Cheilopogon (Amustotrogon) marisrubri, Shakhovskoy & Parin, 2019

Shakhovskoy, Ilia B. & Parin, Nikolay V., 2019, A review of the flying fish genus Cypselurus (Beloniformes: Exocoetidae). Part 1. Revision of the subgenus Zonocypselurus Parin and Bogorodsky, 2011 with descriptions of one new subgenus, four new species and two new subspecies and reinstatement of one species as valid, Zootaxa 4589 (1), pp. 1-71 : 30-36

Cheilopogon (Amustotrogon) marisrubri sp. nov.

urn:lsid:zoobank.org:act:444F6850-2E7B-4A25-AA1B-070BFB7983F3

( Figs. 3 , 11–14 , 18 ; Tables 1–7)

Cypselurus hexazona (non Bleeker). Parin & Bogorodsky, 2011: 683–686 [658–660 in English translation], fig. 1 (in part; description, distribution (Red Sea )).

This species was previously identified as C. hexazona in the collections studied both in juvenile and adult stages.

Material examined. Sixty four specimens, 33–163 mm SL.

Full morphological study. ZMMU P-24080, holotype (139.5 mm SL), 14°05’N 42°20’E, 15.10.1960 . IORAS 03413 (1, 148 mm SL), 21°21’N 38°04’E, 12.06.1977 . IORAS 03414 (1, 163 mm SL), Red Sea, 7.03.1983 . IORAS 03415 , paratypes (2, 54.5–94.5 mm SL), Gulf of Aden , end of 1962 . IORAS 03416 (1, 69 mm SL), Gulf of Aden or Red Sea . IORAS 03417 (1, 133 mm SL), 20°07’N 37°44’E . IORAS 03418 (8, 33– 53 mm SL), 17°43’N 39°20’E, 8.06.1977 . IORAS 03419 (3, 141– 157.5 mm SL), 13°27’N 42°51’E, 4- 5.06.1964 . IORAS 03420 (1, 106.5 mm SL), Red Sea, ~ 25°N . IORAS 03421 (2, 136– 160.5 mm SL), 15°55’N 41°32’E, 19.04.1960 . IORAS 03422 (2, 135– 137.5 mm SL), 17°56’N 39°49’E, 28.01.1980 . IORAS 03423 , paratypes (3, 127, 133 and 134 mm SL), 14°05’N 42°20’E, 15.10.1960 . IORAS 03424 (1, 45 mm SL), 19°39’N 38°45’E, 11.06.1977 . IORAS 03425 (3, 143– 159 mm SL), 16°48’N 41°01’E, 25.05.1978 . IORAS 03426 (8, 76– 102.5 mm SL), 14°05’N 42°20’E, 15.10.1960 . USNM uncat. (3, 40.5–139 mm SL), 17°51’N 38°55’E, 19.06.1958 . ZMH 8709 * (1, 131 mm SL), 11°55’N 43°39’E, 29.11.1964 . SOSC Ref. No. 145 (7, 131.5– 158 mm SL), 20°35’N 38°08’E, 24- 25.12.1964 .

Partial morphological study. IORAS 03427 (5, 61,5– 99 mm SL), 19°19’N 38°35’E, 21.10.1963 . IORAS 03428 (1, 101 mm SL), 20°42’N 37°34’E, 20.10.1963 . IORAS 03426 (6, 58– 73 mm SL), 14°05’N 42°20’E, 15.10.1960 . FRSKU 39842 * (1, 134 mm SL), Suez, Egypt, 20.11.1966 . BMNH 1983.6.17.1-2 4 (2, ~ 133–141 mm SL), Red Sea .

