First record of the rare freshwater alga Tetrasporopsis fuscescens (Chrysomerophyceae, Ochrophyta) in North America

Abstract

This study presents the first record of the ochrophyte alga Tetrasporopsis fuscescens in North America, confirmed with light and transmission electron microscopic photomicrographs, cytochemical and molecular phylogenetic analyses. T. fuscescens was recorded rarely, being found in the benthos of only twelve stream sites: nine locations in Southern California and three in Northern California. More than half of the streams were non-perennial, characterized by long dry periods. Tetrasporopsis cells were gold-colored, spherical, with a distinct wall, assembled in the periphery of macroscopical gelatinous colonies, which start as tubular or sac-like structures, but later become membranous. The cells have 1-2 parietal chloroplasts, without a stigma or pyrenoid, and reproduction occurs by longitudinal cell division. Other features of the genus are as follows: cells in the colonies also divide by what appears to be smaller autospores with remnant cell walls remaining, the colonial mucilage consists of cylindrical dichotomously branched tubes radiating from the center of the colony to which attach the peripheral cells, and older cells become filled with large oil droplets. A combined gene tree of sequences from nuclear SSU rDNA, plastid rbcL, psaA, psbA and psbC showed that T. fuscescens specimens from Europe and U. S. A. formed a clade, which clustered with taxa classified in the class Chrysomerophyceae.

Genome of a novel Sediminibacterium discovered in association with two species of freshwater cyanobacteria from streams in Southern California

“…Transmission electron microscopy (TEM, Fig. 1a ) was performed with fresh cultured material from both cyanobacterial strains as described in Stancheva et al (2019) . Briefly, cells were fixed with 2% glutaraldehyde in 0.1 M cacodylate buffer and postfixed in 1% OsO4 in 0.1 M cacodylate buffer for 1 hr on ice.…”

Substratum‐associated microbiota

“…Stancheva, Skaloud, Pusztai, Loflen, and Sheath (2019) provided the first record of the Ochrophyte, Tetrasporopsis fuscescens (A.Braun ex Kütz.) Lemmermann in North America from rivers in California.…”

Characterizing the microbial metagenome of calcareous stromatolite formations in the San Felipe Creek in Anza Borrego Desert

“…Our study area, Southern California has a Mediterranean climate with cool, wet winters and hot, dry summers (Luo et al 2017) which determines the intermittent flow regime of many local streams. The biotic communities of non-perennial streams, which cease to flow at some point in time or space, are largely defined by drying disturbances (Busch et al 2020) and contain many benthic algae which are adapted to desiccation (Stancheva et al 2019). These streams have alkaline low-nutrient water and two distinct states: wet with flowing surface water, and dry (without flow) state with duration from nearly month to a year in southern California (Busch et al in press).…”