First record of Oxynoe panamensis (Pilsbry & Olsson, 1943) (Mollusca: Opistobranquia) in the Ancash Region, Peru (2016-2017)

Abstract

For the first time, we recorded the species Oxynoe panamensis in the Ancash Region, describing the taxonomic characters that identify it. We analyzed its lengths, relative density, space-time distribution, and some oceanographic variables such as temperature (°C), dissolved oxygen (mL/L), and salinity (psu) at the El Dorado natural bank (9°18’S/78°56’W). We collected 16 live O. panamensis specimens, recording sizes ranging from 22 to 40 mm in length. Their relative densities were low, with values from 1 to 3 ind./m2, with a decreasing pattern from June 2016 to June 2017, being completely disappeared by November 2017. The spatial distribution and frequency of occurrence showed a similar pattern as the density, with 20.8% of occurrence and “extended” distribution in June 2016 to an occurrence of 3.8% and “restricted” distribution in June 2017. The oceanographic variables in the species’ environment showed values that varied from 18.0 to 21.2 °C; 2.81 to 5.89 mL/L of dissolved oxygen, and 34.82 to 35.29 psu of salinity. The latitudinal distribution of O. panamensis in the Peruvian north-central coast (9.18°S) was extended, coexisting on a meadow of Caulerpa filiformis.