New data on Discradisca Stenzel, 1964 (Brachiopoda, Discinoidea) from South and South-East Asia: description of D. borneensis n. sp. from NW Borneo and taxonomic status of D. semicornea (Preston, 1908)

Brachiopods are one of the minor phyla of marine invertebrates, and representatives of the superfamily Discinoidea Gray, 1840 are rare. To date, six species of the genus Discradisca Stenzel, 1964 are known, mainly from coastal waters around the world. A new species of Discradisca is described here from northwestern Borneo: Discradisca borneensis n. sp., widely distributed in shallow waters of the South China Sea, in Sarawak, Sabah (East Malaysia) and Brunei Darussalam. The low conical dorsal valve of the new species is ornamented by 125-135 tuberculate radial costellae. The irregularly subhexagonal ventral valve has an elongated, ovoid pedicle foramen, and rounded, smooth and white pedicle area. The outer part of the ventral valve is ornamented by numerous (about 180) closely spaced radial costellae without tuberculated appearance. During this work, it was noted that Acmaea semicornea Preston, 1908, a little-known gastropod species described from the Andaman Islands (India), also belongs to the genus Discradisca. Examination of the type material shows that it is a senior synonym of Discradisca indica Dall, 1920, a species widely distributed in South Asia. Although the name semicornea was previously unused by researchers specialising in brachiopods, it has priority over the name indica, which has been used for a long time but does not meet the criteria of the International Code of Zoological Nomenclature (Art. 23.9) for a reversal of precedence.