Himantura lobistoma, a new whipray (Rajiformes: Dasyatidae) from Borneo, with comments on the status of Dasyatis microphthalmus

• Main Authors: Bernardette Mabel Manjaji Matsumoto, Last, Peter R.
• Format: Article
• Language: English; English
• Published: Springer Verlag 2006
• Subjects: QH301-705.5 Biology (General)
• Online Access: https://eprints.ums.edu.my/id/eprint/27574/1/Himantura%20lobistoma%2C%20a%20new%20whipray%20%28Rajiformes%20Dasyatidae%29%20from%20Borneo%2C%20with%20comments%20on%20the%20status%20of%20Dasyatis%20microphthalmus%20ABSTRACT.pdf; https://eprints.ums.edu.my/id/eprint/27574/3/Himantura%20lobistoma%2C%20a%20new%20whipray.pdf; https://eprints.ums.edu.my/id/eprint/27574/; https://link.springer.com/article/10.1007/s10228-006-0350-6

A new long-snouted whipray, Himantura lobistoma, is described on the basis of seven specimens collected from the southeastern sector of the South China Sea, off western Borneo. It belongs to a subgroup of Himantura species provisionally defined herein as the “uarnacoides” complex that includes five nominal species: H. chaophraya, H. granulata, H. hortlei, H. pastinacoides, and H. uarnacoides. These whiprays all have a similar lateral disc shape (i.e., pectoral-fin apices broadly rounded rather than narrowly rounded or angular), a plain colouration (i.e., usually uniform light to dark brown dorsally, and pale or whitish ventrally with or without a dark margin), a long and slender whiplike tail, and plate like denticles in a broad dorsal band in adults. Himantura lobistoma can be distinguished from the superficially similar H. hortlei by its highly protrusible mouth and pelvic girdle with prominent lateral prepelvic processes. It differs from other members of the “uarnacoides” complex by a combination of internal and external morphological characteristics (e.g., having an extremely elongate snout and very small eyes). Another long-snouted stingray from the region, Dasyatis microphthalmus Chen, inadequately described and known only from the lost holotype, is considered a nomen dubium. It had been assigned to Himantura based on the absence of an obvious ventral cutaneous tail fold but may be conspecific with D. acutirostra.