Warren's six-gill sawshark
| Warren's six-gill sawshark | ||||||||||||
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Head of Pliotrema warreni , view from the side and from below, drawing from the first description |
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| Scientific name | ||||||||||||
| Pliotrema warreni | ||||||||||||
| Regan , 1906 |
Warren's six-gill saw shark ( Pliotrema warreni ) is a species of shark from the family of saw sharks (Pristiophoridae) that occurs on the coast of southern and southeastern Africa, from South Africa to southern Mozambique, at depths of 25 to 430 meters.
features
Warren's six-gill sawshark can reach a maximum length of 136 cm, and possibly 170 cm. Males stay smaller than females. 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, serrated teeth that are close together on the side edge of the "saw", and more or less large spines on the underside. Below the laterally arranged eyes the rostrum continues as a protruding degree and ends below the rear edge of the injection holes . In contrast to the other two types of six-gill saw sharks, the rostrum between the base of the barbels and the nostrils is not narrowed in Warren's six-gill saw sharks. The barbels are two-thirds the length of the rostrum from the top of the rostrum.
The tail stalk is triangular in cross section, the tail is 18 to 19% of the total length of the fish. Warren's six-gill sawshark is colored medium to dark brown on the back with a clearly distinctive yellow stripe. The ventral side is white. There are two dark vertical stripes on the rostrum. The rostral teeth have dark edges.
Systematics
Warren's six-gill saw shark was first scientifically described in 1906 by the British ichthyologist Charles Tate Regan, together with the genus of the six-gill saw shark ( Pliotrema ) and named after Dr. E. Warren, who sent a fish collection, including the type specimens of the shark species, to the British Museum (Natural History) . Pliotrema warreni was the only species in the genus until 2020. In a revision of the genus Pliotrema published in March 2020 , two more species were described, Anna's six- gill sawshark ( Pliotrema annae ), which occurs near Zanzibar, and Kaja's six- gill sawshark ( Pliotrema kajae ), the one on the coast of Madagascar and above the Mascarene Plateau lives.
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
- ↑ Chales Tate Regan: Descriptions of new or little known fishes from the coast of Natal. Annals of the Natal Government Museum. Vol. 1, No. 1, pp. 1-6 ( BHL ).