Stolonica reducta ( Sluiter, 1904 )

Kott, Patricia, 2006, Observations on non-didemnid ascidians from Australian waters (1), Journal of Natural History 40 (3 - 4), pp. 169-234: 220-223

publication ID 10.1080/00222930600621601

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Stolonica reducta ( Sluiter, 1904 )


Stolonica reducta ( Sluiter, 1904)  

Styela reducta Sluiter 1904, p 72   .

Stolonica reducta: Kott 1985, p 236   and synonymy.


Previously recorded (see Kott 1985): Western Australia (Trigg I.), Coral Sea (Lihou and Marian Reefs); Indonesia. New record: Queensland (18.845 ° S, 146.795 ° E, 7.5 m) GoogleMaps   .


Zooids are small, dome-shaped, sessile and black in preservative, the black spherical pigment cells obscuring the body organs. Three branchial folds are on each side. The open gut loop on the posterior half of the left side is slightly curved; the pear-shaped stomach with about eight branchial folds and a slightly curved caecum occupies the proximal half of the ascending limb of the gut loop. Small endocarps are on the body wall but gonads were not detected in the newly recorded highly contracted zooids.


The newly recorded zooids resemble those previously described in their size, shape, naked test, number of branchial folds, course of the gut loop and shape of the caecum. The stomach has fewer folds and is shorter than Kott (1985) reported in specimens from the Coral Sea and the spherical black pigment cells have not previously been reported. These differences could be the result of intraspecific variation or two species could be involved.

Botryllus stewartensis Brewin, 1958  

( Figure 10H View Figure 10 )

Botryllus stewartensis Brewin 1958, p 444   ; Kott 1990b, p 286 and synonymy.


Previously recorded (see Kott 1990b): Western Australia (Albany); South Australia (Spencer and St Vincent Gulfs); Victoria (Ninety Mile Beach, Port Phillip Bay ); New South Wales ( Port Kembla , Port Stephens , Port Hacking ); Queensland (Moreton Bay); New Zealand (South I. and Stewart I.). New record: South Australia (Edithburgh, 3–4 m, SAM E3289 View Materials )   .


The newly recorded colonies are squat, sandy lobes (to 1 cm high and 1 cm diameter) on a basal mat. Each lobe contains a single common cloacal system consisting of a circle of zooids around a central common cloacal aperture. The zooids open from the upper flat surface, which is slightly depressed in the preserved colonies. The test is delicate and soft, and covered with sand, although sand is not present internally. Zooids are as previously described with about 10 rows of about 15 stigmata and three delicate internal longitudinal vessels running the length of the branchial sac. The ventral internal longitudinal vessel is close to the endostyle. A small, curved gastric caecum is at the pyloric end of the stomach.


The species shows little variation, despite its wide geographic range. The height of the flattopped colony lobes does vary, sometimes reaching 3.5 cm but their diameter is less variable, reaching only 1.5 cm. The presence of a circular zooid system and the sandy external covering are characteristic. Other temperate species have a similar recorded range, across the southern Australian coast from Albany and up the eastern coast to Moreton Bay. However, the occurrence of the species in the South Island and Stewart I. ( New Zealand) suggest a possible sub-Antarctic affinity.

Sandy species of the subfamily Botryllinae   are unusual. Botrylloides saccus Kott, 2003   from Kangaroo I. has similar circular systems but small almost spherical colony lobes on short, thin stalks. Botryllus purpureus ( Oka, 1932)   has encrusting colonies with sand embedded throughout the test. Other ascidian species with a similar distribution in temperate Australia and New Zealand are Ascidiella aspersa ( Mueller, 1776)   , Asterocarpa humilis ( Herdman, 1899)   , Dumus areniferus Brewin, 1952   , Euclavella claviformis ( Herdman, 1899)   , and Sigillina australis Savigny, 1816   . Also, a few species groups and genera, namely the pachydermatina group ( Pyura   ), certain Polycarpa spp.   ( P. zeleta   , P. pegasus   , and P. tinctor   and related species), some Molgula spp.   and Hypsistozoa spp.   , also indicate a biogeographic relationship between temperate Australian waters and New Zealand (see Kott forthcoming).

Pyura irregularis ( Herdman, 1882)  

Cynthia irregularis Herdman 1882, p 141   .

Pyura irregularis: Kott 1985, p 305   and synonymy.


Previously recorded (see Kott 1985): Tasmania (Hobart, d’Entrecasteaux Channel , Port Davey ), Victoria ( Bass Strait , Port Phillip Bay , Westernport ), New South Wales ( Port Jackson ). New records: Tasmania ( Port Davey , SAM E2876 View Materials , E2878 View Materials , E2888 View Materials ; Tasmanian Canyons (Big Horseshoe—Broken Reef, 115 m ))   .


These specimens resemble other material assigned to this species, which is indigenous and confined to a limited geographic range in southeastern Australia from south of Tasmania to the mid-eastern coast of the continent. The test is dark brown in preservative and is sandy and brittle, ridged and wrinkled. Anteriorly the body narrows to the terminal branchial aperture and the atrial opening on a conspicuous siphon about halfway down where the body suddenly increases in diameter. The siphons usually are turned away from each other. The peritubercular-V is characteristically long and narrow (about half the length of the dorsal lamina). The U-shaped slit on the dorsal tubercle (deep in the V) has both horns turned in. There are seven or eight branchial folds with up to 20 tough internal longitudinal vessels on the folds and three or four between. The gut forms a simple open D-shaped loop. The anal border is divided into pronounced rounded lobes. Gonads (one on each side of the body) are separated into double rows of hermaphrodite sacs each side of the gonoducts and endocarps are on gonads and the descending limb of the gut loops   .


The species is readily identified by its tough wrinkled test, long siphons turned away from each other, the dorsal tubercle deep in the long peritubercular V and the open D-shaped gut loop with endocarps on it.


South African Museum


Royal British Columbia Museum - Herbarium














Stolonica reducta ( Sluiter, 1904 )

Kott, Patricia 2006

Stolonica reducta:

Kott P 1985: 236

Pyura irregularis:

Kott P 1985: 305

Botryllus stewartensis

Kott P 1990: 286
Brewin BI 1958: 444

Styela reducta

Sluiter CP 1904: 72

Cynthia irregularis

Herdman WA 1882: 141