Additions to the Taxonomy of the Antarctic Dark-Mouth Skate <i>Bathyraja arctowskii</i> (Dollo, 1904), with Descriptions of the Syntypes and Morphology of Teeth, Dermal Denticles and Thorns

Abstract

The taxonomy of the enigmatic dark-mouth skate, Bathyraja arctowskii (Dollo, 1904), from the Southern Ocean was finally resolved after more than 100 years of ambiguity in 2021. This species is the smallest known species of the species-rich deep-water skate genus Bathyraja Ishiyama, 1958, which attains a total length of only about 61 cm and appears to be a wide-ranging and locally common species in the Southern Ocean. It differs from its congeners in the small adult size, dark-pigmented mouth cavity and underside of nasal curtain, lack of thorns on upper disc, as well as small and slender egg cases. Although the identity of this species was unambiguously clarified, the syntype egg cases could not be examined due to the COVID-19 pandemic. This examination has now become possible, and detailed data of the syntypes are provided in the present paper for the first time, together with hitherto unknown details of tooth, dermal denticle and thorn morphology. Furthermore, a lectotype and two paralectotypes are designated from the syntypes.

Keywords

• odontology
• ichthyodorulites
• microscopic morphology
• egg capsules
• Southern Ocean
• Arhynchobatidae