Cheilopogon (Ptenichthys), 1843

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 : 43-45

Cheilopogon (Ptenichthys) sp.2

( Figs. 3 , 15b , 17 c–d, 18, 19; Tables 1–7, 9)

Hirundichthys speculiger praecox Whitley, 1937: 218–219 (original description; Australia). Cypsilurus melanocercus (non Ogilby). Whitley 1957: 60–61, figs. 5, 6 (description of a juvenile, Garden Island, Port Jackson). Cypselurus hexazona (non Bleeker): Belyanina 1993: 124, fig. 5d (in part: only the juvenile 24.7 mm SL; eastern Australia).

Parin & Bogorodsky 2011: 683–686 [658–660 in English translation] (in part; description, distribution (eastern

Australia)).

Material examined. Twelve specimens 17.5–72.5 mm SL.

Full morphological study. AMS I.19461-060 (1, 48 mm SL), 14°40’S 145°28’E, 4.11.1975 . AMS I.23902-001 (1, 67 mm SL), 32°28’S 152°05’E, 26.05.1982 . AMS I.26494-013 (1, 31 mm SL), 14°39’S 145°26’E . AMS I.26529-008 (1, 38.5 mm SL), 14°40’S 145°27’E . AMS IA.6045 (1, 72.5 mm SL), 32°56’S 151°46’E .

Partial morphological study. AMS I.20735-001 (2, 21– 29 mm SL), 23°30’S 152°05’E . AMS IA.1608 (1, ~ 35 mm SL), 32°55’S 151°48’E . AMS IB.1436 (1, 33 mm SL), 33°52’S 151°16’E, 2.12.1945 . AMS IB.6342 (3, 17.5– 19 mm SL), 31°39’S 152°50’E, January 1963 .

Types. Parin and Bogorodsky (2011) listed Hirundichthys speculiger praecox Whitley as a junior synonym of C. hexazona . The holotype of H. s. praecox ( AMS IA.4050, Inside Port Jackson) was examined by the second author. Characters of this specimen are given below and a photograph of the specimen is available on the Australian Museum website.

SL 43 mm. D 13, A 9, P I 13, Spred ~27, Str 7½, Vert 46 (30 + 16). Measurements (in % SL): c 23.7, o 10.4, io 1 9.3, H 16.7, h 8.1, p 13.7, cV 1 30.4, pV 44.8, Dc 31.1 (30.2 from the right side), lP 64.4, lP 1 41.8, lV 49.3, HD 16.2. First anal-fin ray beneath 5th–6th dorsal-fin ray. Lower part of body with dark bands: below eye, below pectoralfin base, between pectoral and pelvic fins, near pelvic-fin base, in front of anal fin, and above anal fin base; the last two bands are barely visible. Pelvic fins dark. Left and right pectoral fins differ in pigmentation: left fin pale with dark base (with a paler triangular area near lower part of the fin base), large dark spot in middle of fin near upper margin, and broad dark band along postero-inferior margin. Right pectoral fin dark with pale lower edge and two pale triangular areas near upper edge proximally and distally. A paler, faintly-visible band shines through near fin base. Dorsal fin pale, with only slight pigmentation anteriorly near fin base and along upper margin. Anal fin pale with small dark spot near ends of middle rays. Chin barbels absent.

These data leave us no doubt that H. s. praecox and Cheilopogon (Ptenichthys) sp.2 belong to the same species.

Note to Table 9: Nos. 1-3— AMS IB.6342, No. 4— AMS I.20735-001, No. 5— AMS I.20735-001, No. 6— AMS I.26494- 013, No. 7— AMS IB.1436, No. 8— AMS IA.1608, No. 9— AMS I.26529-008, No. 10— AMS I.19461-060, No. 11— AMS I.23902-001, No. 12— AMS IA.6045.

Description. 5 The meristic and morphometric characters are given in Tables 1–7 and 9. D 13–14, A 9–10, P I 13–14 (usually I 14), Spred 27–30, Str 7½–8½, Sp.br 22–23 (6–7 + 16), Vert 45–46 (30 + 15–16). Palatine teeth absent in all examined specimens. Snout relatively short, upper jaw usually slightly pointed at tip. Lower jaw slightly longer than upper or, less commonly, equal. Barbels absent in all examined fish. Jaw teeth few, small, conical, arranged in 1–2 rows.

Fish 31–72.5 mm SL with elongate body, greatest body depth 5.5–6.2 in SL. Body width 1.15–1.26, and depth of caudal peduncle 2.06–2.54 in greatest body depth. Greatest head depth and head length 5.5–6.2 and 3.95–4.35 in SL, respectively. Head length 1.05–1.28 in dorso-caudal distance. Eyes large, their diameter 9.6–11.4 in SL, 2.28– 2.69 in c and 0.96–1.03 in io.

Pectoral fins relatively short (longer in fish from higher latitudes), their length 1.35–1.7 in SL. Tip of pectoral fin usually almost to end of dorsal-fin base or barely beyond it (in fish from higher latitudes it can extend beyond middle of caudal peduncle). First pectoral-fin ray unbranched, its length 2.4–2.9 in SL and 1.55–1.8 in lP.

Base of pelvic fin is much closer to posterior edge of head than to origin of caudal fin lower lobe (cV/pV = 0.65–0.70). Length of pelvic fin 2.03–2.25 in SL and 1.3–1.55 in lP. Tip of fin always protrudes beyond origin of lower lobe of caudal fin.

