INVESTIGADORES
IGLESIAS Ari
congresos y reuniones científicas
Título:
Revision of ?Fitzroya? tertiaria Berry based on holotype cuticle and new material with attached female cones, Cretaceous (Cenomanian), Austral Basin, Argentina
Autor/es:
ROCÍO IRIBARREN; ARI IGLESIAS; ZAMUNER ALBA B.; POIRE DANIEL; SEBASTÍAN RICCHIANO; WILF PETER
Lugar:
Corrientes
Reunión:
Simposio; XV Simposio Argentino de Paleobotánica y Palinología; 2012
Institución organizadora:
Universidad Nacional del Nordeste
Resumen:
?Fitzroya?
tertiaria Berry is the only South American fossil
species still referred to the modern genus Fitzroya
(alerce, Cupressaceae). In various publications, the species has also been
referred to Dacrycarpus
(Podocarpaceae), but without detailed
review of the type specimen. We revise the holotype, along with new material from the type locality
(Chalia River-Mata Amarilla Formation) and other Cretaceous localities in Santa
Cruz (Piedra Clavada Formation). The holotype (USNM-37859) includes twigs with
imbricate leaves and cuticle, which we studied nondestructively using fluorescence
microscopy and SEM. Our studies rule out the assignment to Fitzroya due to the absence of typical cuticular characters such as
stomata in bands and Florin rings, and to all
other genera in Cupressaceae ss. due
to the lack of whorled phyllotaxis. Affinity to Podocarpaceae is rejected
because the holotype has no typical podocarpaceous stomata (paratetracytic), including Dacrycarpus due to the lack of acicular
leaves and foliar dimorphism. Our revision places the holotype among the "taxodioid"
Cupressaceae based on the presence of spirally
arranged adpressed scaly leaves, cycloctic stomatal apparatus, and Athrotaxis type stomata. Furthermore, the
assignement is confirmed with new material in organic connection to a female
cone. The presence of raised guard cells, straight subsidiary cell walls, and
quadrangular epidermal cells becoming elongated to the leaf margins are shared
with Athrotaxis. Thus, the only
fossil record of Fitzroya in South
America should be rejected in favor of a closer relation with a genus that today
lives in Tasmania and has Cretaceous records in southern Patagonia.