Cyclophorus cucphuongensis K. C. M. von Oheimb, 2019

Cyclophorus cucphuongensis K. C. M. von Oheimb View in CoL , sp. nov.

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Etymology. The name refers to the type locality of this species in Cuc Phuong National Park.

Conchological description. Medium-sized Cyclophorus species, overall shell shape rounded, aperture typically circular. Shell height 23.3 to 29.9 mm (mean = 26.5 mm), shell breadth 28.7 to 35.4 mm (mean = 31.4 mm). Number of whorls 5 to 5.25. Early whorls without or with bluish colouration. Shape of body whorl usually uncompressed or slightly compressed; rounded or well-rounded. Lip reflected and simple. Lip colour yellow or ivory. Wing-shaped projection at columellar margin present and pronounced, or present and not pronounced. Peripheral band usually dark brown, medium brown, or not distinguishable from background colouration. Colour pattern generally variable. Typical elements of pattern above position of peripheral band: flames and zig-zag stripes in different shades of brown. Typical elements of pattern below position of peripheral band: spiral lines and spiral bands in different shades of brown.

Type specimens. VNM052 ( Fig 9a View Fig 9 ; holotype), specimen in ethanol; NHMUK 20140276/ 4; GenBank accession numbers MG720887 (COI), MG720937 (16S), MG720987 (28S); female individual; shell height 27.2 mm, shell breadth 32.7 mm, number of whorls 5.25 . VNM053 ( Fig 9b View Fig 9 ; paratype), specimen in ethanol; NHMUK 20140287/2 (ethanol-preserved frozen tissue sample NHMUK Barcode 014041337); GenBank accession numbers MN153325 (COI), MN153374 (16S), MN153421 (28S); male individual; shell height 27.0 mm, shell breadth 31.3 mm, number of whorls 5.25. VNM054 ( Fig 9c View Fig 9 ; paratype), specimen in ethanol; NHMUK 20140287/3 (ethanol-preserved frozen tissue sample NHMUK Barcode 014041338; viable cell preparation NHMUK Barcode 014041352); GenBank accession numbers MN153326 (COI), MN153375 (16S), MN153422 (28S); male individual; shell height 27.0 mm, shell breadth 31.1 mm, number of whorls 5.25.

Locality and sampling data. VNM052: Vietnam, Ninh Binh, Cuc Phuong National

Park (20.28845˚, 105.66767˚); 07 September 2013; leg. Hao Van Luong & team. VNM053, VNM054: Vietnam, Ninh Binh, Cuc Phuong National Park (20.35548˚, 105.63342˚); 08 September 2013; leg. Hao Van Luong & team.

Diagnosis. Cyclophorus cucphuongensis sp. nov. can be differentiated from all herein characterised Cyclophorus species based on DNA sequence data. Diagnostic nucleotide substitutions of the cytochrome c oxidase subunit I (COI) gene: 89:T, 91:C, 208:T, 289:T, 343:C, 401:C, 487:C, 556:G, 574:G/C (numbers indicate the position in the studied COI fragment).

Remarks. This species corresponds to lineage 10 in Oheimb et al. [ 6]. The studied material of C. cucphuongensis has been found in central and eastern Cuc Phuong National Park in both western Ninh Binh province and southeastern Hoa Binh province ( Fig 4 View Fig 4 ). None of the other herein characterised species is known to occur sympatrically with this species. Cyclophorus takumisaitoi occurs in northwestern Cuc Phuong National Park. The shell shape of C. takumisaitoi is similar to that of C. cucphuongensis ( Fig 2 View Fig 2 ). The shell of C. takumisaitoi is slightly smaller than that of C. cucphuongensis ( Fig 3a View Fig 3 ). The lip of C. takumisaitoi tends to have a more reddish colour than that of C. cucphuongensis , which tends to be more yellowish. The wing-shaped projection at the columellar margin is absent in C. takumisaitoi , while being present in C. cucphuongensis , and the shell colouration of C. takumisaitoi is more uniform with a less prominent peripheral band. Furthermore, C. paracucphuongensis occurs in western Cuc Phuong National Park. The shell shape of C. paracucphuongensis is similar to that of C. cucphuongensis ( Fig 2 View Fig 2 ). The shell of C. paracucphuongensis is of similar size as that of C. cucphuongensis ( Fig 3a View Fig 3 ). On the basis of currently available shell morphological data, these two species cannot be differentiated.