Identification and characterization of one novel type of Triactinospomyxon with short spore axis

This study identifies and characterizes one novel type of triactinospomyxon in oligochaete specimen of Branchiura sowerbyi Beddard collected from a fish pond used for rearing gibel carp located in Caidian Experimental Station of the Institute of Hydrobiology. It is nominated as Triactinospomyxon caidianensis type. The spore is of characteristic triactinomyxon "anchor" shape and possesses a spore body with sporoplasm containing 32 germ cells, 3 polar capsules, and 3 caudal processes. Compared with other triactinomyxon spores described previously, T. caidianensis type has a short spore axis with 76.5 μm in length and a very short style with 38.9 μm in length. Molecular analyses on 18S rDNA sequences indicate that the novel T. caidianensis type is most closely related to Triactinomyxon sp SA-2005, Antonactinomyxon sp KAB-2001, and Synactinomyxon sp KAB-2001 with 80.33% to 81.92% identities. On the basis of spore morphology and genetic data, the T. caidianensis type presented in this paper differs from those already known and described in the literatures.