Apristurus

Kawauchi, Junro, Weigmann, Simon & Nakaya, Kazuhiro, 2014, Apristurus breviventralis, a new species of deep-water catshark (Chondrichthyes: Carcharhiniformes: Scyliorhinidae) from the Gulf of Aden, Zootaxa 3881 (1), pp. 1-16 : 9

Key to the species of Apristurus in the western Indian Ocean

1a. Pre-outer nostril length much greater than interorbital width.................... A. longicephalus (‘ longicephalus group’)

1b. Pre-outer nostril length much shorter than interorbital width.................................................... 2

2a. Upper labial furrows as long as or shorter than lower ones; spiral valve counts low (8–9); supraorbital sensory canals continu- ous........................................................................ A. microps (‘spongiceps group’)

2b. Upper labial furrows longer than lower ones; spiral valve counts high (13–23); supraorbital sensory canals discontinuous........................................................................................3 (‘ brunneus group’)

3a. First dorsal-fin origin behind pelvic-fin insertion.......................................... A. breviventralis sp. nov.

3b. First dorsal-fin origin above pelvic-fin base................................................................. 4

4a. Pectoral-pelvic space about as long as anal-fin base (ceratotrichia)........................................ A. indicus

4b. Pectoral-pelvic space much longer than anal-fin base (ceratotrichia).............................................. 5

5a. Interdorsal space very long, about equal to prespiracular head; 13–16 spiral valves......................... A. saldanha

5b. Interdorsal space shorter, much less than prespiracular head, 19–23 spiral valves........................ A. melanoasper