On two species ofRiocypris(Crustacea, Ostracoda) from northern Patagonia and their relation toEucypris fontana: implications in paleoenvironmental reconstructions

Abstract

Two species of ostracods new to Patagonia, Argentina, are described. One of them, Riocypris whatleyi sp. nov., is described for the first time, and the second, Riocypris sarsi (Daday, 1902) comb. nov., is reallocated from genus Eucypris to genus Riocypris. Inter- and intra-specific variations in shape, size, and sexual dimorphism were evaluated based on geometric morphometric analysis. Moreover, morphological and morphometric comparative analyses were applied to re-examine living and quaternary specimens recovered from previous studies. Based on these results, a generic reassignment for the Patagonian Eucypris fontana (Jurine, 1820) into the genus Riocypris is proposed. Contributing to the knowledge on the systematic and autecology of this enigmatic species, widely distributed in Patagonia and frequently used in paleolimnological reconstructions, generates science-based evidence for their use as indicator species. Additionally, our results emphasize the usefulness of studying the living representatives (i.e., with valves and appendages) for elucidating the taxonomic status of the individual specimens, especially those present in paleontological records and used as bioproxies in paleolimnological studies.

Changes in ostracod assemblages and morphologies during lake‐level variations of Lago Cardiel (49°S), Patagonia, Argentina, over the last 15.6 ka

“…This species was also recently recorded in Laguna Los Juncos (41°S), a semi‐permanent shallow lake with water conductivity around 1000 μS cm −1 , in northern Patagonia (Coviaga et al . ). Thus, this represents a new record of this species in a Quaternary sequence, highlighting the need for more ecological studies in order to improve the current knowledge about the environmental preferences of this species.…”

“…The present results also point out that subfossil and modern specimens from Lago Cardiel (CAR 99‐7P core, CB and CT) and surrounding areas of this lake (2H and RB) are more similar than modern specimens from ST, LH, LV and El Toro lake (Coviaga et al . ) where rounded morphotypes prevail, indicating that R. whatleyi valve morphology is temporally stable but spatially variable (Fig. , ).…”

“…), but these morphological variations were subtle. However, recently, the rounder morphotype was found living in LV as well as in El Toro lake, a semi‐permanent environment also with higher pH (~9.3) and Mg 2+ (3.0 to 2.9 mEq L −1 ) but with lower Ca 2+ content (0.1 to 0.2 mEq L −1 ), exposing a wider range of occurrence (Coviaga et al . 2018a, b).…”

“…() and Coviaga et al . (). The most representative specimens were photographed using a scanning electron microscope (SEM).…”

“…R. whatleyi Coviaga et al, 2018b andR. sarsi (Daday, 1902), and led to the reassignment of those specimens originally determined as E. fontana to R. whatleyi (Coviaga et al 2018b).…”