Barathronus parfaiti ( Vaillant, 1888 )

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 : 252

Barathronus parfaiti ( Vaillant, 1888)

Table 2. Figs. 1 , 24

Alexeterion parfaiti Vaillant, 1888: 283-284 , pl. XXV, fig. 2 (type locality: 44°29’N, 13°32’W). Alexeterion parfaiti: Goode & Bean 1896: 343 , fig. 300. Barathronus parfaiti: Roule 1915: 57–58 (in part.); Roule 1916: 18–19 and 1919: 73–74, pl.II, fig. 4 (= Barathronus roulei n.

sp.); Legendre 1934: 406 (= Oculospinus cf. brevis Koefoed, 1927 ); Grey 1956: 221 (in part); Nybelin 1957: 313–314 (=

Meteoria erythrops Nielsen, 1969 ); Nielsen 1969: 53–57 (in part.). Barathronus sp.: Nielsen et al. 1968: 242, 247 (= Barathronus roulei n. sp.).

Material examined Holotype: MNHN 86-554 (SL 40 mm, juvenile), between France and the Azores , 44°29’N, 13°32’W, RV Talisman, st. 137, small trawl, 4975–5005 m, 27 Aug. 1883.

Remarks. The holotype (MNHN 86-554) is the only known specimen of B. parfaiti . It is in a poor condition, being very soft and almost completely eviscerated. A second specimen in the Oceanographic Museum in Monaco (MOM P0I-0003655) was referred to B. parfaiti by Roule (1915: 57), but according to Nybelin (1957: 314) it is closer to Barathronus bicolor Goode & Bean, 1886 . Nielsen (1969: 54) based the description of B. parfaiti on the holotype and the MOM-specimen. However, with the new material available for this paper it became evident that the MOM-specimen represents an undescribed species (see page 23).

Diagnosis. Because of the condition and being a juvenile, only a few morphometric characters were recorded (those in Table 2 are from Vaillant (1888: 284)) and some of the meristic characters are approximations. The following combination of characters seems diagnostic: dorsal-fin rays 80–85, anal-fin rays 60–65, pectoral-fin rays 21, precaudal vertebrae 37, total vertebrae 84, long rakers on anterior gill arch 29, remains of a broken fang laterally on vomer and peritoneum transparent. Vaillant mentioned that the meristic characters were difficult to obtain and his counts are quite different from the present counts which are based on radiographs and mentioned in parentheses: dorsal fin rays 48 (80–85), anal fin rays 40 (60–65) and no pelvic fin rays (1).

Description. The present state of the specimen makes it difficult to obtain a usable description so below is given the original description by Vaillant (1888: 283) kindly translated from French by Guy Duhamel (MNHN): body elongate, compressed especially posteriorly. The greatest height is not more than 1/ 6 in length and the thickness 1/ 8 in length at the level of the pectoral fin. Head equal to 1/6 of length; the globular shape of the head gives it a rather strange form which reminds of Uranoscopus , Synanceia , etc. The head is truncated in front. The mouth, rounded as a horseshoe, is vertically orientated; the lower jaw is almost vertical when the mouth is closed. The two mandibles form a forward directed oval. Intermaxilla narrow, about the same size as the maxilla which expands at its posterior tip, or more precisely its inferior part because it is vertically orientated. The teeth are sharp-pointed and of equal size on the mandible and on the antero-superior part of intermaxilla; the posterior part seems edentate. No teeth visible on vomer and palatines. Eyes very small, about 1/15 of head length, seen as black-pigmented spots. Eye was hardly visible even then the specimen was newly caught. Branchial opening large extending very far forward. The small size of the specimen and membranous state of the hard parts makes it difficult to distinguish the opercular bones. Anus placed at mid-body. No scales and lateral line absent. The unpaired fins are fused, beginning dorsally at the level of anus and a little further back ventrally. The rays are extremely delicate and 4–5 mm in length. Pectoral fins extending to the level of dorsal fin origin. No pelvic fins. The fin ray counts are extremely difficult to obtain because of the conservation and size of the specimen. The color was uniformly white, slightly pinkish.

Comparisons. The transparent peritoneum and lack of ventral flexure of anteriormost vertebrae make it similar to B. multidens , but it differs by having more long rakers on anterior gill arch (29 vs 23–25) and fewer fangs on vomer (1 + 1? vs 7–11). The size and condition make a comparison to other Barathronus species rather irrelevant.

Distribution ( Fig. 1 ). Barathronus parfaiti was caught between France and the Azores in a trawl working at a depth of 4975–5005 m. All vertebral centra are rectangular and weakly ossified indicating a larval stage so the specimen might have been caught pelagically during hauling of the trawl.

Figures

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

FIGURE 24. Barathronus parfaiti, MNHN 86-554, holotype, SL 40 mm (J. Pfleger photo).