55X23)* (1, 84 mm SL), Kabasaki, Uwajima , Ehime . NSMT P35800 * (7, 59–92 mm SL), 34°17’N 136°44’E, 29– 30.08.1983 . SMF 18168 * (1, 80.5 mm SL), Honshu, Sagami-Bay, Manazuru . URM P23758 * (1, 188 mm SL), Okinawa Fish Market . URM P23759 * (1, 197 mm SL), same place . URM P25846 * (1, 191 mm SL), same place . URM P27398 * (1, 194 mm SL), same place . URM P27399 * (1, 185 mm SL), same place .

East China and Yellow seas. Full morphological study. IORAS 04115 (1, 131 mm SL), 31°51’N 129°59’E, 23.08.1971. IORAS 04114 (1, 202 mm SL), Chefoo (Yantai), China .

Partial morphological study. CAS 118752 ( SU 18752 )* (paratypes) (3, 190– 203 mm SL), Kyushu I., Nagasaki, 1900 . USNM 130403 * (1, 203), China: Ningpo, Chekiang, 1924 . USNM 150415 * (2, 15–18 mm SL), 36°23’N 121°58’E, 31.07.1906 .

Unknown locality. Full morphological study. IORAS 04113 (1, 205.5 mm SL), 20.06.1971. IORAS 04116 (2, 134– 139.5 mm SL). IORAS 04136 (1, 209 mm SL). Tokiharu Abe’s collection, No. 48.398 (1, 74.5 mm SL). Tokiharu Abe’s collection, No. 48.400 (1, 86.5 mm SL). Tokiharu Abe’s collection, No. 48.401 (1, 89 mm SL). Tokiharu Abe’s collection, No. 48.579 (1, 99 mm SL).

Partial morphological study. FRSKU 103528* (5, 194– 212.5 mm SL). HUMZ 3011* (1, 213 mm SL). FRSKU W581* (1, not measured). Tokiharu Abe’s collection, No. 48.399 (1, 76 mm SL). Tokiharu Abe’s collection, No. 48.580 (1, 65 mm SL). USNM 576361 (2, ~ 194–216 mm SL), Japan.

1 These specimens were studied based on photos and X-rays kindly provided by K.E. Bemis ( USNM).

Types. According to Fricke et al. (2023), the holotype of Cypselurus hiraii is ZUMT 47765. We did not study the holotype, but it was described in detail by Abe (1953).

Diagnosis. A large species of Cypselurus having many dorsal-fin rays, predorsal and transverse scales and vertebrae. Pelvic-fin base about midway between head posterior edge and origin of caudal-fin lower lobe. Body elongate, head and eyes small, pelvic and dorsal fins long. Jaw teeth mainly conical, palatine teeth present. Juveniles with a short and flat chin barbel and low dorsal fin; ventral side of the body paler than dorsal one. In adults, pelvic fins pale and anal fin without black dots. D 12–15, Spred 29–38, Str 8–10, Vert 45–47 (29–32 + 14–16).

Description. Meristic and morphometric characters are given in Tables 1–8 and 14. D 12 –15 (usually 13), A 7– 11 (usually 9–10), P I 12–16 (usually I 14–15), Spred 29–38 (usually 31–35), Str 8–10 (usually 9–9½), Sp.br 23–32 (6–9 + 16–24), usually 26–29 (7–8 + 19–22), Vert 45–47 (29–32 + 14–16), usually 46 (30–31 + 15–16). Snout short ( Fig. 1 ), jaws of equal size or lower jaw a little longer (occasionally upper jaw slightly longer). Upper jaw usually not pointed anteriorly. Juveniles up to 93 mm SL with short (reaching from nostril to middle of eye) and flat (usually pear-shaped or cordiform) chin barbel with a median keel ( Fig. 2 ); a few fish without barbel starting at 52 mm SL. Jaw teeth small to medium-sized (not visible or barely visible to naked eyes), conical (some specimens> 90 mm SL also have teeth with additional cusps). Teeth arranged in 1–3 rows. Palatine teeth present, usually sparse.

Body elongate. Greatest body depth increasing slightly with growth: in juveniles 40–100 mm SL body depth 5.9–7.2 in SL; in fish 120–220 mm SL, 5.15–7.1 in SL. Body width 0.95–1.55 and caudal peduncle depth 1.90–3.35 in greatest body depth. Greatest head depth and head length hardly changing with growth ( Fig. 3a ), 5.95–7.2 and 4.05–4.7 in SL, respectively. Head length 1.07–1.33 in dorso-caudal distance. Eyes relatively small, eye diameter decreasing with growth ( Fig. 3b ): in juveniles (40–100 mm SL) 10.3–14.1 in SL, 2.4–3.35 in head length, 1.0– 1.35 in interorbital width and 0.95–1.7 in postorbital distance ( Fig. 3c ); in fish 120–220 mm SL, eye diameter 13.7–16.65 in SL, 3.2–3.75 in c, 0.95–1.4 times in io and 1.4–1.8 in po.

