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Weigmann S.,University of Hamburg | Stehmann M.F.W.,Ichthyological Research Laboratory and Consultant | Thiel R.,University of Hamburg
Zootaxa | Year: 2013

A new genus and species of the carcharhiniform family Pseudotriakidae is described based on three specimens caught near the Socotra Islands in the northwestern Indian Ocean. The first specimen and holotype of Planonasus parini g. n. and sp. n. was caught during cruise 17 of RV 'Vityaz' in 1988/89 along the deep western Indian Ocean. Two further specimens of the new genus and species were caught somewhat later by commercial trawlers close to the locality of the holotype. The new genus differs from the two other pseudotriakid genera Gollum and Pseudotriakis by the presence of oral papillae, the absence of nicitating eyelids, a longer head, an intermediate prenarial snout length, an intermediate number of tooth rows per jaw, a first dorsal fin of intermediate height and length and with a white free rear tip, a caudal peduncle of intermediate length, and fewer vertebrae. Copyright © 2013 Magnolia Press. Source


Weigmann S.,University of Hamburg | Stehmann M.F.W.,Ichthyological Research Laboratory and Consultant | Thiel R.,University of Hamburg
Zootaxa | Year: 2014

Anacanthobatis ori is one of the least known species of the family Anacanthobatidae with only four juvenile specimens reported. The species remained assigned to the genus Anacanthobatis sensu lato due to the lack of an adult male as external and skeletal clasper characters are the essential diagnostic features for the differentiation of genera and subgenera within the family Anacanthobatidae. Since an adult male of A. ori became available, along with an adult female and six further juveniles, the authors reinvestigated the species and present its so far unknown diagnostic characters of clasper morphology and skeleton and scapulocoracoid. The clasper turned out to be the most complex one of all known anacanthobatids as the external components flag, slit, pseudosiphon-like cavity, pecten, and two sentinas are not known from any other anacanthobatid species. Furthermore, a dorsal terminal 1 cartilage is present but displaced proximally of the terminal clasper skeleton, the outer edge of dorsal terminal 2 is deeply serrated, the ventral terminal has a very long, curved, straplike process, and the proximal part of accessory terminal 1 is embedded in the cavity of the baseball-glove-like head of accessory terminal 2. Due to the strong differences in external and internal clasper characters to all other known anacanthobatid species, A. ori is placed in its own, newly erected genus, Indobatis. © 2014 Magnolia Press. Source


Weigmann S.,University of Hamburg | Stehmann M.F.W.,Ichthyological Research Laboratory and Consultant | Thiel R.,University of Hamburg
Zootaxa | Year: 2014

A new species of the widely in temperate and tropical latitudes distributed skate genus Rajella is described based on an almost adult male specimen from the western Indian Ocean off South Mozambique. The holotype of R. paucispinosa n. sp. was caught during cruise 17 of RV 'Vityaz' along the deep western Indian Ocean in 1988/89. It is the northernmost record of a Rajella specimen in the western Indian Ocean. The new species is the 18th valid species of the genus and the fifth species in the western Indian Ocean. It differs from its congeners in the small maximal total length of about 50 cm and only few thorns on the dorsal surface. The new species has only two thorns on each orbit, one nuchal thorn, one right scapular thorn (left one not detectable, abraded), and one median row of tail thorns. Other species of Rajella typically have half rings of thorns on orbital rims, a triangle of thorns on nape-shoulder region, and at least three rows of tail thorns. Another conspicuous feature of the new species is the almost completely white dorsal and ventral coloration. © 2014 Magnolia Press. Source


Weigmann S.,University of Hamburg | Stehmann M.F.W.,Ichthyological Research Laboratory and Consultant | Thiel R.,University of Hamburg
Marine Biodiversity | Year: 2014

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. © 2014 Senckenberg Gesellschaft für Naturforschung and Springer-Verlag Berlin Heidelberg. Source


Weigmann S.,Elasmobranch Research Laboratory | Stehmann M.F.W.,Ichthyological Research Laboratory and Consultant
Zootaxa | Year: 2016

A new deep-water legskate, Sinobatis brevicauda, is described based on two specimens caught on the remote Saya de Mal-ha Bank in the central western Indian Ocean. The new species is easily distinguished from all other described anacantho-batids by the short tail. It is the only Sinobatis species described from the western Indian Ocean and differs from the other anacanthobatid legskates in this area by its large size and light coloration. All other species of Sinobatis are described from the eastern Indian and, particularly, western Pacific oceans. In addition to the short tail, the new species clearly differs from its morphologically closest congener, the Australian S. bulbicauda, in a bicolored white and grayish ventral color-ation with gray and white blotches (vs. uniformly pale or white and skin somewhat translucent) and a filamentous tail with-out flattened, bulbous tip. Furthermore, it is distinguished by several morphometric and meristic differences, e.g. a longer body (length 65% TL vs. 39-61% TL), longer head (dorsal length 34% TL vs. 21-31% TL, ventral length 41% TL vs. 23-36% TL), longer snout (preorbital length 28-29% TL vs. 14-26% TL, preoral length 30% TL vs. 16-28% TL, prenasal length 28% TL vs. 14-25% TL), and fewer diplospondylous (102-112 vs. 121-142) and total (131-141 vs. 148-168) ver-tebrae. S. brevicauda clearly differs from the other anacanthobatids in the western Indian Ocean, Anacanthobatis marmo-rata and Indobatis ori, by having a much shorter tail, strongly different coloration, much larger size, and in many morphometric and meristic differences. Copyright © 2016 Magnolia Press. Source

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