Ritterella rubra Abbott & Trason, 1968

Lambert, Gretchen, 2019, The Ascidiacea collected during the 2017 British Columbia Hakai MarineGEO BioBlitz, Zootaxa 4657 (3), pp. 401-436 : 414

Ritterella rubra Abbott & Trason, 1968

Figure 8 D–G

RHAK 2 BHAK 0601, 0602 UF 2460. Goose Island Group, Duck Island, low rocky intertidal.

One colony with two large heads and many smaller ones but only the large heads collected; largest one 1.8 cm wide at widest part and slightly flattened with short thick stalk, 3.9 cm long but had been cut off above the base. Sandy leathery tunic reddish-orange, lightly encrusted with sand and shell debris but none in the internal tunic which is translucent, somewhat tough and gel-like. Siphons are close together, bright red. Zooids orange, about 14 mm long, with about 14 rows of stigmata; the zooids were somewhat contracted making counts difficult. Stomach globular, very obscurely and irregularly lobed. Atrial chamber full of bright pinkish-red embryos in various stages of development, the most mature with three adhesive papillae in a row and numerous very short ampullae in several rows on each side as described by Abbott & Trason (1968); it was not possible to count them. Postabdomen extends into the stalk, with the ovary at the anterior end and containing a dozen or more orange or pinkish ova; testes follow with some testes covering the posterior portion of the ovary. All the morphological characters agree with the description given by Abbott & Trason (1968) except for the presence of one or two additional rows of stigmata; Abbott & Trason give the number as varying from 10–13 in colonies from the type locality in Monterey County, central California. A colony from SE Alaska ( O’Clair & O’Clair 1998) collected 5/25/1994 and identified by me also had 14 rows of stigmata. A name change was proposed by Brunetti (2007) based on his transferring the species to the genus Synoicum Phipps, 1774 , but this change is rejected because the distinguishing morphological characters for R. rubra place it in the genus Ritterella Harant, 1931 , not Synoicum .

This species is known from British Columbia to central California ( Abbott & Trason 1968, Abbott & Newberry 1980, O’Clair & O’Clair 1998, Lamb & Hanby 2005; Abbott et al. 2007).

Figures

FIGURE 8. Aplousobranchia, Ritterellidae. A–C: Ritterella pulchra. A, whole colony; B, enlargement of one lobe of living colony; C, one zooid. D–G: Ritterella rubra. D, E: two lobes of same colony; F: one zooid; G; enlargement of thorax of same zooid. Scale bars: A, 0.7 cm; B, 1 mm; C, 4 mm; D, 5 mm; E: 7 mm; F, 1.2 mm. Photo D by G. Paulay.