Barathronus pacificus Nielsen & Eagle, 1974

Nielsen, Jørgen G., 2019, Revision of the circumglobal genus Barathronus (Ophidiiformes, Bythitidae) with a new species from the eastern North Atlantic Ocean, Zootaxa 4679 (2), pp. 231-256 : 248-252

Barathronus pacificus Nielsen & Eagle, 1974

Table 2. Figs.1–2 , 21–23

Barathronus pacificus Nielsen & Eagle, 1974: 1067 (type locality: 44°41.1’N, 133°24.1’W).

Barathronus pacificus: Okiyama & Kato 1997: 222 ; Nielsen et al. 1999: 139; Nielsen et al. 2019: 565 .

Barathronus unicolor Nielsen, 1984a: 579 (type locality: 38°28’N, 70°13’W).

Barathronus unicolor: Nielsen et al. 1999: 139 .

Total material examined (46 specimens, SL 42–128 mm): Northwest Atlantic (20 specimens, SL 72-116 mm). Holotype of B. unicolor : MCZ 56936 (SL 113 mm, male), 38°28’N, 70°52’W , RV Chain , cr. 124, st. 505, 2931- 2967 m, bottom trawl, 5 July 1975 . Paratypes of B. unicolor : MCZ 56935 (SL 101–108 mm, male and female), 38°20’N, 70°13’W , RV Chain , cr. 124, st. 501, 3287– 3314 m, bottom trawl, 4 July, 1975 . MCZ 56937 (SL 75–98 mm, females) and ZMUC P77722 (SL 86 mm, male), 38°11’N, 69°50’W , RV Chain , cr. 124, st. 526, 3605– 3642 m, bottom trawl, 12 July 1975 . MCZ 56938 (SL 83–98 mm, male and female) and ZMUC P77723 (SL 85 mm female), 37°54’N, 69°50’W , RV Chain , cr. 124, st. 527, 3824– 3934 m, bottom trawl, 12 July 1975 . MCZ 56939 (SL 89–100 mm, 2 females), 38°20’N, 69°24’W , RV Chain , cr. 124, st. 528, 3477– 3514 m, bottom trawl, 13 July 1975 . VIMS 05237 (SL 72–75 mm, 2 females) and ZMUC P77724-5 (SL 78–107 mm, male and female), 38°4.2’N, 70°26.4’W , RV Advance II, EPA 7801, st. 9, 3750– 3850 m, 45’ otter trawl, 24 June 1978 . VIMS 05236 (SL 104 mm, male), 38°0.2’N, 70°29.7’W , RV Advance II, EPA 7801, st. 14, 3864 m, 45’ otter trawl, 26 June 1978 . Non-types : ARC 8704503 (SL 112–116 mm, male and female), 38°13’N, 69°54’W , RV Oceanus , cr. 183, st.111, 3708 m, 41’ otter trawl, 18 Mar. 1987 . East Atlantic (17 specimens, SL 63–92 mm) . SAMZ 22924 (SL 74 mm, female), SE of Cape Town, 34°37’S, 17°03’E , RV Africana II, st. A315, 2980 m, 8 Dec. 1959 . MNHN 1976-0088 (SL 77 mm, male), SE Atlantic, 21°58.8’S, 9°19.7’E , RV Jean Charcot , Campagne Walda, st. 5, 4163 m, 9 June 1971 . BMNH 2018.11 .13.3 (SL 70 mm, female), NE Atlantic, 20°11.6’N, 21°37’W , RV Discovery , st. 9131#17, RMT8, 3910– 3995 m, 27 Nov. 1976 . BMNH 2018.11 .13.5 (SL 68 mm, male), NE Atlantic, 47°46.7’N, 15°23.3’W , RV Discovery , st. 11116 , OTSB 14 ’, 4800 m, 24 May 1984 . BMNH 2018.11.13.8-9 (SL 77–82 mm, female and male), NE Atlantic, 31°12.6’N, 25°12.5’W , RV Discovery , st. 11261#52 , OTSB 14 ’, 5440 m, 3 July 1985 . BMNH 2018.11 .13.1 (SL 88, female), NE Atlantic, 31°06’N, 25°3.7’W , RV Discovery , st. 11261#58 , OTSB 14 ’, 5400-5440 m, 4 July 1985 . BMNH 11262 #19 (SL 92 mm, male), NE Atlantic, 31°19.8’N, 25°29’W , RV Discovery , st. 11262#19, bottom net, 5432 m, 18 July 1985 . BMNH 2018.11 .13.2 (SL 69 mm, male), NE Atlantic, 49°02.42’N, 16°00.34’W , RV Discovery , st. 52403#14, bottom net, 4850-4860 m, 4 Dec. 1986 . BMNH 2018.1.13.6-7 (SL 77–88 mm, male and female), NE Atlantic, 31°14.9’N, 21°07.5’W , RV Discovery , st. 12174#31 , OTSB 14 ’, 3914–3938 m, 20 Aug. 1990 . MNHN 1976-0229 (SL 63 