Meteoria longidorsalis, Nielsen, 2016

Nielsen, Jørgen G., 2016, Revision of the genera Meteoria and Parasciadonus (Bythitidae) with a new Atlantic, abyssal species of Meteoria, Cybium 40 (3), pp. 215-223 : 219-220

Meteoria longidorsalis n. sp.

(Tab. II, Figs 1 , 6 )

Material examined

Holotype. – USNM 222924 , SL 53 mm, male, Hatte- ras Abyssal Plain, 28°43.1’N, 75°49.7’W to 28°45.6’N, 75°52.5’W, R / V Columbus Iselin , cr. CI-1802, st. 04, 45’ semi-balloon otter trawl, 5105 m, 12 Feb. 1978.

Paratype. – BMNH 2015.5 .27.1, SL 75 mm, female, north of Madeira , 34°45.7’N, 18°30’W , R / V Discovery, st. 11134#1, 14’ semi-balloon otter trawl, 4790-4880 m, 10 Jun. 1984 .

Diagnosis

Meteoria longidorsalis n. sp. is long and slender with slightly protruding lower jaw and an oblique mouth cleft. Head broad and depressed. Palatines edentate and premaxil- lary, vomer and dentaries with a single row of small teeth. Eyes small and deep-set. Dorsal fin rays 58; dorsal fin origin at midpoint of fish; predorsal length 49.5-51% SL. Pectoral fin-peduncle short, higher than long. Pelvic fins absent. Anterior gill arch with hardly visible rakers and filaments.

Description

The principal meristic and morphometric characters are shown in table II. The description is based on the holotype; characters in which the paratype differs from the holotype are shown in brackets. Body elongate and compressed. Skin loose, scaleless and transparent. Head broad, depressed. Mouth opening oblique. Lower jaw slightly protruding. Eyes small, deep-set situated above posterior end of upper jaw. No opercular spine. Vertical fins joined. Dorsal fin origin at midpoint of fish and anal fin origin well behind midpoint of fish. Pectoral fin peduncle short, higher than long. Pelvic fins absent. Anterior gill arch without rakers (8-9 minute) and a few very small gill filaments ventrally on the arch, second arch with small rakers and filaments, third and fourth arches with small rakers and well developed filaments, fifth arch with a few small rakers. Pseudobranchial filaments not observed.

Gonads. – The long testes in holotype form 20% of SL. The much dilated ovaries of the paratype form 18% of SL and contain several large (0.7-0.9 mm in diameter) and many small (ca. 0.2 mm) eggs. Embryos were not observed.

Intromittent organ. – Both male and female specimen with a well-developed, fleshy genital hood; a pair of minute appendages at end of hood. Male with a short penis covered ventrally by the hood.

Axial skeleton (from radiographs). – Number of precaudal vertebrae 37. Anterior neural spine equal in length to the following spines. Parapophyses developed on precaudal vertebrae nos. 25-28 to no. 37. Pleural and epipleural ribs not developed. Vertebral centra rectangular in lateral view.

Dentition. – Premaxillaries, vomer and dentaries with a single row of very small, pointed teeth. Palatines edentate.

Otolith. – Dissolved. Old radiographs show sagittal otoliths about 0.5 mm in length.

Coloration. – Musculature brownish, light brown in paratype. Loose skin transparent. Small, deep-set eyes black.

Distribution

Meteoria longidorsalis n. sp. is known from two specimens, one from east of Florida (5105 m depth) and one from north of Madeira (4790-4880 m depth) both caught in bottom trawls.

Etymology

The specific name, longidorsalis , refers to the long dorsal fin base.

Comparisons

Meteoria longidorsalis n. sp. differs from the other two species of the genus, M. erythrops and M. pauciradiatus , by the higher number of dorsal fin rays (58 vs 47-50), position of the anterior anal fin ray in relation to the dorsal fin (below rays 19-25 vs 11-15) and predorsal length (49.5-51% SL vs 56-64% SL). M. longidorsalis n. sp. seems most similar to M. pauciradiatus with the flat head, the narrow interorbital width and rather few precaudal vertebrae.

Figures

Figure 1. – Records of species of Meteoria and Parasciadonus.

Figure 6. – Meteoria longidorsalis n. sp. A: USNM 222924, holotype, male, SL 53 mm, after 37 years of preserva- tion; B: BMNH 2015.5.27.1, paratype, female, SL 75 mm, photo after 31 years of preservation.