Anal fin origin far behind dorsal-fin origin (1st anal-fin ray below 5th–7th dorsal-fin ray). Dorsal fin with 3–5 rays more than anal fin. Heights of dorsal and anal fins 6.15–7.15 and 8.2–9.25 in SL, respectively. Longest ray in dorsal and anal fins the 2nd or 3rd. Tip of last dorsal-fin ray reaches middle of caudal peduncle. Middle and posterior dorsal-fin rays not elongate.

Pigmentation. Pigmentation of body and fins very similar to that of Cheilopogon (Ptenichthys) sp.1 ( Figs. 16 , 17 and 19 ), with only a few differences. Pigment bands on body near the anus and middle of anal-fin base may be absent; distinct band under eye always present. Ventral side of head with numerous dots on branchiostegal rays. Pectoral fins become dark with wide oblique pale stripe reaching upper edge of fin as early as 72.5 mm SL. Pelvic fins pigmented more uniformly, pale spots near base usually absent and large paler area on the distal part of fin never expressed ( Fig. 17 ).

Coloration in life. Transverse bands on body of live juvenile, 36 mm SL, were bright red ( Whitley 1957).

Intraspecific variation. Fish from higher latitudes (south of 30°S) differ from fish captured in more northern waters (about 14– 23°S) in having slightly longer fins (lP, lP 1, lV, see Table 9). This may be a consequence of either intraspecific variation in these characters, or the taxonomic heterogeneity of the material studied. Unfortunately, the limited number of samples available did not allow us to answer this question with certainty.

Comparative remarks. Cheilopogon sp.1 differs from Cheilopogon sp. 2 in the absence of chin barbels, the presence of a distinct pigment band under the eye and in more uniform pigmentation of pelvic fins, as well as in values of some characters: aA, Hc, lA, Str, D -A, Vert, Vert.pc. Thus, there is no doubt that we are dealing with (at least) two different, although closely related, species.

Cheilopogon sp.2 differs from all known representatives of the subgenus Ptenichthys living in the Western Pacific (see Parin 1996, 1999, 2009), Ch. furcatus , Ch. unicolor , Ch. arcticeps , Ch. intermedius and Ch. cf. heterurus , in a number of characters, and especially in the absence of chin barbels in juveniles. The first two species have long barbels protruding beyond the end of head and sometimes (in Ch. unicolor ) exceeding the body length. Ch. intermedius and Ch. cf. heterurus have short flattened barbels not exceeding the length of head. Juveniles of Ch. arcticeps have not yet been properly described. Only in the work of Parin (1961a) is there a brief description of juveniles, presumably identified as this species. According to this work, juveniles of Ch. arcticeps have two short chin barbels, pale proximally and dark distally, and this pigmentation is extremely similar to that of Cheilopogon sp.1, but the barbels are somewhat longer: 10.8 and 8.6% SL in juveniles of 85 and 108 mm SL, respectively.

It is quite possible that Cheilopogon sp.2 should be considered a valid species and named Cheilopogon (Ptenichthys) praecox (Whitley) . However, because the adult stages of this species are still undescribed (or not matched), we refrain from re-establishing validity until a taxonomic revision of the subgenus Ptenichthys has been carried out.

Thus, Cheilopogon sp.1 partially and Cheilopogon sp.2 have completely lost barbels at the juvenile stage of development, which is probably convergent for representatives of the subgenus Amustotrogon .

Distribution. Cheilopogon (Ptenichthys) sp.2 occurs in the coastal waters of the eastern Australia ( Fig. 3 ).

5. In the description we also included data on H. s. praecox .

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 15. Flying fishes Cheilopogon (Ptenichthys) sp.1 and sp.2. (A)—Cheilopogon sp.1, 48 mm SL, WAM P.6208-001, 28°45’S 113°50’E (drawing by T.N. Belyanina); (B)—Cheilopogon sp.2, 24.7 mm SL, ~19°S ~147°E (after Belyanina, 1993).

FIGURE 16. Flying fish Cheilopogon (Ptenichthys) sp.1. (A)—43 mm SL, FRSKU 114540, 20°00’S 117°04’E; (B)—48.5 mm SL, FRSKU 114540, same place; (C)—65 mm SL, FRSKU 114540, same place; (D)—82.5 mm SL, FRSKU 113559, 20°00’S 116°59’E.

FIGURE 17. Pectoral (left) and pelvic (right) fins in flying fishes Cheilopogon (Ptenichthys) sp.1 (A–B) and Cheilopogon (Ptenichthys) sp.2 (C–D). (A)—48.5 mm SL, FRSKU 114540, 20°00’S 117°04’E; (B)—65 mm SL, FRSKU 114540, same place; (C)—48 mm SL, AMS I.19461-060, 14°40’S 145°28’E; (D)—67 mm SL, AMS I.23902-001, 32°28’S 152°05’E.

FIGURE 19. Flying fish Cheilopogon (Ptenichthys) sp.2. (A)—31 mm SL, AMS I.26494-013, 14°39’S 145°26’E; (B)—38.5 mm SL, AMS I.26529-008, 14°40’S 145°27’E; (C)—48 mm SL, AMS I.19461-060, 14°40’S 145°28’E; (D)—67 mm SL, AMS I.23902-001, 32°28’S 152°05’E; (E)—the same specimen, close up of head.