Ectreposebastes niger ( Fourmanoir, 1971 )

Romanov, Evgeny V., Cherel, Yves & Marsac, Francis, 2021, New record of Ectreposebastes niger (Fourmanoir, 1971) (Setarchidae, Scorpaeniformes): a rare bathypelagic fish from La Pérouse Seamount, Western Indian Ocean, and distribution of Ectreposebastes Garman, 1899 in the Indian Ocean, Zoosystema 43 (15), pp. 283-296 : 286-287

Ectreposebastes niger ( Fourmanoir, 1971)

( Fig. 2 )

Pontinus niger Fourmanoir, 1971: 42 , fig. 6.

TYPE MATERIAL. — Holotype. Pacific Ocean • MNHN-IC-1970-0034 , 122 mm SL, 09°56’S, 141°52’W; 0-1200 m depth; 12.IX.1969; CARIDE 5; R/V Coriolis.

MATERIAL EXAMINED. — La Réunion • MNHN-IC-2019-0078 ; no sex data; 165 mm SL; Southwestern Indian Ocean ; 19°45.84’S, 54°05.28’E- 19°41.43’S, 54°03.80’E; 18.IX.2016; Romanov, IRD LA PÉROUSE leg; R/V Antea .

DISTRIBUTION. — Indo-West Pacific meso- and bathy-pelagic, mostly near continental/peri-insular slopes in tropical and temperate waters.

DESCRIPTION

Individual MNHN-IC-2019-0078 (165 mm SL)

External morphology. Medium-sized, black-coloured scorpaeniform fish with black-yellowish eyes. Pinkish muscles visible through semi-transparent skin in scale pockets; scale pocket edges black. Body relatively high, slightly compressed laterally, flabby, lacking scales (most scales lost, except some pored LL scales) ( Fig. 2 ). Most fin spines, some fin rays broken due to fragile, poorly-ossified nature. First pre-opercular spine weakly developed; others damaged. Lacrimal spines short, intact on the left side but damaged on right. Body proportions shown in Table 1 .

Otoliths. Thick and robust. Otolith shape triangular with pointed rostrum ( Fig. 3 ); ventral rim convex; post-dorsal rim almost straight without depression; pre-dorsal rim forming angle close to 90° with post-dorsal rim. Otolith height almost equal to otolith length (ratio OH/OL 0.75-0.79 for right and left otoliths respectively). Sulcus acusticus: archaesulcoid, ostial, median. Ostium and cauda: undifferentiated, oval. Anterior region: double-peaked; rostrum broad, short, slightly pointed, antirostrum very short, rounded, broad; excisura wide with shallow notch. Posterior region: oblique to round or oblique to irregular.

REMARK

The morphology of our specimen corresponds well to the original description given by Fourmanoir (1971) and later by Mandrytsa (1990). Body measurements are close to the ranges presented in other studies. However, many proportions are close to or even outside of the lower end of reported ranges ( Table 1 ).

GENETIC ANALYSIS

A 555 bp region of the mtDNA COI gene was isolated from the specimen and the sequence was deposited in the INSD (accession number: MN181524 ). The query sequence did not find 100% match to the mtDNA COI region of any other specimens. The nearest matches were non-identified specimens Ectreposebastes sp. (98.13% to 98.31% similarity) and Ectreposebastes imus (97.10% to 98.13% similarity). Neighbour joining tree analysis ( Fig. 6 ) shows distinct clustering between E. imus , E. niger and Ectreposebastes sp. DNA signatures. The E. imus branch is separated from another branch that contains our E. niger specimen ( MN181524 ) and Ectreposebastes sp. specimens (FOAE60706, FOAF803-07) collected from the Southwestern Pacific: Coral Sea (off Australian coast) and from over Lord Howe Rise.

An ABGD analysis aimed at detecting genetic gaps between species ( Puillandre et al. 2012) clustered Ectreposebastes sequences into three lineages, segregating E. imus , E. niger ( MN181524 ) and Ectreposebastes sp.

Figures

FIG. 2. — Individual of Ectreposebastes niger (Fourmanoir, 1971) caught in the pelagic environment during the LA PÉROUSE cruise.Scale bar:10 mm. Specimen MNHN-IC-2019-0078. Photo credit: Francis Marsac.

FIG. 3. — Otoliths: left (A), right (B) of Ectreposebastes niger (Fourmanoir, 1971), 165 mm SL, 183 mm TL, reported in this study. MNHN-IC-2019-0078. Scale bars: 1 mm.

FIG. 6. — Neighbour joining tree of the genus Ectreposebastes Garman,1899 based on DNA sequences of the mitochondrial COI gene. The tree was constructed based on Ectreposebastes spp. sequences publicly available in Barcoding of Life Data System v. 4 (BOLD) and the sequence from our specimen of Ectreposebastes niger (Fourmanoir, 1971) (MNHN-IC-2019-0078, BOLD accession number: MN181524). The optimal tree with the sum of branch length = 0.22318084 is shown. The tree is drawn to scale, with branch lengths in the same units as those of the evolutionary distances used to infer the phylogenetic tree. Trachyscorpia cristulata (Goode & Bean, 1896) (BOLD ID ANGBF14113-19) were used as outgroup.