Range extension of Cutleria hancockii Dawson (Cutleriales, Phaeophyta) to the Southwestern Gulf of California, Mexico

A range extension of Cutleria hancockii Dawson to the southern portion of the Gulf of California is presented based on collections developed in several localities from Bahía de Los Ángeles, Bahía Concepción, Bahía de La Paz and Bahía de Los Muertos between March of 1996 and May of 2000. Punta Perico in Bahía de Los Muertos represents the southern limit of the species extending the known distribution by 400 km. Several modifications in habitat and morphology were observed within the new range. The present reports also extend the vertical distribution of the species from the intertidal zone to subtidal areas with rocky and rhodolith substrates. As part of the habitat modification a reduction in the number of fronds per turf was observed. Morphologically the plants reduce their size significantly along the geographical cline, this suggests that temperature and light intensity are playing a major role in the distribution. An updated description of the species is provided based on the observation of variations in the range of morphological and anatomical features observed in the new collections.