Ref ID : 7686
Jesus Martin; [Evolution des Patrons Morphogenetiques et Phylogenese dans le Sous-ordre des Sporadotrichina (Ciliophora, Hypotrichida)]. Protistologica XVIII(4):431-447, 1982
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Available data concerning the origin and the development of different ciliary primordia in both experimental and physiological situations have been utilized in an attempt to establish the phylogenetic relations of the Oxytrichidae and Euplotidae Borror 1972, both families constituting the current S.O. Sporadotrichina Faure-Fremiet, 1961 of the Order Hypotrichida. The stomatogenic pattern of Stichotrichina, being different from that of Sporadotrichina, becomes a taxonomic criterion which can be utilized to distinguish both suborders as two consecutive stages in the evolution within the order. Effectively, the stomatogenic pattern of the Oxytrichidae appears to derivate from the parakinetal pattern of the Stichotrichina because the last one appears to be the rule in Oxytrichids induced to regenerate by partial ablation of the AZM. This sits the value of the ratio cortex buccal/cortex somatique close to the characterizing Stichotrichina. It is argued in favour of a capacity of inhibition of the AZM on the stomatogenic activity of an area presumably determined "a la JERKA-DZIADOSZ". This explains the appearance of the oral primordium at left of the transversal cirri n(o) 1, the sole structural guidance included at the posterior end of the stomatogenic area, the first region unrespressed as consequence of the cellular lengthening inherent to the cell cycle. Development of the ventral and dorsal ciliature of Oxytrichidae also supports the idea of a lineal phylogenetic relation with Stichotriches. This is specially clear after comparison of Paraurostyla with the evolutive series Pleurotricha-Laurentiella-Gastrostyla-Onychodomus-Stylonychia-Oxytricha. The original conception of both suborders as divergent evolutive lines (Faure-Fremiet, 1961) appears to be currently inconsistent. The origin of Euplotidae still remains uncertain because the organization and development of the dorsal ciliature, being primitive, is in contradiction with the organization and development of the FVT system which is similar in all its features to that of the Oxytrichidae. They can be even considered as their descendants in which the tendancies towards the amplification of the peristome and towards the reduction in number of FV cirri (concomitant with the increase in size which appears in the last family) appears to reach its maximal expression. This makes improbable a case of evolutive convergency.