Family CLAVOPORIDAE Osburn & Soule, 1953

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Family CLAVOPORIDAE Osburn & Soule, 1953

Compiler and date details

July 2001 - Dr Philip Bock

Clavoporidae Osburn & Soule, 1953.

Introduction

The family Clavoporidae was introduced for the genus Clavopora by Soule (in Osburn 1953). D'Hondt (1975a; 1975b) included Pseudalcyonidium with Clavopora in the Clavoporidae, but the group is a heterogeneous one, even though the general colony form is the same in all members.

The colony consists of two major parts: a head of autozooids and an elongated peduncle or stalk composed of kenozooids, often with modified muscle systems. The peduncle is either attached to the substratum by an encrusting basal disc, or is anchored by ramifying kenozooidal rhizoids. Clavopora and related forms have colonies with a relatively small autozooidal head and a multizooidal peduncle, each kenozooid being traversed by large, modified parietal muscles. A species assigned to Clavopora hystricis Busk (1874) was reported from the Antarctic by Mawatari (1968). Pseudalcyonidium differs in having a proportionately larger head element, and a peduncle which apparently consists of a single, very elongated kenozooid with a centrally placed muscle system. Both types of peduncle are retractile and capable of other movements, according to d'Hondt (1975a; 1975b).

Most records of C. hystricis and other species of Clavopora are from fairly shallow waters. Records of Pseudalcyonidium are all from very deep water (from 400 to over 3000 m depth), in the northern Atlantic. Like several other deep-sea ctenostomes (eg Pachyzoon and Aethozoon), their distribution is very extensive. Australian specimens from samples in the Museum of Victoria resemble those from the north Atlantic closely. Five colonies are from off New South Wales, from 363 to 429 m, ten are from Victoria, from 1500 m; and one from Tasmania, from 720 m. The peduncle cuticle appears to be slightly retracted into ridges in many colonies; a faint central mass of tissue is presumably muscular.

Diagnosis

Colony erect, composed of a kenozooidal peduncle, which is sometimes muscular, attached basally by a disc or by rhizoids, and a small, terminal head of autozooids, which are contiguous. Orifice puckered, subterminal. ( after d'Hondt ,1975).