Cypselurus naresii socotranus ( Steindachner, 1902 ) Shakhovskoy & Parin, 2024

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 : 70-71

Cypselurus naresii socotranus ( Steindachner, 1902) new combination

Synonymy and bibliography.

Exococtus socotranus Steindachner, 1902: 318 (original description; open sea between Abdal Kuri and Socotra).

Exocoetus socotranus . Steindachner 1903: 155–156 (description; open sea between Abdal Kuri and Socotra). Fowler & Steinitz 1956: 272 (alluded as a probable synonym of Exocoetus oligolepis Bleeker ). Shakhovskoy & Bogorodsky 2021: 382, 384, figure 2 [re-description of type of Exocoetus socotranus ; synonymous with Cypselurus naresii (Günther) ].

Cypselurus comatus (non Mitchill). Kotthaus 1969: 11–12, figs. 162, 174 (description; Gulf of Aden; in part: only specimen 155 mm SL).

Cypselurus naresii . Kovalevskaya 1982: 114–116, figs. 5–6 (early life history stages; Indian Ocean; in part: only specimens from Gulf of Aden). Parin 1984: EXOC Cyp 10 (description, figures, distribution; western Indian Ocean; in part). Shakhovskoy & Collette 2022: 347–349, pl. 59, upper right photo (short description, distribution; western Indian Ocean; in part).

Cheilopogon sp. Zajonz et al. 2019: 66 (holotype of E. socotranus listed as possessing characters of genus Cheilopogon Lowe ).

Probable misidentifications. Fowler & Steinitz (1956: 271) described a specimen of Cypsilurus socotranus from Eilat, Israel. However, we regard it as a misidentification of Cheilopogon katherinae Shakhovskoy & Parin, 2019 . Afterwards Dor (1984: 61) listed Hirundichthys socotranus in the checklist of Red Sea fishes basing on description of Fowler and Steinitz. Other authors, who have subsequently listed H. socotranus ( Goren and Dor 1994: 15. Zajonz et al. 2000: 152. Golani and Bogorodsky 2010: 62) were probably based on the same misidentification.

Material examined. Sixteen specimens 51–182 mm SL.

Full morphological study. IORAS 04207 (1, 113.5 mm SL), Bandar Imran , Yemen, 4.09.1966 . IORAS 04208 (1, 159 mm SL), 12°35’N 44°45’E, 31.08.1964 . IORAS 04218 (1, 113 mm SL), 14°44’N 50°02’E, 25.10.1960 . IORAS 04236 (4, 109– 123 mm SL), 12°19’N 45°07’E, 20- 21.10.1960 . IORAS uncat* (3, 147– 165 mm SL), 12°22’N 43°59’E, 5.03.1983 . IORAS uncat* (1, 182 mm SL), 12°25’N 45°33’E . USNM 306032 (2, 158– 162 mm SL), 11°25’N 43°58’E, 4.05.1986 .

Partial morphological study. IORAS uncat* (1, 51 mm SL), 13°41’N 42°32’E, 15- 16.10.1960 . IORAS uncat* (1, 146 mm SL), Socotra I., 12.05.1958 . ZMH 4979 * (1, 155 mm SL), 12°03’N 43°46’E, 12.11.1964 .

Holotype of C. n. socotranus was studied by S. V. Bogorodsky (see Shakhovskoy & Bogorodsky 2021). Data from that work are given below. NMW 84634 , between Abd-al Kuri and Socotra Islands , Yemen, 9 January 1889. Length 162.4 mm SL. D 11, A 8, P I 14, Spred ~29, Vert 41 (27 + 14). Measurements (in % SL): c 22.8, o 7.4, lP 66.6, lV 25.7, HD 9.2 . Lower jaw slightly projecting, a bit longer than upper jaw, upper jaw not pointed anteriorly. Jaw teeth are small and conical, perceptible by touch in lower jaw. Pectoral fins pigmented to 10th ray. Pelvic fins with a dark blotch between 2nd–4th rays distally. Pelvic-fin base about midway between rear margin of the head and origin of caudal-fin lower lobe. First anal-fin ray beneath 6th dorsal-fin ray. Second and third dorsal-fin rays the longest.

