Ecological notes on the species of Phacus Dujardin (Euglenophyta) from the central region of Portugal

Abstract

Abstract Twenty-one species, belonging to the genus Phacus, were identified during the study of samples from the central region of Portugal collected in lentic systems. The abundance of each taxon was determined. Water samples were taken for determination, by means of standard methods, of physicochemical parameters (water temperature, pH, organic matter (K2Cr2O7), conductivity, alkalinity, nitrogen as N(NH4+), N(NO2–) and N(NO3–), orthophosphate P(PO43–) and metals in a total of 35 parameters). Some species were found more frequently, namely Phacus agilis Skuja, Ph. aenigmaticus Drez., Ph. caudatus Hubn., Ph. gigas Da Cunha, Ph. triqueter (Ehr.) Duj., Ph. longicauda (Ehr.) Duj. and Ph. tortus (Lemm.) Skv. Eighteen taxa were found in the sampling sites characterized by the following variation intervals of the environmental parameters: water temperature: 11.4–21.6 °C; pH: 6.2–7.5; dichromate oxidability: 10–59 mg l–1; conductivity: 145–779 μS cm–1; nitrogen as NO3–: n.d.–2.852 mg l–1; orthophosphate: n.d.–0.892 mg l–1; chloride: 14.2–109.3 mg l–1; sodium: 10.3–47.5 mg l–1 and total iron: 135–6446 μg l–1. In this work, information concerning the environmental conditions that preceded the occurrence of these species as well as results of the cytological and morphologic studies (with bright field microscopy as a resource) is presented and discussed.