The morphology and ecology of Pleurochrysis carterae var. dentata var. nov. (Prymnesiophyceae), a new coccolithophorid from an inland saline pond in New Mexico, USA

Abstract

Pleurochrysis carlerae var. dentala var. nov. was isolated into culture from a shallow, saline pond near Roswell, New Mexico, USA. This taxon is similar to Pleurochrysis carlerae (Braarud & Fagerland) Christensen, but differs in cricolith morphology and in thermal tolerance. Internal ultrastructure is very similar to that found in other representatives of the Hymenomonadaceae. Two plastids are present, each with a bulging pyrenoid traversed by paired thylakoids. A single Golgi apparatus with peculiar dilations is positioned anteriorly, and appears to be the site of scale and coccolith production. A central nucleus, vacuole, several mitochondria, and numerous coccolithosomes are also evident. The haptonema is evident in noncoccolith-bearing swarmers, but has not been observed in coccolith-bearing motile cells.This taxon grows best in waters high in divalent cations, with optimal growth observed in SERI Type I water at 25°C and 25 mmhos cm−1 conductivity. Growth was also good in artificial seawater at higher conductivities (40–70 mmhos cm−1). Several stages in the life cycle of this organism have been observed, including a benthic, pseudofilamentous stage, a noncoccolith-bearing swarmer stage arising from the benthic stage, and a motile coccolith-bearing stage, the latter being the most common phase observed in culture. Syngamy has been observed twice.