A Checklist and Seasonal Account of the Deepwater Rhodophyta around Cozumel Island on the Caribbean Coast of Mexico LUZ ELENA MATEO-CID 1, *, A. CATALINA MENDOZA-GONZÁLEZ 1 , AND RICHARD B. SEARLES 2 1 Laboratorio de Ficología, Departamento de Botánica, Escuela Nacional de Ciencias Biológicas, I. P. N., Prol. Carpio y Plan de Ayala, 11340, México, D. F. 2 Department of Biology, Duke University, Durham, NC 27708-0338 USA. *Corresponding author: lmateoc@ipn.mx ABSTRACT.—Red seaweeds were investigated, using SCUBA, from waters around the island of Cozumel off the east coast of the Yucatan Peninsula in Mexico. One hundred and eighteen species of Rhodophyta were collected and identified. Forty-five of these are reported for the first time from Cozumel, and of these 11 are new records for Mexico. There was a distinct change in the deep water flora between wet and dry seasons; the dry season had more species with northern ranges in comparison with the flora in general. The wet season had few north-ranging species. Fifty-four epiphytic or hemiparasitic species were identified, most frequently on Halimeda tuna, Dictyota cervicornis and Sargassum spp. This account brings the total mac- roalgal taxa reported from Cozumel to 385, the richest flora of any locality in the Caribbean region of Mexico. KEYWORDS.—marine algae, benthic algae, red algae INTRODUCTION In an earlier paper (Mendoza-González et al. 2000) we reported on the Phaeophyta and Chlorophyta collected in the deep wa- ters around Isla Cozumel. Although there have been seven previous references to the seaweeds of Cozumel (Huerta 1958, 1961; Taylor 1972; Garza 1975; Huerta and Garza- Barrientos 1980; Huerta et al. 1987; and Ma- teo-Cid and Mendoza-González 1991), none of these reports were based on deep- water collections. Mateo-Cid and Men- doza-González reported a total of 168 taxa of Rhodophyta in the shallow waters of Co- zumel. Thirty seven and a half percent of these were present only during the wet sea- son and 6.5% only in the dry season. MATERIALS AND METHODS Materials and methods in the current pa- per are the same as reported by Mendoza- González et al. (2000). Collections were made from depths of 8-30 m, although ad- ditional plants could be seen in even greater depths. A list of the species col- lected, depths over which they were col- lected, months of collection, a sources for illustrations and descriptions of each spe- cies, and location of voucher specimens are included in Table 1. New records for the island of Cozumel and for Mexico are indi- cated in the table. Species names are ac- cording to Wynne (1998), Nam (1999) and Ortega et al. (2001) unless otherwise noted. RESULTS One hundred and eighteen taxa of Rhodophyta were collected and identified (Table 1). Forty-five of these taxa were new records for Cozumel, and of these 11 are new records for Mexico. There were signifi- cant changes in the flora with the change in the seasons (Appendix). Almost a third of the 168 taxa of red algae occurred as epi- phytes (Table 2). Notes on the distribution and classification of some taxa are given below. Titanoderma pustulatum (J. V. Lamour.) Nägeli Wynne (1998) listed this species under the genus Lithophyllum but in his notes on ms. received June 8, 2005; accepted August 31, 2005 Caribbean Journal of Science, Vol. 42, No. 1, 39-52, 2006 Copyright 2006 College of Arts and Sciences University of Puerto Rico, Mayagu ¨ ez 39