Eudistoma globosum Kott, 1957

Kott, Patricia, 2006, Observations on non-didemnid ascidians from Australian waters (1), Journal of Natural History 40 (3 - 4), pp. 169-234: 190-195

publication ID

http://doi.org/ 10.1080/00222930600621601

persistent identifier

http://treatment.plazi.org/id/011D87C1-FFE5-CD59-1FBF-FA30E1A4FC17

treatment provided by

Felipe

scientific name

Eudistoma globosum Kott, 1957
status

 

Eudistoma globosum Kott, 1957  

Eudistoma globosum Kott 1957, p 72   ; Kott 1990a, p 210.

Distribution

Previously recorded (see Kott 1990a): Western Australia (Houtman’s Abrolhos, Cockburn Sound , Margaret River ); Queensland ( Capricorn Group ). New records: Tasmanian Canyons ( Ling Hole , 174 m)   .

Description

Colonies are about 3 cm high, simple, upright lobes with a short, thick, cylindrical stalk and a conical naked head. The long zooids, characteristic of the genus, open all around the head and extend crowded and parallel to one another down into the base of the stalk. Sand is crowded in the stalk and projects up into the centre of the lower half of the head.

Remarks

Zooids of species in the genus Eudistoma   are very similar. The zooids all have short thoraces with numerous stigmata, characteristic long oesophageal necks with the stomach and gonads in the pole of the gut loop at the posterior end of the zooid and muscular body wall with an almost continuous outer coat of transverse fibres and inner longitudinal bands that continue into the abdomen. Because of this lack of diversity in the zooids, distinguishing characters are often more likely to be found in the colonies and the larvae.

The form of the small, simple, compact colonies of the present species and the distribution of sand in them is characteristic. The genus is not known from the sub- Antarctic south of New Zealand and the Tasmanian Canyons, and its original provenance may be from the tropics, where it is most diverse. However, the record from Margaret River and its occurrence south of Tasmania suggests that it is a temperate species which extends northwards on each side of the continent.

Pseudodistoma australe Kott, 1957  

Pseudodistoma australis Kott 1957, p 101   .

Pseudodistoma australe: Kott 1992a, p 428   and synonymy; 2003, p 1625 [not 1985 (sic) 5 1992a].

Distribution

Previously recorded (see Kott 2003): Western Australia (Exmouth Gulf to Cockburn Sound); South Australia (Great Australian Bight, Cape Jaffa); Victoria ( Port Phillip Heads ); Queensland (Swain Reefs). New record   : Tasmania ( Port Davey , 8–10 m, SAM E3231 View Materials )   .

Description

The colony is soft and translucent, its upper surface expanded into four short conical lobes like a crown. It converges slightly toward the base, where it appears to have been fixed to a wide, flat surface about 4 cm in diameter. Zooids extend up the colony parallel to one another and the independently opening six-lobed apertures are around the outside of the terminal lobes. Thorax and abdomen are, together, relatively short. Three rows, each of about 12 branchial stigmata, are in each half row and a short gut loop with a smooth-walled stomach is about halfway down the short abdomen. The posterior abdomen is very long, with strong bands of muscles along each side. Gonads were not detected in the newly recorded colonies, which appear to be in a vegetative stage, although there is a large embryo in the brood pouch (at the postero-dorsal end of the thorax) in a few of the zooids.

Remarks

These gelatinous, translucent rose-coloured colonies with a thick, soft stalk consisting of one or more terminal lobes, are characteristic of this wide-ranging apparently indigenous species. The new record is the most southern location known and confirms its wide range, often from temperate localities albeit extending into the tropics on both sides of the continent.

Pseudodistoma gracile Kott, 1992a  

( Figure 9A View Figure 9 )

Pseudodistoma gracilum Kott 1992a, p 433   and synonymy.

Distribution

Previously recorded (see Kott 1992a): South Australia (Great Australian Bight, Investigator Group, Kangaroo I.); Victoria (Beachport, Western Port ); New South Wales ( Jervis Bay , Port Jackson ); Queensland (Great Barrier Reef); New Caledonia. New records: South Australia (Kangaroo Is, 8–10 m, SAM E3270 View Materials ); Tasmania (Maria Is; Port Davey, 4– 6 m, SAM E3269 View Materials )   .

The new records from Tasmania are the most southerly locations yet recorded for this species.

Description

The colonies have the robust, contractile zooids of the usual form entangled in the soft, disintegrating mucus-like test as described previously.

Remarks

Although colonies and zooids resemble those of the Japanese P. fragile Tokioka, 1958   , the present species broods only a single embryo at a time, while the Japanese species has a long brood pouch with up to five embryos being brooded at a time and a significantly longer larval trunk (see Kott 1992a). Like other species in this genus it is more often recorded from temperate locations than from tropical ones.

Pseudodistoma inflatum Kott, 1992  

( Figure 9B View Figure 9 )

Pseudodistoma inflatum Kott 1992a, p 435   .

Distribution

Previously recorded (see Kott 1992a): New South Wales (South Solitary Is, Byron Bay , Coff’s Harbour ); Queensland ( Mooloolaba ). New record: New South Wales ( Coff’s Harbour , 5–7 m, SAM E3297 View Materials ). The new record is from the restricted geographic range previously recorded for this species (from northern New South Wales to the Queensland / New South Wales border)   .

Description

The colony is small, sessile, its upper surface divided into two rounded lobes that narrow toward the base, where some sand is embedded, although there is none in the gelatinous and translucent test of the upper part of the colony.

Pseudodistoma pilatum Kott, 1992  

( Figures 3A–C View Figure 3 , 9C View Figure 9 )

Pseudodistoma pilatum Kott 1992a, p 439   .

