Nybelinella brevianalis

description

Description. The principal meristic and morphomorphic characters are shown in Table 1. Body elongate and slender. Head higher and broader than body. Skin loose, transparent and without scales. Lower jaw slightly protruding. Eyes small and deep-set with a centrally placed pigmented part (0.4 mm in diameter) surrounded by a narrow, black ring (1 mm in diameter). Nostrils and head pores very difficult to observe due to torn skin. Vertical fins joined. Origin of dorsal fin well in front of midpoint of fish. Origin of anal fin far behind midpoint of fish (preanal length 73 % SL). Pelvic fins, with one short ray in each, placed below basis of pectoral fins. Anterior gill arch without rakers on upper branch and lower branch with 20 equally sized, small rakers all provided with small denticles. Gill filaments extremely small. Length of distended ovaries 17 mm. Many fertilized eggs (1 mm in diameter) and several free embryos (10 mm long). Urogenital hood ends in a pair of torn claspers. Axial skeleton (Fig. 10). Number of precaudal vertebrae 42. All neural and haemal spines ovate-formed. Parapophyses and ribs not developed. The two vertebrae just in front of the anterior vertebra with an ov

Revision of the genus Nybelinella (Teleostei, Bythitidae) with a new Atlantic, abyssal species

diagnosis

Diagnosis. Nybelinella brevianalis is long, slender and compressed. Dorsal fin with 81 rays, anal fin with 45 rays and pectoral fins with 25 rays. Totally 76 (42 + 3 4) vertebrae. Origin of anal fin below dorsal fin no. 33. Upper branch of anterior gill arch without rakers and lower branch with 20 equally sized, small rakers. Small teeth on vomer. All neural and haemal spines ovate-formed (see note to Key to Species). Predorsal 44.0 % SL and preanal 73 % SL. Comparisons. Nybelinella brevianalis differs from N. brevidorsalis and N. erikssoni by having fewer anal fin rays (45 vs. 50 - 57), no rakers on epibranchials (rakers present) and all neural and haemal spines ovate-formed (vs. all spines thin and pointed). From N. brevidorsalis it differs furthermore by having more dorsal fin rays (81 vs. 70), shorter predorsal length (44.0 vs. 52 % SL) and origin of anal fin below dorsal fin ray no. 33 (vs. 19) and from N. erikssoni it differs by a longer preanal length (73 % vs. 58 – 64 % SL).

Revision of the genus Nybelinella (Teleostei, Bythitidae) with a new Atlantic, abyssal species

distribution

Distribution (Fig. 1). Known from one specimen trawled at abyssal depth (4914 – 4938 m) west of Madeira in the Northeast Atlantic Ocean.

Revision of the genus Nybelinella (Teleostei, Bythitidae) with a new Atlantic, abyssal species

etymology

Etymology. The specific name, brevianalis, refers to the short anal fin.

Revision of the genus Nybelinella (Teleostei, Bythitidae) with a new Atlantic, abyssal species