Aplidium phortax ( 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 : 1174-1175

Aplidium phortax ( Michaelsen 1924)

( Figure 6f )

Amaroucium phortax ( Michaelsen, 1924) : 389–400, figs 20, 21.

Aplidium (Amaroucium) phortax . Brewin, 1946: 92–94, fig. 2.

Aplidium phortax Kott, 1963: 109 , figs 23, 24. (See Kott 1985 for synonymy.)

Aplidium phortax Millar, 1982: 22 , fig. 9.

Material examined

New records. NEW ZEALAND, Bluff Harbour , Tiwai Point, wharf pile (46.592°S. 168.352°E, 8 m, 20 August 2007, NIWA68109 ) .

Previously recorded. New Zealand, Tauranga ( Michaelsen 1924); d’ Urville Island ( Sluiter 1900, as Amaroucium ritteri ); Otago ( Brewin 1946); Stewart Island ( Michaelsen 1924); Chatham Islands ( Sluiter 1900, as Amaroucium obseum ); Fiordland ( Page et al. 2014); Eastern Australia and Solomon Islands ( Kott 1963).

Description

This species has firm gelatinous, dull yellow (5Y5/10) to cream colonies reaching a maximum diameter of 150 mm and a thickness of 50 mm on wharf piles in Bluff Harbour ( Figure 6f ). The subdermal canals are finely branched, giving colonies a brain-like pattern below the transparent test surface. The zooids are arranged in irregular oval to elongate systems, and indistinct common cloacal apertures are visible throughout the colony. Zooids in colonies from Bluff Harbour are typical, with a relatively small thorax and abdomen and a long narrow post-abdomen. The thorax has a narrow atrial aperture surmounted by a short, stout lappet. There are 14 rows of stigmata with approximately 12 stigmata per row in the branchial sac. The stomach is small with 32 fine folds. Ova develop in the anterior half of the post-abdomen, and up to 19 testis follicles are in a parallel row posterior to the ovary. Remarks

Morphological characters of the specimen described from Bluff Harbour are consistent with conspecifics that are widely distributed throughout New Zealand ports and harbours. Characters of the colony described here are the same as the Stewart Island variety A. phortax var. ptychodes Michaelsen (1924) , with 32 rather than 23–26 stomach folds in typical specimens ( Millar 1982).

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).