Pectoral fins relatively long, their length slightly increasing with growth to about 140 mm SL, and then nearly constant ( Fig. 4 ): in juveniles 40–100 mm SL pectoral fin 1.45–1.75 in SL and in fish 120–220 mm SL, 1.45–1.65 in SL. Tip of pectoral fin reaching from middle to end of dorsal-fin base or slightly beyond. First pectoral-fin ray unbranched, its length slightly increasing with growth: in juveniles 40–100 mm SL it fits 2.5–3.1 in SL and 1.56– 1.88 in lP; in fish 120–210 mm SL, 2.0– 2.7 in SL and 1.31–1.77 in lP.

Pelvic-fin base slightly closer to posterior edge of head than to origin of caudal-fin lower lobe or about midway, in large fish sometimes closer to the latter (cV / pV = 0.80–1.17); pelvic fins slightly shifting posteriorly as fish grows ( Fig. 4a ). Pelvic-fin length decreasing strongly from juveniles to adults ( Fig. 3e ): in juveniles 40–100 mm SL pelvic fin 2.3–2.8 in SL and 1.42–1.74 in lP; in fish 120–220 mm SL, 2.65–3.7 in SL and 1.71–2.36 in lP. Tip of pelvic fin of juveniles 40–95 mm SL reaching (nearly reaching) origin of caudal-fin lower lobe or protruding beyond; in juveniles 95–120 mm SL reaching from middle of caudal peduncle to origin of caudal-fin lower lobe; in fish 130–160 mm SL reaching from end of anal-fin base to middle of caudal peduncle and in fish> 160 mm SL reaching from posterior one-third to end of anal-fin base (rarely slightly further).

Anal-fin origin far posterior to dorsal-fin origin (1st anal-fin ray under 5 th –8 th dorsal-fin ray, usually under 6th–7th). Dorsal fin with 2–6 rays more than anal fin. Height of dorsal and, particularly, anal fins decreasing with growth. In juveniles 40–100 mm SL, HD 7.6–9.2 and HA 9.25–12.8 in SL; in fish 120–220 mm SL, HD 7.85–10.6 and HA 11.9–16.1 in SL. Longest ray of dorsal and anal fins—2 nd or 3 rd (occasionally 4 th or 5 th dorsal-fin ray the longest). Tip of last dorsal-fin ray reaching from middle of caudal peduncle to origin of caudal-fin upper lobe (occasionally slightly further). Middle and posterior rays of dorsal fin not elongate, penultimate rays usually not extending beyond tip of last ray.

Pigmentation. Body of juveniles, like in adults, with typical flying fish “pelagic” pigmentation (darker dorsally, paler ventrally, Fig. 5 ), though occasional juveniles with ventral side of body darker than dorsal one. Body bands absent (except the smallest juvenile 22 mm SL having a dark band above middle of anal fin, Fig. 5a ).

Some juveniles 45–80 mm, like juveniles of C. naresii (see below), with a wide dark brown longitudinal stripe through the eye. The lower surface of the head of juveniles 22–80 mm SL more or less densely covered with brown melanophores with pale lower “lip”, gill cover margin and branchiostegal rays distally. In some lighter specimens the head’s lower surface pale with chin only pigmented. With growth, pigment on lower surface of head begins to disappear (persisting longest anterior to articular bone), and in fish> 100 mm SL, lower surface of head pale.Adults with a few small specks on gill cover and (or) under eye or without specks. Chin barbel ( Fig. 2 ) of juveniles brown or dark brown with paler base, opposite (ventral in stretched anteriorly barbel) side entirely brown in some fish.