Distribution

Previously recorded (see Kott 1992a): South Australia (Great Australian Bight, Gulf St Vincent). New records: Tasmania (Tasman Peninsula, 12–14 m, SAM E3244 View Materials ; 10–14 m, E3296). The newly recorded location is the most southerly recorded for this species   .

Description

The colonies are as previously described, with the long, narrow, cylindrical sandy stalks arising from a common base and a terminal cylindrical glassy, transparent head with the relatively crowded zooids opening all around it. The sand becomes less crowded toward the top of the stalk and is only sparse in the head. In this species the oesophagus is long and the four-chambered pseudodistomid stomach is in the distal one-third of the relatively long abdomen. The posterior abdomen is long and narrow, about twice to three times the length of the abdomen, with two broad bands of muscles and a short row of gonads at the posterior end (in the base of the stalk).

Polyclinum incrustatum Michaelsen, 1930  

( Figures 3D View Figure 3 , 9D View Figure 9 )

Polyclinum neptunium   f. incrustatum Michaelsen 1930, p 542   .

Polyclinum incrustatum: Kott 1992a, p 450   and synonymy.

Distribution

Previously recorded (see Kott 1992a): Western Australia (Bunbury, Albany ); South Australia ( Great Australian Bight , Spencer Gulf ); Victoria ( Portland ). New record: Tasmania ( Port Davey , 4–6 m, SAM E3274 View Materials )   .

Description

The colonies are as previously described, soft, grey oval pillows, with sand in the surface, although it is only sparse internally. Common cloacal apertures, slightly orange in the newly recorded specimens, are evenly distributed and protrude slightly from the otherwise smooth surface of the colony. Each cloacal aperture contains the very long, narrow atrial lips of the circle of zooids that surround it. These atrial lips project from the body wall just anterior to the small, round atrial opening of each zooid and they appear to close down over the forward-projecting atrial opening. A small post-atrial papillum also projects from the middorsal line. Zooids have 18 rows of about 14 stigmata per half row, and about the same number of flat, rounded branchial papillae on each of the transverse interstigmatal vessels. Gonads were not detected in the newly recorded colonies, and a long, narrow posterior abdominal vegetative stolon is present.

Remarks

The specimens are consistent with those described previously for this species. It is distinguished from Poyclinum marsupiale   by its more numerous rows of stigmata, the less protuberant common cloacal apertures and the crowded zooids in complex systems rather than the circular systems of zooids that surround each common cloacal aperture in P. marsupiale   , and when embryos are present, by the lack of a brood pouch projecting from the thorax.

Polyclinum marsupiale Kott, 1963  

( Figure 9E View Figure 9 )

Polyclinum marsupiale Kott 1963, p 83   ; 1992a, p 452 and synonymy.

Distribution

Previously recorded (see Kott 1992a): Western Australia (Rottnest I., Albany)   ; South Australia (Kingston, Victor Harbour); Victoria (Portland, Deal I.); Tasmania (Hunter I.). New record   : South Australia (Kangaroo I., SAM E2866–7 View Materials , E3298 View Materials )   .

Description

Sandy, more or less circular cushions with rounded margins are fixed to the substratum by most of the under surface, although one specimen ( SAM E2867 View Materials ) has an extension of part of the under surface attached to a bryozoan skeleton that holds the circular plate-like colony aloft, like a mushroom. Elevations, each containing a circle of zooids around a terminal cylindrical common cloacal aperture, project from the upper surface. The test is colourless and brown zooids are visible through it. Sand is only sparse in the internal test. A long narrow atrial lip from the body wall anterior to the small circular atrial aperture of each zooid is inserted into the test around each common cloacal aperture. The atrial lip has a straight or a pointed tip, or it is produced into a fringe of four or five pointed lobes or up to 10 minute denticulations. A small post-atrial papillum projects from the body wall just behind the atrial aperture. About 16 rows of stigmata have about 15 stigmata per half row and about the same number of flat branchial papillae on each transverse vessel. The stomach is small and smooth-walled; the gonads are in a sac constricted off from the abdomen. The proximal part of the vas deferens runs a convoluted course over the surface of the gonads and it may straighten out as the gonads mature. Embryos are crowded in a brood pouch protruding from the thorax behind the atrial cavity in the newly recorded specimens ( SAM E3298 View Materials collected in November)   .

Remarks

The specimens are consistent with those described previously for this temperate species. It is distinguished from Polyclinum incrustatum   by its brown zooids, presence of a brood pouch constricted off from the thorax, fewer rows of stigmata and cloacal systems that consist of a simple circle of zooids around a protruberant common cloacal aperture.

SAM

South African Museum

Kingdom

Animalia

Phylum

Chordata

Class

Ascidiacea

Order

Aplousobranchia

Family

Polycitoridae

Genus

Eudistoma

Loc

Eudistoma globosum Kott, 1957

Kott, Patricia 2006
2006
Loc

Pseudodistoma australe:

Kott P 1992: 428
1992
Loc

Pseudodistoma gracilum

Kott P 1992: 433
1992
Loc

Pseudodistoma inflatum

Kott P 1992: 435
1992
Loc

Pseudodistoma pilatum

Kott P 1992: 439
1992
Loc

Polyclinum incrustatum: Kott 1992a , p 450

Kott P 1992: 450
1992
Loc

Polyclinum marsupiale

Kott P 1963: 83
1963
Loc

Eudistoma globosum

Kott P 1990: 210
Kott P 1957: 72
1957
Loc

Pseudodistoma australis

Kott P 1957: 101
1957
Loc

Polyclinum neptunium

Michaelsen W 1930: 542
1930