Tricellaria occidentalis ( Trask, 1857 )

Grischenko, Andrei V., Dick, Matthew H. & Mawatari, Shunsuke F., 2007, Diversity and taxonomy of intertidal Bryozoa (Cheilostomata) at Akkeshi Bay, Hokkaido, Japan, Journal of Natural History 41 (17 - 20), pp. 1047-1161 : 1091-1093

Tricellaria occidentalis ( Trask, 1857)

( Figure 16C–F )

Menipea occidentalis Trask 1857, p 102 , Plate 4, Figure 4 .

Menipea occidentalis: Jelly 1889, p 173 ; Robertson 1905, p 254, Plate 6, Figures 22–25 ; Yanagi and Okada 1918, p 409; O’Donoghue and O’Donoghue 1923, p 159; 1925, p 99; Okada and Mawatari 1936, p 59; 1937, p 437.

Menipea compacta Ortmann 1890, p 21 .

Menipea compacta dilatata Ortmann 1890, p 21 , Plate 1, Figure 2 .

Menipea compacta form triplex Hincks 1882, p 461; 1884, p 208, Plate 9, Figure 8 .

Menipea occidentalis catalinensis Robertson 1905, p 255 , Plate 7, Figures 26 , 27 ; Yanagi and Okada 1918, p 409; Okada 1929, p 15, Plate 1, Figure 3 ; Okada and Mawatari 1937, p 437; Osburn 1950, p 122, Plate 13, Figures 8 , 9 .

Tricellaria occidentalis: Harmer 1923, p 353 ; Silén 1941, p 79; Osburn 1950, p 122, Plate 13, Figures 6 , 7 ; Mawatari 1951, p 9, Figures 1–7 ; Mawatari and Mawatari 1981b, p 49; Kubota and Mawatari 1985a, p 85, Figures 8 , 9 ; Gordon 1986, p 61, Plate 20E; Gordon and Mawatari 1992, p 25, Plates 2F, 6F; Soule et al. 1995, p 86, Plate 26A–C; Kubanin 1997, p 122; Liu et al. 2001, p 498, Plate 30, 6–7; Seo 2005, p 365, Plates 90–92.

Tricellaria occidentalis dilatata Harmer 1923, p 353 .

? Tricellaria inopinata d’Hondt and Occhipinti Ambrogi 1985, p 36 , Figures 2 , 3 ; Dyrynda et al. 2000, p 2001, Figure 2a–d .

Material examined

ACW, two intact colonies (NHM 2006.2.27.47); MBS, intact colony (NHM 2006.2.27.48); ANC, two intact colonies (NHM 2006.2.27.49). Additional material: 31 specimens.

Description

Colony ( Figure 16C ) bushy, tightly arborescent, composed of dense branches curved and rolled inward. Colony up to 3 cm high, yellow to tan in colour when alive, attached by a bundle of rhizoids ( Figure 16D ) originating from zooids situated low in colony. Branching dichotomous, regular, branching pattern type 9, with proximal extremity of zooid F and G not in contact ( Hayward and Ryland 1998 after Harmer 1923). Most internodes have three zooids, but distal ones with ovicells have five to nine zooids. Internodes connected by strong, tubular chitinous joints, brown in colour; flexible nodes crossing well proximal to opesia of both outer and inner zooids. Zooids in biserial series, alternate, elongate, narrowing proximally, 0.45–0.78 mm long (0.63¡ 0.10 mm), varying significantly in size depending upon their location in internode and in colony. Opesia oval or elliptical, 0.22– 0.28 mm long (0.25¡ 0.02 mm), 0.11–0.14 mm wide (0.12¡ 0.01 mm), occupying 30– 50% of zooidal length; cryptocyst negligible. Zooids ( Figure 16E ) typically have six hollow, tubular jointed spines; most proximal pair straight, located near middle of opesia and tilted slightly inward; next pair straight or turned slightly outward; outer distalmost spine strongly calcified, elongate (up to 0.65 mm long), originating from dorsal side of distal zooidal margin; inner distalmost spine often strongly reduced or lacking. In some zooids the external proximal spine is bifid. Axial zooids at bifurcations have six spines: two pairs along distolateral margins of opesia, straight or tilted slightly outwards, and a medialmost pair of tubular, hollow, elongate spines originating from dorsal side of distal wall from closely set, heavily calcified cylindrical bases; these latter two spines are often asymmetrically placed with respect to the midline, with one occupying the midline position and longer and heavier than the other. Scutum attached to inner border of opesia, proximal to middle of opesia, varing in form from spine-like to a broad flabellate process with two to four or more lobes. Non-axial zooids have large lateral avicularium with hooked rostrum; mandible triangular, with hooked tip. Frontal avicularia absent. Ovicells ( Figure 16F ) globular, smooth, wider than long, 0.16–0.21 mm long (0.18¡ 0.01 mm), 0.20–0.24 mm wide (0.21¡ 0.01 mm), with around 10 small, circular or oval pores. Some zooids situated low in colony have proximally directed kenozooids (rhizoids or radicle fibres) originating from a slight, flattened disc on dorsal or lateral wall, close to nodal joints. Ancestrula not observed.

