Congriscus maldivensis ( Norman, 1939 )

Huang, Jian-Fu, Chen, Hong-Ming & Chan, Tin-Yam, 2024, Three new records of the conger eels (Anguilliformes: Congridae) from Taiwan and the Dongsha Islands, Zootaxa 5550 (1), pp. 145-158 : 153-157

Congriscus maldivensis ( Norman, 1939)

Figs 8–11 ; Table. 3

Conger maldivensis Norman, 1939:37 , fig. 11 (holotype, 352 mm TL, paratypes, 2 specimens 302 and 340 mm TL, BMNH 1939.5.24.610–612, Maldives, depth 494 m).

Congriscus maldivensis : Castle, 1968:695, pl. 106D (brief redescription of paratype TL 340 mm). Karrer, 1982:18, fig. 4 (3 occurrences near northwestern Madagascar, depth 700 m). Adam et. al., 1998:8 (2 occurrences near the Maldives, depth 354 m).

Specimen examined. Dongsha Island, South China Sea, commercial bottom trawl, about 580 m: TOU-AE7668 (1, 241), 2 Dec. 2019, coll. J.-F. Huang . ASIZP 57965 (3, 286–353), 19 Aug. 1991, coll. K.- T. Shao . NMMST-P00879 (1, 221), 17 Aug. 1991, coll. K.- T. Shao . NMMB-P33385 (1, 248), 13 Feb. 2019, coll. H.-C. Ho. NMMB-P33795 (8, 187–264), 14 Jan. 2019, coll. H.-C. Ho. NMMB-P33828 (1, 253), 14 Jan. 2019, coll. H.-C. Ho. NMMB-P34024 (13, 174–288), 13 Feb. 2019, coll. H.-C. Ho. NMMB-P34888 (2, 180–183), 13 Feb. 2019, coll. H.-C. Ho.

Description of Taiwanese specimens. Head length 15.1–17.4% of TL; preanal length 41.5–43.4; predorsal length 17.5–20.2; trunk length 24.3–27.0; tail length 56.6–58.5. Depth at gill opening 39.5–56.5% of HL; depth at anus 24.8–42.5; interorbital width 7.3–12.5; interbranchial width 12.0–36.1; eye diameter 19.2–24.1; snout length 22.9–28.0; pectoral fin 31.4–38.8; gill opening 9.3–17.8; upper jaw length 33.1–42.6; lower jaw length 27.7–38.1.

Body stout, anteriorly oval in cross section, gradually becoming compressed posteriorly; trunk length about one fourth of total length; tail much longer than body, exceeding body about a half of total length. Dorsal-fin origin slightly behind base of pectoral fin. Anal fin starting immediately behind anus. Gill opening moderately small, slightly smaller than eye diameter.

Head medium sized; snout moderately long; eye moderately large, slightly shorter than snout. Upper and lower jaws with well-developed lips; upper jaw slightly protruding beyond lower jaw. Mouth moderately large, rictus extending to middle of eye.

Lateral line complete, 5–7 pores before pectoral fin base; 7–10 pores before dorsal-fin origin, 43–46 pores before anal-fin origin.

Head pores ( Fig. 10 ): supraorbital canal with 6 pores; first and second pores located in front of ansterior nostril, third pore located above ansterior nostril, fourth pore located above posterior nostril, fifth pore located above eye, sixth pore located above posterior margin of eye. Infraorbital canal with 9 pores, 6 below eye and 3 behind eye; first, second, and third pores located between anterior and posterior nostrils, fourth pore located below anterior margin of eye, fifth pore located below middle of eye, sixth pore located below posterior margin of eye, while seventh, eighth, and nineth pores located behind eye. Mandibular canal with 8 pores. Preopercular canal with 3 pores. Supratemporal commissure with 3 pores. No pore on frontal. Predorsal vertebrae 10–13; preanal vertebrae 45–47; precaudal vertebrae 49–52; total vertebrae 141–146.

Teeth conical and blunt ( Fig. 11A, B ); 2–3 rows of conical teeth on intermaxilla; vomerine teeth conical and forming a short triangular patch, increasing in size posteriorly, 2–4 rows in front and 1–2 rows at rear; maxillary and mandibular teeth in anteriorly in 2–3 rows and wider, posteriorly in 1 row and gradually narrower.

Coloration. When fresh ( Fig. 8A, B ), body light yellow. Ventral surfaces of head and belly whitish, dorsal surfaces of head and pectoral fin light grayish. Fin rays light grayish. Small black dots on the pectoral fin. Preserved specimens ( Fig. 9A, B ) with ventral surfaces of head and belly yellowish to paler, dorsal surfaces of head and pectoral fin light grayish.

Distribution. Known previously only from the Maldives, Madagascar, Philippines, northwestern Australia, New Caledonia, Vanuatu, Fiji, Wallis, and Futuna and now recorded in Dongsha Island, South China Sea, at depths of 354– 700 m.

Remarks

Karmovskaya (2004) found several morphometric and meristic differences between the southwestern Pacific material and topotypic specimens from the Maldives. The present Dongsha Islands material also has some morphometric and meristic differences from the original description of Congriscus maldivensis , such as head length slightly shorter (15.1–17.4 vs. 17.8–18.1% TL), trunk length slightly longer (24.3–27.0 vs. 21.7–25.0% TL), preanal length slightly longer (41.5–43.4 vs. 39.8–42.8% TL), predorsal length slightly longer (17.5–20.2 vs. 16.4–17.4% TL), interorbital width slightly shorter (7.3–12.5 vs. 14.8–18.7% HL), snout length slightly longer (22.9–28.0 vs. 19.4–22.2% HL), greater numbers of precaudal vertebrae (49–52 vs. 47–48), and preanal pores (43–46 vs. 40–42). It still needs to be verified whether the differences between the materials from the Pacific and Indian Oceans represent geographical variations of the same species.

Figures

FIGURE 8. The fresh specimen of Congriscus maldivensis, TOU-AE7668, 241 mm TL. A. Whole body. B. Head anterior body.

FIGURE 9. The preserved specimen of Congriscus maldivensis, TOU-AE7668, 241 mm TL. A. Whole body. B. Head anterior body.

FIGURE 10. Congriscus maldivensis, TOU-AE7668, 241 mm TL. Lateral view of head showing head pores and partial laterial line pores.

FIGURE 11. The jaw teeth of Congriscus maldivensis, TOU-AE7668, 241 mm TL. A. Upper jaw. B. Lower jaw.