 The genus name Nebrius is derived from the Greek word <unk> or <unk> , meaning the skin of a <unk> . The specific epithet <unk> is Latin for " rust @-@ colored " . Other common names for this species include giant <unk> shark , Madame X ( a name coined by the shark fisherman Norman Caldwell in the 1930s for the then @-@ unidentified Australian specimens ) , nurse shark , rusty <unk> , rusty shark , <unk> shark , spitting shark , and tawny shark . Based on morphological similarities , Nebrius is believed to be the sister genus of Ginglymostoma , with both being placed in a clade that also contains the short @-@ tail nurse shark ( <unk> <unk> ) , the whale shark ( <unk> <unk> ) , and the zebra shark ( <unk> <unk> ) . 