Remarks

Many characters of T. occidentalis , such as presence or absence of lateral avicularia, number of zooids per internode, and size and shape of scuta, may vary considerably even within a single colony ( Gordon 1986; Gordon and Mawatari 1992). This variation, noted by Robertson (1905), Yanagi and Okada (1918), Okada (1929), and Osburn (1950), and superbly illustrated by Mawatari (1951), has caused taxonomic difficulties and resulted in descriptions of several varieties of this species. In specimens from Akkeshi, the scutum varies in form from spine-like to a broad flabellate process with two to four or more lobes, which is within the range of variation of T. occidentalis (see also Soule el al. 1995).

Dyrynda et al. (2000) concluded that Japanese and some other populations previously reported under the name Tricellaria occidentalis Trask are actually T. inopinata d’Hondt and Occhipinti Ambrogi, 1985 , a fouling species recently described from the Lagoon of Venice. According to Dyrynda et al. (2000), T. inopinata is of Pacific origin, is widely distributed along the coasts of western North America and Japan, occurs in Australia and New Zealand, and has been introduced to Britain and the Mediterranean. They note that the original source region of the species in the Pacific, before anthropogenic introductions to other areas, is unknown. Dyrynda et al. (2000) regarded T. inopinata as consistently morphologically distinguishable from T. occidentalis Trask , which they considered to be restricted to the western coast of North America. However, they considered many of the Pacific records of T. occidentalis var. catalinensis Robertson, 1905 to be T. inopinata . Our material has one of the distalmost pair of spines on axial zooids located in the midline and better developed than the other; zooids occasionally with a bifid spine; and a quite variable scutum, sometimes broad with a spiky margin. According to Dyrynda et al. (2000) these are all characters distinguishing T. inopinata from T. occidentalis . Unfortunately, these authors did not provide a detailed description and illustrations of the latter, noting that the type description of T. occidentalis was inadequate, that the type material was lost, and that they had been able to examine only limited quantities of mostly very old material. Here we retain the name T. occidentalis , pending a detailed redescription of T. occidentalis Trask as distinct from T. inopinata d’Hondt and Occhipinti Ambrogi and clarification of the range of the former.

Distribution

Trask (1857) originally listed Tricellaria occidentalis as occurring from Cape Flattery to Santa Barbara, California. It is now a widely distributed, invasive and fouling species occurring in Japan ( Mawatari 1951), Australia ( Bock 1985), New Zealand ( Gordon 1986; Gordon and Mawatari 1992), China ( Liu et al. 2001), and Korea ( Seo 2005); it has also been reported from the Mediterranean ( d’Hondt and Occhipinti Ambrogi 1985; Occhipinti Ambrogi 1991) and Britain ( Dyrynda et al. 2000). Records from the western coast of North America exist from British Columbia ( Hincks 1882, 1884; O’Donoghue and O’Donoghue 1923) south to Baja California, Mexico ( Robertson 1905; Osburn 1950; Soule et al. 1995). In the western Pacific, T. occidentalis has been reported from Peter the Great Gulf, Sea of Japan ( Kubanin 1997); the coast of South Korea, including the Yellow Sea ( Seo 1996, 2005); China ( Liu et al. 2001), the Pacific coast of Honshu, Japan ( Mawatari 1951); Akkeshi, Muroran, Mori, and Shirikishinai, Pacific coast of Hokkaido ( Mawatari and Mawatari 1981b); and Oshoro Bay, Sea of Japan coast of Hokkaido ( Kubota and Mawatari 1985a).

Figures

Figure 1. Map of Akkeshi Bay showing the 10 sampling stations (filled squares); 5, 10, and 20 m depth contours are indicated. Inset shows the location of Akkeshi Bay on Hokkaido Island, northern Japan.

