Maskray

Abstract: Empruthotrema stenophallus n. sp. (Monogenea: Monocotylidae) is described from specimens from the nasal tissue of the blue-spotted maskray Dasyatis kuhlii (Muller and Henle, 1841) collected in shallow waters off Pulau Banggi and Pulau Mabul, Sabah, Borneo, Malaysia. This is the first monogenean species to be described from an elasmobranch collected from Sabah. E. stenophallus can be distinguished from the other 6 members of the genus by the morphology of the sclerotized male copulatory organ, which is narrow, short, and distally tapered. E. dasyatidis Whittington and Kearn, 1992, previously documented from the nasal tissue of several of elasmobranch species from Australia, is recorded from 8 host species distributed around Malaysian Borneo. These represent new host and locality records for this monocotylid. The difficulties in identifying species of Empruthotrema and the apparent lack of host specificity by some members of the genus are discussed.

Abstract: Morphological deformities in blue-spotted maskray, Neotrygon kuhlii (Muller & Henle, 1841) were observed from the regular fishery of the Gulf of Mannar, Southeast coast of India. The deformities were mostly noticed in the head (pectorals not fused) and the vertebral column (scoliotic/lordotic/kyphotic curve). The detailed observations on various deformities have been briefly described in the present investigation.

Abstract: The blue-spotted maskray from Guadalcanal Island (Solomon archipelago) is distinct by its colour patterns from Neotrygon kuhlii with which it was previously confused, and belongs to a genetic lineage clearly separate from all other known species in the genus Neotrygon. It is here described as a new species, Neotrygon vali sp. nov., on the basis of its nucleotide sequence at the cytochrome oxidase 1 (CO1) gene locus. It is diagnosed from all other known species in the genus Neotrygon by the possession of nucleotide T at nucleotide site 420 and nucleotide G at nucleotide site 522 of the CO1 gene.

Abstract: The present paper reviews the phylogeography of an emblematic Indo-West Pacific stingray and aims at linking its taxonomic implications with conservation management. The blue spotted maskray was once understoodto be a single species widely distributed in the Indo-West Pacific, from the Red Sea to Fiji and from southern Japan to New South Wales. Genetics have shown that it actually consists of a number of distinct lineages with parapatric distribution. Phylogenetic data suggest an evolutionary origin of this species complex in the southwestern Pacific in the Miocene. The blue-spotted maskray progressively colonized the Indo-West Pacific from the East to the West. The lineages in the western Coral Triangle and the Indian Ocean are the most recent. Against this updated taxonomic and phylogeographic background, there remains a need for research on the population dynamics and fisheries management of this increasingly threatened species complex.This paper is dedicated to the memory of Dr Irma S. Arlyza.