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Str D-A

Species/subspecies, region 6 6½ 7 7½ 8 8½ 9 9½ 10 10½ 1 2 3 4 5 6 C. hiraii (Sea of Japan) - - - - 1 7 10 11 1 - - 2 16 17 7 - C. hiraii (Pacific Ocean) - - - - 4 9 11 24 1 - - 3 13 39 10 1 C. hiraii (Yellow and East China seas) - - - - 4 - 2 - - - - - 1 4 1 - Cypselurus hiraii (species total) - - - - 9 17 31 40 2 - - 6 36 68 19 1 C. o. opisthopus (Indian Ocean) - - 1 5 1 2 - - - - - 2 5 3 - - C. o. opisthopus (Philippines) - - 4 6 6 1 - - - - - 7 14 4 - - C. o. opisthopus (New Guinea) - - 7 41 13 24 - - - - - 16 54 18 - - C. o. opisthopus (all regions) - - 12 52 21 27 - - - - - 25 74 25 - - C. o. crockeri - 2 1 6 - 3 - - - - - 6 5 1 - - Cypselurus opisthopus (species total) - 2 13 58 21 30 - - - - - 31 79 26 - - C. n. naresii - - - 4 1 - - - - - - 2 3 1 - - C. n. ordinarius (W Pacific Ocean) - - 4 42 4 4 - - - - 1 17 41 13 1 - C. n. ordinarius (E Indian Ocean) - - 2 12 3 1 - - - - 1 7 13 3 - - C. n. ordinarius (Bay of Bengal and Andaman Sea) - 1 4 28 7 19 1 - - - 1 3 33 27 1 - C. n. ordinarius (all regions) - 1 10 82 14 24 1 - - - 3 27 87 43 2 - C. n. septentrionalis a - - - - - - - 1 - - - 1 2 6 4 - C. n. albitaenia (Arabian Sea) - - - 4 1 5 1 - - - - 1 9 4 1 - C. n. albitaenia (Indian Ocean) - - - 16 3 13 1 3 - - - 2 20 17 1 - C. n. albitaenia (all regions) - - - 20 4 18 2 3 - - - 3 29 21 2 - C. n. socotranus - - - - - 5 1 3 - 1 1 1 11 3 1 - Cypselurus naresii (species total) - 1 10 106 19 47 4 7 - 1 4 34 132 74 9 - C. persimilis (Indian Ocean) - - 2 5 1 - - - - - - 3 4 1 1 - C. persimilis (Philippines) 1 - 5 9 3 3 - - - - 1 13 12 3 - - C. persimilis (New Guinea) - 2 11 30 2 3 - - - - - 11 33 4 - - Cypselurus persimilis (species total) 1 2 18 44 6 6 - - - - 1 27 49 8 1 -

Str D-A

Species/subspecies, region 6 6½ 7 7½ 8 8½ 9 9½ 10 10½ 1 2 3 4 5 6 C. a. folletti (E Pacific Ocean) - - 1 7 12 12 - 1 - - - 1 17 33 4 - C. a. angusticeps (Polynesia) - - 1 18 4 1 - - - - - - 3 14 10 1 C. a. angusticeps (Hawaii) - - - 1 5 - - - - - - - 1 6 3 - C. a. angusticeps (W Pacific Ocean) - - 7 65 4 - - - - - - 1 5 46 31 3 C. a. angusticeps (E Indian Ocean) - - 1 16 14 5 - - - - - 1 1 22 12 4 C. a. angusticeps (W Indian Ocean) b - - - 5 5 1 - - - - - - 2 9 5 - C. a. angusticeps (all regions) - - 9 105 32 7 - - - - - 2 12 97 61 8 Cypselurus angusticeps (species total) - - 10 112 44 19 - 1 - - - 3 29 130 65 8 C. comatus (N-W Atlantic)c 1 - 25 26 6 2 - - - - - 3 31 39 2 - C. comatus (S-W Atlantic) c - - 2 7 - 3 - - - - - - 7 7 - - Cypselurus comatus (species total) c 1 - 27 40 6 6 - - - - - 3 42 50 2 -

TABLE 4. Total gill rakers counts for Cypselurus hiraii , C. opisthopus , C. naresii , C. persimilis sp. n., C. angusticeps and C. comatus .

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43.0–100.0 C. hiraii 173.8 95 111.0–221.0 69.4 45 19.0–100.0 C. opisthopus 157.8 112 102.0–186.0 61.1 77 29.0–96.0 a 156.3 C. naresii 127 101.0–200.0 220.3 60 201.0–258.0 C. 156.3 91 persimilis 129.0–180.5 69.1 30 36.5–95.0 C. 172.4 b

128 angusticeps

100.5–200.0 212.0 70 200.5–235.0 58.4 19 27.5–99.0 C. comatus 176.9 8.4–10.3 5.7

8.6 (n=12) (n=2)

7.3–9.2 5.7–5.8

10.4 (n=31) -

9.1–11.4 7.0 9.0 (n=80) (n=1) 8.0–10.2

9.0 (n=44) -

7.6–10.4 6.7

9.0 (n=86) (n=4)

