Pyura bouvetensis ( Michaelsen, 1904 )

Primo, Carmen & Vázquez, Elsa, 2007, Ascidians collected during the Spanish Antarctic expedition CIEMAR 99 / 00 in the Bransfield and Gerlache Straits, Journal of Natural History 41 (29 - 32), pp. 1775-1810 : 1803-1804

Pyura bouvetensis ( Michaelsen, 1904)

Boltenia bouvetensis Michaelsen, 1904 .

Boltenia salebrosa Sluiter, 1905 ; Sluiter 1906.

Boltenia turqueti Sluiter, 1905 ; Sluiter 1906.

Pyura turqueti: Hartmeyer 1909 ; Sluiter 1914; Arnback-Christie-Linde 1938; Van Name 1945.

Boltenia scotti Herdman, 1910 .

Boltenia antarctica Beneden and Longchamps, 1913 ; Herdman 1923.

Pyura legumen Kott, 1954 ; Vinogradova 1962.

Pyura bouvetensis: Millar 1960, 1968 ; Monniot and Monniot 1982, 1983, 1994; Tatián et al. 1998a, 1998b; Sanamyan and Sanamyan 2002; Ramos-Esplá et al. 2005; Arntz et al. 2006.

Pyura georgiana Kott, 1969 ; part Kott 1971; Monniot and Monniot 1974.

Distribution

New record: Bransfield Strait (Station B3: eight specimens; Station B5: 10 specimens; Station B6: two specimens; Station B7: seven specimens). Previously recorded: Antarctic continent ( Kott 1969; Monniot and Monniot 1983; Ramos-Esplá et al. 2005); South Shetland, South Orkney ( Kott 1969; Monniot and Monniot 1983; Tatián et al. 1998a, 1998b, 2005; Ramos-Esplá et al. 2005), and Bouvet Islands ( Millar 1968; Arntz et al. 2006); Antipodes Island ( Monniot and Monniot 1982). From 30 to 1555 m depth.

Description

Up to 38 mm plus a stalk of 243 mm.

Remarks

Four closely related species of stalked Pyura are recognized in Antarctica and the subantarctic: Pyura legumen ( Lesson, 1830) , Pyura georgiana ( Michaelsen, 1898) , Pyura bouvetensis ( Michaelsen, 1904) , and Pyura lycoperdon Monniot and Monniot, 1983 , with minor but constant differences ( Monniot and Monniot 1983).

The characteristics that separate P. bouvetensis from the other species are: globular body, long stalk located over a third of the ventral face at the level of the gut loop, tunic with variable small spines, weak musculature, right gonad divided in two to nine lobes, left gonad in the gut loop, endocarps over the gonads, quite small parietal organs distant from gonads and gut, and no atrial organs. Some of these characteristics are not exclusive to the species, but as a whole they are definitive.

Pyura discoveryi ( Herdman, 1910)

Halocynthia discoveryi Herdman, 1910 ; Herdman 1923.

Pyura discoveryi var septemplicata Sluiter, 1914 .

Pyura discoveryi: Hartmeyer 1911 ; Arnback-Christie-Linde 1938; Van Name 1945; Kott 1954, 1969, 1971; Millar 1960; Vinogradova 1962; Vasseur 1974; Monniot C 1978; Monniot and Monniot 1982, 1983, 1994; Tatián et al. 1998a, 1998b, 2005; Ramos- Esplá et al. 2005.

Distribution

New record: Bransfield Strait (Station B1: three specimens; Station B3: one specimen; Station B6: one specimen; Station B7: two specimens; from 9 to 52 mm height). Previously recorded: Antarctic continent; South Shetland, South Orkney, and South Georgia Islands ( Vinogradova 1962; Kott 1954, 1969; Monniot and Monniot 1983, 1994; Tatián et al. 1998a, 1998b, 2005; Ramos-Esplá et al. 2005). From 30 to 2350 m depth.

Remarks

This is a common Antarctic species with a characteristic aspect. The most significant character is the presence of a strong membrane at the base of both siphons, possibly a sphincter to close the openings, maybe as a defence mechanism ( Kott 1969). Other important characteristics are: poorly developed seventh branchial fold, arborescent liver, and Polycarpa -like gonads.