Family PEROPHORIDAE

Museums

Museum list

Regional Maps

Family PEROPHORIDAE

Compiler and date details

P. Kott, Queensland Museum, Brisbane, Queensland, Australia

Introduction

Species of the family Perophoridae Giard, 1872 are colonies in which small zooids develop from the mesodermal tissue in the vessels of the thin axial or basal stolons which connect them to one another. The gut loop is to the left of the flat branchial sac, and internal longitudinal vessels and from four to 25 rows of stigmata are in the branchial sac. The apertures have up to 14 lobes around each rim. Gonads are in the gut loop. The ovary is small and sac-like. The testis is undivided or lobed or divided into up to ten long club-shaped follicles (Perophora Wiegmann, 1835); or it is a mass of small pyriform or branched follicles (Ecteinascidia Herdman, 1880). The genus Perophora has been revised by Goodbody (1994).

Embryos are incubated in a brood pouch in the parietal body wall. They are large with ocellus and otolith and antero-median adhesive organs with axillary cones in ectodermal cups like aplousobranch ascidians. The aplousobranch-like viviparous larvae of Perophoridae and the role of the mesodermal tissue in the replicative process has led Berrill (1950) to postulate a clavelinid rather than phlebobranch affinity for the family. The proposal is supported by the fact that an epicardium has not been detected. However, nor have traces of phlebobranch nephrocytes or excretory vesicles been found around the gut or elsewhere in the body wall. Nevertheless, the gut loop in the parietal body wall, the gonads enclosed in the gut loop and the form of the pharynx are all significant phlebobranch characters and arguments for a phlebobranch affinity appear to be the most compelling. The aplousobranch-like appearance of the larval trunk probably is the result of convergence associated with viviparity, for the sessile adhesive organs are only superficially similar to the stalked ones of aplousobranch species. A viviparous habit occurs in most colonial ascidians, and appears to be adaptive rather than indicative of a phylogenetic relationship.

The family is well represented in Australian waters by eight species of the exclusively tropical genus Ecteinascidia and six species of Perophora, a genus known from both tropical and temperate waters. Perophora hutchisoni is one of the few known trans-Tasman species. Kott (1985, 2003) has documented the Australian members of the family and reviewed its affinities.