Cypridopsis silvestrii (Daday, 1902)

(2) Cypridopsis silvestrii (Daday, 1902) was first described

– as Potamocypris silvestrii Daday, 1902 –

from a single ovigerous female collected from the Santa Cruz province in Chilean Patagonia.However, the original description and illustration present a maxillula palp with an elongated, cylindrical distal segment, and this feature prevents the species from belonging to the genus Potamocypris , where all species have this segment short and conspicuously spatulate. Potamocypris silvestrii was later transferred to the genus Plesiocypridopsis by Martens & Behen (1994), a generic position accepted by Martens & Savatenalinton (2011), Karanovic (2012), and Meisch et al. (2019a).

Recently, Pérez et al. (2019) and Ramos et al. (2021) (see also Sabater et al. 2023) presented a detailed redescription of C. silvestrii , showing a carapace with a left valve over right valve ventral overlap (the carapaces in Plesiocypridopsis and Potamocypris display the reverse overlap).

The latter character, in combination with other features led Pérez et al. (2019) to relocate C. silvestrii to the genus Cypridopsis , a generic position which is, provisionally, accepted herein. However, we note that C. silvestrii does not entirely fit the genus Cypridopsis , because: (a) the male sexual organ differs significantly from that of the type species, Cypridopsis vidua , which has only recently been described by Martens et al. (2023); (b) the carapace of C. silvestrii appears laterally compressed in dorsal view ( Pérez et al. 2019: fig. 2g –h), contrasting with a rather globular shape in species in Cypridopsis s. str. (e.g., Meisch 2000: figs 155d, 157d, 158c); and (c) the distal pincer organ of the third thoracopod (cleaning leg) displays a conspicuously long and straight h2-seta ( Pérez et al. 2019: fig. 5h), while this seta is distinctly shorter and recurved in Cypridopsis s. str. (e.g., Meisch 2000: figs 156f and 159h). We conclude that Cypridopsis silvestrii might belong to a separate, yet undescribed genus in the Cypridopsini , as is also most likely the case with the Lake Tanganyika Cypridopsis species (see Jacobs & Martens 2022).