Schizoporella japonica Ortmann 1890
Creators: name: Ryland, John S.
name: Holt, Rohan
name: Loxton, Jennifer
name: Spencer Jones, Mary E.
name: Porter, Joanne S.
Publisher: name: Zenodo
Year: 2014
Subjects: Biodiversity
Taxonomy
Animalia
Bryozoa
Gymnolaemata
Cheilostomatida
Schizoporellidae
Schizoporella
Schizoporella japonica

description: Schizoporella japonica Ortmann, 1890
(Figures 2–5)
Schizoporella unicornis var. japonica Ortmann, 1890: 49, pl. 3, fig. 35.
Schizoporella unicornis: Okada 1929: 20, fig. 7; Powell 1970: 1849, figs 2–3; Ross & McCain 1976: 164, figs 1–6; Kubota & Mawatari 1985: 201, fig. 3A–E; Thorpe & Ryland 1987: 281 (Friday Harbor, in part); Osburn 1952: 317, pl. 37, figs 1–2 (part; some = S. pseudoerrata); Soule et al. 1995: 204, pl. 75A–F.
Schizoporella japonica: Dick et al. 2005: 3742, figs 15–16; Grischenko et al. 2007: 1115.
Material examined. See Appendix 1. Holotype. Strasbourg Museum, MZS Bry001 as S. unicornis var. japonica; type Locality Sagami Bay, Japan, collected Dr L. Döderlein, 1880–1881. A photograph of the supporting stone and holotype colony is shown in Fig. 4E.
Description of British material. Colonies at first more or less circular (Fig. 4F), rapidly becoming extensive, pale whitish-pink to vivid orange-red (Figs 2, 4; British material between Munsell 2.5YR6/14 and 10.0R6/10 (see Kelly & Judd 1955)); mainly unilaminar but frequently with raised edges or displaying slightly elevated lobes (Fig. 2B, C). Zooids generally in obviously linear series, quincuncial away from bifurcations; rectangular; conspicuously longer (often twice as long) than broad (0.5–0.7 × 0.25–0.35 mm; Table 1); length:width proportions (1.7–2.5:1) varying according to distance from a bifurcation (Figs 2D–E, 3A, E); the dividing line between series distinct, slightly depressed; frontal shield with marginal areolae and regularly distributed pseudopores, except sometimes (in Holyhead material) for an incipient suboral umbo; the distolateral pair of areolae somewhat larger. Frontal pseudopores very numerous (c. 600 mm -2, range ~ 400−800 mm -2). Orifice shallower than wide (0.8–0.9:1), though variable within a colony (110–140 × 150–175 µm); the sinus shallow and broad (0.3–0.4:1; 20–35 × 80–120 µm), with sinuous margins, delimited by horizontal, obtusely pointed condyles (Figs 2F, 3D); distal margin of orifice and lip of sinus with minute tubercles. Operculum matching the orifice, with no additional sclerites (Fig. 2F). Some Scottish specimens with occasional orifices closed by perforated calcification (Fig. 5H). Holyhead specimens most commonly with a single avicularium lateral to the orifice but frequently none; distolaterally directed, inner end of hinge-line level with the condyles; mandibles triangular, their height scarcely exceeding the hinge width (Fig. 3A, B, D, E). The Scottish material has 0–5 avicularia per autozooid, with most colonies typically featuring 1–3; there may also be frontal avicularia, of the same basic form but slightly larger and with an elevated chamber (Fig. 5B, C). Ovicells prominent, subglobular, with numerous pores except near the mid-proximal margin; with slender sinuous ridges ascending from the distal zooid, between the pores, and converging in a mid-proximal direction (Fig. 3B, C); sometimes>1 (up to 5 in Scottish material) per autozooid (Fig. 5F–G, and discussion below). Polypide with c. 19 tentacles (Friday Harbor). Embryos reddish, apparently increasing in size during development; half-sized embryos present at Holyhead even in midwinter (February). Ancestrula with D-shaped orifice and 8 marginal spines; a central, patterned circular area on the frontal calcification (Fig. 4A–C); approximately 350–400 × ~ 300 µm overall (settlement panel, Stromness).
