Cheilopogon formosus formosus (Kotthaus, 1969)

(Figs. 1–3; Tables 1–5)

Cypselurus formosus Kotthaus, 1969: 17–19, Figs. 168, 169 (original description, waters of western India).

Cypselurus hexazona (non Bleeker). Parin 1996: 302 (in part; description, considering C. formosus as a junior synonym of C. hexazona). Parin & Bogorodsky 2011: 683–686 [658–660 in English translation] (in part; description, distribution).

Material examined. Nine specimens 38–144 mm SL.

Full morphological study. IORAS 03412 (1 specimen, 144 mm SL), Cochin, India, 9.02.1980 .

Partial morphological study. ZMH H4985 * (ex IOES 79 a), holotype (1, 53.5 mm SL), 14°44’7N, 73°54’E, 15.02.1965 . ZMH H4986 *, paratypes (7, 38– 52 mm SL), 14°44’7N, 73°54’E, 15.02.1965 .

The holotype and paratypes of Cypselurus formosus Kotthaus, 1969, were studied by the second author. Their characters are given below.

Holotype (Figure 1b). ZMH H4985 (ex IOES 79 a), Meteor, 15.02.1965, 14°44’7N 73°54’E, 53.5 mm SL. D 13, A 10, P I 13, Spred 25, Str 7½. Measurements (in % SL): c 25.4, o 9.7, io 1 9.3, H 16.0, h 8.2, p 13.6, cV 1 32.3, pV 40.0, aV 56.2, Dc 28.4, lP 63.9, lV 40.7, HD 19.8, HA 13.0. The longest ray of dorsal fin – the 2nd; of anal fin – the 4th. Dorsal fin with black spot between 2nd and 12th rays. Anal fin with black spot on distal part, between the 4th and 9th rays. Pectoral fins pale with dark areas at base of the upper part and near posterior margin. Pelvic fins with dark spot distally.

Paratypes. ZMH H4986, Meteor, 15.02.1965, 14°44’7N 73°54’E, seven specimens 38–52 mm SL. All paratypes with traces of 6 transverse dark bands on the body (Fig. 1a): near pectoral-fin base, near pelvic-fin base, between pectoral and pelvic fins, between base of pelvic fin and anal-fin origin, near posterior parts of dorsal and anal fins, near end of caudal peduncle. In addition, there is another band on the head that passes through the eye .

Description. There was only one large specimen (in poor condition) at our disposal, which we identified as Ch. formosus formosus (Figs. 1 c–e), with the following characters: D 12?, A 10?, P I 14, Spred 28, Str 7½, Sp.br 23 (7 + 16). SL 144 mm. Measurements (in %SL): aA 78.8?, aD 70.2?, aV 59.7, cV 32.7, pV 38.1, c 25.8, po 11.8, o 8.2, ao 5.5, io 9.5, Dc 26.4?, lP 68.6?, lP 1 42.5, lV 29.7?, lD 18.6, lA 11.1?, HD 12.6, p 13.1?. Pectoral fins dark with paler triangle stripe (“mirror”) and three dark spots behind it (Fig. 1d); pelvic fins 3 hyaline with dark stripe distally (Fig. 1e); dorsal fin relatively high, pale brown. Tip of pectoral fin extends to middle of caudal peduncle; tip of pelvic fin reaches posterior third of anal-fin base. Tip of last dorsal-fin ray protrudes not far beyond middle of caudal peduncle. Jaw teeth large, conical and recurved, arranged in two rows near symphysis. Palatine teeth few in number (1 tooth on anterior part of palatines and 1–2 teeth on the posterior).

A detailed description of Ch. formosus formosus juveniles is given in the work of Kotthaus (1969). The characters of those fish are shown in Tables 1–5. The measurements of 6 juveniles 40.2–52.5 mm SL, made by Kotthaus, are as follows: aA 76.2–81.4 (mean 79.3), aD 60.7–74.5 (67.7), aV 57.1–60.9 (58.2), c 21.8–23.5 (22.6), o 9.3–10.7 (9.9), ao 3.5–6.0 (4.5), io 9.3–10.7 (9.8), H 17.1–19.8 (18.2), h 7.0–8.6 (7.7), lP 61.9–71.2 (66.4), lV 38.6–43.5 (41.1), lD 19.0–21.4 (20.3), lA 12.6–16.3 (13.7), HD 17.4–22.6 (20.0), HA 11.3–14.5 (12.7), p 11.2–12.5 (11.6).

Common names. The name “slender toothy flying fish” (Russian: “cтpoйный зyбacтый длиннoкpыл”) is proposed here.

Comparative remarks. Based on the data of Kotthaus and our material, the following conclusions can be drawn. Specimens of Ch. formosus formosus overall are similar to those described here as Ch. formosus pseudospilopterus and Ch. formosus andamanicus (see below) and, apparently, they are conspecific. However, there are also some differences, sufficient in our opinion for isolating a subspecies: Ch. f. formosus differs in higher values of HD, HA and h (Figs. 2c, e, f) and in fewer pectoral-fin rays (in the last 2 characters it differs only from Ch. f. andamanicus). At the same time, the strong differences of juveniles in head length and body width are explained by a discrepancy between the measurements of Kotthaus and our method. Thus, the head length of the holotype of Cypselurus formosus is 22.6% SL according to the data of Kotthaus, but as much as 25.4% SL, according to our measurements. Also, the body width of the holotype, measured from its photograph (Fig. 168 in Kotthaus 1969; see also Fig. 1b in this paper), is about 14% SL, while according to Kotthaus’ data only 11.4% SL; it is thus obvious that he measured the width not at bases of pectoral fins, but behind them.

There are also differences in pigmentation compared to the other subspecies: the pelvic fins of juveniles of Ch. f. formosus are not pigmented at the base. In addition, according to Kotthaus, Ch. f. formosus has strongly developed palatine teeth, which are larger in number than jaw teeth; this was not observed in the other subspecies we studied. The only specimen available of Ch. f. formosus has teeth located not only on the anterior part of the palatines, as the representatives of two other subspecies have, but also on the posterior part.

Thus, we refer fish from the waters of Indonesia and Thailand, the Andaman Sea and the western coast of India to three different subspecies of one species – Ch. formosus .

Distribution. Cheilopogon f. formosus occurs along the western coast of India from Goa to Cochin (Fig. 3). The distribution of this subspecies, as well as the species as a whole, is likely wider in reality and its rarity may be explained by its habitation mainly in coastal waters from where we had few samples.

3. Here and elsewhere the pigmentation of the underside of pelvic fins is meant.