Holotype ( Fig. 11f ). ZMMU P-24080, R / V "Vityaz" Cruise 33, Sta. 4781, Sample 13, 14°05’N 42°20’E, captured by dip net and night light near the surface, on 15.10.1960. The immature female, 139.5 mm SL. D 11, A 10, P I 14, Spred 29, Str 7½, Sp.br 24 (6 + 18), Vert 40 (26 + 14). Measurements (in % SL): aA 76.7, aD 73.3, aV

4. These specimens have been studied basing only on photographs and x-rays provided by J. Maclaine ( BMNH). 56.8, cV 31.5, pV 40.3, c 25.2, po 11.3, o 8.0, ao 5.8, io 9.1, Hc 16.3, H 17.2, h 6.5, Dc 26.3, lP 65.3, lP 1 37.4, lV 25.3, lD 16.4, lA 11.5, HD -, HA -, p 15.1. Body dark above and pale below, without bands. Gill covers with specks. Pectoral fins pale gray with weakly discernable “mirror” to 4th ray and pale posterior edge. Tip of pectoral fin protrudes slightly beyond end of dorsal-fin base. Pelvic fins transparent, tip reaching 5th anal-fin ray. Dorsal fin gray; anal fin transparent. First anal-fin ray below 4th dorsal-fin ray. Caudal fin pale brown, slightly darker at base. Lower jaw longer than upper jaw; teeth relatively large (hardly visible with a naked eye), conical, arranged in two rows on both jaws near symphysis. Palatines with single tooth.

Paratypes. IORAS 03423 , 3 specimens 127, 133 and 134 mm SL , R / V "Vityaz" Cruise 33, Sta. 4781, Sample 13, 14°05’N 42°20’E, 15.10.1960 . IORAS 03415 , 2 specimens 54.5 and 94.5 mm SL, the Gulf of Aden , end of 1962 .

Description. Meristic and morphometric characters are given in Tables 1–7. D 11–12, A 9–11, P I 13–15 (usually I 14), Spred 25–30 (usually 26–29), Str 7–8 (usually 7½), Sp.br 21–25 (5–7 + 16–19), Vert 39–41 (25–26 + 13–16). Palatine teeth, if present (absent in 58% of the specimens studied), few in number: usually 1–4 teeth on anterior of palatines; occasional specimens with 5–10 teeth; absent in all juveniles under 55 mm SL. Snout oblong, upper jaw usually slightly pointed at tip. Lower jaw longer than upper jaw or, in rare cases, of equal size; teeth usually unicuspid. Occasional specimens with few teeth with 1–2 additional cusps. Teeth of adults conical, arranged in 1–2 rows (very rarely in 3), and not as numerous and large (usually not visible or barely visible with the naked eye) as in Ch. formosus . Only in a few fish some teeth are curved at the tip. Jaw teeth of juveniles relatively small, conical or needle-shaped, and fewer in number than in large fish (arranged in one and only occasionally in two rows). Few recurved teeth are found only at about 130 mm SL and above (found in 28% of fish 130–163 mm SL studied).

Body elongate. Greatest body depth does not change with growth, 5.2–6.25 in SL. Body width 1.06–1.27, depth of caudal peduncle 2.01–2.92 in greatest body depth. Greatest head depth and head length almost do not change with growth, 5.4–6.5 and 3.7–4.2 in SL, respectively. Head length 0.94–1.17 in dorso-caudal distance. Eyes large, diameter greatly decreasing with growth: in juveniles 35–105 mm SL, 8.5–11.9 in SL, 2.1–3.05 in c and 0.9– 1.25 in io; in large fish 125–165 mm SL, 11.5–13.1 in SL, 3.0– 3.3 in c, 1.1–1.25 in io.

Pectoral fins relatively short, length almost does not change with growth ( Fig. 12a ), 1.5–1.7 in SL. Tip of pectoral fin usually nearly to end of dorsal-fin base or protruses slightly beyond it, reaching no further than middle of caudal peduncle. First pectoral-fin ray unbranched; its length increasing slightly with growth ( Fig. 12b ): in juveniles 35–105 mm SL, 2.4–3.0 in SL and 1.55–1.9 in lP; in large fish 125–165 mm SL, 2.3–2.85 and 1.45–1.75, respectively.

