The Echinoid Directory

Family Kamptosomatidae Mortensen, 1934, p. 162

[nom. corr. Kamptosominae]

Diagnosis	Echinothurioids with: test paper-thin primary tubercles perforate and crenulate ambulacra with just a single occluded element alternating with primary elements on ambital plates 10 large buccal plates on the peristomial membrane, plus a few small ambulacral plates around the margin.
Range	Recent; Pacific (abyssal).
Classification and/or Status	Euechinoidea, Echinothurioida
Remarks	The crenulate primary tubercles and presence of large buccal plates bearing tube-feet are both characters that are also found in Diadematoids. However, unlike diadematoids there are a small number of wedge-shaped ambulacral plates incorporated into the peristomial membrane around its edge. Kamptosomatidae appear to bridge the gap between Diadematoida and other Echinothurioida. It is sister group to all other echinothurioids in thge analysis of Kroh & Smith (2010). Phylogenetic analysis by Mooi et al (2004), however, places Kamptosoma within crown group echinothurioids, and specifically within the Phormosomatidae. The reduction of ambulacral plating in Kamptosoma is thus seen as derived. Mooi, R., Constable, H., Lockhart, S. & Pearse, J. 2004. Echinothurioid phylogeny and the phylogenetic significance of Kamptosoma (Echinoidea: Echinodermata). Deep Sea Research II 51, 1903-1919. Kroh, A. & Smith, A. B. 2010. The phylogeny and classification of post-Palaeozoic echinoids. Journal of Systematic Palaeontology 8, 147-212.