Acer sanctae-crucis Acer protojaponicum The Late Early Pleistocene Flora Of Oriolo, Faenza (Italy): Assembly Of The Modern Forest Biome Denk, Thomas Sami, Marco Teodoridis, Vasilis Martinetto, Edoardo Fossil Imprint 2022 2022-08-26 78 1 217 262 SORDELLI, 1896 SORDELLI 1896 [243,607,2043,2068] Magnoliopsida Sapindaceae Acer Plantae Sapindales 23 240 Tracheophyta species aemilianum   Text-fig. 13a, d–g 1896  Acer aemilianumSORDELLI, p. 156, pl. 30, fig. 8. 1988  Acer polymorphumSIEBOLD et ZUCC. pliocenicaSAPORTA; Jorda et al., p. 54, pl. 1, figs 10–13. M a t e r i a l. Oriolo MSF 645, 645-1, 660, 660-1, 661, 661-1. D e s c r i p t i o n. Leaf, petiolate, petiole ca. 3 cmlong, with widened proximal part, lamina up to 52 mmlong, 71 mmwide, primary venation palmate, number of primary veins 7–9 (–11), number of lobes 7–9 (–11), lobe apex attenuate, secondary venation craspedodromous, margin finely serrate or double-serrate along the upper 2/3 or 4/5 of the free lobes. R e m a r k s. The leaf remains from Oriolo clearly belong to  A. aemilianumdescribed by Sordelli (1896)from strata referred to as “Pliocene” (but possibly Early Pleistocene) in the surroundings of Fidenza (Emilia-Romagna). Leaves belonging to  Acersection Palmata( Van Gelderen et al. 1994, Grimm et al. 2006, Renner et al. 2008; including close to 50 modern species) from Miocene and Pliocene strata of western Eurasia have been referred to as  Acer vindobonensis(ETTINGSH.) BERGER, 1955( Ettingshausen 1851, Berger 1955) and  A. sanctae-crucis STUR, 1867( Stur 1867, Knobloch 1998; Tab. 1).  Acer vindobonensiswas based on a leaf fragment from Late Miocene strata of Austria( Ettingshausen 1851; as  Sterculia vindobonensisETTINGSH.) and described as palmate leaf with five entire margined lobes.  Acer sanctae-crucis, described from Middle Miocene strata of Slovakia, has 7-lobed leaves, the lobes being elongate triangular with finely serrate margin. Subsequent authors either treated  A. sanctae-crucisas synonym of  A. vindobonensis(e.g., Menzel 1906, Zastawniak 1972, KovarEder 1988, Kovar-Eder et al. 1996, Walther and Zastawniak 2005) or as distinct species (e.g., Berger 1955, Iljinskaya 1968, Knobloch 1998). In addition, two fossil-species of sect. Palmataoriginally described from East Asiawere reported from Europe. Of these,  A. protojaponicumTANAI et ONOE, 1959, is distinct by its shallowly lobed leaves, whereas  A. nordenskioeldiNATH., 1883, reported by Berger (1955, 1957), resembles  A. vindobonensis( Tab. 1). Further, Saporta (1873, 1879; see also Andreanszky 1959) used the name of a modern East Asian species for Pliocene (Cantal, France) maple leaves,  A. polymorphumSIEBOLD et ZUCC., 1845(synonym of  A. palmatumTHUNB., 1784), and added pliocenicumwithout indicating a taxonomic rank. Similarly, Menzel (1906)used the modern name  A. polymorphumand added miocenicum. While it is not the aim of this paper to revise western Eurasian  Acerremains of sect. Palmata, we note that most of the taxonomic disagreement between previous authors discussing possible differences or conspecifity between  A. vindobonensisand  A. sanctae-crucismay be due to the fact that all previous authors compared these fossil-taxa (with the exception of the distinct  A. protojaponicum) to a single modern species,  A. palmatum(  A. polymorphum). One exception is the work by Stur (1867), who indicated similarities with various species of sect. Palmata. Table 1summarizes leaf characteristics of previously described fossil members of sect. Palmatafrom western Eurasia and lists similarities to modern species. This is highly informative in the case of  A. vindobonense, for which a subentire margin has been refuted (e.g., Walther and Zastawniak 2005), perhaps simply because such a margin is not found in the modern  A. palmatum. However, there are other members of sect. Palmatathat can be compared with the subentire to remotely serrate leaves of  A. vindobonensis, such as  Acer sinense( Tab. 1), which produces leaves nearly identical to  A. vindobonensis. Thus, considering a broader set of modern species as possible modern analogues of fossil-taxa, we suggest that a thorough revision of both western Eurasian and East Asian fossil-taxa of sect. Palmatais needed (T. Denk, in preparation).  Text-fig. 13. a, d–g:  Acer aemilianum. b, c:  Acer palmatumand  A. sieboldianummodern leaves (NMNS Cleared Leaf Database). a: Oriolo MSF 661, 7-lobed leaf. b: Specimen U 1049, lobe detail showing finely serrate leaf margin. c: Specimen T 0246, 9-lobed leaf with coarsely serrate leaf margin. d: Oriolo MSF 645-1, 9-lobed leaf with two small additional lobes. e: Oriolo MSF 645. f: Oriolo MSF 660, 9-lobed specimen. g: Oriolo MSF 660-1. White arrows indicate position along lamina lobes where marginal serration starts. Scale bars 10 mm (a–c, f, g), 50 mm (d, e).   