New species of Ferugliocladus (Ferugliocladaceae) from Patagonia, Argentina, and homology discussion among Upper Paleozoic coniferophytes.

GALLEGO, JULIETA; CÚNEO, RUBÉN; ESCAPA, IGNACIO

New Orleans

Congreso; Botany 2013; 2013

Permian conifers in Gondwana are known principally by the record of vegetative organs, however a few reports of reproductive organs are registered. The family Ferugliocladaceae, so far recovered from several Permian localities in South America, comprises two genera, i.e. Ferugliocladus and Ugartecladus, which are known from pollen and seed cones attached to leafy shots of Paranocladus type and seeds referred to Eucerospermun. One of the principal characteristics of this family is the terminal position of the cones and the apparent absence or extreme reduction of ovuliferous scales, structure that has been considered as crucial in the evolution of conifers and dwarf-shoot concept. Herein, we describe a new species of Ferugliocladus from the Lower Permian Rio Genoa Formation in Patagonia, Argentina. This new species is based in seed cones traits, which are bigger in size and bear a higher number of seeds per cone (50 or more). Ferugliocladus and Ugartecladus, together with the also gondwanic Genoites and Buriadia, have been proposed as a separated coniferophyte lineage in the Southern Hemisphere. One of the evolutionary hypotheses that relates these taxa with Cordaitalean ancestry proposes that stalked ovules represent a reduced dwarf-shoot, where the scale leaves have been lost. An alternative homology hypothesis includes the interpretation of seed cones in Ferugliocladaceae as simple, and therefore without any clear homology relationships with Cordaitales. This lineage differs from the Northern Hemisphere walchian conifers in the absence or extremely reducing of dwarf shoots in seed cones, at the time that a strong biogeographic differentiation process could be involved. In this context it is interesting to trace the evolutionary history of Paleozoic conifers from the Northern and Southern hemisphere, and discuss the alternative homology hypotheses formerly proposed, as well as the implications for the origin and diversification of Mezosoic and extant conifer families.