Nybelinella Nielsen, 1972

Nielsen, Jørgen G., 2017, Revision of the genus Nybelinella (Teleostei, Bythitidae) with a new Atlantic, abyssal species, Zootaxa 4247 (1), pp. 45-54 : 45-46

Nybelinella Nielsen, 1972

Nybelinia Nielsen, 1969: 22 (type species Barathronus erikssoni Nybelin, 1957 by monotypy; preoccupied by Nybelinia Poche, 1926 (Vermes) .

Nybelinella Nielsen, 1972 replacement name for Nybelinia Nielsen, 1969 taken the same type species. Nybelinella: Nielsen 1972: 55 ; Cohen & Nielsen 1978: 62; Nielsen 1986: 1170; Nielsen 1990: 576; Nielsen et al. (1999: 140).

Diagnosis. Because of the significant increase of material (from four to 24 specimens) the generic diagnosis has been modified. Body elongate and compressed. Skin loose, transparent and scaleless. Pectoral peduncle as long as high with 23–27 fin rays. One short ray in each pelvic fin. Dorsal fin with 70–92, caudal fin with 7–9 and anal fin with 45–57 rays. Head broader and deeper than body. Mouth opening oblique ending in front of indistinct, deep-set eyes. Lower jaw slightly protruding. All teeth small and pointed; palatines edentate. Anterior gill arch with 20–27 small rakers of which 0–11 are slightly prolonged. Precaudal vertebrae 37–42 and total vertebrae 72–79. Vertebral centra in adults almost rectangular in lateral view and generally poorly ossified. Sagittal otolith small and semispherical. Females with a pair of claspers distally on urogenital hood. Males with penis more or less covered ventrally by urogenital hood; claspers not developed.

Comparisons. Of the seven genera (see Nielsen 2015: Table 1 ) in the aphyonid clade of Bythitidae Nybelinella seems most similar to Barathronus Goode & Bean, 1886 and Meteoria Nielsen, 1969 , with an oblique mouth opening and short pectoral peduncle. Nybelinella differs from Barathronus by having 20–27 short rakers on anterior gill arch (vs. 23–35 rakers, about five times as long) and vertebral centra rectangular in lateral view (vs. hour-glass shaped). From Meteoria it differs by having 20–27 short rakers on anterior gill arch (vs. no rakers), 23– 27 pectoral fin rays (vs. 12–15 rays), one short pelvic fin ray (vs. no rays), more dorsal fin rays (70–92 vs. 47–58) and more anal fin rays (45–57 vs. 31–40).

N. erikssoni N. brevianalis N. brevidorsalis