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Three green algae – Palmellopsis texensis, Chlorococcum pinguideum and Chlorella minutissima – were isolated from the soil remnants among the plant roots of a herbarium specimen, kept 20 years in air-dry conditions without any chemical or freezing preservation treatment. The first two species are new for the algal flora of Bulgaria. Cytomorphology and reproduction of the isolate similar to Palmellopsis texensis were investigated in detail and data obtained were compared with the original species description of Groover & Bold (1969). Two differences from the original diagnosis were detected: presence of pulsating vacuoles in the vegetative cells of our isolate and its reproduction only by zoospores. All features of the architecture of zoospores coincide well with the original description. Further studies could verify if our isolate belongs to Palmellopsis texensis, as it is for the moment designated here, or is a distinct species.

The genus Vitreochlamys Batko comprises green flagellates with a swol- len cell wall, closely related to the matrices of the multicellular Volvocales and Tetrasporales. The first Antarctic record of this genus consisted of a population in- habiting a small coastal pond in front of Argentinean Primavera station, which did not fit into any known species. This study deals with the taxonomic description of this population under Vitreochlamys primaverae sp. nov., and the ecological charac- terization of its type environment. The erection of this new species is sustained by its comparison with the three most similar species (V. aulata (Pascher) Batko, V. nekrassovii ( korshikov) Nakazawa and V. gloeocystiformis (Dill) Nakazawa) using a number of reliable morphological diacritic features, as well as by its note- worthy biogeographical insulation, adaptation to extreme environmental condi- tions and poor low-range dispersion ability, probably on account of its particular environmental requirements.