Figure 2. Dendrogram (below) showing similarity of sampling localities based on species presence/absence, and a map (above) showing the geographical distribution of three groups of sampling localities (circled) that are less than 70% similar in species composition between groups.

Figure 3. Electra korobokkura Nikulina, 2006. (A–C) NHM 2006.2.27.1; (D) NHM 2006.2.27.2. (A) Colony fragment with uniserial branches; (B) colony fragment with anastomosing, multiserial branches; (C) zooids without spinous processes; (D) zooids with spinous processes. All unbleached. Scale bars: 2 mm (A, B); 1 mm (C); 0.5 mm (D).

Figure 4. Electra arctica Borg, 1931. ZIRAS 36/50535. Colony on rock collected by A. V. Grischenko, 12 September 1992, Sea of Okhotsk, western Kamchatka shelf (57°36.039N, 156°9.009E), depth 78–81 m. (A) Portion of colony showing anastomosing, narrowly multiserial branches; (B) autozooids and kenozooids; (C) enlargement of autozooids and kenozooids; (D) autozooids with operculum in place and kenozooids with nearly completely closed aperture. Specimen lightly bleached. Scale bars: 2 mm (A); 1 mm (B); 0.5 mm (C, D).

Figure 5. Electra asiatica n. sp. (A, G) NHM 2006.2.27.19; (B) NHM 2006.2.27.20; (C, D) NHM 2006.2.27.21; (E, F) NHM 2006.2.27.24. Colony from Ptichiy Island, Sea of Okhotsk (H). (A, B) Colonies radiating in coherent, fan-shaped lobes from the point of origin, unbleached; (C) colony margin with developing zooids, unbleached; (D) astogenetically mature zooids, unbleached; (E) astogenetically mature zooids, bleached; (F) astogenetically mature zooids with a small interzooidal kenozooid (lower right quadrant), bleached; (G) ancestrula and periancestrular zooids; enlargement of ancestrular area seen in panel (A), unbleached; (H) astogenetically mature zooids, bleached. Scale bars: 2 mm (A, B); 0.5 mm (C–H).

Figure 6. Conopeum nakanosum n. sp. (A, F) NHM 2006.2.27.26; (B, D) NHM 2006.2.27.27; (C, E) NHM 2006.2.27.25; (G, H) NHM 2006.2.27.28. (A) Colony margin with differentiating zooids, bleached; (B) zooids with developing angular cone-shaped kenozooids, bleached; (C) mature zooids with erect and curved spines, unbleached; (D) group of mature zooids with granulated cryptocyst, bleached; (E) distally facing triangular avicularia replacing kenozooids, unbleached; (F) distal view of kenozooids, bleached; (G) lateral view of zooids showing multiporous septula, bleached; (H) interior of distal zooidal wall showing developing angular kenozooids and also multiporous septula, bleached. Scale bars: 0.5 mm (A, G); 1 mm (B–D); 0.2 mm (E, F, H).

Figure 7. Callopora craticula (Alder, 1856). NHM 2006.2.27.29. (A) General view of colony fragment, unbleached; (B) immature zooids near colony margin, unbleached; (C) mature zooids showing ovicells and associated avicularia, unbleached; (D) group of immature zooids and vicarious avicularium on right, unbleached. Scale bars: 0.5 mm (A); 0.2 mm (B–D).

Figure 8. Callopora sarae n. sp. (A, E) NHM 2006.2.27.5; (B) NHM 2006.2.27.3; (C, D, F) NHM 2006.2.27.4. (A) Zooids at colony edge, unbleached; (B) immature zooids with spines, lateral and proximal avicularia, unbleached; (C) immature zooids, showing bases of spines and lateral avicularia, bleached; (D) two immature zooids showing bases of additional spines on outer distolateral gymnocyst, bleached; (E) mature zooids with ovicells and associated avicularia, unbleached; (F) mature zooids with heavily calcified ovicells, bleached. Scale bars: 0.5 mm (A–C, E, F); 0.4 mm (D).

Figure 9. Cauloramphus cryptoarmatus n. sp. (A, C, E) NHM 2006.2.27.14; (B, F) NHM 2006.2.27.31; (D) NHM 2006.2.27.13. (A) Colony margin with developing zooids, unbleached; (B) zooids at colony margin in interaction with Cribrilina annulata, showing numerous additional avicularia developing along vertical walls from pore chambers, bleached; (C) autozooids, unbleached; (D) autozooids, showing strongly developed granulated cryptocyst, bleached; (E) two zooids showing details of avicularia and spines, unbleached; (F) ancestrula surrounded by periancestrular zooids, bleached. Scale bars: 0.5 mm (A–D, F); 0.4 mm (E).

