Revista Chilena de Historia Natural 77 (2): 293-304, 2004
RESEARCH ARTICLE
A dichotomous species of Codium (Bryopsidales, Chlorophyta) is colonizing
northern Chile
In late 2001 and early 2002, a dichotomous species of Codium appeared
colonizing the low intertidal and shallow subtidal bottoms of Caldera Bay, northern Chile (27°03’ S, 70°51’ W). Due to the ecological
and economic impact the species is having in Caldera Bay and its potential spread along the Chilean coastline, we studied the
taxonomic identity of the species and examined its relationships with other dichotomous species of Codium reported for
temperate Pacific South America. Morphological analyses suggest that the seaweeds from Caldera Bay belong to Codium fragile
(Suringar) Hariot. Not only is there strong agreement in internal and external morphological characters, but among all the
species reported for Peru and Chile, this is the only one exhibiting utricles with rounded, apiculate tip terminating in a mucron. This
species has a broad geographic distribution in temperate waters. In Chile it was known only from the coasts of Valdivia to the Straits of
Magellan (39°48’ S, 73°26’ W to 53°10’ S, 73°49’ W). This is the first record of C. fragile in northern Chile, and this study
discusses several alternative hypotheses for the presence of the species into this area. The morphological characteristics of the
material collected in Caldera partially agree with diagnostic characters known for C. fragile subspecies tasmanicum
and C. fragile subspecies tomentosoides. However, the rapid population spread of the species in
northern Chile, and recent molecular analysis support the identification of this form as the invasive C. fragile subspecies
tomentosoides.
Key words:
Codium,
introduced species, Chlorophyta, seaweed, northern Chile
