Benthocometes robustus ( Goode & Bean, 1886 )

Nielsen, Jørgen G., 2010, Revision of the bathyal fish genus Benthocometes (Teleostei: Ophidiidae) with a new species from off NW Australia, Zootaxa 2561, pp. 59-68 : 64-67

Benthocometes robustus ( Goode & Bean, 1886)

Figs. 5–9

Neobythites robustus Goode & Bean, 1886: 161 (type locality off Moro Castle, Cuba). Pteridium armatum Döderlein, 1886: 5 (type locality off Sicily).

Sirembo muraenolepis Vaillant, 1888: 273 (type locality off Cape Bojador, Western Sahara). Benthocometes robustus: Bougis & Ruivo 1954 (detailed anatomical description).

Material examined (29 specimens, SL 20–123 mm): West Atlantic Ocean

Holotype: MCZ 28084, 86 mm SL, off Moro Castle, Cuba, R/V Blake, st. 94, bottom trawl, 458–732 m, Dec 1878.

Paratype: USNM 29057, 94 mm SL, off Delaware, R/V Fish Hawk, haul 1043, bottom trawl, 238 m, 10 Oct 1881.

Non-types: MCZ 167725, 57 mm SL, northwestern Atlantic, 38°49’18’’N, 72°56’42’’W, NMFS, field no. AL06-08:001, Yankee otter trawl, 0–299 m, 6 Sep 2006. USNM 396083, 4 spms., 89–110 mm SL, Campeche- Cuba, Gulf of Mexico, 23°56’N, 87°32’W, R/V Silver Bay, cr. 17, st. 1184,bottom trawl, 274 m, 5 Jun 1959. USNM 396084, 2 spms., 97–108 mm SL, Nicaragua, 12°52,N, 82°09’W, R/V Oregon, cr. 4, st. 10205, bottom trawl, 443 m, 21 Nov 1968. ZMH 107403, 2 spms., 100–107 mm SL, ZMUC P 77683, 95 mm SL, and P 77386, 96 mm SL, off southern Brazil, 24°21’S, 43°45’W, R/V Walther Herwig, st. 90/68, bottom trawl, 500 m, 2 Mar 1968.

Bumpheads *: MCZ 39284, 95 mm SL, Old Bahama Channel, 22°48’N, 78°48’W, Atlantis (Harvard- Havana Exped.), st. ATLAN 2980B, bottom trawl, 403–412 m, 10 Mar 1938. MCZ 39299, 81 mm SL, off Ciudad de la Havana, 23°05’N, 82°33’W, Atlantis (Harvard-Havana Exped.), st. ATLAN 3303, bottom trawl, 476 m, 23 Mar 1939. MCZ 39298, 59 mm SL, Bahia de Matanzas, Cuba, 23°10’N, 81°28’W, Atlantis (Harvard-Havana Exped.), st. ATLAN 3480, bottom trawl, 366 m, 11 May 1939. ZMUC P 77791, 78 mm SL, off north coast of Cuba, 22°09’N, 81°09’W, Atlantis (Harvard-Havana Exped.), st. ATLAN 3325, bottom trawl, 549 m, 4 Apr 1939.

East Atlantic Ocean and Mediterranean Sea

IIPB, 348-349-350/1967, 118– 122 mm SL, near Barcelona, bottom trawl, 400 m, 14 Jun 1967. IIPB 515 and 517/1988, 106– 123 mm SL, and ZMUC P 77806, 109mm SL, near Barcelona, 41°17’N, 2°17’E, 455 m, 8 Apr 1988. IPB 66/ 2000, 98 mm SL, off southeastern Spain, 36°29’N, 2°12’W, 665 m, 30 May 2000. MNHN 86-523 (holotype of Sirembo muraenolepis ), 100 mm SL, and MNHN 86-524 (paratype of Sirembo muraenolepis ), 100 mm SL, off Cape Bojador, Western Sahara, R/V Talisman, dredge no. LXIX, 410 m, 1883. ZMUC P 77784, 20 mm SL, western Mediterranean, 37°15’N, 2°55’E, R/V Dana, st. 1124III, pelagic, 0–50 m, 27 Sep 1921. ZMUC P 77785, 39 mm SL, western Mediterranean, 36°10’N, 2°46’E, R/V Dana, st. 1132II, pelagic, 0–60 m, 3 Oct 1921. No cat. no., Univ. la Laguna, Tenerife, 97 mm SL, Candelaria, east coast of Tenerife, Canary Isls., shrimp trap, 260 m.

* Abnormal specimens with enlarged tissue dorsally on head, cf. Fig. 6 .

Diagnosis. Benthocometes robustus is diagnosed by the follow combination of characters: Anterior gill arch with 9–12 long rakers; 7–10 predorsal pterygiophores; palatine dentition elongate; predorsal length 26.5– 31.0 % SL; upper jaw length 11.0–13.0 % SL; dorsal fin origin above vertebrae nos. 6–7; anal fin origin below dorsal fin rays nos. 17–20; head pores poorly developed; many, small, granular teeth. For a comparison with the only other Benthocometes species, B. australiensis ; see p. 2.

Description. The major meristic and morphometric characters are shown in Table 1 . The 29 specimens are separated into three columns: those from the eastern Atlantic and Mediterranean, the “bumphead” specimens all from off Cuba and the typical B. robustus from the western Atlantic. Except for the enlarged tissue dorsally on the head of the four “bumpheads” there are no differences between the specimens from the three columns. Radiographs show that the “bump” is made up of soft tissue.

