Farkas, Ziegler, Pham, Ong & Fritz, 2019
Photographs Thomas Ziegler.
A new, critically endangered species of softshell turtle, Pelodiscus variegatus sp. n. is described from north-central Vietnam and Hainan Island, China, distinguished by a unique set of genetic and morphological traits from all other congeners (P. axenaria, P. maackii, P. parviformis, P. sinensis, and unnamed genetic lineages). Morphologically, P. variegatus is characterized, among others, by its strong ventral ornamentation in all age classes.
Keywords: China, genetics, morphology, softshell turtles, Vietnam
|Figure 2. Two paratypes of Pelodiscus variegatus sp. n. in life. |
A, C MTD 44045, female, 75.2 mm PL B, D MTD 42834, female, 86.6 mm PL.
Photographs Thomas Ziegler.
Pelodiscus variegatus sp. n.
Diagnosis: In the 12S rRNA gene, Pelodiscus variegatus differs from all other species and genetic lineages of Pelodiscus by the presence of cytosine (C) instead of thymine (T) at position 96 of the reference alignment (Suppl. material 1). In the cyt b gene, P. variegatus differs from all other species and genetic lineages of Pelodiscus by the presence of adenine (A) instead of cytosine (C) in position 130 and by the presence of thymine (T) instead of cytosine (C) in positions 204, 741, and 1081 of the reference alignment (Suppl. material 2). In the mtDNA fragment corresponding to the partial ND4 gene plus adjacent DNA coding for tRNAs, P. variegatus differs from all other species and genetic lineages of Pelodiscus by the presence of adenine (A) instead of guanine (G) in position 94 of the reference alignment (Suppl. material 3). These and further species-specific differences are shown in Tables 1–3.
Etymology: The specific epithet variegatus (spotted) is a Latin adjective in masculine gender alluding to the highly contrasting markings, especially the large plastral blotches, of the new species.
|Figure 5. Habitat of Pelodiscus variegatus sp. n.: Song Rac Lake, Cam Xuyen District, Ha Tinh Province, Vietnam. Photograph An Vinh Ong.|
Remarks: In addition to the characters used here for diagnosing P. variegatus, Gong et al. (2018) described some further genetic differences to other Pelodiscus species.
Fritz et al. (2010) suggested that the taxon now named Pelodiscus variegatus resembles P. parviformis, prompting the TTWG (2011, 2012, 2014, 2017) to identify the Pelodiscus records from Vietnam with the latter species. However, as explained in Gong et al. (2018), this is no longer tenable in the face of the genetic distinctness of the two species.
Traditionally, Chinese softshell turtles from Hainan were identified as P. sinensis (e.g., Pope 1935; Ernst and Barbour 1989; Ernst et al. 2000; TTWG 2011, 2012, 2014, 2017). However, the few old (early 20th century) museum specimens serving as record sources represent either P. variegatus (AMNH 28345, AMNH 30125, FMNH 6626, FMNH 6627, MVZ 23946, NMW 30219:1, NMW 30232:3) or P. parviformis (NMW 30232:1–2, NMW 30232:4–8). Thus, the native occurrence of P. sinensis sensu stricto on Hainan seems questionable, even though this species is now most likely bred there in local farms. We cannot exclude that also some of the presence points of P. sinensis from southwestern mainland China mapped by the TTWG (2017) refer to P. parviformis or P. variegatus (and in part perhaps to P. axenaria).
While Pelodiscus sinensis is listed as “Vulnerable (VU)” by the IUCN Red List of Threatened Species (Asian Turtle Trade Working Group 2000), the conservation status of P. axenaria, P. maackii, P. parviformis, and now P. variegatus, remains unassessed, in spite of their proven genetic distinctness (Fritz et al. 2010; Yang et al. 2011; Gong et al. 2018). Given their restricted distributional ranges and the intense exploitation to which they are subjected, all these species would certainly classify for a higher category rating. In this vein, the most recent red list of Chinese vertebrates compiled by Jiang et al. (2016) proposed the conservation status of P. axenaria, P. parviformis and P. sinensis be upgraded to “Endangered (EN)” and indicated P. maackii to be “Data Deficient (DD).” Rhodin et al. (2018) suggested for P. parviformis “Critically Endangered (CR)” and for P. sinensis “Endangered (EN),” whereas P. axenaria and P. maackii were identified as “Data Deficient (DD).” Consequently, also P. variegatus, which was included in P. parviformis by Rhodin et al. (2018), should be classified as “Critically Endangered (CR).”
Balázs Farkas, Thomas Ziegler, Cuong The Pham, An Vinh Ong and Uwe Fritz. 2019. A New Species of Pelodiscus from northeastern Indochina (Testudines, Trionychidae). ZooKeys. 824: 71-86. DOI: 10.3897/zookeys.824.31376