A NEW LYNGBYA SPECIES FROM AQUARENA SPRINGS, SAN MARCOS, TEXAS

Mills, J. T. 1 & Johansen, J. R. 21 Department of Biology, St. Edwards University, Austin, TX 78704.USA; 2 Department of Biology, John Carroll University, University Heights, OH 44118 USA A large Lyngbya species was isolated from Aquarena Springs, a series of freshwater, nonmineral springs flowing from the Edwards Aquifer that are impounded to form Spring Lake. The species grows in rather large, loosely formed clumps at a depth of 2‐3 meters, and consists of sheathed filaments from 55 to 60 um in thickness containing a single trichome that ranges from 45‐50 um in thickness in each sheath. The sheath is 5‐6um thick. Our isolate is similar to Plectonema wollei Farlow ex Gomont, a large, thick sheathed morphospecies which has recently been placed in Lyngbya wollei (Farlow ex Gomont) Onodera et al. It is also similar to Blennothrix species, another large‐trichomed genus with a distinctive form of false branching. However, the Lyngbya from Aquarena Springs shows no evidence of false branching of any type, forms loose clusters rather than mats, and is larger than any of the species currently described in any of the genera in question. When we sequenced the 16SrRNA and associated 16S‐23S internal transcribed spacer (ITS), phylogenetic analysis indicated the taxon was most similar to Oscillatoria sanctae. However, there are so few taxa in the Oscillatoriaceae sensu stricto that have been sequenced, phylogenetic placement of the taxon by molecular analysis alone is not possible at present. Two different ITS configurations were obtained, one with both the tRNA “ Ile ” gene and the tRNA “ Ala ” gene, the other with no tRNA genes. Our work represents the first molecular analysis of any form in the large‐trichomed Lyngbya clade.