Figure 16. (A, B) Bugula pacifica Robertson, 1905. NHM 2006.2.27.15. (A) General view of colony fragment, unbleached; (B) zooids, showing distal spinous projections and avicularia, unbleached. (C–F) Tricellaria occidentalis (Trask, 1857). (C) NHM 2006.2.27.48; (D–F) NHM 2006.2.27.49. (C) General view of colony fragment, unbleached; (D) basal surface of branch with kenozooids (rhizoids or radicle fibres), unbleached; (E) internode with immature zooids, unbleached; (F) abraded internode containing mature zooids with ovicells, unbleached. Scale bars: 1 mm (A); 0.5 mm (B, D, F); 2 mm (C); 0.4 mm (E).

Figure 22. Desmacystis sandalia (Robertson, 1900). (A, D) NHM 2006.2.27.59; (B, C) NHM 2006.2.27.60. (A) Colony margin with developing zooids; (B) immature zooids; (C) mature zooids showing transversely elongate vestigial ovicells and relatively smooth frontal walls; (D) mature zooids with frontal shields reinforced by radially arranged ridges of calcification. Scale bars: 0.5 mm.

Figure 23. Parasmittina avicularissima (Gontar, 1982). (A, H) NHM 2006.2.27.72; (B, C, F, G) NHM 2006.2.27.73; (D, E) NHM 2006.2.27.74. (A) Zooids differentiating at colony margin; (B) immature zooids, showing oral spinescars, lyrula, and condyles; (C) immature zooids with lateral triangular avicularia; (D) autozooids with oval proximo-lateral avicularia and large frontal avicularium directed proximally; (E) autozooids with frontal avicularia directed distally; (F) zooids with developing and completed ovicells; (G) mature zooids with ovicells possessing single pore; (H) ancestrular region. Scale bars: 0.5 mm (A, C–H); 0.4 mm (B).

Figure 24. Raymondcia rigida (Lorenz, 1886). (A) NHM 2006.2.27.68; (B, D) NHM 2006.2.27.67; (C, E) NHM 2006.2.27.12; (F) NHM 2006.2.27.70. (A) Colony margin with developing zooids; (B) immature zooids; (C) autozooids with developing ovicells; (D) umbonate mature zooids with ovicells covered by merging segments from adjacent zooids; (E) inflated mature zooids; (F) ancestrula with periancestrular zooids. Scale bars: 0.5 mm.

Figure 25. Raymondcia klugei (Gontar, 1982). (A, C) NHM 2006.2.27.66; (B) NHM2006.2.27.6; (D) NHM 2006.2.27.8; (E) ZIRAS 2/44556; (F) NHM 2006.2.27.7. (A) Colony margin with developing zooids; (B) immature zooids; (C) mucronate autozooids, lateral view; (D) distolateral view of autozooids showing suboral avicularia tilted inside; (E) autozooids, paratype specimen; (F) ancestrular region. Scale bars: 0.5 mm (A, E, F); 0.4 mm (B–D).

Figure 26. Parkermavella orientalis (Androsova and Gontar in Gontar 1982). (A) NHM 2006.2.27.31; (B–E) NHM 2006.2.27.84; (F) NHM 2006.2.27.83. (A) Colony margin with developing zooids; (B) immature zooids; (C) orifice of immature zooid, showing condyles and suboral avicularium; (D) group of mature zooids with ovicells, showing variability in positions of oral avicularia; (E) mature zooids with three oral avicularia; (F) ancestrular region. Scale bars: 0.5 mm (A, B, D–F); 0.1 mm (C).

Figure 27. Schizoporella japonica Ortmann, 1890. (A, D–G) NHM 2006.2.27.87; (B, C) NHM 2006.2.27.85; (H) NHM 2006.2.27.86. (A) Developing zooids at colony margin; (B) immature zooids; (C) zooids with developing ovicells; (D) mature zooids with oral and frontal avicularia directed laterally and distally; (E) mature zooids, showing details of orifice and avicularia; (F) ancestrular region. Scale bars: 0.5 mm (A–D, F); 0.4 mm (E).