Contribution to the taxonomy and distribution of Pristiophorus nancyae (Elasmobranchii: Pristiophoriformes) from the deep western Indian Ocean

Abstract

The African dwarf sawshark Pristiophorus nancyae is one of the least known species of the genus. The species was described in 2011 based on type specimens in rather poor condition and with a very restricted distribution off southern Mozambique. Since nine further specimens in mostly excellent condition became available, the authors reinvestigated the species. These new records document a considerable extension of the distribution northwards to off Kenya and off the Socotra Islands. Scanning electron microscope (SEM) images of dermal denticles and a description of ontogenetic changes in dermal denticle arrangement and shape are presented for the first time. A more detailed photographic documentation and the first radiograph of the species are also given, along with updated and extended morphometrics and meristics, providing insights into wider ranges of natural variation. Furthermore, first images and description of clasper morphology and skeleton are provided. Detailed morphometrics and meristics, as well as SEM images of dermal denticles, are presented for the first time for P. cirratus, P. nudipinnis and P. schroederi.