Trididemnum alexi Lambert, 2003

Lambert, Gretchen, 2019, The Ascidiacea collected during the 2017 British Columbia Hakai MarineGEO BioBlitz, Zootaxa 4657 (3), pp. 401-436 : 411

Trididemnum alexi Lambert, 2003

Figure 4 D–F

IHAK 52 BHAK 2870 UF 2557. Mouth of Kwakshua , Scuba, 5–22 m. On branching bryozoan .

IHAK 55 BHAK 1732, 1733 UF 2543, 2544. Kwakshua Petroglyph Cliff, Scuba, 17–20 m, high current, vertical rock wall. Five colonies.

IHAK 60 BHAK 3241 UF 2560. Rattenbury Pinnacle, Scuba, 17–20 m. On living unidentified scallop; with many small amphipods Polycheria osborni Calman, 1898 in burrows on tunic surface .

The colonies are thick, encrusting and may attain a large size of 10 cm or more across and up to 2 cm in thickness. They are usually a dark purple or purplish brown in color, due to numerous pigment granules in the tunic and zooids. Small stellate tunic spicules are sparse. Colonies of what are probably this species were collected by dredging by Huntsman (1912a) near Nanaimo, British Columbia but identified only as dark colonies of Trididemnum sp. with sparse spicules. For complete description see Lambert (2003). Distribution: British Columbia to Washington ( Lambert 2003; Lamb & Hanby 2005).

Figures

FIGURE 4. Aplousobranchia, Didemnidae. A–C: Diplosoma listerianum. A: colony on Scyra acutifrons; B, C: close-ups of zooids from two different color morphs. D–F: Trididemnum alexi. D: colony on living scallop; E: same colony closeup with amphipod Polycheria osborni burrowed into tunic surface; F: tunic spicules. Scale bars:A, 1 cm; B, 1.5 mm; C, 1.3 mm; D, 1.6 cm; E, 3.2 mm; F, 35 µm. Photos B and D by G. Paulay.