Additional characters of the holotype may be found in Steindachner (1902, 1903). Steindachner (1903) regarded E. socotranus as very close to (or even identical with) E. brachysoma Bleeker [= C. oligolepis apus (Valenciennes) ]. However, we are confident that E. socotranus is a junior synonym of C. naresii (see rationale in Shakhovskoy & Bogorodsky 2021), though peculiarity of specimens from the Gulf of Aden and Socotra permits us to single out them into a subspecies C. naresii socotranus ( Figs. 30 , 31 ).

Differential diagnosis. This subspecies is a dwarf coastal morph of C. naresii , its maximum size is only 182 mm SL. Cypselurus n. socotranus differs from all other subspecies in fewer total (40–41 vs. 40–45, usually ≥ 42) and precaudal (25–27 vs. 26–30, usually ≥ 27) vertebrae ( Table 6), shorter pelvic fins ( Fig. 20c ) and a shorter chin barbel, which is lost as early as 109 mm SL ( Fig. 20d ), as well as in pigmentation of anal fin and chin barbel (see above): anal fin is devoid of pigmentation in fish> 121 mm SL, and short tapered chin barbel is mainly pale ( Fig. 30d ). Also, C. n. socotranus slightly differs from all conspecifics except C. n. septentrionalis in more transverse scales (8½–10½ vs. 6½–9½, usually <8½, see Table 2), larger dorso-caudal distance (25.1–27.3% SL vs. 22.0–27.1, usually <25.1% SL) and more anterior position of pelvic-fin base (aV 58.8–62.7, usually <61.0% SL vs. 59.5–65.4, usually> 61.0% SL ( Fig. 20 ); index cV/pV 0.91–1.07, usually <1.00 vs. 0.91–1.22, usually> 1.00).

Common name. The name “Socotran pharao flying fish” (Russian: “сокотранский стрижехвост-фараон”) is proposed here.

Distribution. This subspecies is distributed ( Fig. 24 ) mainly in coastal waters of the Gulf of Aden east to Socotra (IORAS uncat.); also a juvenile (drifted with surface currents?) was captured in the southern Red Sea (IORAS uncat., 13°41’N 42°32’E).

Figures

FIGURE 24.Distribution of Cypselurus naresii (∆—C.n.naresii, —C.n. septentrionalis (our data), —C. n. septentrionalis (data of Imai 1959, Tsukahara 1959 and Chen 1987), ○—C. n. ordinarius, ◊—C. n. albitaenia, □—C. n. socotranus). 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.

FIGURE 30. Cypselurus naresii socotranus. (A)—109 mm SL, IORAS 04236, 12°19’N 45°07’E; (B)—113.5 mm SL, IORAS 04207, Bandar Imran, Yemen; (C)—158 mm SL, USNM 306032, 11°25’N 43°58’E (after Shakhovskoy & Collette 2022); (D)—121 mm SL, 04236, 12°19’N 45°07’E (close up of chin barbel and ventral side of head).

FIGURE 31. Pectoral (A–C) and pelvic (D–E) fins of Cypselurus naresii socotranus. (A)—109 mm SL, IORAS 04236, 12°19’N 45°07’E; (B)—123 mm SL, IORAS 04236, same place; (C)—159 mm SL, IORAS 04208, 12°35’N 44°45’E; (D)— 121 mm SL, IORAS 04236, 12°19’N 45°07’E; (E)—158 mm SL, USNM 306032, 11°25’N 43°58’E.

FIGURE20.Sizevariationofmorphometriccharacters(in%SL)inCypselurusnaresii:x—C.n.naresii;◊—C.n.septentrionalis; □—C. n. socotranus; Δ—C. n. ordinarius (lilac—western Pacific Ocean, red—eastern Indian Ocean, orange—Bay of Bengal and Andaman Sea); ○—C. n. albitaenia (dark blue—Indian Ocean, light blue—Arabian Sea). (A)—preventral distance (aV); (B)—greatest body depth (H); (C)—pelvic-fin length (lV); (D)—length of chin barbel (Lcir).