Barathronus bicolor Goode & Bean, 1886

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 : 237-239

Barathronus bicolor Goode & Bean, 1886

Table 1. Figs. 1 , 7–8

Barathronus bicolor Goode & Bean, 1886: 164 (type locality: 16°03’10’’N, 61°52’20’’W).

Barathronus bicolor: Gilchrist 1906: 158 ; Nielsen et al. 1968: 247; Nielsen 1969: 31; Rannou et al. 1975: 1255; Nielsen et al. 1999: 138; Nielsen et al. 2015: 58.

Material examined (74 specimens). Old material (54 specimens, SL 58–140 mm). See Nielsen (1969 —station data for 42 specimens), Rannou et al. (1975 —station data for 9 specimens) and Nielsen, Mincarone & Di Dario(2015 - station data for 3 specimens). New material (20 specimens, SL 72–115 mm): MNHN 1963-0630 (SL 98 mm, female), Gulf of Mexico , 24°25’1.2’’N, 83°28’58.8’’W , RV Oregon , st. 4145, trawl, 549 m, 14 Dec. 1962 . TCWC 6154.2 (SL 115 mm, female), Gulf of Mexico , 18°54’N, 94°58.8’W , RV Alaminos , st. 69A11-27, trawl, 780–825 m, 14 Aug. 1969 . TCWC 3972.1 (SL 100 mm, female), Gulf of Mexico , 19°01’N, 94°59’W , RV Alaminos , st. 69A11-39, trawl, 1300–1390 m, 15 Aug. 1969 . TCWC 3791.12 (SL 85 mm, female), Caribbean Sea, 11°33.8’N, 73°45.1’W , RV Alaminos , st. 70A10-31, trawl, 735 m, 17 July 1970 . TCWC 6319.10 (SL 100 mm, female), Gulf of Mexico , 27°27.8’N, 92°46’W , RV Alaminos , st. 71A7-43, trawl, 1010–1100 m , 22 July , 1971 . TCWC 6326.2 (SL 72 mm, female), Gulf of Mexico , 25°52’N, 93°15.8’W , RV Alaminos , st. 71A8-13, 20 meter trawl, 3270 m, 31 July 1971 . TCWC 5322.1 (SL 95 mm, male), Gulf of Mexico , 23°17.4’N, 97°02.4’W , RV Alaminos , st. 72A13-23, 20 m trawl, 1010–1080 m, 12 July 1972 . TCWC 5323.1 (SL 95 mm, male), Gulf of Mexico , 27°26.4’N, 94°07.6’W , RV Alaminos , st.72A13-39, 20 m trawl, 1290 m, 14 July 1972 . TCWC 3561.5 (SL 90 mm, male), Gulf of Mexico , 27°15.3’N, 93°41.1’W , RV Alaminos , st. 73A10-20, trawl, 810–1140 m, 23 June 1973 . TCWC 5324.1 (SL 103 mm, female), Gulf of Mexico , 29°11’N, 87°57’W , RV Oregon II, st. 37718, 40’ trawl, 552 m, 30 Oct. 1982 . ZMH 119884 (SL 95 mm, female), off Cape Fear, 33°38’N, 76°04’W , RV Anton Dohrn 2, trawl, 796–800 m, 11 Aug. 1979 . UF 222576 (2 spms., SL 98–105 mm, female and male), Caribbean Sea, 10.27° N, 76.05°W , RV Pillsbury , st. PIL388, trawl, 814–1050 m, 15 July 1966 . UF 233386 (SL 92 mm, female), Anguilla, 18.49°N, 63.41°W , RV Pillsbury , PIL988, trawl, 686–724 m, 23 July 1969 . UF 235370 (SL 107 mm, female), Tongue of the Ocean, 24.18°N, 77.39°W , RV Columbus Iselin , CI302, trawl, 1452–1465 m, 3 Apr. 1975 . UF 131282 (SL 112 mm, female), Tongue of the Ocean, 23.57°N, 76.71°W , RV Columbus Iselin , st. CI370, trawl, 1267–1296 m, 23 Aug. 1975 . UF 109362 (SL 100 mm, female) Strait of Florida , 24°14’31.2’’N, 82°36’49.8’’W , RV Bellows , st. FFS98-5B, 510 m, 1 May 1998 . ZMUC P77463 (SL 91 mm, male), Gulf of Mexico , 24°49’N, 96°27’W , RV Oregon , st. 4814, 40’ shrimp trawl, 914 m, 12 Apr. 1964 . ZMUC P77708 (SL 90 mm, male), Tongue of the Ocean, 24°25.9’-24.2’N to 77°24.0’- 23.6’W , RV Columbus Iselin , cr. CI-8007, st. C039, 30’ otter trawl, 1584–1594 m, 14 Sep. 1980 . ZMUC P77709 (SL 105, female), Tongue of the Ocean, 23°48.2’- 48.6’N, 77°04.5´- 07.8’W , RV Columbus Iselin , cr. CI-8007, st. CO42, 30’ otter trawl, 1376– 1371 m, 15 Sep. 1980

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.

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 ).

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. 10A ) 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. 7B 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.

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.

Figures

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

FIGURE 7. Barathronus bicolor: A—ZMUC P77709, female, SL 105 mm, after 40 years of preservation (M. Krag photo). B—UF 222576, male, SL 105 mm, after 55 years of preservation (M. Krag photo).

FIGURE 8. Left otolith of Barathronus bicolor, ZMUC P77708, male, SL 90 mm.

FIGURE 10. Barathronus diaphanus, ZMUC P771586, female, SL 112 mm: A—shortly after capture (G. Brovad photo). B—after 12 years of preservation (M. Krag photo).

FIGURE 11. Barathronus diaphanus MNHN 1995-914, male, SL 104 mm (M. Krag photo).