Anna's six-gill sawshark
| Anna's six-gill sawshark | ||||||||||||
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| Pliotrema annae | ||||||||||||
| Weigmann , Gon , Leeney & Temple , 2020 |
Annas Sixgill Sawshark ( Pliotrema annae ) is a species of shark in the family sawshark (Pristiophoridae). It is only known from four specimens that were caught on the coast of eastern Africa near Zanzibar at depths of 20 to 35 meters during the night. The species may also be found further north on the coasts of Kenya and Somalia and can be found in deeper regions during the day.
features
Three of the four specimens are 95 to 98 cm long, the fourth 58 cm long specimen is missing the saw. All are females. As with all six-gill saw sharks, the body is long, cylindrical and slim. The head is flattened in front of the gill slits and has a greatly elongated and flattened snout with the saw-like rostrum typical of saw sharks. The rostrum has a distinctive pair of barbels in front of the nostrils, large and small teeth that are close together on the side edge of the "saw", and more or less large spines on the underside. In contrast to the other two types of six-gill saw sharks, the rostrum of Anna's six-gill saw shark is relatively short and the number of teeth on the sides of the rostrum is correspondingly smaller (16 or 17 large teeth). The length of the rostrum and head is about 34% of the total length. In Anna's six-gill sawshark, the rostrum is somewhat narrowed between the base of the barbels and the nostrils. The barbels are in the middle of the rostrum. In the upper jaw, the shark species has 35 to 37 rows of small teeth with conical tips and broad bases.
Anna's six-gill sawshark is colored medium to dark brown on the back without a vertical stripe. The ventral side is white with some fuzzy dark spots. There are two dark vertical stripes on the rostrum. Rostrum and rostral teeth have dark borders.
Systematics
Anna's six-gill saw shark was described in a revision of the genus Pliotrema published in March 2020 together with Kaja's six-gill saw shark ( Pliotrema kajae ) by the German ichthyologist Simon Weigmann and some colleagues and named after his niece. The genus Pliotrema described in 1906 by the British ichthyologist Charles Tate Regan was previously considered to be monotypical .
Individual evidence
- ↑ a b c Simon Weigmann, Ofer Gon, Ruth H. Leeney, Ellen Barrowclift, Per Berggren, Narriman Jiddawi, Andrew J. Temple: Revision of the sixgill sawsharks, genus Pliotrema (Chondrichthyes, Pristiophoriformes), with descriptions of two new species and a redescription of P. warreni Regan. PLOS ONE , March 2020, doi: 10.1371 / journal.pone.0228791