Barathronus pacificus

description

To 12.8 cm (5 in) SL (Nielsen and Eagle 1974). North and southeast Atlantic, southwest and northeast Pacific Ocean (Fricke et al. 2020); between Australia and New Zealand (Okiyama and Kato 1997); Oregon to northern California (Matarese et al. 1989). Benthopelagic (Nielsen and Cohen in Nielsen et al. 1999); depth: 3,334 – 3,860 m (10,938 – 12,664 ft) (min.: Nielsen and Eagle 1974; max.: Pearcy et al. 1982). We follow Møller et al. (2016) and place this species (previously in the family Aphyonidae) in the Bythitidae.

Checklist of marine and estuarine fishes from the Alaska-Yukon Border, Beaufort Sea, to Cabo San Lucas, Mexico

description

Description. For a detailed description of the type specimens of B. pacificus and B. unicolor see Nielsen & Eagle (1974: 1067) and Nielsen (1984 a: 583). A comparison between the two sets of types show only minor differences corresponding to the intraspecific variation found in other Barathronus species. The principal meristic and morphometric characters are shown in Table 2. Comparisons. It is not possible with any degree of certainty to decide which of the four remaining species with transparent peritoneum is most similar to B. pacificus. The reason is that three of the species are known from one specimen only, two of which are juveniles and the third is a ripe female. The fourth species is known from two adult males.

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

diagnosis

Diagnosis. Barathronus pacificus differs from all other Barathronus species by the presence of a pair of small bulbs at base of penis (Fig. 22) and from the other four Barathronus species with a transparent peritoneum by the following combination of characters: dorsal-fin rays 63 – 80, anal-fin rays 55 – 72, pectoral-fin rays 22 – 27, precaudal vertebrae 35 – 40, total vertebrae 78 – 89, anterior gill arch with 28 – 35 long rakers, 4 – 8 fangs on vomer. Small otolith, rounded and thick (Fig. 23).

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

discussion

Remarks. The description of B. pacificus Nielsen & Eagle, 1974 was based on three specimens from the Northeast Pacific Ocean and the description of B. unicolor Nielsen, 1984 was based on 18 specimens from the Northwest Atlantic Ocean. Since then further 25 specimens have been caught mainly in the Northeast Atlantic but also in the Southeast Atlantic and in Australian waters so the two species are now recorded from the Northeast and Southwest Pacific Ocean and from both sides of the Atlantic Ocean. In Table 2 counts and measurements of the 46 specimens examined has been split up in four geographical areas. A comparison shows no differences between the areas which strongly indicates that the specimens belong to the same species. Consequently, B. pacificus Nielsen, 1974 will be considered a senior synonym of B. unicolor Nielsen, 1984.

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