According to Pritchard and Trebbau (1984), 2 subspecies of Phrynops nasutus are known in Venezuela from 3 specimens. Among these putative P. nasutus, one referable to Phrynops nasutus nasutus (now a synonym of Mesoclemmys nasuta) was a live captive specimen kept in the Parque Zoológico El Pinar, in Caracas (Fig. 1). A second specimen was preserved and deposited in the Museum of Comparative Zoology at Harvard University (MCZ 58099, Fig. 2) and was assigned to Phrynops nasutus wermuthi (now a synonym of Mesoclemmys raniceps), and the third, the type specimen of Hydraspis maculata housed in the Natural History Museum in London (NHMUK1946.1.22.14, Fig. 3) was not assigned to any subspecies of P. nasutus.

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Some authors have recently discussed the lack of documentation of M. nasuta in Venezuela (Barrio-Amorós and Narbaiza 2008; Rivas et al. 2012); however, there are no mentions of M. raniceps. On the other hand, Rojas-Runjaic et al. (2011) recorded the latter from the upper basin of the Orinoco River in Venezuela, although the report seems to have been based on literature review.

In 1987, Bour and Pauler resurrected Phrynops raniceps and considered P. n. wermuthi to be a junior synonym of this species, a decision that has been accepted by most authors (e.g., Iverson 1992; Soini 1996). Bour and Zaher (2005) developed a new taxonomic arrangement that placed both P. nasutus and P. raniceps (as well as 8 other species) in the genus Mesoclemmys. Current knowledge of the distribution of Mesoclemmys considers M. nasuta to be restricted to French Guiana and Surinam (Bour and Pauler 1987; McCord et al. 2001; Bour and Zaher 2005) and M. raniceps to have a broad geographic range that includes Brazil, Bolivia, Perú, Ecuador, Colombia, and Venezuela (Iverson 1992; McCord et al. 2001; Bour and Zaher 2005; Rueda-Almonacid et al. 2007; Turtle Taxonomy Working Group 2014).

The specimen previously identified as P. n. nasutus that was kept alive in the Parque Zoológico El Pinar in Caracas (Fig. 1), with the locality of origin unknown, was illustrated in Pritchard and Trebbbau (1984:plates 33a–b) and has been reidentified by us to be an adult female Mesoclemmys zuliae. That specimen differs from M. nasuta (character of the latter in parentheses) mainly by having a triangular intergular scute, almost as wide as long (pentagonal, with convex anterior side; much narrower than long); the dorsum of the head gray with a black stripe from the snout through the eye to the rear of head (uniform chestnut brown to black, without a stripe from the snout through the eye to the rear of head); and the throat uniformly pale (dark with pale edges). Interestingly, the description of M. zuliae by Pritchard and Trebbau (1984) was based in part on a captive specimen found in a zoo called Parque Sur in Maracaibo, Venezuela. It is possible that an individual of M. zuliae was carried to the Zoológico El Pinar in Caracas in the same way that another individual was carried to the Maracaibo Zoo.

The second specimen (MCZ 58099, Fig. 2), a juvenile from “Rio Orinoco, Venezuela”, was identified by A. Rhodin (see Pritchard and Trebbau 1984, 132) as P. n. wermuthi (now M. raniceps; see above). However, we had doubts that MCZ 58099 is a specimen of M. raniceps, because it could be a specimen of Mesoclemmys heliostemma, a morphologically similar, recently described species that inhabits the Amazon River basin and the upper Orinoco in southern Venezuela (McCord et al. 2001; Molina et al. 2012). To investigate this matter further, we compared our data for MCZ 58099 with the data obtained by Molina et al. (2012) to distinguish between M. heliostemma and M. raniceps. Our results (see Table 1) show that MCZ 58099 is morphologically more similar to M. heliostemma than to M. raniceps. Two specific diagnostic characters are head width, which is not as wide as it is in M. raniceps, and shell height, which is smaller than it is in M. raniceps. The head width:carapace length ratio is 0.30 (0.34 in similar-sized M. raniceps and 0.29 in similar-sized M. heliostemma) and shell height:carapace length ratio is 0.30 (0.34 in similar-sized M. raniceps and 0.28 in similar-sized M. heliostemma). Juveniles of the 2 species have different head color patterns, but unfortunately, the skin over the head of MCZ 58099 was almost completely removed for skull preparation. In spite of this, it is possible to see light-colored scales on the small piece of skin left intact behind the left tympanum, another diagnostic character for M. heliostemma.

Table 1. Measurements of a juvenile individual of Mesoclemmys heliostemma (MCZ 58099) from the Orinoco River, Venezuela. Measurements follow Molina et al. (2012).

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The third specimen, the holotype of H. maculata (NHMUK 1946.1.22.14, Fig. 3), was described by John Edward Gray (Gray 1873a). In the short description of H. maculata Gray 1873, the type locality was listed as “Tropical America”. He also referred to it in another publication (Gray 1873b) in which he mentioned that the type specimen was a juvenile individual from South America. His text reads:

3. Hydraspis maculata, Gray.

a. Animal, in spirits, young.

H. maculata, Gray. Ann. & Mag. N. Hist. 1873.

S. America. Mus. Utrecht. 66, 8, 14, 233.

Hydraspis maculata was later synonymized with Rhinemys nasuta by Boulenger (1889), and almost a century later Bour and Pauler (1987) placed it in the list of synonyms of P. nasutus (now M. nasuta, see above). This was followed by McCord et al. (2001) and even the most recent edition of the taxonomic list of the chelonians of the world (Turtle Taxonomy Working Group 2014); however, Bour and Zaher (2005) reidentified the specimen as M. raniceps, based on morphology and head color pattern, particularly the short intergular in comparison to the medial femoral sulcus and the presence of a black stripe on each side of the head, extending from the snout through the eyes and finishing at the back of the tympani (Fig. 3), both important diagnostic characters distinguishing M. raniceps from M. nasuta (Bour and Pauler 1987). The inclusion of “Mus Utrecht” in data provided by Gray (1873b) mistakenly led Bour and Pauler (1987) to think that the species was native to Suriname, formerly Dutch Guiana; thus, the inclusion of H. maculata as a synonym of M. nasuta (R. Bour, pers. comm., September 2014).

The type of H. maculata cannot be attributed to M. heliostemma (characters of this species in parentheses) because it does not possess the facial band typical of the juvenile individual of this species (presence of a yellow or orange V-shaped facial band in life; pale in preserved specimens), for the presence of a black stripe on each side of the head, from the snout through the eyes to the rear of head (without black stripes on the sides of the head or reticulations over the head), for the light tympani (black in all stages), and the throat with light margins (throat completely dark colored). We agree with Bour and Zaher (2005) in that the type of H. maculata must be included in the synonymy of M. raniceps.

Pritchard and Trebbau (1984) reported the type locality of H. maculata as “Venezuela”, but this was in error since Gray (1873a, 1873b) explicitly stated “Tropical America” and “S[outh] America”, not “Venezuela”. According to Bour and Pauler (1987), this mistake was attributable to a typographical error made by Boulenger (1889), who misplaced the species name H. maculata in the text and, therefore, wrongfully linked the species to Venezuela (R. Bour, pers. comm., September 2014).

According to this historical review and the new interpretation of the available data, we consider that there are currently no specimens referable to M. raniceps from Venezuela. The only species of Mesoclemmys definitely present in Venezuela are Mesoclemmys gibba (apparently a common species), M. zuliae (an endemic species), and M. heliostemma (known in Venezuela from two specimens, the holotype and the MCZ specimen, MCZ 58099).