Leptoderma macrophthalmum Byrkjedal, Poulsen & Galbraith, 2011, sp.n.
Creators: name: Byrkjedal, Ingvar
name: Poulsen, Jan Yde
name: Galbraith, John
Publisher: name: Zenodo
Year: 2011
Subjects: Biodiversity
Taxonomy
Animalia
Chordata
Actinopterygii
Osmeriformes
Alepocephalidae
Leptoderma
Leptoderma macrophthalmum

description: Leptoderma macrophthalmum sp.n.
(Fig. 2–3)
Holotype. NORTH ATLANTIC, 42o47’ N – 29o38’ W, 8 July 2004, 2107– 2063 m gear depth, soft bottom, R/V “G. O. Sars”, super station 42, local station 368, ser. 1150, bottom trawl (shrimp trawl). ZMUB 19686.
Diagnosis. The species differs from three of the four other congeneric species (L. affinis, L. macrops and L. retropinna) by having a distinct gap between the posterior ends of the dorsal and anal fins and the beginning of procurrent caudal finrays. This gap is absent in the three species mentioned, but present in the fourth (L. lubricum), from which L. macrophthalmum differs by having a lack of dermal papillae along the lateral line, pectoral fins lower on body, a larger eye relative to head dimensions, and a shorter pre-dorsal length.
Description. SL 151 mm, fresh weight 16 g. Dimensions as per cent of SL as follows: Pre-dorsal length 49.3, pre-anal length 45.7, pre-pelvic length 39.5, dorsal fin base 31.1, dorsal procurrent caudal fin section 15.5, anal procurrent caudal fin section 15.1, anal fin base 40.7, pectoral fin length (left) 7.3, pelvic fin length (left) 4.8, greatest body depth 12.8, caudal peduncle depth 2.1, maximal head width (behind eyes) 11.3, head length 23.2, snout length 7.0, horizontal orbital diameter 9.3, post-orbital head length 7.2, upper jaw length 7.9. Eye diameter as percent of head length 40.3. Fin-ray counts as follows: D 32, procurrent dorsal fin 21, A 47, procurrent anal fin 20, pectoral fins 8 (left and right), pelvic fins 8 (left and right), caudal fin 16. Number of gillrakers on first arch 19. Five branchiostegal rays on each side. Total number of vertebrae 67 (15 + 52).
No scales present. Body slender and compressed, greatest body depth a distance from the snout of 13.9 % of SL. Eyes large, upper margin protruding above the dorsal profile of the head. The dorsal profile of the forehead in the fresh specimen convex, but straightening over the snout (shrinkage caused by preservation has decreased the convexity of the forehead profile). Pectoral fins are set fairly low, their upper fin-ray in level with dorsal corner of the gill opening.
Pores along the lateral line about 48, difficult to observe. No dermal papillae found along the lateral line, on the head, or along the back. Three supraorbital pores, four suborbital pores, three preopercular pores, and four mandibular pores, all of these large. Nostrils with large longitudinal openings, partly covered by a dermal flap.
Mouth subterminal. Small, well separated conical teeth present in one row on premaxilla and dentary, the latter teeth of minute size. Supramaxilla slender, pear-shaped and curved.
Head and anterior part of body black, turning gradually lighter brownish towards posterior.
Molecular characterization. The mitogenome sequence of the specimen is 16,607 bp long and shows a typical vertebrate gene order with L and H-strand coding of the 13 protein coding genes, 2 rRNA genes and 22 tRNA genes (Table 2). Compared to the other two species of Leptoderma available, the mitochondrial genome in this new species is 6 and 9 bp longer than L. retropinna and L. lubricum, respectively. Mitogenomic p-distances between the new species and congeners show a difference of 5.2% compared to Leptoderma lubricum and 6.1% compared to L. retropinna with polymorphisms distributed fairly equal throughout the genome. Most polymorphisms are found at third codon positions of protein coding genes and in the control region (Table 2).
Etymology. The specific epithet macrophthalmum (from Greek makros, large, and Greek ophthalmos, eye) refers to the large eyes found in this species.
Mitogenome of Leptoderma mac- Number and position of mt polymorphisms between L. macrophthalmum and a
rophthalmum L. lubricum L. retropinna
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Mitogenome of Leptoderma mac- Number and position of mt polymorphisms between L. macrophthalmum and a rophthalmum L. lubricum L. retropinna
a Gaps excluded from the data since only about 20 gaps are present in the alignments (most located in 16S and CR) b Two additional transitions in intervening non-coding regions included
description: Published as part of Byrkjedal, Ingvar, Poulsen, Jan Yde & Galbraith, John, 2011, Leptoderma macrophthalmum n. sp., a new species of smooth-head (Otocephala: Alepocephalidae) from the Mid Atlantic Ridge, pp. 49-56 in Zootaxa 2876 on pages 51-54, DOI: 10.5281/zenodo.277564