(Figure 5)
Sertularella polyzonias — Fraser, 1937: 156, pl. 35, fig. 187 [not Sertularella polyzonias (Hincks, 1861] Sertularella polyzonias, var. gigantea Hincks, 1874: 151, pl. 7, figs. 11–12.
Sertularella gigantea — Mereschkowsky, 1878 b: 339, pl. 14, figs. 6–7.
Material. CANADA: British Columbia. Queen Charlotte Land District. Masset Harbor, 14. ix. 1935, part of multilevel epizoic complex, without gonothecae, ROMIZ B 4036. CANADA: British Columbia. Queen Charlotte Land District. Masset Harbor, 14. ix. 1935, epizoic on Bryozoa (Bugula sp), without gonothecae, ROMIZ B 4037.
CANADA: British Columbia. Queen Charlotte Land District. Masset Harbor, 14. ix. 1935, epizoic on Bugula sp, without gonothecae, ROMIZ B 4038. CANADA: British Columbia. Queen Charlotte Land District. Masset Harbor, 14. ix. 1935, epizoic on stolon of Plumularia lagenifer a Allman, 1885, without gonothecae, ROMIZ B 4039. CANADA: British Columbia. Queen Charlotte Land District. Masset Harbor, 14. ix. 1935, epizoic on Abietinaria filicula (Ellis & Solander, 1786), without gonothecae, ROMIZ B 4040. CANADA: British Columbia. Queen Charlotte Land District. Masset Harbor, 14. ix. 1935, without gonothecae, ROMIZ B 4041. CANADA: British Columbia. Masset Harbor, 14. ix. 1935, short hydrocauli, without gonothecae, ROMIZ B 4042. CANADA: British Columbia. Queen Charlotte Land District. Masset Harbor, 14. ix. 1935, on Symplectoscyphus turgidus (Trask, 1857), without gonothecae, ROMIZ B 4043. CANADA: British Columbia. Queen Charlotte Land District. Masset Harbor, 14. ix. 1935, on Symplectoscyphus tricuspidatus (Alder, 1856), without gonothecae, ROMIZ B 4044. CANADA: British Columbia. Queen Charlotte Land District. Masset Harbor, 14. ix. 1935, on Sertularia sp. without gonothecae, ROMIZ B 4045. CANADA: British Columbia. 54 ˚ 12 ’ 48 ”N, 133 ˚07’ 24 ”W, 29. iv. 1961, two hydrocauli, without gonothecae, 82.2 meters, coll D.B. Quayle, ROMIZ B 4046. CANADA: British Columbia. 49 ˚ 13 ’00”N, 125 ˚ 57 ’00”W, 12. v. 1961, 20.1 meters, hydrocauli, without gonothecae, coll. D.B. Quayle, ROMIZ B 4047. CANADA: British Columbia. 48 ˚ 43 ’00”N, 123 ˚ 26 ’ 30 ”W, 13. v. 1961, 51.2 meters, hydrocauli, without gonothecae, coll. D.B. Quayle, ROMIZ B 4048. Other material: CANADA: British Columbia. 48 ˚ 43 ’00”N, 123 ˚ 26 ’ 30 ”W, 13. v. 1961, 51.2 meters, coll. D.B. Quayle, sections of hydrocauli, without gonothecae, CMNI 1982 - 1383. CANADA: British Columbia. 48 ˚ 43 ' 0.0012 ", 123 ˚ 26 ' 30.0006 ", 13. v. 1961, 51.2 meters, coll. D.B. Quayle, hydrocauli, without gonothecae, CMNI 1982 - 1384. CANADA: British Columbia. 54 ˚ 13 ’00”N, 132 ˚09’00”W, 29.iv. 1961, 98.8 meters, coll. D.B. Quayle, hydrocauli, without gonothecae, CMNI 1982 - 1391. CANADA: British Columbia. 54 ˚ 12 ’ 48 ”N, 133 ˚07’ 24 ”W, 29. iv. 1961, stolonal colony, without gonothecae, coll D.B. Quayle, CMNI 1982 - 1403.
Reported distribution. Greenland (Hincks 1874, as Sertularella polyzonias, var. gigantea). All Russian and Far Eastern Seas (except Chukchi Sea), Norwegian and Greenland seas, Davis Strait (Naumov 1969). Kamchatka (Kirchenpauer 1884). Okhotsk Sea, Sea of Japan, some Arctic regions (Linko 1912). North Atlantic, Nova Scotia to Nantucket and Vineyard Sound (Fraser 1944).
Description. Colony monosiphonic, occasionally epizoic on other hydroids. Basal part of stem connecting with hydrorhiza may show four or more annulations. Perisarc slightly thickened. Internodes short, 1230–1580 mm, hydrothecae alternating on same plane, one hydrotheca per internode. Internode directly connected to previous hydrotheca. Base of internode with 1–2 oblique annulations; distinctive notch on basalmost part of internode immediately adjacent to abcauline side of previous hydrotheca. Hydrotheca tubular, narrowing distally, almost straight or slight abcauline tilt; a slight constriction, if present, proximal to hydrothecal aperture; walls smooth or slightly undulated. Hydrothecae 2000–2380 mm long, 1270–1410 mm at widest point. Hydrotheca almost free, length of adnate part 1620–2000 mm. Sinus moderate to deep with pointed denticles, four triangular flaps forming a peak at midpoint and extending slightly past hydrothecal aperture margin. Hydrothecal aperture margin may be reduplicated. Hydrothecal aperture usually at right angles to hydrothecal axis. Gonothecae not found.
Remarks. Sertularella gigantea is widely distributed over the circumboreal region of the Pacific and the Atlantic (Yamada 1957). However, this species has not hitherto been reported from the Pacific coast of Canada; in part due to confusion with S. polyzonias. This is the first reported occurrence of S. gigantea from the North American west coast. Sertularella gigantea, with hydrothecae measuring more than 1000 mm in depth (length of the abcauline side), has been regarded as a larger form of S. polyzonias (Linnaeus, 1758) (e.g. Broch 1918; Calder 1970). Smaller forms with hydrothecae measuring less than 1000 in depth are considered to be the typical form (Schuchert 2001). Broch (1918) reported the occurrence of intermediate forms along the west coast of Greenland, differing only in size, but these are comparatively few. Schuchert (2001) observed striking morphological differences in the two forms, although he was equivocal about whether the two forms are conspecific. Furthermore, recent molecular work by Moura et al. (2011) using 16 S rRNA sequences indicates that haplotypes of S. polyzonias are somewhat divergent (up to 1.9 % of sequence divergence). I follow Mereschkowsky (1878), Nutting (1904) and Naumov (1969) in regarding S. gigantea to be a valid separate species. Observed differences in the hydrothecae and gonothecae are given in Table 3. Fraser’s (1937) description of S. polyzonias from Alaska and the Pacific coast of Canada largely corresponds to S. gigantea.
*Material examined: ROMIZB 1039, ROMIZ B 3886 **Material examined: ROMIZ B 4064