Lapparentemys, Gaffney & Meylan & Wood & Simons & De Almeida Campos, 2011

Gaffney, Eugene S., Meylan, Peter A., Wood, Roger C., Simons, Elwyn & De Almeida Campos, Diogenes, 2011, Evolution Of The Side-Necked Turtles: The Family Podocnemididae, Bulletin of the American Museum of Natural History 2011 (350), pp. 1-237 : 24-26

Lapparentemys , new genus

SYNONYMY:? Roxochelys vilavilensis Broin, 1971 .

TYPE SPECIES:? Roxochelys vilavilensis Broin, 1971 .

INCLUDED SPECIES: Lapparentemys vilavilensis ( Broin, 1971) .

DISTRIBUTION: Paleocene of Bolivia.

ETYMOLOGY: Restudy of the type and two additional specimens of Roxochelys wanderleyi indicate that the species vilavilensis Broin, 1971 , is not referable to the genus Roxochelys . Thus, we erect a new generic name,

Lapparentemys , in honor of the many important contributions of France de Lapparent de Broin to our understanding not only of pleurodires, but of all turtles.

REVISED DIAGNOSIS: A podocnemidid known from the skull and postcrania; pectoral scales contact mesoplastra uniquely among Podocnemididae ; skull relatively high and narrow in contrast to Bauruemys ; orbits facing dorsolaterally; interorbital groove as found in Podocnemis absent; temporal emargination slight in contrast to Bauruemys but deeper than in Peltocephalus ; postorbital large in contrast to Podocnemis ; parietal-quadratojugal contact long; cheek emargination reaches above level of orbit; medial expansion of triturating surface, median maxillary ridge, absent; wide concavity on the midline, formed by the premaxillae and anterior maxilla, present; accessory ridge in triturating surface absent; vomer present; vomer-maxilla contact wide; fossa precolumellaris shallow as in Podocnemis expansa ; foramen jugulare posterius closed; interparietal scale equilateral triangle; cavum pterygoidei with small anterior opening for foramen cavernosum; horizontal occipital shelf present as in Podocnemis ; chorda tympani not enclosed in processus retroarticularis; nuchal bone width greater than length; seven neurals extending to costal seven.

The shell of this medium-size Pelomedusoides pleurodire (to 400 mm straight carapace length) differs from other South American Cretaceous and early Tertiary Pelomedusoides in having a relatively thick, elongate shell with deep scute sulci but no distinct surface sculpture; vertebral scales are narrow and parallel sided; a relatively short, wide nuchal bone is narrow anteriorly; first neural four sided; axillary buttress not extending onto second costal, reaching to third peripheral anteriorly; suture for axillary buttress broad and curving with parallel sides; second costal not thickened to support axillary buttress; bridge peripherals weakly guttered dorsally; iliac scar with anterior margin concave and crossing from the eighth onto the seventh costal both medially and laterally; internal gutter of posterior peripherals and pygal absent; gular scales restricted to epiplastra; intergular narrow; short humeral contact on midline; pectoral scales contact epiplastron and entoplastron; pectoral scale contact to mesoplastron variable.

Lapparantemys vilavilensis ( Broin, 1971) , new combination

? Roxochelys vilavilensis Broin, 1971

TYPE SPECIMEN: MNHNP VIL 1 ( Broin, 1971: pl. 31, figs. 1, 2), a complete carapace and plastron.

TYPE LOCALITY: 2 kms south of Vilavila, later designated Villa Viscarra, Cochabamba Province, Bolivia.

HORIZON: Originally ( Broin, 1971: 445) described from the late Cretaceous El Molino Formation, the horizon was later (Muizon et al., 1983; Broin, 1991) identified as the early Paleocene Santa Lucía Fm.

DIAGNOSIS: As for genus.

ETYMOLOGY: Named for the type locality near Vilavila ( Broin, 1971: 445).

REFERRED MATERIAL: Specimens from the type locality listed in the hypodigm ( Broin, 1991) include: MNHNP VIL 2 , partial shell ; MNHNP VIL 3 , plastron ; MNHNP VIL 4 , partial plastron ; MNHNP VIL 5 , juvenile shell ; MHNC 6902 , partial shell ; MHNC 6903 , plastron .