8.0–9.9 5.2–7.6

6.9 8.6 (n=35) (n=1) 7.8–9.6 6.1 9.2 (n=66) (n=1) 7.8–10.3

9.1 (n=20) -

7.8–9.8 7.4

9.0 (n=82) (n=3)

8.0–10.0 7.0–7.7

7.7 8.6 (n=40) (n=1) 7.8–9.5

10.0 (n=3) -

9.8–10.1 7.2

9.2 (n=14) TABLE 7. (Continued)

Measurements, % SL Species SL, mm io 1 Hc H h Dc lP lP 1 lV lD lA HD HA p lcir 14.9 15.0 6.9 27.5 62.0 36.5 40.1 19.3 11.0 12.1 9.2 14.4 7.2 69.9 - (n=58) (n=58) (n=58) (n=60) (n=60) (n=60) (n=60) (n=60) (n=60) (n=47) (n=52) (n=57) (n=40) 43.0–100.0 13.9–16.2 13.9–16.9 6.1–7.8 25.3–29.5 57.4–69.2 32.1–40.0 35.9–43.6 16.7–21.7 9.0–13.0 10.9–13.1 7.8–10.8 13.2–15.9 4.7–10.8 C. hiraii 6.7 15.9 16.9 6.4 26.9 65.1 40.5 30.9 18.7 9.7 10.8 7.3 13.8 173.8 (n=15) (n=13) (n=26) (n=27) (n=38) (n=27) (n=23) (n=26) (n=23) (n=24) (n=16) (n=18) (n=26) - 111.0–221.0 6.3–7.5 15.2–16.8 14.1–19.4 5.5–7.6 24.8–29.6 60.8–68.7 36.9–50.6 27.0–37.5 16.7–20.3 8.4–11.3 9.4–12.7 6.2–8.4 12.3–15.5 15.9 16.5 7.5 25.3 52.6 29.8 36.7 17.7 9.9 17.0 9.1 15.1 8.5 69.4 9.8 (n=1) (n=31) (n=32) (n=32) (n=34) (n=36) (n=31) (n=36) (n=31) (n=31) (n=31) (n=28) (n=31) (n=30) 19.0–100.0 C. 13.0–17.8 13.0–20.2 6.1–8.1 23.0–27.5 33.5–60.8 22.1–34.1 27.0–39.6 16.0–20.0 8.7–11.4 14.0–20.4 7.2–10.4 11.8–17.1 4.8–13.8 opisthopus 17.4 19.1 7.4 24.8 62.5 37.7 30.0 16.7 9.2 14.4 7.5 14.7 157.8 8.0 (n=3) (n=76) (n=75) (n=81) (n=93) (n=59) (n=72) (n=66) (n=82) (n=80) (n=36) (n=41) (n=81) - 102.0–186.0 7.5–8.5 15.3–19.5 16.2–21.8 6.4–8.4 23.0–26.7 57.7–67.3 31.6–44.1 26.0–36.8 15.0–18.7 7.6–12.6 10.2–21.4 6.4–9.4 13.3–16.1 16.2 16.7 7.7 24.9 63.7 40.9 39.5 17.3 10.4 11.6 9.5 14.5 58.6 61.1 - (n=42) (n=44) (n=46) (n=57) (n=56) (n=52) (n=56) (n=45) (n=44) (n=22) (n=36) (n=45) (n=65) 29.0–96.0 14.6–18.1 14.6–19.9 6.9–8.5 23.1–27.5 50.5–71.7 36.0–45.5 35.9–44.1 15.7–20.0 8.6–13.3 9.5–13.0 7.7–11.2 13.1–16.3 8.3–197.0 8.6 17.1 18.5 7.5 24.8 68.3 42.7 31.9 16.8 9.4 10.7 7.4 14.3 28.6 156.3 C. naresii a (n=11) (n=83) (n=86) (n=98) (n=115) (n=85) (n=80) (n=87) (n=94) (n=95) (n=38) (n=64) (n=91) (n=46) 101.0–200.0 7.6–9.6 15.8–19.2 16.4–22.0 6.0–8.6 22.0–27.3 62.9–72.7 37.4–49.0 24.7–39.6 14.5–19.0 6.8–12.1 8.6–12.0 5.4–9.1 12.5–16.3 3.9–113.7 17.1 18.7 7.3 24.4 67.3 42.4 28.0 16.4 8.7 9.9 6.7 13.8 220.3 8.4 (n=4) (n=37) (n=41) (n=46) (n=55) (n=41) (n=39) (n=42) (n=38) (n=38) (n=16) (n=17) (n=40) - 201.0–258.0 7.6–9.1 15.3–18.7 15.9–21.8 6.4–8.1 22.3–26.4 63.4–70.6 38.0–46.5 25.9–31.4 14.0–18.7 6.6–10.4 8.7–11.0 5.4–7.9 12.3–15.2 17.8 19.4 7.5 23.9 66.8 42.2 28.1 15.9 9.1 10.4 7.0 14.9 156.3 8.6 (n=7) C. persimilis (n=67) (n=74) (n=72) (n=77) (n=63) (n=69) (n=71) (n=70) (n=71) (n=39) (n=50) (n=73) - 129.0–180.5 8.1–9.0 15.9–19.5 17.2–21.9 6.8–8.2 21.8–25.5 62.3–71.0 37.0–45.2 24.0–31.0 14.3–17.7 7.5–10.5 9.0–12.4 5.9–7.9 13.1–16.0 18.4 19.2 7.8 29.2 72.5 42.7 40.0 21.3 12.0 13.8 10.6 15.7 25.6 69.1 - (n=19) (n=21) (n=21) (n=27) (n=22) (n=23) (n=18) (n=21) (n=21) (n=11) (n=18) (n=20) (n=26) 36.5–95.0 17.3–20.0 17.5–20.8 6.7–8.7 27.5–31.3 69.4–76.1 39.7–45.6 38.4–41.6 19.2–24.1 9.8–14.6 12.1–15.0 9.2–12.3 13.0–17.4 15.2–35.8 8.5 17.7 19.1 7.2 28.5 69.6 41.8 31.8 20.6 11.1 11.4 7.7 14.0 19.9 C. 172.4 (n=12) (n=87) (n=96) (n=99) (n=127) (n=85) (n=90) (n=93) (n=91) (n=92) (n=56) (n=57) (n=98) (n=25) angusticeps b 100.5–200.0 7.3–9.6 16.1–19.4 17.2–21.5 6.3–8.2 26.5–31.0 65.2–75.0 37.2–46.5 26.0–40.7 18.7–22.7 9.3–12.6 9.6–13.7 6.4–9.9 12.6–16.2 11.4–30.7 8.1 17.2 18.9 6.9 28.1 67.6 40.6 28.0 19.9 10.7 10.5 6.8 13.4 212.0 (n=13) (n=44) (n=52) (n=52) (n=68) (n=39) (n=43) (n=45) (n=47) (n=47) (n=23) (n=19) (n=52) - 200.5–235.0 7.4–8.9 16.1–18.6 16.7–21.7 6.4–7.6 25.5–30.0 61.8–72.1 35.5–46.0 25.7–30.8 18.1–21.6 9.1–12.3 9.4–11.6 5.9–7.7 12.2–14.4 ......continued on the next page

