Podocnemis medemi, Wood, 1997

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 : 63-64

‘‘Podocnemis’ ’ medemi Wood, 1997

TYPE SPECIMEN: IGM 1863, plastron and partial carapace, figured by Wood (1997: figs. 9.3, 9.4B).

TYPE LOCALITY: Cuenca de Melgar, Carmen de Apicalá, upper Magdalena River valley, Columbia (see Kay, et al., 1997, for locality data and references).

HORIZON: Honda Group ( Wood, 1997).

DIAGNOSIS: ‘‘Differs from all other pelomedusids referred to Podocnemis in having a relatively short, rounded anterior and posterior plastral lobes; extremely narrow, Vshaped anal notch; proportionately small, squarish first pair of marginal scutes; enormous size (estimated midline carapace length 5 101.5 cm); and position and shape of ischial scar on xiphiplastron (triangular in shape, expanded laterally, and moderately withdrawn from margin of anal notch)’’ ( Wood, 1997: 159).

REFERRED MATERIAL: See Wood (1997).

PREVIOUS WORK: Wood (1997).

DISCUSSION: Although this is another shell species readily differentiated from other shell species, its phylogenetic relationships are characterized by Wood (1997: 168) ‘‘The relationship of Podocnemis medemi to other members of the genus is unclear.’’ As with a number of these incertae sedis species, the absence of a good shell character diagnosis for the living Podocnemis is a problem preventing identification of these taxa as Podocnemis .

‘‘Podocnemis’’ negrii Carvalho, Bocquentin, and Lapparent de Broin, 2002

TYPE SPECIMEN: UFAC-PV 4441, partial carapace and partial plastron figured by Carvalho et al. (2002: figs. 1, 2).

TYPE LOCALITY: Five km south of Rio Branco, Acre, Brazil ( Carvalho et al., 2002).

HORIZON: Solimões Fm., Miocene ( Carvalho et al., 2002).

DIAGNOSIS: Differs from other Podocnemis in having a midline crest formed in the area of the second and third vertebral scales, with an apex on the sulcus between the scales; lacks plastral tubercles; anterior plastral lobe is relatively long and the gular and intergular scales are relatively short; most similar to Podocnemis sextuberculata ( Carvalho et al., 2002) .

REFERRED MATERIAL: Only the holotype.

PREVIOUS WORK: Carvalho et al. (2002).

DISCUSSION: Although Carvalho et al. (2002) argue that this species is the sister taxon to Podocnemis sextuberculata , they do not produce diagnostic characters arguing that it belongs to the genus Podocnemis . Even though this shell is similar to P. sextuberculata , the characters in common are not unique among the family and do not securely identify the shell as a member of the genus Podocnemis . The fact that this is one of the oldest records for this genus is therefore in doubt. The oldest secure record for Podocnemis is P. bassleri , which may be a synonym for P. expansa .