Gurayacypris, Battish, 1987

Comparisons between Gurayacypris and other

Notodromadinae genera

A key indicative character of the genus Gurayacypris is the presence of a scalloped line of concrescence which is not found in any other genera of Notodromadinae or in other subfamilies of the family Notodromadidae . This structure can be seen under a light microscope. Based on the aspects of eye tubercles and valve surface, Gurayacypris resembles Notodromas and Argentodromas as these three genera have improminent eye tubercles and their valve surfaces are not strongly ornamented. However, Gurayacypris is more similar to Notodromas than to Argentodromas because the former two have a sexually dimorphic Cp, unlike Argentodromas (see Smith & Kamiya, 2014; Diaz & Martens, 2018). In Cypridoidea, sexual dimorphism in the Cp shape has been recognised in Candonidae (e.g., Fabaeformiscandona subacuta ( Yang, 1982) , F. dolabella Smith & Janz, 2008 , F. pedana Smith & Janz, 2008 ; see Smith & Kamiya, 2007; Smith & Janz, 2008; Escrivá et al., 2012), Ilyocyprididae (e.g., Ilyocypris angulata Sars, 1903 , I. dentifera Sars, 1903 , I. thailandensis Savatenalinton, 2021 ; see Smith et al., 2019; Savatenalinton, 2021) and Notodromadidae . Among these three families, Notodromadidae shows the most distinctive sexual dimorphism in the Cp but which occurs only in two genera (see Battish, 1987; Smith & Kamiya, 2014; present study). Another significant feature of Gurayacypris is the sexual dimorphism of the T2 which is a rare feature as it appears in very few species. Among Notodromadidae genera, such a feature of the T2 has been seen only in Gurayacypris , which makes it a diagnostic character for the genus at present. A key to the genera of the subfamily Notodromadinae is also provided in this study.

Sexual dimorphism of the T2

The T2 of non-marine ostracods is a walking limb with a similar morphology in both sexes. Beside in Gurayacypris , sexual dimorphism in the appendage has also been recorded in some Cyprididae members, e.g., Cyprinotus cassidula Smith & Chang, 2020 (see Smith & Chang, 2020) and Martensina thailandica Savatenalinton, 2022 (see Savatenalinton, 2022). Dimorphism is more pronounced in Gurayacypris than in the other two species, where the difference between sexes lies only in the more robust serration of the terminal claw in males. On the other hand, in Gurayacypris , the T2 is slender in the male and stubby in the female. The three setae on the terminal segment are longer in males and are all slender; females have a claw (h2) and two setae (h1 and h3). The female character state is typical for all other Cypridoidea. It is possible that, like the modification of the T 1 in males, this sexual dimorphism is related to the mating process. However, no observations to confirm this are available so far.