AMNH 14444, a well-preserved and nearly complete skull (figs. 21, 22), lacking the distal end of the crista supraoccipitalis and the edges of the pterygoid flange. The skull is slightly distorted by dorsolateral compression from the right side, ventromedial compression from the left side. The fossa temporalis on both sides is free of matrix, but the cavum cranii is not. The lower jaw is present and is complete except for the right articular region. A small portion of the carapace is associated with the skull and it agrees with the other Lapparentemys shells. Locality and Horizon: ‘‘El Molino, Vila vila’’ (label).

WUS 2160, a complete shell (fig. 90) with skull (figs. 23–25) lacking the right skull roof and cheek. Before preparation the skull was articulated to the shell by the cervical vertebrae. The left premaxilla lacks its medialmost portions and the right one is mostly missing. The right maxilla lacks its labial ridge and the area below the orbital margin. The pterygoid flanges are broken, the right one is missing, and the left one is nearly all present. Only the anteroventral portion of the crista supraoccipitalis remains, the rest is missing. The lower jaws are present and nearly complete; only part of the left prearticular is missing. Locality and horizon: Santa Lucía Fm., Cochabamba Department, Bolivia, purchased George Helsp Fossils, 1994 (label).

RM 20.5155, skull, shell (fig. 89), cervicals, and limb bones in partial articulation. Specimen poorly preserved due to small cracks and displacements throughout. Locality and horizon: ‘‘Santa-Lucia, Tiupampa (label),’’ collector, Pierre-Yves Gagnier.

PREVIOUS WORK: Both Broin (1971) and (1991) provide important descriptions and figures of skulls and shells of this taxon. Numerous papers have referred to this taxon but provided no additional information.

DISCUSSION: We refer two additional specimens to Roxochelys wanderleyi (following Romano et al., 2009; see discussion below) greatly expanding our knowledge of the shell. As a result of this redescription based on new shell material of R. wanderleyi , the type species of Roxochelys , it is apparent that ‘‘? Roxochelys vilavilensis ’’ Broin, 1971, cannot be referred to Roxochelys . Therefore, we have created a new genus, Lapparentemys .

Lapparentemys and Pricemys are linked by the possession of a shallow fossa precolumellaris.

Our examination of MNHNP material identified by Broin (1971, 1991) as ‘‘? Roxochelys vilavilensis , ’’ leads us to believe that there may be more than one taxon in the original hypodigm and subsequently assigned specimens. In order to avoid possible problems of overlapping species, we have restrict- ed our concept of vilavilensis to the holotype and other specimens listed above. We consider MNHNP VIL-6 and MHNC 6904 to represent two possible, additional unnamed taxa that are excluded from our concept of Lapparentemys vilavilensis .

MNHN VIL-6 is a small round carapace with an associated plastron ( Broin, 1991: pl. I, figs. 1–4). It has a very different overall shell shape than the type of vilavilensis or other specimens with skulls referable to vilavilensis . In our opinion the small size is not due to immaturity as all sutures are closed and the shell is well ossified. In MNHNP VIL-6 the pleuro-marginal sulci are on the costoperipheral sutures, which is not the case in the type of vilavilensis or other specimens with skulls that are referable to vilavilensis . The epiplastron differs in having a long straight anterior margin and a more transverse posterior margin. Where the posterior margin of the epiplastron articulates with the hyoplastron it is straight and without a major posterior projection that can be seen in MNHNP VIL-3, which was collected with the vilavilensis type specimen. Furthermore, on the ventral surface, the pectoral scales reach the epiplastral suture, but do not cross onto the epiplastron as in vilavilensis . The vertebral scales in MNHNP VIL-6 are shorter and somewhat more hexagonal than in Lapparentemys vilavilensis .

MNHC 6904 is a specimen from Tiupampa ( Broin, 1991: pl. II, figs. 8–11). It has a longer, narrower shell more similar to vilavilensis in overall form, but differs from vilavilensis in having a robust axillary buttress located on the posterior part of the first costal and producing some thickening of the second costal. The epiplastron has the same basic shape as vilavilensis but the pectoral scale appears to not reach the epiplastron as it does in material of vilavilensis . Unlike vilavilensis , the vertebrals of this specimen are more hexagonal. Resolution of the phylogenetic position of MNHN VIL-6 and MNHC 6904 is beyond the scope of this study. They are discussed to stress that they are not used in our concept of Lapparentemys vilavilensis .