BYTHITIDAE, T.N.Gill, 1861

Nielsen, Jørgen G., 2018, Revision of the cosmopolitan deep-sea genus Sciadonus (Teleostei, Bythitidae) with two new species, Cybium 42 (2), pp. 177-187 : 177-178

BYTHITIDAE : Sciadonus Garman, 1899

Synonymy

Sciadonus Garman, 1899: 172 , type species by monotypy

Sciadonus pedicellaris Garman, 1899 .

Leucochlamys Zugmayer, 1911a: 11 , type species by monotypy Leucochlamys cryptophthalmus Zugmayer, 1911 .

Leucochlamys : Nielsen, 1969: 69; Rannou et al., 1975: 1254; Cohen and Nielsen, 1978: 62.

Sciadonus : Nielsen, 1969: 62; Rannou et al., 1975: 1254; Cohen and Nielsen, 1978: 62; Nielsen, 1986: 1171; Nielsen et al., 1999: 142.

Diagnosis

The number of known specimens of the genus Sciadonus has increased considerably (from 11 to 304) since the diagnosis by Nielsen et al. (1999: 142), which involves that the generic diagnosis has been modified. Body long, slender and compressed. Loose, transparent, scaleless skin. Lower jaw protruding. Upper jaw ends below or slightly behind small, deepset eyes. Mouth almost horizontal. Palatines edentate. Vomer with or without small fangs. Basibranchial tooth patches not developed. Pectoral peduncle about three times as long as high. Dorsal fin rays 68-107; caudal fin rays 5-7; anal fin rays 38-60; pectoral fin rays 9-16; pelvic fin rays 0-1. Anterior gill arch without long and with 12-15 very small rakers. Vertebral centra in adults almost rectangular in lateral view. Males with well-developed urogenital hood ventrally covering penis. Females with a pair of claspers at urogenital opening.

Comparisons

Sciadonus differs from the six other genera in the aphyonid clade of the Bythitidae by the pectoral peduncle being about three times as long as high (vs length and height equal). It is most similar to Parasciadonus Nielsen, 1984 by the horizontal mouth and lack of long gill rakers. Rannou et al. (1975: 1255) suggested synonymizing Leucochlamys Zugmayer, 1911 and Sciadonus Garman, 1899 , which was effectuated by Cohen and Nielsen (1978: 63).