Sideroxylon sp.

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 : 202

Sideroxylon sp.

hypothetic “whole-plant” Pl. 5, Fig. 20 (Ca’ Viettone, Pliocene), Figs 21–25 (Ciabòt Cagna, latest Miocene)

M a t e r i a l. Concerning the sites studied in the present paper, several seeds were found at Ciabòt Cagna. Similar fossils from other Italian sites are cited below.

R e m a r k s. The flatted and strongly lignified circular objects occurring at Ciabòt Cagna have smooth external ornamentation, but the internal structure (Pl. 5, Figs 24, 25b), is clearly diagnostic of the external tegument of an originally spherical ruminate seed. The reconstruction of the original shape was facilitated by comparative analyses with almost undeformed specimens from the Ca’ Viettone Pliocene locality ( Martinetto 1995, Bertoldi and Martinetto 1995, Martinetto et al. 2018). Since a ruminate structure in extant globose seeds was cited for Sideroxylon ( Swenson and Anderberg 2005) , the fossils were compared to seed samples of five extant species of this genus located by Rubén Barone (and now incorporated in the Modern Carpological Collection of the Turin University; Martinetto et al. 2014). The most diagnostic characters of the fossils, i.e., spherical shape with smooth surface and apparent internal ridges, were found to be shared (Pl. 5, Fig. 20) with the extant Sideroxylon mascatense (A.DC.) T.D.PENN. from western Asia (Pl. 5, Fig. 19), whereas the seeds of other extant species differed in the ribbed external surface ( S. canariense LEYENS, LOBIN et A.SANTOS , S. marginatum COUT. , S. mirmulans R.BR. ) or the elongated shape ( S. spinosum L.). The morphology of seeds of S. mascatense was verified and photographed in an herbarium specimen (V-067541) which was made available by the Museum of Evolution of the Uppsala University (UPS) and checked by an expert in the taxonomy of Sapotaceae (U. Swenson) .

We concluded that the shared characters are significant for the assignment of the fossils from Ca’ Viettone and Ciabòt Cagna to Sideroxylon . Fossils of the same type had been formerly reported from several Italian sites, but they were identified as Sapindoidea margaritifera (R.LUDW.) KIRCHH. ( Bertoldi and Martinetto 1995, Cavallo and Martinetto 1996, Basilici et al. 1997, Ravazzi and Martinetto 1997, Martinetto 1999, 2001, Martinetto et al. 2018). The detection of this member of the Sapotaceae at the Ciabòt Cagna Messinian site and at several Italian Pliocene sites suggests that the seed-bearing plant may have produced, at least in part, the Sapotaceae pollen grains that were reported in Italian Neogene palynofloras since several years ( Bertoldi et al. 1994, Bertini 2001, Bertini and Martinetto 2011).