Morphology and Affinities of Pantocarpon Fruits (cf. Apiales: Torricelliaceae) from the Maastrichtian Deccan Intertrappean Beds of Central India

Premise of research. Permineralized fruits of Pantocarpon Kapgate, Patil, Ilamkar & Ramteke have been reinvestigated to better understand this abundant component of the Deccan Maastrichtian-Paleocene flora of central India. Methodology. Peels and X-ray microcomputed tomography (mu-CT) were used to compare the morphology and anatomy of the silicified fruits with that of possible extant relatives. Pivotal results. We show, for the first time, the surface morphology of these fruits, which are encased within opaque chert, and clarify additional characters of morphology and anatomy. By varying the orientation of digital sectioning planes through the fruit using mu-CT data, we show that five different generic names (Pantocarpon and the junior synonyms Bicarpelarocarpon, Plectroniocarpon, Loganiocarpon, and Verbenaceocarpon) were previously applied to the same entity, each based on holotypes studied in different physical planes of section. Several distinctive characters, including tricarpellate syncarpous fruits, paired apical apertures, empty sterile locules, single-seeded fertile locules, and longitudinal germination valves, are shared with the extant eudicot family, Torricelliaceae (Apiales). The pair of endocarp apertures resembles that in Aralidium and Torricellia. There are some obvious differences, however, from fruits of the three living genera. In Torricellia, Melanophylla, and Aralidium, there are two sterile locules (lateral) and a single fertile one (median), whereas in Pantocarpon, there are two fertile locules (lateral) and a single sterile one (median). Conclusions. Recognition of Pantocarpon as a potential member of Torricelliaceae is interesting because it would be the most ancient record known for the family (next youngest being middle Eocene, ca. 47 Ma) and provides additional biogeographic information. The occurrence of this taxon in India at about 66 Ma, when the subcontinent was still isolated from other major landmasses, indicates that this region may have played a role in early evolution of the family, which is now disjunct between Madagascar, China, and Malesia.