Bicolored Aphionid

description

Description. For a detailed description based on 42 specimens see Nielsen (1969: 34). The principal meristic and morphometric characters are shown in Table 1. Comparisons. Table 1 shows that B. bicolor is very similar to B. diaphanus with an overlap in all characters mentioned. The only differences are found in the coloration of body and in the form of the penis. All freshly caught specimens of B. diaphanus are bright red (Fig. 10 A) while a red specimen of B. bicolor has never been observed. The latter statement is based on observations made by colleagues with year-long trawling experiences in the Gulf of Mexico and the Caribbean Sea. Fig. 7 B shows that the penis in ripe specimens of B. bicolor is long (up to 15 % SL) and slender with the thickness at basis of penis 13 % length of penis while the thickness at basis of penis of an equally long specimen of B. diaphanus (Fig. 11) is 31 % of length of penis. The distribution of the two species is non-overlapping as B. bicolor is found in the West Atlantic and B. diaphanus from off East Africa to Japan and southwestern Pacific. A DNA analysis of the two species has not been made.

Revision of the circumglobal genus Barathronus (Ophidiiformes, Bythitidae) with a new species from the eastern North Atlantic Ocean

diagnosis

Diagnosis. Barathronus bicolor differs from the other five species of the genus with dark-pigmented peritoneum by the following combination of characters: dorsal-fin rays 62 – 78, anal-fin rays 46 – 59, pectoral-fin rays 22 – 27, long rakers on anterior gill arch 28 – 35, precaudal vertebrae 31 – 36, total vertebrae 68 – 75, 1 – 5 fangs on vomer, paired bulbs at basis of penis not developed, no ventral flexure of anteriormost vertebrae. Penis in ripe specimens long (up to 15 % SL) and slender. Newly caught specimens light brownish with dark-blue peritoneum. Otolith almost circular three times as long as thick and centrally placed sulcus 3 – 4 times in length of otolith (Fig. 8).

Revision of the circumglobal genus Barathronus (Ophidiiformes, Bythitidae) with a new species from the eastern North Atlantic Ocean

discussion

Remarks. B. bicolor is the most commonly caught Barathronus species due to the extensive trawling in the Gulf of Mexico and the Caribbean Sea - often on the upper Continental Shelf.

Revision of the circumglobal genus Barathronus (Ophidiiformes, Bythitidae) with a new species from the eastern North Atlantic Ocean

distribution

Distribution (Fig. 1). Barathronus bicolor is found in the West Atlantic from Cape Fear N. C. (33 ° 38 ’ N) (ZMH 119884) southwards to off Rio de Janeiro (23 ° 46.7 ’ S) (USU 01502). Gilchrist (1906: 158) refers a 120 mm specimen caught ENE of Cape Agulhas to B. bicolor, but the identification cannot be checked as the specimen is lost. The specimens were caught at depths of 366 – 1640 m, except for one from 3270 m — all in bottom working trawls.

Revision of the circumglobal genus Barathronus (Ophidiiformes, Bythitidae) with a new species from the eastern North Atlantic Ocean