Apalone amorense sp. nov.
Valdes, N., J. R. Bourque, and N. S. Vitek. 2017.
A new soft-shelled turtle (Trionychidae, Apalone) from the Late Miocene of north-central Florida.
Bulletin of the Florida Museum of Natural History 55(6):117–138.
Trionychid fossils from the late Miocene (late Clarendonian) Love Bone Bed in Alachua County, Florida, are described as a single taxon that represents a new species, Apalone amorense sp. nov. A phylogenetic analysis recovers A. amorense as sister to all extant representatives of Apalone. The new species is relatively small at adult size compared to other species of Apalone and exhibits a mosaic of similarities with extant species of Apalone. It shares the presence of four plastral callosities, lack of surface contact between the jugal and parietal, and a mid-sized postorbital bar with A. ferox, and unfused hyo-hypoplastra (except in some older individuals where these fuse), variably open suprascapular fontanelles in all but the largest individuals, and dermal sculpturing similar to A. mutica and A. spinifera. The age and proposed phylogenetic position of A. amorense are consistent with previously published estimated divergence dates for the clade.
Mario Vargas-Ramírez, Carlos del Valle, Claudia P. Ceballos and Uwe Fritz (2017)
Trachemys medemi n. sp. from northwestern Colombia turns the biogeography of South American slider turtles upside down.
JOURNAL OF ZOOLOGICAL SYSTEMATICS AND EVOLUTIONARY RESEARCH 55(4): 326–339
South America was invaded by slider turtles (Trachemys spp.) twice, with one immigration wave estimated to have reached South America 8.6–7.1 million years ago (mya) and a second wave, 2.5–2.2 mya. The two widely disjunct South American subspecies of Trachemys dorbigni (northeastern and southern Brazil, Río de la Plata region of Argentina and Uruguay) are derived from the first dispersal pulse, while the two South American subspecies of Trachemys venusta (Colombia, Venezuela) originated from the second immigration event. We describe a new species of slider turtle from the lower Atrato river basin of Antioquia and Chocó departments, northwestern Colombia. This new species, the Atrato slider (Trachemys medemi n. sp.), is the first representative of the older immigration wave inhabiting northern South America. Using phylogenetic analyses of 3,242 bp of mitochondrial and 3,396 bp of nuclear DNA, we show that T. medemi is more closely related to T. dorbigni than to the geographically neighboring subspecies of Trachemys grayi and T. venusta from Central America and northern South America. The two subspecies of T. dorbigni are separated from the Atrato slider by the Andes and the Amazon Basin, and occur approximately 4,600 km and 3,700 km distant from T. medemi. According to molecular clock calculations, T. medemi diverged from the last common ancestor of the two subspecies of T. dorbigni during the Pliocene (4.1–2.8 mya), with T. dorbigni diversifying later (2.3–1.9 mya) in eastern South America beyond the Amazon basin. The divergence of the T. dorbigni subspecies overlaps with the estimated arrival of T. venusta in South America (2.5–2.2 mya). This time is characterized by massive climatic and environmental fluctuations with intermittent dispersal corridors in South America. According to their distribution, it seems likely that the ancestors of the extant subspecies of T. dorbigni dispersed along the eastern corridor, leaving a relict population northwest of the Andes with T. medemi. The distribution range of T. medemi is surrounded by taxa derived from the second southern range expansion of slider turtles, so that it can be concluded that T. venusta circumvented the habitats occupied by the ancestors of the Atrato slider when entering South America.