Acer integerrimum VIV.

Niccolini, Gabriele, Martinetto, Edoardo, Lanini, Benedetta, Menichetti, Elena, Fusco, Fabio, Hakobyan, Elen & Bertini, Adele, 2022, Late Messinian Flora From The Post-Evaporitic Deposits Of The Piedmont Basin (Northwest Italy), Fossil Imprint 78 (1), pp. 189-216 : 200-201

Acer integerrimum VIV. in Keferstein 1834 and Acer sp.

hypothetic “whole-plant” Pl. 3, Fig. 1 ( A. integerrimum ), Pl. 3, Fig. 2, Pl. 5, Fig. 11 ( Acer sp. )

M a t e r i a l. A leaf photographed in the field. In addition, four Acer endocarps and a complete winged fruit (see below for taxonomy), which were found in a layer just below the leaf-bearing one, fulfil one of the lines of evidence cited by Kvaček (2008): “identical or similar systematic affinities” to infer connection to the foregoing leaf in a hypothetical “wholeplant” reconstruction ( Martinetto and Macaluso 2018).

R e m a r k s. The fossil-species “ Acerites integerrima ” was first described from the gypsum-bearing (Messinian) successions of Italy ( Viviani 1833), but the original diagnosis was not detailed, and the drawing of the single cited specimen (possibly lost) was rather poor. However, Viviani (1833: 131) gave no diagnosis for the new genus Acerites and, because he included two new species in this genus – Acerites ficifolia and Acerites integerrima (although with diagnosis) –, both these names could be considered as invalid, being combined with an invalidly published genus. Keferstein (1834: 817) included the species “ integerrima ” in a list of fossils of the genus Acer and gave (indirect) reference to Viviani’s diagnosis. So, the name Acer integerrimum may be considered validated in this way.

A specimen from another Messinian site of Italy (as Acer integerrimum ) was later described by Massalongo and Scarabelli (1859). In the late 20 th century this fossil-species was considered to occur in other parts of Europe (e.g., Mai and Walther 1988: 172) with specimens which were suitable for a better description of the diagnostic characters, recently summarized by Kvaček et al. (2020). Further leaf specimens of Acer integerrimum (e.g., Martinetto 2003, Teodoridis et al. 2015), showed more consistently the characters of the leaves attributed to this fossil-species and their variation in the Neogene of Italy. The recovered image of a leaf with entire-margined lobes from the Pollenzo section shows all the characters of this fossil-species, and in particular is very similar to a reference specimen ( Massalongo and Scarabelli 1859: pl. 18, fig. 3) cited by Mai and Walther (1988). The morphology of the leaves of this fossil-species, also studied in other European localities, permits its assignment to sect. Platanoidea ( Kvaček et al. 2020). Additionally, sect. Platanoidea is also indicated by the morphology of the flat, almost smooth (with only faint ribs) and poorly lignified body of a winged fruit from Pollenzo (Pl. 3, Fig. 2). Four associated endocarps show a fingerprint-like ornamentation (Pl. 5, Fig. 11) corresponding to that observed in extant analogs of sect. Platanoidea.

Our joint treatment of the various remains cited above indeed points to considering a hypothetic “whole-plant” concept ( Martinetto and Macaluso 2018). However, in order to assess if both leaf and fruits originate from the same “whole-plant” an exceptional fossil bearing both parts (presently unknown) would be needed, as illustrated by Kvaček and Sakala (1999) for Decodon gibbosum . Therefore, at the present state of the art, the fruits have to be treated as Acer sp.