Boury-Esnault, N. (2002 ). Order Chondrosida Boury-Esnault & Lopes, 1985. Family Chondrillidae Gray, 1872. Pp. 291-297. In: Hooper, J.N.A. & Van Soest, R.W.M. (eds) Systema Porifera - A guide to the classification of sponges. (2 volumes) Kluwer Academic/ Plenum Publishers: New York, 1708 + xvliii. ISBN 978-1-4615-0747-5 (eBook electronic version).
Order Chondrosida Boury-Esnault & Lopes, 1985. Family Chondrillidae Gray, 1872. Pp. 291-297. <i>In</i>: Hooper, J.N.A. & Van Soest, R.W.M. (eds) <i>Systema Porifera - A guide to the classification of sponges</i>. (2 volumes) Kluwer Academic/ Plenum Publishers: New York, 1708 + xvliii.
Chondrosida Boury-Esnault & Lopes (Demospongiae) contains only a single family Chondrillidae Gray, including junior synonym Chondrosiidae Schulze, with seven nominal genera of which four are valid: Chondrosia, Chondrilla, Thymosia and Thymosiopsis.
Chondrillidae was previously considered close to both the order Hadromerida and other tetractinellid orders, such as Astrophorida, warranting recognition in a new order as there was no argument in favour of one solution over the other. This order was subsequently
supported by recent molecular data confirming its monophyly although there are still no clear phylogenetic hypotheses on relationships with the other orders of Demospongiae. Chondrosids are oviparous, encrusting to massive with a marked cortex enriched with fibrillar collagen, inhalant apertures localised in special structures and a skeleton (when present) composed of siliceous spicules or spongin fibres. Chondrosid species are widely distributed mainly in shallow waters, exceptionally up to 750m depth. They are often present in semiobscure conditions, on vertical walls, at the entrance of submarine caves, or below rocks.