Body short and robust; head short with blunt snout. Head and body fully scaled with small (1.3 mm under pectoral fin in 102 mm SL specimen), oval, overlapping scales. Lateral line running midway between dorsal edge and midline of fish ending about one head-length from base of caudal fin. Vertical fins joined. Origin of dorsal fin above midpoint of pectoral fin, anal fin origin anterior to midpoint of fish, pectoral fin placed below midline of body reaching about halfway to anus, pelvic fins reaching halfway to anus. Anterior nostril a low tube with a skin flap, posterior a mere hole. Tip of snout with 10–12 rather broad skin flaps. Diameter of eye equal to or larger than length of snout. Upper jaw ending just behind or below posterior margin of eye. Opercle with two sharp spines, upper pointing backwards and lower postero-ventrally; neither reaching hind margin of opercle. Anterior gill arch ( Fig. 2 B) with 1–2 small, spiny knobs on upper branch and lower branch with 9–12 long rakers and 4–9 small, spiny knobs. The number of rakers plus knobs varies between 16 and 22. Longest of the ca. 65 gill filaments shorter than rakers. Pseudobranchial filaments well developed.

Head pore system: Pores poorly developed. Supraorbital pores absent, infraorbital pores five, Mandibular pores 3–4 and preopercular pores absent. In three of the four “bumpheads” a pore is developed in midline on snout in front of eyes appearing as a small lump on Fig.6 .

Dentition ( Fig. 3 B): Teeth small and numerous with a few exceptions. Premaxillaries with about 50 teeth developed, small and granular, in irregular rows anteriorly. Some specimens with a few uniserial fangs posteriorly. Vomerine tooth patch round with 6–20 small, pointed teeth. Palatine dentition elongate with about 20 small, pointed teeth. Dentaries with about 50 small, granular teeth in irregular rows anteriorly ending with a few, uniserial fangs posteriorly. One elongate, median basibranchial tooth patch.

Sagittal otolith ( Fig. 4 D): Otolith oval with angle anteriorly at dorsal rim; height 70%, thickness 30 % and sulcus 75% of otolith-length with cauda 70% the length of ostium.

Axial skeleton (based on radiographs, Fig. 7 ): Number of precaudal vertebrae 11–12. Anterior neural spine half length of second spine. Precaudal vertebrae 1 to 7–8 with pointed neural spines, 9 to 12–14 with blunt spines, remaining neural spines pointed. One to four of anterior haemal spines blunt, rest with pointed tips. Neural spines 6–7 to 12 with enlarged bases. Parapophyses on vertebrae 6–7 to 11–12. Pleural ribs on vertebrae 3 to 11–12. Epipleural ribs indistinct.

Coloration: (Most of the specimens have been preserved for more than 50 years.) Body light brown with many small, black spots, abdomen and branchial cavity bluish and eyes blue with lighter lens. In a few specimens darker brown epidermis remains. The unripe 57 mm specimen ( Fig. 8 ) has a much more dense pigmentation all over head and body, maybe a subadult character.

Biology. Adult specimens of B. robustus were all caught in bottom-fishing non-closing trawls and are considered benthopelagic. The smallest non-larval specimen examined was an unripe female, 57 mm SL ( Fig. 8 ). The only known larvae are two specimens caught in the western Mediterranean Sea in the upper 50 meters ( Nielsen & Evseenko 1989). They are rather long, reaching a standard length of 20 and 39 mm ( Fig. 9 ). The 30 mm juvenile illustrated by Emery (1886, pl. X, fig. 21) under the name Pteridium atrum , was cited by Cohen (1964: 7) as a probable B. robustus , which was not accepted by Nielsen & Evseenko (1989: 12) due to very different meristic characters.

Bougis & Ruivo (1954: 261) mentioned that B. robustus probably is ovoviparous or viviparous based on the examination of three females and one male specimen. I have checked 17 specimens of which 12 were females and 5 males. Embryos were not found in any of the females, some of which had enlarged ovaries, and none of the males had developed a copulatory organ, so B. robustus must be considered oviparous.

Distribution. Benthocometes robustus is not rare in the West Atlantic Ocean from off New Jersey (38°49’N, 72°57’W – MCZ 167725) southwards to off Rio Grande do Sul, Brazil (34°30’S, 51°53’W – Haimovici et al. 1994) including the Gulf of Mexico and the Caribbean Sea (the MCZ holds 83 specimens from off Cuba). In the East Atlantic it is known from two localities off northwestern Africa and from several localities in the Mediterranean from off Spain to Cyprus (N. Dewhurst, pers. comm.. 2010).

Figures

FIGURE 2. Anterior, right gill arch: A. Benthocometes australiensis, holotype. B. Benthocometes robustus. ZMUC P 77683, SL 95 mm.

FIGURE 3. Pattern of vomerine and palatine dentition: A. Benthocometes australiensis, holotype. B. Benthocometes robustus. USNM 396083. SL 103 mm.

FIGURE 4. Right sagitta of Benthocometes australiensis (left scale bar), holotype: A. Median view, B. Anterior view, C. Dorsal view and of Benthocometes robustus (right scale bar), ZMUC P 77683, SL 95 mm: D. Median view.

FIGURE 5. Benthocometes robustus. ZMUC P 77806, SL 109 mm. Western Mediterranean.

FIGURE 6. Benthocometes robustus, bumphead. ZMUC P 77791, SL 78 mm. Off Cuba. (Arrow indicates head pore in midline of snout).

FIGURE 7. Benthocometes robustus, paratype. USNM 29057, SL 95 mm. Radiograph.

FIGURE 8. Benthocometes robustus. MCZ 167725, SL 57 mm. Off New Jersey.

FIGURE 9. Benthocometes robustus, larva. ZMUC P 77785, SL 39. Western Mediterranean.