Pelvic-fin base situated closer to posterior edge of head than to origin of lower lobe of caudal fin (cV / pV = 0.63–0.90). Pelvic fins shift slightly posteriorly as fish grows ( Fig. 12e ). Length of pelvic fins decreases quite markedly from juveniles to adults ( Fig. 12c ). In juveniles (35–105 mm SL) pelvic fins 2.5–3.7 in SL and 1.5–2.4 in lP; in large fish (125–165 mm SL), 3.5–4.55 and 2.35–2.9, respectively. Tip of pelvic fin of juveniles 35–55 mm SL reaches middle of caudal peduncle or protrudes slightly behind it, never reaching origin of lower caudal-fin lobe; in juveniles 55–70 mm SL it reaches from end of anal-fin base to middle of caudal peduncle; in fish 70–110 mm SL it reaches from middle to the end of anal-fin base; in fish 125 mm SL and over, it usually does not reach middle of anal fin, and only occasionally protrudes beyond it.

Anal-fin origin far behind dorsal-fin origin (1st anal-fin ray under 4th or 5th (occasionally under the 6th) dorsal-fin ray). Dorsal fin with 1–3 rays more than anal fin. Heights of dorsal and anal fins decrease markedly as fish grows ( Fig. 12d ). In juveniles (35–105 mm SL) HD 5.7–9.2 and HA 9.2–15.6 in SL; in large fish (125–165 mm SL) HD 9.0–11.8 and HA 14.3–18.2 in SL. Longest ray in dorsal and anal fins the 2nd or, occasionally, the 3rd. Tip of the last dorsal-fin ray reaches (or almost reaches) the middle of caudal peduncle or slightly beyond it. Central and posterior dorsal-fin rays not elongate.

Pigmentation. In juveniles 33–70 mm SL, 5–6 bands can be distinguished on the lower part of body ( Figs. 11 a–c): near pectoral-fin base, between pectoral and pelvic fins, near pelvic-fin base, above anus (often barely visible), above middle of anal fin (often barely visible) and near caudal-fin base. Gill covers with aggregations of melanophores. No band below eye. In fish 70–125 (135) mm SL, body bands begin to disappear, starting from posteriormost, and usually there are no more than 3 or 4 weakly-discernible bands on underside of body ( Figs. 11d, e ). Fish larger than 130 mm SL, usually without bands on body, although remains of bands can sometimes persist up to a length of 155 mm SL.

Unlike Ch. formosus , the head in Ch. marisrubri juveniles is always pale from below, usually with only a few dots near anterior margin of lower jaw and on isthmus. Adults with few small specks on gill covers, but specks usually absent below eyes.

Pectoral fins of juveniles 33–50 mm SL pale with large oval dark spot distally near lower edge, and with dark band and row of 2–4 oval dark spots near base. There is also pigment aggregation near tip of first ray ( Figs. 13a, b ). In fish 50–75 mm SL, the pigment areas on proximal part merge and fin becomes dark with wide oblique transverse pale band reaching upper edge of fin. Further, in fish 75–105 mm SL, proximal and distal pigment areas begin to unite near upper edge of fin, and fin becomes brown (proximally sometimes paler than distally) with large “mirror” extending to 3rd–5th ray, and sometimes reaching upper edge of fin ( Figs. 13c, d ). Occasionally, about 5 dark spots distally on fin ( Fig. 13c ). In fish 125 mm SL and longer, pectoral fin from pale brown to brown (prevailing coloration north of 20°N, see Fig. 13e ) or from gray to pale gray (prevailing coloration south of 18°N, see Figs. 13 f–h) to 6th–9th ray, with small, barely noticeable “mirror” (sometimes absent) and pale posterior edging. Pectoral fins of the fishes from the southern part of range often become much paler in their lower and posterior parts, with pigment clearly visible only near upper rays ( Figs. 13g, h ).

