Systematics and distribution of the echinoderms from bahía de la paz

Los objetivos del presente trabajo fueron los de determinar el elenco sistemático, la riqueza y la distribución local de las especies del phylum Echinodermata en la Bahía de La Paz. Para ello, se realizó una revisión exhaustiva de la literatura publicada sobre el tema desde el siglo pasado hasta 1995, complementada con el análisis de los especímenes recolectados en la zona e incluidos en las colecciones de equinodermos de la UNAM y la UABCS. Una vez analizada y validada taxonómicamente la información, se encontró que en la Bahía de La Paz se han registrado 92 especies de equinodermos: 21 especies de la clase Asteroidea, 18 de la clase Ophiuroidea, 26 de la clase Echinoidea y 27 de la clase Holothuroidea. Tal nivel de riqueza de especies de equinodermos está entre los más altos conocidos, tanto en el Pacífico de México como en la región del Pacífico oriental tropical. El 41% de las especies se ha localizado en una sola zona de la bahía y apenas el 7% fue encontrado en toda su extensión. El elevado nivel de riqueza específica de la Bahía de La Paz puede explicarse como una combinación del gran esfuerzo de muestreo que se ha aplicado en la zona, junto con la ocurrencia incidental de varias especies, la ubicación de la bahía (cercana a una zona de transición zoogeográfica) y la diversidad de hábitats locales. The objectives of this paper were to present a taxonomic list and determine the richness and local distribution of the species of the phylum Echinodermata at Bahía de La Paz. An exhaustive review of published material on this subject from the last century to 1995 was made, and complemented with an analysis of specimens collected in the zone and included in the UNAM and UABCS collections. After the taxonomic information was analyzed and validated, it was found that, at Bahía de La Paz. 92 echinoderm species have been recorded: 21 species of the class Asteroidea, 18 of the class Ophiuroidea, 26 of the class Echinoidea and 27 of the class Holothuroidea. This level of echinoderm species richness is one of the highest known for the Pacific coast of Mexico and the tropical eastern Pacific region; 41% of the species have been found only in one zone of the bay and just 7% inhabit the whole site. The high level of species richness of Bahía de La Paz might be explained as a combination of a large sampling effort in the zone, together with the incidental occurrence of severa1 species, the location of the bay (near a zoogeographical transition zone) and the variety of local habitats

Ophiuroidea (Echinodermata) from coral reefs in the Mexican Pacific

There are numerous and important coral reefs in the Mexican Pacific, but scarce studies of brittle stars conducted in these ecosystems. In this regard, this work provides the first annotated checklist of brittle stars associated with coral communities and reefs in the Mexican Pacific and an illustrated key to identify the species. We also provide taxonomic descriptions, spatial and bathymetric distributions and some important remarks of the species. We report a total of 14 species of brittle stars belonging to nine genera and seven families. Ophiocnida hispida in Jalisco, Ophiophragmus papillatus in Guerrero, and Ophiothrix (Ophiothrix) spiculata and Ophiactis simplex in Colima are new distribution records. The record of O. papillatus is remarkable because the species has not been reported since its description in 1940. The brittle stars collected in this study, represent 22.2% of the total species previously reported from the Mexican Pacific. Presently, anthropogenic activities on the coral reefs of the Mexican Pacific have increased, thus the biodiversity of brittle stars in these ecosystems may be threatened. � R. Granja-Fern�ndez et al