Student 10-Minute Presentation
Systematics, Evolution, and Biodiversity
Student
Student Competition
Gianpiero Fiorentino
PhD Candidate
New Jersey Institute of Technology
East Orange, New Jersey
Phillip Barden (he/him/his)
Associate Professor
New Jersey Institute of Technology
Newark, New Jersey
Rodolfo S. Probst
Postdoctoral Fellow
University of Utah
Salt Lake City, Utah
Adrian Richter (he/him/his)
JSPS International Postdoctoral Fellow
Okinawa Institute of Science and Technology
Onna, Okinawa, Japan
The Neotropical ant genus Basiceros is enigmatic. Their behavior, predatory preference, and general ecology remain largely unknown, yet they are well distributed across Central and South America. Basiceros ants are much larger than all other closely related genera. While large body size in this clade was considered an ancestral trait, followed by universal body size reduction, the discovery of the first fossil representative of the genus, from Miocene-aged Dominican amber demonstrates a possible reversal of this pattern. We reconstructed a total evidence phylogeny of the genus which we used to assess the relationship of the fossil to its extant congeners. We then quantified morphological variation across Basiceros species using linear measurements and dimension reduction techniques. Our results show that this fossil species is morphologically distinct and is sister to all other modern Basiceros. Finally, we performed an ancestral character reconstruction to recover an evolutionary trajectory for body size within the genus. The ancestral state of Basiceros and its related genera was likely small, followed by a rapid embiggening of universal body size remarkably accompanied by no reversals to smaller size across the lineage.