Measurements, % SL

Species SL, mm

io 1 Hc H h Dc lP lP 1 lV lD lA HD HA p lcir 56.8 18.5 19.2 7.7 26.7 63.5 40.1 39.1 18.0 10.1 12.7 9.9 14.5

58.4 9.3 (n=7) (n=18) (n=3) (n=10) (n=8) (n=5) (n=18) (n=4) (n=17) (n=8) (n=8) (n=14) (n=12) (n=9)

27.5–99.0 8.4–9.8 25.8– 18.1–19.0 17.9–20.7 7.4–8.1 25.1–27.7 59.1–68.2 37.6–42.8 35.4–41.3 16.9–19.3 9.0–11.3 11.3–15.1 7.8–12.9 13.3–15.3

C. comatus 101.4

8.3 17.9 19.1 6.8 26.5 64.8 40.5 29.6 17.7 10.0 10.6 7.0 13.9 47.4

176.9

(n=27) (n=13) (n=43) (n=40) (n=42) (n=40) (n=29) (n=43) (n=24) (n=24) (n=30) (n=21) (n=42) (n=4)

108.0–210.0

7.0–9.4 16.9–18.6 16.6–21.6 6.1–7.6 25.3–28.2 60.4–68.1 35.2–44.6 25.6–35.9 17.0–18.8 8.6–11.4 9.1–11.9 6.0–8.2 12.7–14.9 38.1–69.4

a Data of Kotthaus (1969), Chen (1987) and Shakhovskoy & Bogorodsky (2021) are also included.

b Data of Kotthaus (1969) are also included.