Proximal ½–⅓ of pelvic fins of juveniles 33–45 mm SL paler with only numerous dots; distally with 5–6 dark longitudinal streaks along rays or large dark spot ( Fig. 14a ). In juveniles 42–70 mm SL, dots on proximal part of the fin begin to disappear, remaining only near fin base, sometimes forming a small gray spot ( Fig. 14b ). In fish 75–100 mm SL, dots near fin base completely disappear, and distal spot also begins to decrease in size ( Fig. 14c ), remaining only near outer margin, between the 2nd–4th rays. In fish 100 mm SL and larger, pelvic fins completely devoid of pigment on membranes, with only dots remaining on some rays.

Dorsal fin of juveniles 33–70 mm SL covered with dots of varying degrees of intensity (usually denser on central part of fin and near base of anterior rays), with dark upper margin and pale patch on posterior part. In fish 70–100 mm SL pigment begins to disappear from fin, remaining mainly on upper part. In fish larger than 100 mm SL dorsal fin gray.

Anal fin of juveniles 33–70 mm SL transparent with small aggregation of dots (or, rarely, with a spot) posteriorly near ends of rays. Fin entirely transparent in fish larger than 70 mm SL.

Caudal fin of juveniles 33–70 mm SL ( Figs. 11 a–c) pale with brown pigment along rays of lower lobe (except for uppermost rays), usually forming two aggregations (bands). Base of fin and tip of upper lobe also pigmented. In fish 70–135 mm SL the pigment spreads throughout the fin, and it becomes light brown with paler fork (one specimen 94.5 mm SL had the pigmentation characteristic of juveniles under 70 mm SL). Lower lobe sometimes darker than upper. Fish over 135 mm SL with pale brown (or, less often, gray or yellowish) caudal fin, and usually with darker fin base ( Fig. 11f ).

Coloration in life. Body, head and caudal-fin base of a fish 133 mm SL (IORAS 03417) dorsally bright blue, pectoral fins blackish (based on photograph of a freshly caught specimen made by S.V. Bogorodsky).

Maximum size. The maximum length of Ch. marisrubri in our material was 163 mm SL (IORAS 03414, Red Sea). Females and males do almost not differ in size: the maximum length (SL) of males was 158 mm, of females 163 mm.

Intraspecific variation. Fish larger than 125 mm SL can be distinguished as two morphs that differ slightly in a number of characters, however, with much overlap. The first morph generally has more intensely pigmented pectoral fins (usually pale brown in color), fewer predorsal scales (most often 26–27) and no palatine teeth (present only in 30% of specimens). The second morph usually has gray or pale gray pectoral fins, sometimes almost transparent distally, more predorsal scales (usually 28 or more) and many (60%) with a few palatine teeth. Representatives of the first morph were captured mainly north of 20°N, and representatives of the second morph mainly south of 18°N. The nature of these morphs is difficult to understand. We were not able to sort them out reliably using the methods at our disposal. Perhaps we are dealing with cryptic species, or these forms are intraspecific groupings within a polymorphic species. We are inclined to the second option. However, this issue requires further research.

Etymology. The name " marisrubri " reflects distribution of this species mainly in the Red Sea.

Common names. The name “Common Red Sea flying fish” (Russian: “oбыкнoвeнный кpacнoмopcкий длиннoкpыл”) is proposed here.

Comparative remarks. This species differs from Ch. formosus in reduced dentition, including smaller and fewer teeth, which are rarely recurved, in pigmentation (in adults there are no specks below the eyes, the pectoral fins are paler; in juveniles the the head is pale ventrally, the body bands persist much longer, pectoral and pelvic fins are pigmented more densely), in smaller values of cV/pV ( Fig. 12e ), aV, cV, lD, lV (except for the smallest juveniles, see Fig. 12c ), lP (in juveniles) and lP 1 (up to about 70 mm SL) ( Fig. 12a,b ), HA ( Fig. 12d ) and larger values of pV, lP / lV (except for the smallest juveniles, see Fig. 12f ), as well as in more pectoral-fin rays and rakers on lower limb of the first gill arch (Tables 1, 4).

Juveniles of Ch. marisrubri are similar in pigmentation to juveniles of Cheilopogon (Ptenichthys) sp. 1 and, especially, to Ch. (P.) sp. 2 (see below). However, they have considerably shorter pelvic fins and fewer vertebrae.

