Meteoria erythrops Nielsen, 1969

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 : 217-219

Meteoria erythrops Nielsen, 1969

(Tab. II, Figs 1-5 )

Meteoria erythrops Nielsen, 1969: 58 (type locality east of the Azores).

Meteoria erythrops : Nielsen, 1972: 52; Cohen and

Nielsen, 1978: 62; Krefft, 1978: 14; Nielsen et al., 1999: 139.

Gen. et spec. indet.: Nybelin, 1957: 313.

Material examined

Holotype. – ZMH 25142 , SL 63 mm, female, east of Azores , 42°06.3’N, 14°42’W, R / V Meteor, cr. 3, st. 37, Agassiz trawl, 5320 m, 18-19 Mar. 1966.

Non-types. – NHMG Pi. 1746, SL 25 mm, juvenile, west of Azores , 40°32’N, 35°24’W, Swedish Deep-sea Exped., st. 387, bottom trawl, 4540-4600 m, 7 Sep. 1948 ; ZMUC P77544 , SL 70 mm, male, off NE Spain, 42°54’N, 13°25.1’W , R / V Meteor , st. 25/15, Agassiz trawl, haul 91, 5243 m, bottom temp. 2.6°C, 16-17 Sep. 1968 .

Diagnosis

Meteoria erythrops is long, compressed and rather slen- der with slightly protruding lower jaw and oblique mouth cleft. Head profile convex. Tiny, black eyes deep-set. A small area surrounding the eyes red-brown. Height of head and anterior body-depth equal. Head slightly broader than body. Palatines edentate. Dorsal fin origin well behind midpoint of fish. Dorsal fin rays 48-50. Predorsal length 56-64% SL.

Description

The principal meristic and morphometric characters are shown in table II. Body rather elongate and compressed. Skin scaleless, transparent and very loose. Square head of same height as the body and only slightly broader. Mouth opening oblique with slightly protruding lower jaw. Small, deep-set eyes situated above posterior end of lower jaw. No opercular spine. Dorsal fin origin well behind midpoint of fish (predorsal length 56-64% SL) and anal fin origin further back (preanal length 69-73% SL). Pectoral fin peduncle higher than or equal to length of peduncle. Anterior gill arch ( Fig. 4 ) with 8-10 minute rakers in the outer row of the two larger specimens and 2-3 minute rakers in the small specimen (NHMG Pi. 1746), all placed on ceratobranchial. Gill filaments absent dorsally and poorly developed ventrally on the anterior arch while gill filaments on rakers 2-4 are fully developed. Pseudobranchial filaments not observed.

Gonads. – The 8 mm long ovaries of the holotype rather distended. Left ovary with about 450 eggs of which 98% are less than 0.25 mm in diameter (in average 0.1 mm) and the rest 0.35 mm in diameter. Histological examination of part of the ovary shows no fertilized eggs. Histological examination of part of the 15 mm long testes of ZMUC P77544 shows numerous spermatids, but no spermatozoa or spermatophores, which are generally found in adult males in the aphyonid clade. Intromittent organ ( Fig. 5 ). Urogenital opening of the 70 mm long male (P77544) ventrally covered by a fleshy, genital hood covering a small penis-like papil- la. Examination of the gonads shows unripe testes and it is known from other species in the aphyonid clade e.g. Barathronus bicolor Goode & Bean, 1886 that the penis is very short in unripe specimens ( Nielsen, 1969: 42). Ripe female (ZMH 25142) with very small, genital hood. Claspers absent in both sexes.

Axial skeleton. – Number of precaudal vertebrae 40-41. Anterior neural spine equal in length to the following three spines and remaining neural spines all somewhat shorter. Parapophyses only developed on the last two precaudal vertebrae. Pleural and epipleural ribs absent. Vertebral centra rectangular in lateral view. Skeleton poorly ossified.

Dentition. – Anteriorly premaxillaries provided with 3-4 irregular tooth-rows near symphysis including a few doublesized, recurvated teeth. Number of tooth-rows decrease posteriorad to one row. Vomer with 14 pointed teeth in 1-2 rows placed on median half of bone. Dentaries with 2-3 uneven rows of recurvated, pointed teeth. Palatines edentate.

Otolith. – Dissolved. An old radiograph of ZMUC P 77544 (70 mm SL) shows sagittal otoliths about 0.5 mm in length.

Coloration. – The following colour observations were made six months after the capture of the holotype: skin transparent so the underlying tissues colour the specimen. A red brown area surrounding each of the black eyes. Peritoneum dorsally speckled with black pigment which also occurs at base of pectoral fin rays. The liver is brown.

Distribution ( Fig. 1 )

The three known specimens of Meteoria erythrops are all caught in non-closing bottom fishing gear (Agassiz and bottom trawls) in the northeastern Atlantic at depths of 4540- 5320 meters.

Comparisons

Meteoria erythrops differs from the other two species of the genus, M. longidorsalis n. sp. and M. pauciradiatus , by the convex head profile (vs flat head profile), larger interorbital width (7.1-8.7 vs 4.9-6.1% SL) and more precaudal vertebrae (39-41 vs 34-37). It is difficult to decide to which of the two species M. erythrops is most similar because no male specimen of M. pauciradiatus is known.

Figures

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

Figure 2. – Meteoria erythrops, ZMH 25142, holotype, female, SL 63 mm. A: Drawing; B: Photo after 49 years of preservation.

Figure 3. – Meteoria erythrops, ZMUC P77544, male, SL 70 mm, after 47 years of preservation.

Figure 4. – Meteoria erythrops, ZMH 25142, holotype: anterior, right gill arch.

Figure 5. – Meteoria erythrops, ZMUC P77544, male, SL 70 mm. Intromittent organ: a, anus; gh, genital hood (Robert Nielsen illust.)