Forma de citar:Monje-Dussan, C., Martínez, C., Escapa, I., y Madriñán, S. 2016. Nuevos registros de helechos y coníferas del Cretácico Inferior en la cuenca del Valle Superior del Magdalena, Colombia. Boletín de Geología, 38(4): 29-42. RESUMENEn este trabajo se describen nuevos registros de la macroflora del Cretácico Inferior (Aptiano-Albiano) de Colombia. El material estudiado fue colectado en la Cuenca del Valle Superior del Magdalena en tres localidades del departamento del Tolima, en las formaciones Yaví y Caballos. Los restos fósiles comprenden especímenes de filicopsidas y coníferas. Entre los helechos se encuentra la familia Marsileaceae, un grupo importante identificado en la flora fósil ya que se propone como el primer registro de un helecho acuático para el Cretácico Inferior en Colombia. Adicionalmente, abundantes restos de frondes estériles al menos bipinnadas con pínulas lanceoladas y venación pecopteridea son asignadas al morfogénero Cladophlebis sp. Las coníferas por su parte, presentan estructuras vegetativas asociadas a estructuras reproductivas. Los ejes con hojas más frecuentes fueron asignados al morfogénero Brachyphyllum sp. mientras que las escamas ovulíferas aisladas poseen características morfológicas de tipo Araucarites sp. (Araucariaceae). En conjunto, estos hallazgos constituyen un punto clave para entender la biogeografía y evolución de estos grupos y así mismo contribuyen a ampliar el conocimiento de la flora del Cretácico en Colombia.Palabras clave: Cretácico, Colombia, Valle Superior del Magdalena, pteridofitas, gimnospermas NEW RECORDS OF FERNS AND CONIFERS FROM THE LOWER CRETACEOUS IN THE UPPER MAGDALENA VALLEY BASIN, COLOMBIA ABSTRACTDescriptions of new plant macrofossils from the Lower Cretaceous (Aptian-Albian) of Colombia are presented. The studied material was collected in the Upper Magdalena Valley Basin in three exposing levels from the Yaví and Caballos formations. The fossil remains are associated to filicopsids and conifers. Within the ferns, the family Marsileaceae, constitutes an important group identified in the fossil flora because it is proposed as the first record of aquatic ferns for the Lower Cretaceous of Colombia. Additionally, abundant sterile bipinnate fronds with lanceolate pinnule and pecopteridea venation remains were included in the morphogenus Cladophlebis sp. The studied conifers presented vegetative structures associated to reproductive organs. The most abundant sterile fragments were included within the morphogenus Brachyphyllum sp. and ovuliferous scales of Araucarites sp.(Araucariaceae) type. Together these new findings represent a key aspect to understand the biogeography of the mentioned groups and, simultaneously, contribute to the knowledge of the Cretaceous plant fossils from Colombia.

Migration of Boreotropical megathermal taxa during the Oligocene and Miocene played a key role in assembling diversity in tropical regions. Despite scattered fossil reports, the cashew genus Anacardium offers an excellent example of such migration. The fossil woods described here come from localities in Veraguas, Panama mapped as Oligocene-Miocene. We studied, described, and identified two well-preserved specimens using wood anatomical characteristics and completed extensive comparisons between fossil and extant material. The studied fossil woods share several diagnostic features with the modern Anacardium genus, including large solitary vessels, large intervessel-pitting, a simple vessel-ray pitting pattern, and mostly 1–3 seriate rays with large rhomboidal solitary crystals. We propose a new fossil species named Anacardium gassonii sp. nov., that adds an essential piece to the understanding of the historical biogeography of the genus. In addition, our findings confirm previous interpretations of this species’ migration from Europe to North America and its crossing through Panama, leading to subsequent diversification in South America. This discovery provides an important link to the historical migration patterns of the genus, supporting the notion of an Eocene migration to the Neotropics via Boreotropical bridges, as well as an Oligocene-Miocene crossing of Central America followed by diversification in South America.

Lectotypes are designated for 17 names in the genus Ficus: Ficus ajajuensis, F. alvareziana, F. bullenei, F. crocata, F. galeata, F. gramalotensis, F. havanensis, F. juruensis, F. leavensii var. thinophila, F. matiziana, F. rufa, F. squamulosa, F. standleyana, F. trigona, F. venosissima, F. vulpina and F. wuiana.

Neotypes are designated for the following three names: Ficus populnea subvar. diversifolia, F. populnea subvar. longipetiolata, and F. populnea subvar. subcuspidata. Lectotypes are designated for following 20 names: Ficus expansa, F. foveata, F. glandulosa, F. laevigata, F. oblongata, F. pedunculata, F. populnea subvar. cerasicarpa, F. populnea subvar. flavicosta, F. populnea subvar. reticulosa, F. populnea subvar. sancti-eustachii, F. populnea subvar. sancti-joannis, F. populnea subvar. subcordata, F. populnea subvar. subdepressa, F. populnea subvar. subpyriformis, F. populnea var. bahamensis, F. populoides var. elongata, F. portoricensis, F. umbrifera, Urostigma angustifolium, and U. sancti‑crucis.