On the enigmatic brown alga Acinetospora crinita (Ectocarpales, Fucophyceae)

Abstract

The present paper reports on the study of French and Danish strains of Acinetospora crinita (Harvey) Kornmann and their responses in growth and reproduction to various combinations of temperature and salinity. The distribution of the species in both hemispheres may be explained by the temperature requirements for growth and reproduction. The limit at lower latitudes in both hemispheres is a lethal limit, at higher latitudes it is probably a growth and reproduction limit. Acinetospora crinita is a stenohaline species and only occurs in high salinity areas in Danish waters. This paper also discusses the status of the genus Acinetospora, which has been considered to be a phase in the life history of some Feldmannia and Hincksia species. We conclude that there are several characters that justify independent status at the genus and species level. The large variation in reproductive patterns is enigmatic and adds to the taxonomic confusion. In A. crinita various reproductive structures occur: megasporangia/acinetosporangia, unilocular sporangia (some are apomeiotic), monosporangia, plurilocular sporangia which are presured to be gametangia, and a strain is known from the United States with reproduction solely by fragmentation. The combination of reproductive structures appears to be unique to specific strains.