Alicia Durán-González

The Echinoderms of Mexico: Biodiversity, Distribution and Current State of Knowledge

Mexico is one of the most biodiverse countries on the planet. Knowledge of echinoderm diversity in Mexico started in the XIX Century with Louis Agassiz in 1841. Currently, 643 species of echinoderms are known from Mexico, with Class Ophiuroidea the richest (197 species); Class Asteroidea follows with 185 species, then Class Echinoidea with 119 species, Class Holothuroidea with 113 species, and Class Crinoidea with 29 species. The Mexican deep sea has been little studied, and most expeditions covering this area have been made by institutions in other countries where a great amount of information is deposited but access to it can be difficult. It is necessary to have available catalogues of the Mexican echinoderms with information on their biology, ecology, distribution, and fisheries, in order to facilitate access to information, and promote further studies on the echinoderms of Mexico. Fossil echinoderms are present in the sedimentary basin of Mexico and thus have potential practical use as paleoecological indicators, complementing stratigraphic studies. Although taxonomic studies have resulted in a rather large species list, ecological, life history, and other studies are scarce. Studies on sea cucumber aquaculture in Mexico have not yet started, in spite of the high market value of these animals and their detritivorous habit which makes them attractive for cultivation. It is recommended that aquaculture studies be undertaken. These and other suggestions for advancement of the knowledge and sustainable utilization of echinoderms in Mexico are discussed in the present chapter.

Morphological comparison of Astropecten cingulatus and a new species of Astropecten (Paxillosida, Astropectinidae) from the Gulf of Mexico

Astropecten cingulatus is a conspicuous species, which displays a large superomarginal plate series on the abactinal surface. Herein we describe a new species from off the Texas coast that shows the superficial appearance of A. cingulatus, including these large superomarginal plates, but with armature differing from that of typological A. cingulatus. This species shows the actinal surface of the inferomarginal plates without the squamules present on A. cingulatus. In addition, the adambulacral plates possessed but a single central large spine surrounded by a circle of spines rather than spine rows. The abactinal paxillar region was also very narrow. Statistical analysis of these and other morphological characters showed the specimens differed significantly from those of A. cingulatus. The regression of the slope of R:SM# vs. R was significant but the intercept was not. Therefore the two species are indistinguishable at small sizes based on R:SM. Compared to known Atlantic Astropecten spp. these observed characters warrant the description of a new species, Astropecten karankawai, for the specimens from off the coasts of Texas and Mexico.