Additional descriptions. Colonies collected from different parts of the world may vary, may offer reproductive stages not seen elsewhere, or be described in a slightly different manner. Full descriptions accompanied by SEM illustrations have recently been provided for each of the main geographic areas from which S. japonica is known—Alaska and the Pacific coast of North America (Dick et al. 2005) and Japan (Grischenko et al. 2007). Salient features have been selected.
Alaska. Colony encrusting, unilaminar but sometimes bilayered as a result of overgrowth; colour ranging from whitish to red. Zooids distinct, separated by suture lines and shallow grooves. Frontal surface slightly to moderately convex, with marginal areolae and frontal pseudopores; pseudopores becoming infundibular with age and thickening calcification, the frontal shield becoming reticulate. Orifice medial or offset, with an avicularium beside it; usually broader than long, anter semi-circular, separated by paired blunt stout condyles, directed medially; operculum light golden brown, transparent. Avicularia paired, single or absent on any given zooid; additionally, occasional zooids bearing a somewhat larger frontal avicularium with raised rostrum and chamber. With increasing secondary calcification, the ovicells—similar to those from Holyhead—become increasingly rugose (Dick et al. 2005).
Japan. Colonies as from Alaska but red to bright orange. Zooids with frontal shield uniformly porous except suborally, with 7–9 larger areolae along each margin; usually with a small suboral umbo. Oral avicularia most commonly single but frequently absent or paired; situated lateral or proximolateral to orifice; mandible elongatetriangular, its tip acute, with distal to distolateral orientation; crossbar complete; chamber comparatively small, with 1–3 minute pores laterally around the base; sometimes, in older parts of the colony and associated with complete ovicells, one avicularium is larger, with raised chamber. Zooidal communication via 3–5 distal and 6 lateral basal pore-chambers. Ovicells prominent, hemispherical, partially overhanging the orifice, evenly porous, with larger slit-like pores around the base; sparsely distributed or in a reproductive band within the colony. Ancestrula oval, imperforate, 0.33 × 0.28 mm; orifice D- shaped, 0.13 × 0.15 mm, with 8 marginal spines; 3 zooids budded distally (Grischenko et al. 2007).
Remarks. Variations and discussion. Some striking variations that appear characteristic of S. japonica have been reported earlier and observed by us. A remarkable feature is the occurrence in Scottish material of multiple ovicells, arranged serially one behind another, and occasionally stacked (Fig. 5F–G). Powell (1970) and Powell et al. (1970) earlier described and illustrated a similar aberration in specimens from British Columbia and Washington State, and in a colony found on a scallop shell transplanted with oysters (Crassostrea gigas) from Onagawa Bay, on the Pacific coast of Honshu, Japan. Powell et al. (1970), using transplant experiments in Willapa Bay, Washington, attributed this occurrence of multiple ovicells to creosote-treated wood and the presence of petroleum derivatives in the water of harbours and marinas. It is not clear whether the occurrence of this phenomenon in Scotland is attributable to pollution; however, multiple ovicells were observed at sites all around the Scottish coastline. Powell et al. (1970) also noted that S. japonica (as S. unicornis) occurred in hyposaline water, down to salinities of 15.
All of the British occurrences have been in marinas, suggesting that—unlike the Pacific coast of North America (see later)—small, ocean-going vessels must have been the vectors (Fig. 4F shows colonies on a boat hull). We have no evidence to suggest whether Japan or North America was the source.
Distinction from Schizoporella unicornis. On the Atlantic coasts of Western Europe, including the British Isles, confusion of S. japonica is likely only with S. unicornis, although the usual habitats of the two species are quite different. Schizoporella japonica is so far known only from harbours and marinas, and is a typical fouling species; S. unicornis occurs in non-fouling situations, on stones, rocks, shells and kelp holdfasts on the lower shore and sublittorally. Comprehensive descriptions, variously illustrated, are available (Hayward & Ryland 1979; 1999; Ryland 1990; 1995; Tompsett et al. 2009) but, to facilitate ready comparison the morphological differences are summarized in Table 2.
description: Published as part of Ryland, John S., Holt, Rohan, Loxton, Jennifer, Spencer Jones, Mary E. & Porter, Joanne S., 2014, First occurrence of the non-native bryozoan Schizoporella japonica Ortmann (1890) in Western Europe, pp. 481-502 in Zootaxa 3780 (3) on pages 485-490, DOI: 10.11646/zootaxa.3780.3.3, http://zenodo.org/record/4910530