Biology. Males mature at 148 mm SL, females at 156 mm SL; some individuals of both sexes are close to maturity from 133 mm SL. Mature and close to mature fish were captured between 13°N and 22°N from April to June (mature fish were caught only in June). The smallest juveniles (33–40 mm SL) were also captured in June. Two fish close to maturity were also captured in October (14°05’N 42°20’E). Judging by this, we can assume two spawning seasons in Ch. marisrubri : the main, spring-summer, season lasts at least from April to June and a secondary, autumn, season beginning probably in October.

Distribution. Ch. marisrubri is endemic to the Red Sea, where it is widely distributed ( Fig. 3 ) from the Suez (FRSKU 39842, 134 mm SL, 20.11.1966) to the Bab el Mandeb Strait, and also occurs in the Gulf of Aden (IORAS 03415, 54.5 and 94.5 mm SL, date of capture—end of 1962). Juveniles of Ch. marisrubri have not been found north of 20°N.

Figures

FIGURE 3. Distribution of flying fishes Cheilopogon formosus formosus (□), Ch. formosus pseudospilopterus (Δ), Ch. formosus andamanicus (◊), Ch. marisrubri (○), Cheilopogon (Ptenichthys) sp.1 (x) and Cheilopogon (Ptenichthys) sp. 2 (+). Filled symbols indicate capture location for fishes ≤100 mm SL, open symbols indicate capture location for fishes>100 mm SL.

FIGURE 11. Flying fish Cheilopogon marisrubri. (A)—33 mm SL, IORAS 03418, 17°43’N 39°20’E; (B)—39 mm SL, IORAS 03418, same place; (C)—53 mm SL, IORAS 03418, same place; (D)—94.5 mm SL, IORAS 03415, Gulf of Aden; (E)—106.5 mm SL, IORAS 03420, Red Sea, ~ 25°N; (F)—139.5 mm SL, ZMMU P-24080 (holotype), 14°05’N 42°20’E.

FIGURE 12. Size variation of morphometric characters in Cheilopogon marisrubri (+) and Ch. formosus (○). (A)—length of pectoral fin (lP); (B)—length of the first pectoral fin ray (lP1); (C)—length of pelvic fin (lV); (D)—height of anal fin (HA); (E)—distance from the head rear margin to the base of pelvic fins divided by postventral distance (index cV/pV); (F)—length of pectoral fin divided by length of pelvic fin (index lP/lV). Note: for Ch. formosus data from Kotthaus (1969) are included.

FIGURE 13. Pectoral fin pigmentation in flying fish Cheilopogon marisrubri. (A)—33 mm SL, IORAS 03418, 17°43’N 39°20’E; (B)—54.5 mm SL, IORAS 03415, Gulf of Aden; (C)—94.5 mm SL, IORAS 03415, same place; (D)—106.5 mm SL, IORAS 03420, Red Sea, ~ 25°N; (E)—133 mm SL, IORAS 03417, 20°07’N 37°44’E; (F)—133 mm SL, IORAS 03423 (paratype), 14°05’N 42°20’E; (G)—136 mm SL, IORAS 03421, 15°55’N 41°32’E; (H)—159 mm SL, IORAS 03425, 16°48’N 41°01’E.

FIGURE 14. Pelvic fin pigmentation in flying fish Cheilopogon marisrubri. (A)—33 mm SL, IORAS 03418, 17°43’N 39°20’E; (B)—54.5 mm SL, IORAS 03415, Gulf of Aden; (C)—94.5 mm SL, IORAS 03415, same place.

FIGURE 18. Size variation of morphometric characters in flying fishes Cypselurus bosha (□), C. olpar (○), Cheilopogon formosus (x), Ch. marisrubri (+), Ch. katherinae (◊), Cheilopogon sp. 1 (∆) and Cheilopogon sp. 2 (▲). (A)—length of pectoral fin divided by length of pelvic fin (index lP/lV), (B)—length of pelvic fin (lV), (C)—greatest head depth (Hc).