Schizoporella japonica Ortmann, 1890

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 : 1115-1118

Schizoporella japonica Ortmann, 1890

( Figure 27 ) Schizoporella unicornis var. japonica Ortmann 1890, p 49 , Plate 3, Figure 35 . Schizoporella japonica: Dick et al. 2005, p 3742 , Figures 15A–H , 16A–D (illustration of holotype).

Schizoporella unicornis: Okada 1929, p 20 , Text figure 7; Osburn 1952, p 317, Plate 37, Figures 1 , 2 ; Powell 1970, p 1849, Figures 2 , 3 ; McCain and Ross 1974, p 13, Figure 2c, d ; Ross and McCain 1976, p 164, Figures 1–6 ; Mawatari and Mawatari 1981b, p 51; Kubota and Mawatari 1985b, p 201, Figure 3A–E ; Liu et al. 2001, p 596, Plate 48; Soule et al. 1995, p 204.

Material examined

KAI, colony on rock (NHM 2006.2.27.39), colony on rock (NHM 2006.2.27.85); BAC, ancestrular colony detached from bivalve shell (NHM 2006.2.27.86), extensive colony detached from bivalve shell (NHM 2006.2.27.87), extensive colony on bivalve shell (NHM 2006.2.27.88). Additional material: 80 specimens .

Description

Colony encrusting, unilaminar, occasionally with bilaminar overgrowth of one portion of colony by another, forming extensive irregularly circular patches up to 5.5 cm across, red to bright orange when alive. Zooids ( Figure 27A, B ) rectangular to hexagonal, 0.52–0.73 mm long (0.63¡ 0.05 mm), 0.30–0.43 mm wide (0.38¡ 0.03 mm), separated by shallow grooves. Frontal wall weakly to moderately convex, uniformly perforated from margin to margin with small circular pores except in suboral area, with seven to nine larger areolar pores along each lateral margin. Frontal pores become infundibular with development of calcification in mature zooids. Usually frontal wall rises into a small conical median umbo proximal to orifice. Orifice ( Figure 27B, E ) broader than long, 0.11–0.15 mm long (0.13¡ 0.01 mm), 0.15–0.17 mm wide (0.16¡ 0.01 mm); sinus broadly U-shaped, flattened on bottom; conspicuous condylar shelves bearing blunt condyles. Oral avicularia ( Figure 27B ) situated lateral or proximolateral to orifice, close to condylar shelf; mandible elongate-triangular, with acute tip, directed distolaterally to distally, cross-bar complete; chamber comparatively small, narrow, smooth, with one to three minute pores laterally around base. Oral avicularia usually single ( Figure 27B ), often absent ( Figure 27C ), occasionally paired. Additionally, some colonies have zooids with large frontal avicularia ( Figure 27D, E ) similar in form to oral avicularia, but with a highly raised, smooth chamber. Position of frontal avicularia variable; they can lie close to orifice, but a little more proximal than oral avicularium, on opposite side; just proximal to oral avicularium on same side; along zooidal lateral margin; or centrally on frontal surface. Large avicularia close to orifice point distolaterally; those in central or lateral region of frontal wall point distally or laterally. Large frontal avicularia developed predominantly in mature zones of colony, among zooids with complete ovicells. Ovicell ( Figure 27C, D ) hemispherical, prominent, 0.30–0.35 mm long (0.32¡ 0.02 mm), 0.29–0.36 mm wide (0.33¡ 0.02 mm), lying on frontal wall of daughter zooid and partially overhanging zooidal orifice; rugose, with heavily calcified, finely granulated radiating ribs, evenly perforated by numerous small pores, with larger round to slit-like pores around base. Occasionally ovicell has a small, knob-like central umbo. Ovicellate zooids can be sparsely distributed among non-fertile zooids or concentrated as a reproductive band within colony. Zooids intercommunicate via three to five distal and six lateral basal pore chambers. Ancestrula ( Figure 27F ) oval, imperforate, 0.33 mm long, 0.28 mm wide, with eight spines around D-shaped orifice (0.13 mm long, 0.15 mm wide) with straight proximal margin. Ancestrula buds three small zooids distally; surrounded by seven zooids.

Remarks

Ortmann (1890) reported nominal S. unicornis ( Johnston, 1844) from Japan, and additionally erected a new variety, S. unicornis var. japonica . Dick et al. (2005) recently examined Ortmann’s type specimens and elevated variety japonica to species rank, as S. japonica .

Distribution

In the western Pacific, S. japonica (reported as S. unicornis ) extends from China ( Liu et al. 2001) northward to Hokkaido Island, where it has previously been recorded at Akkeshi, Muroran, and Shirikishinai on the Pacific side ( Mawatari and Mawatari 1981b) and at Oshoro Bay on the Sea of Japan ( Kubota and Mawatari 1985b).

Schizoporella japonica was introduced on Pacific oysters ( Crassostrea gigas ) from Japan to the Pacific coast of North America during the 20th century; it is now widely distributed from San Francisco, California to southeastern Alaska ( Powell 1970; McCain and Ross 1974; Ross and McCain 1976; Dick et al. 2005). As mentioned by Dick et al. (2005), the actual range of S. japonica may be much more extensive, since this species could have been introduced on oysters to other parts of the world as well.

Family STOMACHETOSELLIDAE Canu and Bassler, 1917

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 15. Tegella arctica (d’Orbigny, 1851). (A, C) NHM 2006.2.27.44; (B) NHM 2006.2.27.46; (D) NHM 2006.2.27.43. (A) General view of group of autozooids, unbleached; (B) zooids from region near colony margin, bleached; (C) immature zooids with small paired angular and large frontal avicularia, unbleached; (D) mature zooids with ovicells and associated frontal avicularia, unbleached. Scale bars: 1 mm (A); 0.5 mm (B, C); 0.4 mm (D).

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 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).

Figure 35. Microporella trigonellata Suwa and Mawatari, 1998. (A, E) NHM 2006.2.27.96; (B–D) NHM 2006.2.27.95; (F) NHM 2006.2.27.52. (A) Colony margin with developing zooids; (B) immature zooids; (C) distal half of immature zooid, showing orifice, ascopore, and avicularium; (D) mature zooids; (E) heavily calcified, abraded mature zooids; (F) ancestrula and periancestrular zooids. Scale bars: 0.5 mm (A, B, D–F); 0.2 mm (C).