Axoneme patterns of spermatozoa of Asian horseshoe crabs

Ultrastructural studies of flagella of spermatozoa of horseshoe crabs revealed that three Asian species (Tachypleus tridentatus, T. gigas andCarcinoscorpius rotundicauda) had a 9+0 axoneme pattern that was different from the usual 9+2 pattern ofLimulus polyphemus. This difference is consistent with the phylogeny of horseshoe crabs.