A new anchialine Stephos Scott from the Yucatan Peninsula with notes on the biogeography and diversity of the genus (Copepoda, Calanoida, Stephidae)

Abstract

Surveys of the anchialine crustacean fauna of the Yucatan Peninsula (YP), Mexico, have revealed the occurrence of calanoid copepods. The genus Stephos Scott, 1892, belonging to the family Stephidae is among the most frequent and widely distributed groups in anchialine caves but has not been hitherto recorded from the YP. Recent collections from an anchialine cave in an island off the northern coast of the YP yielded many specimens of a new species of Stephos. The new taxon, S. fernandoi sp. n., is described here based on male and female specimens. The new species is clearly distinguished from its congeners by the following characters: male left fifth leg with three terminal lamellae plus subdistal process, right leg with distal row of peg-like elements; female fifth leg with single long, acute apical process; genital double-somite with two rows each of 4 long spinules adjacent to operculum; legs 2-4 with articulated setae. The diversity of the genus shows regional differences; the Australia-Western Pacific region is the most diverse (eleven species), followed by the Mediterranean (seven species) and the Northeastern Atlantic (six species); only four species are known from the Northwestern Tropical Atlantic (NWTA). The morphology of the female fifth leg was examined to explore possible biogeographic trends in the genus; patterns suggest multiple colonization events in the highly diverse regions and a relatively recent radiation in the NWTA, characterized by anchialine forms. The introduction of stephid copepods in the region may be a relatively recent event derived from colonization of benthopelagic ancestral forms and subsequent invasion onto cave habitats. The new species appears to be linked to the strictly anchialine Miostephos.

Anchialine biodiversity in the Turks and Caicos Islands: New discoveries and current faunal composition

“…Considering the new records presented herein, it is evident that substantial undocumented diversity is still to be found in the anchialine realm. New species are constantly described even in relatively wellinvestigated and easily accessible anchialine systems, including for example those in Yucatán Peninsula and Lanzarote, where six (Rubio et al, 2015;Suárez-Morales et al, 2017b, 2017aAngyal et al, 2018;Grego et al, 2019;Sánchez & Martínez, 2019) and five new species (Martínez et al, 2016b;Gobert et al, 2019;Worsaae et al, 2019aWorsaae et al, , 2019b, respectively, have been described within the last five years. These numbers highlight the importance of continued exploration, particularly considering that some anchialine species may use different habitats rather than caves, appearing only occasionally in caves (Martínez et al, 2013).…”

How is the anchialine fauna distributed within a cave? A study of the Ox Bel Ha System, Yucatan Peninsula, Mexico

“…Although basic ecological questions are of great importance, few studies have been published regarding the population dynamics of key species, trophic interactions and seasonal variations in diversity and abundance in these environments (Pohlman et al 1997, Havird et al 2015, Brankovits et al 2017. Two main reasons have hindered the progress of this type of studies: first, the very specialized diving techniques needed to gather samples and data from the flooded cave environments (Iliffe 2018) and second, the poor knowledge about the total diversity of these systems reflected in the constant finding of new species (e.g., Alvarez et al 2017, Suárez-Morales et al 2017.…”

Ecological patterns in anchialine caves

“…and the isopod Metacirolana mayana . The shrimp Procaris mexicana was found in El Aerolito, La Quebrada and Tres Potrillos, but not in Bambú [ 5 , 20 , 47 , 54 , 55 ]. This indicates that the specific composition of each anchialine cave is unique, a pattern previously observed for sponges and fishes in Mediterranean marine caves [ 3 , 26 ].…”