Extensive intraspecific morphological variation in Enteromorpha muscoides (Chlorophyta) revealed by molecular analysis

Enteromorpha muscoides (Clemente y Rubio) Cremades and E, clathrata Roth (G reville) are morphologically variable species that can easily be distinguis hed from other Enteromorpha species but not from each other. The key morpho logical character separating the two species is the presence or absence of spine-like branches: E, muscoides has small spine-like branches throughout the thallus, whereas E, clathrata lacks spines. The spiny branches in E, mu scoides are not as obvious in summer as in winter, so summer samples may be difficult to distinguish from those of E, clathrata, In this study, molecu lar data were used to investigate whether these two species, as defined by morphological characters, might be conspecific, The sequences of the intern al transcribed spacers ITS1 and ITS2 and the 5.8S gene differed by 0%-0.6% between all samples of both E, muscoides and E, clathrata, Phylogenetic ana lysis of these sequences in an alignment with 13 other representatives of b oth Enteromorpha and Ulva showed that this highly supported monophyletic E, muscoides/E clathrata clade is separated by long branch lengths from other Enteromorpha and Ulva clades, Based on these results, we suggest that Ente romorpha muscoides (Clemente y Rubio) Cremades and Enteromorpha clathrata R oth (Greville) are conspecific, with the older name E, muscoides taking pri ority.