CHO, T.O.1*, S. FREDERICQ1, S.N. MURRAY2, and S.M. BOO3. 1Department of Biology, University of Louisiana, Lafayette, LA 70504 UAS; 2Department of Biology, California State University, Fullerton, CA 92834 UAS; 3Department of Biology, Chungnam National University, Daejon 305-764 Korea. - New systematic insights in the Ceramium sinicolacomplex: resurrection of C. interruptumS. & G. (Ceramiaceae, Rhodophyta).
Setchell & Gardner (1924) provided a taxonomic treatment for the genus
Ceramiumfrom lower California and the Gulf of California,
Mexico, in which they described several new species, including C.
sinicolaS. & G. described from Ensenada, BCN and C.
interruptumS. & G. described from the vicinity of La Paz, BCS. The
latter was later reduced to variety rank in C. sinicolaby
Dawson (1950), a taxonomic decision that has subsequently been widely
adopted. Phylogenetic analyses inferred from three molecular markers
(chloroplast-encoded rbcL, the RUBISCO spacer, and nuclear encoded SSU
rDNA) from recent collections from the Pacific Northwest (California,
Oregon) and the Gulf of California reveal a well supported assemblage
of three corticated taxa: Ceramium codicolaJ. Ag. 1894, C.
sinicolaand C. sinicolavar. interruptum. Sequence
divergence values among the three taxa are sufficient to warrant
separate species ranking; hence, we reinstate Ceramium
interruptum as a widely distributed epiphyte for the region.
C. sinicolais more closely related to C. codicolathan to
C. interruptum, with the former two restricted to the host
Codium. The molecular-based relationships are congruent with
evolutionary trends in cortication pattern and attachment mode.
Key words: Ceramiaceae, Ceramium sinicola, floristics, molecular phylogeny, Rhodophyta, systematics