Ankumia van Veen, 1932: a valid name, but a flawed generic concept (Ostracoda, Platycopina, Cytherelloidea)

Abstract. Recent study of the syntype material of the type species of the monotypic genus Ankumia van Veen, 1932 (A. bosqueti van Veen, 1932) confirmed a pathological retention of moults, expressed by multilayered ridge-like structures, used for the original diagnosis of the genus (Jones, 2003). For this reason, it was proposed that the genus Ankumia should be abandoned as a nomen dubium in favour of Platella Coryell & Fields, 1937. This interpretation was challenged by Malz & Lord (2004), who saw no reason to treat Ankumia as nomen dubium and, acknowledging the unequivocal cytherellid nature of the species, posed and addressed two taxonomical questions: (1) do pathological individuals of cytherellids justify specific and/or generic ranking?; (2) why should Ankumia be abandoned in favour of Platella?

In addressing their first question, Malz & Lord (2004) correctly answered in the negative. However, they claimed that ‘... demonstration of a corresponding “normal” species (including “pathological individuals”) among the associated cytherellids is wanting’. The author disagrees with this statement because he described and illustrated two morphological shell-types among the specimens assigned as syntypes of Ankumia bosqueti in the van Veen/Bonnema collection. They are the ‘Cytherella shell-type’ (Jones, 2003, pl. 1, figs 2–8) and the ‘Ankumia shell-type’ (Jones, 2003, pl. 1, fig. 1; pl. 2 figs 1–14), which correspond to the ‘normal’ species, and to the pathological individuals of that species, respectively. The Ankumia shell-type possesses concentric ribs that become progressively thinner from the adult to the juvenile stages. Of the 22 syntypes studied, 13 . . .