reticulate swellshark) Cephaloscyllium isabellum Bonnaterre, 1788 (draughtsboard shark) Cephaloscyllium laticeps A. H. A. Duméril, 1853 (Australian swellshark) Cephaloscyllium pictum Last, Séret & W. T. White, 2008 (painted swellshark) Cephaloscyllium sarawakensis Ka. Yano, A. Ahmad & Gambang, 2005 (Sarawak pygmy swellshark) Cephaloscyllium signourum Last, Séret & W. T. White, 2008 (flagtail swellshark) Cephaloscyllium silasi Talwar, 1974 (Indian swellshark) Cephaloscyllium speccum Last, Séret & W. T. White, 2008 (speckled swellshark) Cephaloscyllium stevensi E. Clark & J. E. Randall, 2011 (Steven's swellshark) Cephaloscyllium sufflans Regan, 1921 (balloon shark) Cephaloscyllium umbratile D. S. Jordan & Fowler, 1903 (blotchy swellshark) Cephaloscyllium variegatum Last, Séret & W. T. White, 2008 (saddled swellshark) Cephaloscyllium ventriosum Garman, 1880 (swellshark) Cephaloscyllium zebrum Last, Séret & W. T. White, 2008 (narrowbar swellshark) Cephaloscyllium sp. 1 Not yet described (Philippine swellshark) Cephaloscyllium sp. not yet described (tiger swellshark) Cephaloscyllium sp. not yet described (New Guinea swellshark) Cephaloscyllium sp. not yet described (dwarf balloon shark) Cephaloscyllium sp. not yet described (dwarf oriental swellshark) Cephaloscyllium sp. not yet described (New Caledonia swellshark) Cephaloscyllium sp. not yet described (Red Sea swellshark) Phylogeny and evolution Morphological and molecular phylogenetic studies have shown the closest relative of Cephaloscyllium to be Scyliorhinus, and these two genera and Poroderma form the subfamily Scyliorhininae, the most basal clade of the order Carcharhiniformes. The oldest confirmed Cephaloscyllium fossils come from Miocene epoch (23–5.3 Mya) deposits in California, though based on the rate of DNA divergence in sharks, the swellshark lineage likely dates back to the Cretaceous period (145.5–65.5 Mya). Distribution and habitat Cephaloscyllium is widely distributed in the Indian and Pacific Oceans, in temperate and tropical waters, but not close to the equator. Swellshark diversity is greatest around Australia and in the west-central Pacific, where multiple endemic species are found. The most far-flung members of the genus are C. sufflans off southeastern Africa, C. silasi off southwestern India, C. umbratile in the northwestern Pacific, and C. ventriosum along the western coast of the Americas. One hypothesis states Cephaloscyllium originally evolved in Australia and New Guinea, and subsequently dispersed outwards in a series of colonization events, eventually reaching Africa and the Americas. Cephaloscyllium species, bottom-dwelling sharks, can be found from the intertidal zone to a depth of on upper continental and insular slopes. Description Swellsharks are stocky and spindle shaped, with the trunk tapering substantially to the caudal peduncle. The head is short (comprising less than a fifth of the total