This shark has a limited range

The Error Seamount catshark (Bythaelurus stewarti), is a shark belonging to the family Scyliorhinidae in the order Carchariniformes. It is considered microendemic to Error Seamount, a guyot located in the Arabian Sea in the western Indian Ocean. 121 specimens have been examined from Mount Error Guyot.


Family: Scyliorhinidae – Catsharks

Genus: Bythaelurus 

Species: stewarti


Phylum– Chordata

Class– Chondrichthyles


Common NameGround Sharks

Family– Scyliorhinidae

Common NameCatsharks




Average Size and Length: The Error Seamount catshark has a maximum size of 44 cm/1.4 feet, vs. 39 cm/1.3 feet of the Bristly catshark. Males mature at 35–39 cm/1.1-1.3 feet, vs. 21–28 cm/8.3-11 inches of in the Bristly catshark.

Denticles: The Error Seamount catshark has smaller and less densely concentrated denticles than the Bristly catshark; the morphology is different. In particular, the Error Seamount catshark has smaller and less elongate branchial, trunk and lateral caudal denticles that are set much less densely and have a surface that is very strongly and fully structured by reticulations, vs. structured by reticulations only in basal fourth in the Bristly catshark.

Demographic, Distribution, Habitat, Environment and Range: The Error Seamount catshark is considered microendemic to Error Seamount (Mount Error Guyot), a guyot located in the Arabian Sea in the northwestern Indian Ocean. It is a deep-water catshark.

Aesthetic Identification: The closest relative to the Error Seamount catshark is the Bristly catshark (B. hispidus), which it differs from in its larger size, darker and more mottled coloration. The Error Seamount catshark has a darker fresh coloration and dark grayish-brown mottling of the ventral head, vs. the ventral head of the Bristly catshark typically uniformly yellowish or whitish.

Biology and Reproduction: The Error Seamount catshark differs from all congeners in that they have a higher spiral valve turn count. They have 11–12 vs. 8–10 in the Bristly catshark.

The Error Seamount catshark differs from the Bristly catshark in having more slender claspers that are gradually narrowing to the bluntly pointed tip without knob-like apex, vs. claspers that are broader and with a distinct knob-like apex.

More than likely they are oviparous.

Behavioral Traits, Sensing and Intelligence: Unknown.

Error Seamount Catshark Future and Conservation: They are not evaluated. Their range is extremely small.

Error Seamount Catshark Recorded Attacks on Humans: Not a threat to humans.

Thiel, Ralf; Kaschner, Carina Julia; Weigmann, Simon (2018-12-12). “A new microendemic species of the deep-water catshark genus Bythaelurus (Carcharhiniformes, Pentanchidae) from the northwestern Indian Ocean, with investigations of its feeding ecology, generic review and identification key“.