Measurements, % SL

Region SL, mm

io 1 Hc H h Dc lP lP 1 lV lD lA HD HA p lcir 15.3 15.4 27.3 61.6 36.8 39.0 19.4 10.7 12.2 9.1 15.0

74.4 7.1 (n=16) 7.0 (n=8) - (n=16) (n=16) (n=16) (n=16) (n=16) (n=16) (n=16) (n=16) (n=11) (n=15) (n=16)

46.0–100.0 6.5–7.8 5.5–10.4 14.8–16.2 14.8–16.9 25.7–28.6 59.0–65.2 35.0–39.1 35.9–43.6 16.7–20.8 9.0–11.6 10.9–13.1 7.8–10.6 14.2–15.9

Sea of Japan

6.7 26.7 30.0 11.4

162.3 15.7 16.8 (n=7) 6.1 (n=7) 65.0 (n=7) 41.3 (n=7) 18.5 (n=6) 9.7 (n=7) 7.1 (n=7) 13.8 (n=7)

(n=6) (n=11) (n=7) (n=6) - 111.0–219.0 (n=1) 15.7–17.9 5.7–7.3 62.6–66.5 37.6–46.9 16.9–19.6 9.1 –10.6 6.3–8.0 13.0 –14.9

6.3–7.3 25.0 –28.2 27.0–35.2 10.0–12.7

12.0

14.7 14.7 27.7 62.1 36.3 40.7 19.4 11.2 9.3 14.2 7.4 66.8 6.8 (n=38) (n=32)

- (n=38) (n=38) (n=40) (n=40) (n=40) (n=40) (n=40) (n=40) (n=33) (n=37) (n=31) 43.0–96.0 6.1–7.6 11.2

Pacific 13.9–15.7 13.9 –16.0 25.3–29.5 57.4–69.2 32.1–40.0 37.9–43.4 18.1 –21.7 9.6–13.0 8.5–10.8 13.2–15.9 4.7–10.8 –13.0

Ocean

6.5 16.0 16.8 27.1 65.2 31.7 19.2 9.7 10.5 13.7

184.3 6.5 (n=13) 40.8 (n=9) 7.5 (n=6)

(n=7) (n=6) (n=13) (n=16) (n=13) (n=12) (n=10) (n=10) (n=6) (n=12) - 112.0–221.0 5.5–7.6 37.8–50.6 6.6–8.4

6.3–6.7 15.2–16.8 14.1–19.4 24.8 –29.6 63.5–67.3 27.7–37.5 17.7–20.3 8.4–11.3 9.5–11.8 12.3–15.5

Yellow and 16.1 30.8

187.2 7.5 6.5 (n=2) 27.0 64.9 (n=2) 39.0 (n=2) 17.8 (n=2) 9.5 (n=2) 13.9 (n=2)

East China (n=2) 16.4 (n=1) (n=2) 9.4 (n=1) 7.7 (n=1) - 131.0–203.0 (n=1) 6.3–6.7 24.8 –29.1 63.5–66.3 38.0–40.0 16.7–18.9 9.0–10.0 13.5–14.3

seas 16.1–16.2 28.8–32.8

Pectoral fins of juveniles 22–120 mm SL ( Fig. 6a–c ) brown or dark brown to 9 th –11 th ray usually with pale tips of 1 st –3 rd rays. In fish> 120 mm SL ( Fig. 6d–e ) pectoral fins pale brown to dark brown to 7 th –9 th ray with pale tip and, in some fish, with a narrow pale posterior edging. Pigmentation usually extending one ray lower distally than proximally (in juveniles usually vice versa), occasionally a small pale stripe (so-called “mirror”) present.

Pelvic fins of juveniles 22–100 mm SL ( Fig. 7a–c ) entirely brown or dark brown, usually with pale tips to outer and inner rays. In juveniles> 60 mm SL pelvic fins start to lose pigmentation along 1 st and 6 th rays. In fish 100–167 mm SL ( Fig. 7d ) pelvic fins brown to dark brown (usually slightly paler proximally) with pale margins along 1 st and 6 th rays and a narrow pale posterior edging. In fish> 185 mm ( Fig. 7e ) pelvic fins pale (in a specimen 187 mm SL with vestigial pigmentation between 3 rd –4 th rays distally).

Dorsal fin of juveniles 22–75 mm SL ( Figs. 1a , 5a–c ) covered with brown melanophores (especially densely dorsally and posteriorly). In fish 75–100 mm SL ( Fig. 5d ), dorsal fin pale brown or brown, paler basally and anteriorly, the last ray usually pale. In fish ≥ 120 mm SL dorsal fin gray to pale brownish, in smaller fish (<145 mm SL) usually with darker upper margin ( Fig. 5e ).

Anal fin of juveniles 22–95 mm SL ( Fig. 1a ) pale with sparce brown melanophores near fin base (sometimes absent) and dense melanophores between 3–5 posterior rays distally (usually aggregated into a brown spot). Sometimes posterior part of anal fin almost entirely brown. In fish 95–160 mm SL, anal fin pale with few dots between posterior rays distally. In fish> 160 mm SL anal fin devoid of pigmentation.

