The life histories of Boodleopsis vaucherioidea sp. nov. and B. pusilla (Caulerpales) and their phylogenetic implications

Abstract

Boodleopsis vaucherioidea sp. nov. and B. pusilla (Collins) Taylor, Joly & Bematowicz are shown to have similar life histories. Both produce stephanokontan zoospores and biflagellate swarmers in the same thallus. B. vaucherioidea differs from B. pusilla in the wider angles and lack of constrictions at the dichotomies, the thicker filaments of the semi-erect branches, the smaller nuclei and the plastids which have more than one starch grain. The presence of constrictions at the dichotomies is insignificant as a generic feature. Biflagellate swarmers of B. pusilla (gametes?) are produced without reduction of the nuclear DNA contents. Development of zoidangia and sporogenesis are described in some detail for both species. Morphological variation under culture conditions, salinity effects and protoplast regeneration are discussed. Boodleopsis occupies an intermediate position between the homoplastidic Bryopsidaceae and the heteroplastidic Udoteaceae and may be phylogenetically very close to the linking forms between both groups.