Parasite community of the golden cownose ray Rhinoptera steindachneri Evermann and Jenkins 1891 (Chondrichthyes: Myliobatidae), in Acapulco Bay,Guerrero, Mexico

The parasite community of the ray Rhinoptera steindachneri from Acapulco Bay was examined and quantified; analyses were based on the sex of the host and the date of sampling. A total of 171 specimens of R. steindachneri were examined during July–August of 2010, and May and July of 2012. Twenty-one species of parasites were found: three species of Monogenea; eight adult and one larval species of Cestoda; one larval species of Nematoda; five species of Copepoda; two species of Isopoda; and one species of Hirudinea. Cestodes had the greatest species richness (43% of the total species), followed by the copepods (24%). Two species of cestode, Glyphobothrium sp. and Rhinebothrium sp., were collected only from adult rays. At the component community level, species richness showed statistically significant variation between 13 and 16 species, which is similar to previous reports for other species of rays. The parasite component communities and infracommunities of R. steindachneri exhibited similar patterns: high species number and low numerical dominance by a particular species of parasite. The differences of body size of male vs. female rays, and a change in diet and feeding behaviour with the age of R. steindachneri, are likely important factors in the structuring of their parasite communities.     

山瑞鳖产卵与孵化研究

１９９７年对山瑞鳖的产卵和孵化进行了研究,结果表明：人工养殖的山瑞鳖产卵期为每年的５～８月份,６～７月份为产卵高峰期。产卵次数１年１次,每窝产卵数量２～２８只不等,最多出现为１１只／窝,平均１１．０２只／窝,全年卵受精率６４．７７％,山瑞鳖卵平均重９．５８ｇ,受精卵在产山８～２０ｄ;恒温孵化时,随孵化温度的上升,卵化所需时间减少,积温减少,但在３３℃时,胚胎在发育早期死亡,无鳖孵出,孵化温度为２８