Astroniumxylon, Schinopsixylon, and Parametopioxylon n. gen. fossil woods from upper Cenozoic of Argentina: taxonomic revision, new taxon and new records

• Published in: Journal of paleontology 2020-03, Vol.94 (2), p.185-201
• Main Authors: Franco, M. Jimena, Moya, Eliana, Brea, Mariana, Martínez, Camila Martínez
• Format: Article
• Language: English
• Subjects: Anacardiaceae; Angiospermae; Argentina; Arroyo El Espinillo; Astroniumxylon; biogeography; Cenozoic; Cluster analysis; correspondence analysis; Curtiembre Argentina; Diagnostic systems; Entre Rios Argentina; Extinct species; fossil wood; Fossils; Genera; Geology; Humid climates; Ituzaingo Formation; microstructure; Miocene; morphology; Multivariate analysis; Neogene; New records; new taxa; Paleobotany; paleoclimatology; paleoecology; Paleontology; Parametopioxylon crystalliferum; Parenchyma; Plant fossils; Plantae; Schinopsixylon heckii; South America; Spermatophyta; statistical analysis; Taxonomic revision; Taxonomy; Tertiary; Toma Vieja; upper Cenozoic; upper Miocene; Wood
• ISSN: 0022-3360; 1937-2337
• DOI: 10.1017/jpa.2019.97

This paper presents new descriptions of Anacardiaceae fossil woods from the Ituzaingó Formation (late Cenozoic) at the Toma Vieja, Curtiembre, and Arroyo El Espinillo localities, Argentina. We describe eight silicified woods assigned to four different species in three genera, one of which, Parametopioxylon crystalliferum n. gen. n. sp., is new. Similarities between these three genera and the six Anacardiaceae species previously recorded from the late Cenozoic in northeastern Argentina are investigated using multivariate analysis techniques (correspondence and cluster analysis). Our study is based on 33 characters scored for 17 fossil specimens (10 AstroniumxylonBrea, Aceñolaza, and Zucol 2001; five SchinopsixylonLutz, 1979; and two Parametopioxylon n. gen.) and four extant species (Astronium balansae Engl., Astronium urundeuva Engl., Schinopsis balansae Engl., and Metopium sp.). Our main goal is to determine the wood anatomical features useful for distinguishing among these species. Results of the multivariate analyses support the previous classification where Schinopsixylon is distinguished from Astroniumxylon by having exclusively paratracheal axial parenchyma, ≥30% multiseriate rays, and multiseriate rays that are ≥5 cells wide and commonly 301–400 µm in height. Additionally, we propose that Schinopsixylon heckiiLutz, 1979 is synonymous with S. herbstiiLutz, 1979. A diagnostic key for the fossil species studied is given. Wood anatomy of Anacardiaceae fossil woods from Argentina (late Cenozoic) suggests a warm, dry to semi-humid climate for this region, supporting previous studies.