Caudal fin of juveniles 22–50 mm SL ( Fig. 5a–b ) pale with pale brown to brown base and dense brown melanophores or brown pigmentation between rays of lower lobe and sparcer melanophores between rays of upper lobe (mainly between uppermost principal rays and on tip of lobe; sometimes pigmentation on upper lobe entirely absent). Juveniles (45) 50–95 mm SL ( Figs. 1a , 5c–d ) with 1–2 (occasionally 3) dark bands (aggregations of melanophores) on lower lobe and, sometimes, also with 1–2 dark bands on upper lobe. In fish ≥ 120 mm SL ( Fig. 5e–f ) caudal fin grayish-brown to brown, usually with darker base and posterior margin.

Coloration in life. According to Tsukahara (1959), body of adults is dark bluish above and silvery white below, pectoral fins are greyish violet, dorsal, anal and pelvic fins are greyish. Imai (1959) reported that juveniles have dark blue fins. According to Masuda et al. (1975), pectoral fins are pale purplish-brown.

Maximum size. The maximum length of C. hiraii in the material examined was 221 mm SL (ZIN 7475). According to Abe (1953), the largest specimen of this species was 225 mm SL. Abe et al. (1993) reported that females are slightly larger than males— 205–240 mm Fork Length (FL) vs. 195–235 mm FL, respectively. In our materials, the largest female was 221 mm SL and the only male was 202 mm SL.

Intraspecific variation. Samples from different regions differ only slightly ( Tables 1–6 and 8, Fig. 3 ). Pacific fish have on average more vertebrae and pectoral-fin rays as compared with fish from other areas. Juveniles from the Sea of Japan somewhat differ from the Pacific ones in on average wider and deeper body, longer and deeper head, larger eyes but smaller postorbital length, and shorter pelvic fins. Fish from the Yellow and East China seas have dorsal, anal and pelvic fins somewhat shifted posteriorly. However, we regard all these differences as having no taxonomical significance.

Comparative remarks. Cypselurus hiraii differs from C. nossibe (see description of this species in Shakhovskoy & Parin 2022) and all species of the subgenus Poecilocypselurus Bruun in having more vertebrae (Vert 45–47 vs. 38–45, Vert.pc 29–32 vs.24–29). This species also differs from C. nossibe in having more predorsal scales (29–38 vs. 26–30) and gill rakers (23–32 vs. 19–22), smaller head (21.2–24.7 vs. 24.8–27.8% SL) and eyes (in adults 6.0–7.3 vs. 8.5–9.1% SL), lower depths of head and caudal peduncle (Hc 13.9–16.8 vs. 17.5–19.6% SL; h 5.5–7.8 vs. 7.4–9.0% SL), as well as in jaw teeth morphology (conical vs. tricuspid). Cypselurus hiraii may be confused with Cheilopogon doederleinii (Steindachner) in adult stage; however, Ch. doederleinii has fewer gill rakers (23–26 [5–8 + 16–19]) and no palatine teeth ( Abe 1954).

Biology. The only male at our disposal (IORAS 04114, 202 mm SL) was mature or close to mature. Females were mature starting with 203 mm SL. A mature female was captured in the Japan or East China Sea in June (IORAS 04113, precise locality unknown). The smallest juvenile 22 mm SL (IORAS 04131) was captured in August. Based on limited data we can only infer that C. hiraii spawns in summer. Fortunately, many studies were devoted to reproductive biology of this species. In the waters of Japan spawning of C. hiraii was reported from May until early September ( Imai 1958, 1959; Tsukahara 1959; Shiokawa 1967; Kojima 1969a, 1969b, 1971; Masuda et al. 1975; Abe et al. 1993; Kawano et al. 1995b; Ichimaru 2007). According to Kojima (1969a, 1969b, 1971), C. hiraii spawns in coastal areas (within 2 km from shore) 10–30 m deep. The spawning takes place at night-time near the bottom, and eggs are laid mainly on sand. Chen (1987) reported that larvae and juveniles were collected north of 30°N in waters with sea surface temperature of 20–26°C (most caught at 21–23°C). Juveniles of this species are associated with drifting seaweeds ( Imai 1959; Nishida et al. 2008).

