2025/09/17 by Bettina Reichenbacher, А. Ф. Банников, Dirk Erpenbeck · 1 voice
Environmental Science · #Ichthyology and Marine Biology #Coral and Marine Ecosystems Studies #Marine animal studies overview
paper · pdf · doi:10.1080/14772019.2025.2546601
The earliest skeleton-based gobioid fish, the minute goby †Carlomonnius quasigobius Bannikov and Carnevale, Citation2016 (13 mm standard length), originates from the Lower Eocene coral reef fish assemblage of Monte Bolca, northern Italy. Resolving its phylogenetic position is key to understanding gobioid evolution. However, previous analyses have yielded contradictory results, placing it either as a possible stem of Butidae or as a potential stem of the Gobiidae + Oxudercidae clade. Here, we describe a second species of †Carlomonnius from Monte Bolca, †C. carnevalei sp. nov., based on a well-preserved complete specimen, and reassess the phylogenetic relationships of †Carlomonnius within a total-evidence framework. For the latter purpose, we expanded previous data sets by adding seven additional extant gobies (six Butidae, one Gobiidae). With a standard length of 12.5 mm, †C. carnevalei sp. nov. ranks among the smallest known goby species, including both fossil and extant forms. Similarly to †C. quasigobius, †C. carnevalei sp. nov. exhibits a mixture of derived (pelvic fins with a spine and four rays) and plesiomorphic (10 abdominal and 14 caudal vertebrae, autogenous haemal spine of the second preural centrum) traits. It differs from its congener by possessing a divided dorsal fin, a slenderer body with an elongated caudal peduncle, a squarish otolith, and distinct pigmentation. Comparative morphology revealed notable similarities between †Carlomonnius and two other coral reef-associated dwarf gobies: †Oniketia Marramà, Giusberti and Carnevale, Citation2022 (Lower Oligocene) and Eviota (Gobiidae) from the Western Pacific. Bayesian analysis resolved the two †Carlomonnius species as sister taxa (posterior probability [PP] = 0.98) and placed †Carlomonnius as a possible stem Butidae (PP = 0.93). †Oniketia was tentatively resolved as a stem Gobiidae, though this relationship awaits support (PP = 0.85) and is here interpreted with caution. These results suggest that coral reef-associated dwarf gobies had already achieved ecological success early in gobioid evolution and may have arisen through convergent evolution across different lineages. http://zoobank.org/urn:lsid:zoobank.org:pub:FC678569-3643-4CF6-9007-C6D00F16C3A5