Table 1. Comparative morphology of fossil-taxa of  Acersect. Palmata. aBerger1955, bBerger1955, 1957, cGivulescuand Ghiurca 1969, dLeroyand Roiron 1996, eGirardet al. 2019, fTanai1976, 1983, gRayushkina1979. Notes: Saporta (1873, 1879) assigned leaves from Pliocene strata of France (Cantal) to  Acer polymorphumSIEBOLD et ZUCC., 1845 pliocenicum SAPORTA, 1873. These leaves are 7–9-lobed, have remotely dentate lobes, teeth distinct and simple; similar to  A. sinensevar. longilobumW.P. FANG, 1939. Menzel (1906)assigned leaves from the Late Miocene of Germany to  Acer polymorphumSIEBOLD et ZUCC., 1845 miocenicum MENZEL, 1906. These leaves are 5-lobed with two basal additional lobes and are remotely dentate; they would need to be re-examined for taxonomic assessment. Barrón and Diéguez (2001)described a leaf from Early Miocene deposits of Spain as  A. vindobonensis. Although this leaf differs markedly from  A. vindobonenseby the rhombic shape of the lobes, it might belong to sect. Palmata.    Western Eurasia Records of  Acersect. Palmata   Taxon   Acer vindobonensis(ETTINGSH.) BERGER, 1955   A. sanctae-crucis STUR, 1867   A. nordenskioeldiNATH., 1883    A. aemilianum  SORDELLI , 1896   A. protojaponicumTANAI et ONOE, 1959   Age Middle Miocene to Pliocene Middle Miocene, Pliocene Late Miocene Piacenzian to latest Early Pleistocene Late Miocene, Early Pleistocene   Morphology:   No. of lobes 5 lobed 7 lobed 7 lobedb 9 lobed, 7–11 lobed 9 lobed   Margin Entire; weakly serratea Finely serrate Subentire, remotely serrateb Finely serrate upper 2/3 of lobe Serrate   Lobation Deeply disected Deeply disected Deeply disected Deeply disected Shallowly disected   Geography: Austria, Poland, Romania, Czech Republic, Hungary Slovakia, Germany,?Romania,?Ukraine Austria, Italy Italy, France France, Romaniac,d,e   Remarks Similar to  Acer sinensePAX, 1897[  A campbelliisubsp. sinense(PAX) Similar to  Acersect. Palmata, incl.  A. palmatumTHUNB. ex MURRAY, 1784 Similar to  Acer sinensePAX, 1897[  A. campbelliisubsp. sinense(PAX) Similar to  Acersect. Palmata, e.g.  Acer sieboldianumMIQ., 1865. Similar to  Acer japonicumTHUNB. ex MURRAY, 1784.  P.C.DE JONG, 1994].  subsp. amoenum(CARRIÈRE) H.HARA, P.C.DE JONG, 1994]. Among fossil-taxa, leaves with 9 or  1954,  A. ceriferumREHDER, 1911, but not  A. sinense. Revision needed: These records may belong to  A. vindobonensis. more lobes are otherwise only seen in  A. polymorphum pliocenicum( Saporta, 1873, 1879).  Taxon  Remarks  Underlined character states and countries refer to original descriptions and from where the fossil-species were described.  Text-fig. 14. a, b:  Aceraff. campestre. a: Oriolo MSF 664. b: Oriolo MSF 666. c, d:  Aceraff. monspessulanum. c: Oriolo MSF 641. d: Oriolo MSF 662. e:  Aceraff. opulussubsp. obtusatumOriolo MSF669. f, g:  Aceraff. cappadocicumsubsp. lobelii. f: Oriolo MSF 675. g: Oriolo MSF 631. h, i:  Cornussp.Oriolo MSF 655, two views of a strongly folded leaf impression. Scale bars 50 mm (a, e–g), 10 mm (b–d, h, i). The specimens from Oriolo differ from previously described fossil-species of  Acersection Palmataby the lobe margin, which is serrate along most of the lamina, and by the variable and high number of lobes. According to Tanai (1983), lobe number is taxonomically informative in extant and fossil species of A. sect. Palmata. For example, in  A. nordenskioeldifrom East Asia, a great number of examined specimens consistently had 5–7 lobes. Among modern members of sect. Palmata,  A. sieboldianumproduces leaves that match  A. aemilianumby its number of lobes and the serrate margin. During the Middle Miocene to Pliocene, representatives of sect. Palmatawere rare elements of several floras in western Eurasia ( Menzel 1906, Knobloch 1969, Kovar-Eder 1988).    Acer sanctae-crucis s. str.might have had its last occurrence in the Pliocene flora of Willershausen, and  Acer protojaponicumin the Early Pleistocene of France(ca. 2 Ma; Bernasso; Leroy and Roiron 1996, Girard et al. 2019; Tab. 1). The new record from Oriolo extends the fossil record of sect. Palmatain Europe into the Pleistocene, ca. 0.84 Ma, before it was extirpated from Europe and Asia Minor. A time-calibrated molecular phylogeny of maples suggested that the Asian members of the Palmataclade ( Grimm et al. 2006) diverged from the single North American member during the Middle Miocene ( Renner et al. 2008). The fossil record further provides evidence that the section was fairly diverse in western Eurasia before it was extirpated in the Pleistocene.