A new species of Mauremys (Testudines, Geoemydidae) from the late Miocene – Pliocene of Central Macedonia (northern Greece) with exceptionally wide vertebral scutes

Abstract

Our knowledge of Neogene chelonian diversity in northern Greece is increased with the present description of a new species of Mauremys (Testudines, Geoemydidae) from the late Miocene to Pliocene of three localities in central Macedonia (Gefira‐2, Nea Silata, Allatini). This new species, Mauremys aristotelica sp. nov., is characterized by the presence of exceptionally wide vertebral scutes, a trait that is quite rare within Mauremys but has evolved independently in other pan‐testudinoid non‐testudinids. Total evidence phylogenetic analysis confirms the placement of the new species within Mauremys and reveals that its closest relative is Mauremys campanii from the late Miocene of Italy. It is also likely, under parsimony, that all geoemydids with similarly wide vertebral scutes from the Neogene of Eurasia form a clade nested within Mauremys. Our results also shed light on the evolution of geoemydids in the eastern Mediterranean during late Miocene to Pliocene times.

Fossil amphibians and reptiles from the Neogene locality of Maramena (Greece), the most diverse European herpetofauna at the Miocene/Pliocene transition boundary

“…The new specimens add to the previously described material from the same locality by Gad (1990), which is also herein referred to M. aristotelica. The new geoemydid remains further expand the known geographical distribution of this species, which was previously known from three northern Greek localities situated relatively near to Maramena (Vlachos et al, 2019). The new Maramena specimens confirm that the lineage of Mauremys was rather abundant and common in the Neogene of Greece taking into consideration that all previously described fossil specimens from the area pertain to this genus (Georgalis and Kear, 2013;Vlachos et al, 2015;Georgalis et al, 2016c;Vlachos and Tsoukala, 2016;Vlachos et al, 2019).…”

“…The shape of the fifth vertebral, as shown by the sixth left costal UU MAA 7284, is rather rare for published specimens of extant (e.g., Hervet, 2000) or extinct Mauremys (e.g., Chesi et al, 2009) because of the markedly acute lateral angle of that elementand the lateral extension of the vertebral shield. In fact, this feature is highly reminiscent of the recently described species Mauremys aristotelica, which is known from the latest Miocene and Pliocene of northern Greek localities rather close to Maramena, and characterized by rather wide vertebral scutes (Vlachos et al, 2019). A (still undescribed) costal of Mauremys sp.…”

“…This relatively low and seemingly monogeneric diversity of Greek Neogene geoemydids is further supported by the new Maramena finds, although we still agree with previous suggestions that at least two distinct species have been present in the area, judging from the fact that the older (MN 9) Mauremys sp. from Plakias, Crete (Georgalis et al, 2016c), is clearly distinct from the younger (MN 13-16) M. aristotelica (Vlachos et al, 2019). Interestingly, the phylogenetic analysis of Vlachos et al (2019) recovered Mauremys aristotelica as the sister taxon of the slightly older late Miocene (MN 12) Italian species Mauremys campanii (Ristori, 1891), implying a possible dispersal from Italy to the Greek area during the MSC event.…”

“…from Plakias, Crete (Georgalis et al, 2016c), is clearly distinct from the younger (MN 13-16) M. aristotelica (Vlachos et al, 2019). Interestingly, the phylogenetic analysis of Vlachos et al (2019) recovered Mauremys aristotelica as the sister taxon of the slightly older late Miocene (MN 12) Italian species Mauremys campanii (Ristori, 1891), implying a possible dispersal from Italy to the Greek area during the MSC event. The abovementioned, so far undescribed, costal MGPT-PU 142091 from the early Pleistocene of Pirro Nord, southern Italy, could eventually indicate that the lineage of Mauremys campanii + Mauremys aristotelica could even have survived into the Quaternary, but this is of course a hypothesis that needs to be to be evaluated.…”

“…Remarks. The assignment of the Maramena material to Geoemydidae is supported by the presence of a musk pore in a peripheral element, a character considered to be a synapomorphy of this clade by Hirayama (1985) and, accordingly, this feature has been variously applied to identify fossil specimens (among others, Chesi et al, 2009;Colombero et al, 2017;Vlachos et al, 2019). The referral of the material to Mauremys is suggested by the morphology of the nuchal and its scute sulci, which is fully congruent with that of extant members of this genus (e.g., Holman, 1995;Hervet, 2000Hervet, , 2004.…”