Solitudo, Valenti & Vlachos & Kehlmaier & Fritz & Georgalis & Luján & Miccichè & Sineo & Delfino, 2022

Valenti, Pietro, Vlachos, Evangelos, Kehlmaier, Christian, Fritz, Uwe, Georgalis, Georgios L., Luján, Àngel Hernández, Miccichè, Roberto, Sineo, Luca & Delfino, Massimo, 2022, The last of the large-sized tortoises of the Mediterranean islands, Zoological Journal of the Linnean Society 196 (4), pp. 1704-1717 : 1711

SOLITUDO GEN. NOV.

Zoobank registration: urn: lsid: zoobank. org:act: 08DE006C-E90B-4605-9711-952D72904E 5F.

Type species: Testudo robusta Leith-Adams, 1877 ; Zubbo Cave = Zebbug Cave, Malta; Middle Pleistocene .

Etymology: From the Latin word solitudo, feminine, third declension, meaning solitude, loneliness, in allusion to the insular isolation of these tortoises. Also, the termination - tudo alludes to the name Testudo and the testudinid affinities of this new taxon.

Diagnosis: Members of Solitudo belong to Testudinidae because of the ventral fusion of the trochanters of the femur. However, Solitudo species show an incomplete fusion of the trochanters dorsally, in contrast to other testudinid genera in which the trochanters are connected proximally via a rounded ridge. Furthermore, members of Solitudo have femurs that are slender, with a femoral head that is narrower than the combined anteroposterior width of the trochanters and an oblique orientation compared to the anteroposterior plane between 25°–45°, in contrast to other genera with relatively massive femora and broad and less oblique femoral heads, forming an angle that is less than 25° with the anteroposterior plane.

Included taxa: Solitudo robusta ( Leith-Adams, 1877) comb. nov., Solitudo gymnesica ( Bate, 1914) comb. nov., Solitudo sicula sp. nov.

Remarks: The exact placement of Solitudo among Testudininae is unclear and should be examined when new material (skull, shell)is discovered.The femur alone, in its distinctiveness, does not allow firm assessment of the phylogenetic relationship with respect to any potentially related taxon ( Centrochelys , Stigmochelys , Testudo and Titanochelon ). It is noteworthy that the establishment of new fossil taxa on the basis of appendicular elements is not rare among testudinids, and has been used, besides most other insular taxa mentioned already, for the recently described species Chelonoidis marcanoi Turvey et al., 2017 from the Quaternary of Hispaniola ( Turvey et al., 2017).