mm, male) and MNHN 1976-0230 (SL 67 mm, male), NE Atlantic, 47°30’N, 9°34’5.8’’W , RV Jean Charcot , Incal, st. CP16, 4263 m, 10 July 1976 . MNHN 2008-2058 (SL 72, female) , NE Atlantic , 27°30’N, 25°0’0’’W , RV Jean Charcot , Seabed 2, st CP17, Nov. 1980 . MNHN 2005-0280 (SL 68, female), NE Atlantic , 48°53’16.8’’N, 16°35’9.6’W , RV Discovery , Bengal 2 Campagne, st. 13078#11, 4844 m, 1 Apr. 1997 . MNHN 2005-0258 (SL 65, female), NE Atlantic , 48°50’9.6’’ N, 16°26’2.4’’W , RV Discovery , Bengal 3 Campagne, st. 13200#94, 4847 m, 25 July 1997 . ZMH 122183 (SL 73 mm, male), NE Atlantic, 46°7’N, 16°41’W , RV Walther Herwig , st. 70, Agassiz trawl, 4720 m, 6 June 1985 . Southwest Pacific (3 specimens, SL 42–95 mm) . ZUMT 59945 (SL 42 mm), SW Pacific , 30°00’S, 163°00’E , RV Hakuho-maru , KH-95-2, st. 092, 3 m IKMT, 0-0266 m, 31 Aug. 1995 . CSIRO H 8092-03 (SL 86 mm, male), Great Australian Bight, 35°42.95’S, 131°39.38’E , RV Investigator , st. IN2017_C01_178, beam trawl, 3817– 3950 m, 16 Apr. 2017 . CSIRO H 8093-01 (SL 95 mm, male), Great Australian Bight, 35°48.86’S, 131°42.16’E , RV Investigator , st. IN2017_C01_179, beam trawl, 4618–4750 m, 16 Apr. 2017 . Northeast Pacific (6 specimens, SL 66–128 mm). Holotype : - OS 1915 (SL 128 mm, female), NE Pacific, 44°41.1’N, 133°24.1W , RV Yaquina , st. TP-3, beam trawl, 3784 m, 3 June 1970 . Paratypes: OS 1965 (SL 66 mm), NE Pacific, 44°43.3’N, 134°43’W , RV Yaquina , st. NH-450, 22’ semi-balloon shrimp otter trawl, 3860 m, 1 Mar. 1967 . ZMUC P77538 (SL 106 mm, male), NE Pacific, 44°38.8’N, 131°11.04.2’W , RV Yaquina , st. TP-1, beam trawl, 3334 m, 30 May 1970 . Non-types : OS 11646 (SL 111, female), NE Pacific , 44°58.9’N, 133°14.2’W , RV Yaquina , cr. Y7210A, trawl, 3700 m, 7 Dec. 1972 . OS 11645 (SL 100, female), NE Pacific , 39°34.4’N, 127°25.2’W , RV Golden Fleece , GF 81, st. W-N 2, trawl, 4275 m, 4 Dec. 1981 . OS 12519 (SL 88 mm, female), NE Pacific, 37°43.2’N, 127°28.9’W , RV Golden Fleece , GF 81, st. W-N-6, otter trawl, 4250 m, 7 Dec. 1981 .

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 .

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 ).

Description. For a detailed description of the type specimens of B. pacificus and B. unicolor see Nielsen & Eagle (1974: 1067) and Nielsen (1984a: 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.

Distribution ( Figs. 1–2 ). Barathronus pacificus is recorded from the North and Southeast Atlantic Ocean, from off southern Australia and from the Southwest and Northeast Pacific Ocean. One specimen (SL 42 mm) caught in midwater trawl (0–266m) and the rest in bottom trawls between 2931 and 5440 m.

Figures

FIGURE 1. Records of Atlantic Barathronus species. Numbers indicate several stations.

FIGURE 2. Records of Indo-Pacific Barathronus species. Numbers indicate several stations.

FIGURE 21. Barathronus pacificus, OS 12519, female, SL 88 mm (M. Krag photo).

FIGURE 22. Intromittent organ of Barathronus pacificus:A—Northwest Atlantic MCZ 56936, holotype of Barathronus unicol- or, SL 113 mm (from Nielsen 1984a). B—Northeast Pacific ZMUC P77538, paratype, SL 106 mm (Nielsen & Eagle 1974).

FIGURE 23. Right otolith of Barathronus pacificus, CSIRO H 8093-01, male, SL 95 mm: A—inner face. B—ventral view.