Mysidopsis gemina n. sp. (Crustacea: Mysida: Mysidae) from the northern Pacific coast of Costa Rica

Abstract

Mysidopsis gemina n. sp. is described from protected and exposed beach habitats in the provinces of Puntarenas and Guanacaste on the northern Pacific coast of Costa Rica. Morphologically, M. gemina most closely resembles M. furca Bowman, 1957 known from the Atlantic and Gulf Coasts of North America. Both these species are unique within the genus by their distinctively sexually dimorphic telsons. The new Costa Rican species can be distinguished from M. furca and other species of Mysidopsis by a combination of having a male with biarticulated endopods on the first pleopods and pleopods 2-5 with large plate-like pseudopodia (exites). The occurrence of these characters and morphological features within the subfamily Leptomysinae is discussed.

First record of Mysidopsis gemina Price, Heard & Vargas, 2019 (Crustacea, Peracarida, Mysida, Mysidae) on the west coast of Mexico

“…1E). The form of this appendage and the number of setae matches the description of M. gemina (Price et al 2019: Fig. 1F), including the 9 strong serrate setae on the outer lobe apex, and the inner lobe with two apical setae and one medial, short setae on outer margin.…”

“…The male appendix masculina is also large and densely setose, as in the original description. Price et al (2019) referred that the distal border of the peduncle possesses a dorso-medial lobe bearing two tooth-like processes; however, in the material examined there are 3 tooth-like, conical processes (Fig. 1B, arrow).…”

“…Mature specimens of M. gemina were separated from the rest of the samples, examined for details, and illustrated using a Nikon SMZ-10A and Leica MZ6 dissecting microscope, and a Leica DM LS2 compound microscope equipped with a camera lucida. Illustrations were compared with the original description by Price et al (2019). CL, carapace length.…”

“…Eastern Pacific mysid shrimp, also known as opossum shrimp, is poorly known south of California, and many species are known from a single locality or from a reduced area (Price, 2004;Hernández-Payán & Hendrickx, 2020). In the case of western Costa Rica, according to Price et al (2019) only four species of Mysidae had been reported until 2019. Based on samples collected in 2010 and 2012 in two locations on the Pacific coast of northern Costa Rica (Puntarenas and Guanacaste), Price et al (2019) described a new species of the genus Mysidopsis, M. gemina Price, Heard & Vargas, 2019.…”

“…In the case of western Costa Rica, according to Price et al (2019) only four species of Mysidae had been reported until 2019. Based on samples collected in 2010 and 2012 in two locations on the Pacific coast of northern Costa Rica (Puntarenas and Guanacaste), Price et al (2019) described a new species of the genus Mysidopsis, M. gemina Price, Heard & Vargas, 2019. This species was recently collected during sampling operations along a sandy beach in western Mexico, representing the first record outside of Costa Rica, thus extending considerably its distribution range in the eastern Pacific.…”