Trilocypris, Halse & Martens, 2019

Halse, Stuart A. & Martens, Koen, 2019, Four new genera and five new species of ‘ Heterocypris’ from Western Australia (Crustacea, Ostracoda, Cyprinotinae), European Journal of Taxonomy 493, pp. 1-35: 13

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gen. nov.

Trilocypris   gen. nov.

Type species

Trilocypris horwitzi   gen. et sp. nov. (here designated).

Other species

The genus is thus far monospecific.


Valves high posteriorly, moderately arched, LV overlapping RV on all sides. RV with marginal tubercles (sometimes strongly developed) at least along anterior and postero-ventral margins and an outer list. RV with anterior sub-marginal selvage only; posteroventral selvage more clearly inwardly displaced. LV anteriorly with a blunt inner list parallel to valve margin. A1 with all segments of normal length / width ratio.Second segment of Mx1 palp slightly longer than basal width, not curved. Second segment on Lpp with long distal flagellum. Seta d2 on T2 absent. CR in both male and female proximally curved, but without swollen proximal side; attachment to CR uniramous, i.e., distally not bifurcated. Hemipenis in males with three distal lobes.


This new genus is named after one of its most defining characters, namely the fact that the hemipenis in the male has three distal lobes (instead of two as in other Cyprinotinae   ). We shortened ‘trilobe’ to ‘trilo’ for convenience.

Differential diagnosis

Trilocypris   gen. nov. has valve characteristics that are similar to those of Heterocypris   , but differs from all other genera in the Cyprinotinae   by the structure of the hemipenis, which has three distal lobes. This is unique in the subfamily Cyprinotinae   , and possibly even in the entire family Cyprididae   .

The new genus can furthermore be distinguished from Cyprinotus   by the absence of the dorsal hump on the right valve, from Hemicypris   and Homocypris   by the fact that the LV overlaps the RV (inverse in Hemicypris   ; valves symmetrical in Homocypris   ) and from Riocypris   by, among other features, the absence of seta d2 on T2.


Currently known from the Yilgarn region of Western Australia only.


As usual in monospecific genera, it is difficult to determine which characters are valid at the generic level and which at the specific level. The diagnosis of this new genus may need to be adapted if more congeneric species are found.