Playing the detective in Ostracoda taxonomy: on types of the family Trachyleberididae

Abstract

The class Ostracoda possesses one of the most extensive fossil records among all animals. One of the most diverse and abundant ostracod families, the Trachyleberididae Sylvester-Bradley, 1948, inhabits marine environments since the Jurassic and has left an impressive stratigraphic record. Therefore, its fossil records have outstanding utilities for macroevolutionary research to better understand evolutionary history of marine life and to test the evolutionary theories in longer time-scales beyond those available for the most biological studies. However, the morphological characters defining the Trachyleberididae remain controvertial, in part because there is considerable taxonomic confusion regarding the Trachyleberididae’s type genus Trachyleberis Brady, 1898, and its type species Trachyleberis scabrocuneata (Brady, 1880). Here we resolve this confusion to develop robust taxonomic framework of this important ostracod family. We discuss in detail the taxonomic history of all taxa involved in this confusion, and validly fix Trachyleberis scabrocuneata (Brady, 1880) (sensu lectotype and paralectotypes from the Challenger Expedition) as the type species of Trachyleberis. Previous attempts to fix the type species of Trachyleberis either involved mixing of distinct species or decisions contrary to the International Code of Zoological Nomenclature. Additionally, we provide: (1) new diagnoses and discriptions of Trachyleberis and Trachyleberis scabrocuneata (Brady, 1880); (2) SEM photos of Trachyleberis scabrocuneata (Brady, 1880), Trachyleberis sp. nov. 1 (previously confused with Trachyleberis scabrocuneata (Brady, 1880)), Trachyleberis lytteltonensis Harding and Sylvester-Bradley, 1953 (previously mistakenly considered the type species of Trachyleberis) and Trachyleberis raynerae Neale, 1975 (the oldest species of Trachyleberis, which lived during the Cretaceous).