First record of Palmellopsis texensis (Groover et Bold) Ettl et Gärtner (Chlorophyta, Tetrasporales, Palmellopsidaceae) from Bulgaria, found in a 20 years dried soil of a herbarium specimen

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.