Synoicum stewartense ( Michaelsen, 1924 )

Page, M. J., 2018, Colonial ascidians from the Foveaux Strait region of New Zealand, Journal of Natural History (J. Nat. Hist.) 52 (17 - 20), pp. 1157-1180 : 1171

Synoicum stewartense ( Michaelsen, 1924)

( Figure 6c )

Macroclinum stewartense Michaelsen, 1924: 413–421 , figs 26, 27, 28. Synoicum stewartense: Millar, 1982: 15 , fig. 3.

Material examined

New records. NEW ZEALAND, Stewart Island , Bob’ s Point (41° 51.25 ʹ S, 168° 07.57 ʹ E, 15 m, 31 August 2007, NIWA68089 ) .

Previously recorded. Stewart Island, 35 fathoms Michaelsen 1924); in dredged material off Stewart Island ( Brewin 1958a); Chatham Rise ( Millar 1982); Fiordland ( Page et al. 2014).

Description

Closely spaced, flat-topped, sand-encrusted heads 10–15 mm in diameter, each with 15–18 zooids arranged in a circle around a central, raised common cloacal aperture ( Figure 6c ). Zooids are large and pigmented red, with internal structures as described in Page et al. (2014).

Remarks

The central, raised common cloacal aperture, depressed branchial apertures of zooids in a circular system and a low raised rim around the anterior of each colony lobe are consistent with characters for this species described by Michaelsen (1924) and Millar (1982). Adherent sand covers the purple zooids.

Figures

Figure 6. In situ images of: (a) Diplosoma velatum (NIWA68092); (b) Polyclinum novaezealandiae (NIWA68097); (c) Synoicum stewartense (NIWA68089); (d) Aplidium benhami (NIWA68101); (e) Aplidium knoxi (NIWA68091); (f) Aplidium phortax (NIWA68109).