Distribution. According to our data ( Fig. 8a ), C. hiraii occurs mainly in neritic waters of north-western Pacific from coast of China (IORAS 04114, USNM 150415, USNM 130403) to 142°E (IORAS 04120) and from Okinawa (URM collection, Nos. P23758, P23759, P25846, P27398 and P27399) to Hokkaido, Japan (HUMZ collection, Nos. 3018–3021). Fish ≤ 100 mm SL were not found south of 33°N. Juveniles may be carried away by currents as far east as 160°E (IORAS 04127). A juvenile of C. hiraii 87 mm SL (unknown collection, uncat.) was captured in the Amur Bay as early as in 1967.

Saveliev et al. (2014, 2015) reported recent captures of juvenile C. hiraii from waters of Russia (42°00’N 147°00’E and 45°02’N 136°39’E). Larvae and juveniles described as Prognichthys agoo (Temminck & Schlegel) from the waters of Korea by Park and Kim (1987a, 1987b) are likely C. hiraii . Chang et al. (2012) reported juveniles of C. hiraii for waters of Kee-Lung, Taiwan —the southernmost locality for this species; however, they did not provide any data in support of species identification and we regard this occurrence as doubtful.

According to Tsukahara (1959), immature individuals of C. hiraii are economically important in waters of Kyushu, Japan in October and November, and subsequently they leave these waters and migrate southward for the winter.

Figures

FIGURE 1. Cypselurus hiraii. (A)—46 mm SL (IORAS 04132, 41°31’N 142°17’E, drawing by G.N. Pokhilskaya); (B)—144 mm SL (south of Honshu, after Parin 1960a).

FIGURE 2. Chin barbel of Cypselurus hiraii (ventral view of head). (A)—47 mm SL, IORAS 04133, 41°35–58’N 138°28’E; (B)—50 mm SL, IORAS 04132, 41°31’N 142°17’E; (C)—52 mm SL, IORAS 04132, same place; (D)—61.5 mm SL, IORAS 04127, 37°N 160°E; (E)—71 mm SL, IORAS 04133, 41°35–58’N 138°28’E

FIGURE 3. Size variation of morphometric characters (in % SL) in Cypselurus hiraii (◊—Sea of Japan, ○—Pacific Ocean; □—Yellow and East China seas; ∆—locality unknown): (A)—head length (c); (B)—eye diameter (o); (C)—postorbital distance divided by eye diameter (index po/o); (D)—head depth (Hc); (E)—pelvic-fin length (lV); (F)—body width (p).

FIGURE 4. Size variation of morphometric characters (in % SL) in Cypselurus hiraii (◊), C. opisthopus (∆), C. naresii (○), C. persimilis (+), C. angusticeps (□) and C. comatus (x): (A)—cephalo-ventral distance divided by postventral distance (index cV/ pV); (B)—dorso-caudal distance (Dc); (C)—pectoral-fin length (lP); (D)—length of the first pectoral-fin ray (lP1); (E)—height of dorsal fin (HD); (F)—length of chin barbel (Lcir).

FIGURE 5. Cypselurus hiraii. (A)—22 mm SL, IORAS 04131, 40°07’N 144°21’E; (B)—46 mm SL, IORAS 04131, same place; (C)—74 mm SL, IORAS 04125, 39°50’N 144°00’E; (D)—92 mm SL, IORAS 04129, 37°32’N 133°24’E; (E)—120.5 mm SL, IORAS 04119, 34°04’N 137°09’E; (F)—202 mm SL, IORAS 04114, Chefoo (Yantai), China.

FIGURE 6. Pectoral fins of Cypselurus hiraii. (A)—22 mm SL, IORAS 04131, 40°07’N 144°21’E; (B)—60 mm SL, IORAS 04133, 41°35–58’N 138°28’E; (C)—80.5 mm SL, IORAS 04129, 37°32’N 133°24’E; (D)—134 mm SL, IORAS 04116, locality unknown; (E)—202 mm SL, IORAS 04114, Chefoo (Yantai), China.

FIGURE 7. Pelvic fins of Cypselurus hiraii. (A)—22 mm SL, IORAS 04131, 40°07’N 144°21’E; (B)—59.5 mm SL, IORAS 04130, same place; (C)—92 mm SL, IORAS 04129, 37°32’N 133°24’E; (D)—120.5 mm SL, IORAS 04119, 34°04’N 137°09’E; (E)—202 mm SL, IORAS 04114, Chefoo (Yantai), China.

FIGURE 8. Distribution of Cypselurus hiraii and C. opisthopus. (A)—distribution of C. hiraii (□) and C. opisthopus (○—C. o. opisthopus, ∆—C. o. crockeri). 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. (B)—distribution of barbelled juveniles of C. o. opisthopus (+—juveniles with forked barbel; x—juveniles with unforked barbel).