Stephanoceros Ehrenberg

Meksuwan, Phuripong, Pholpunthin, Pornsilp & Segers, Hendrik, 2013, The Collothecidae (Rotifera, Collothecacea) of Thailand, with the description of a new species and an illustrated key to the Southeast Asian fauna, ZooKeys 315, pp. 1-16 : 8

Genus Stephanoceros Ehrenberg

Remarks.

Genus Stephanoceros is diagnosed ( Koste 1978) by having extraordinarily long extensions of the corona (tentacles) bearing transversally implanted rows of medium-long cilia, in addition to short mobile cilia. Following this diagnosis he suggests that Collotheca stephanochaeta (Edmondson), which has short corona lobes bearing similarly inserted rows of cilia, might be better placed in Stephanoceros rather than Collotheca , while he discards the relevance of the absence of such transverse rows of cilia in Stephanoceros millsii (Kellicott) by considering the latter a mere infrasubspecific ecotype of Stephanoceros fimbriatus (Goldfusz).

We believe that the diagnosis of Stephanoceros is questionable, considering that neither the presence of long corona lobes (also in Collotheca judayi Edmondson and Collotheca tenuilobata (Anderson)) nor the presence of transverse rows of cilia on the corona lobes (present in Collotheca stephanochaeta , absent in Stephanoceros millsii , see below) can serve as synapomorphic diagnostic feature for the genus. To the contrary, we hypothesize that the two species now attributed to Stephanoceros are merely species in which the prolongation of corona lobes already present in many species of Collotheca has evolved to its greatest extent. We look forward to a more complete phylogenetic analysis of the taxa, knowing that a molecular phylogenetic study of the group is on-going. A synonymy between Collotheca and Stephanoceros would have to result in the reallocation of all taxa of the junior Collotheca to the senior Stephanoceros .