Schizoporella errata ( Waters, 1878 )

Tompsett, Scott, Porter, Joanne S. & Taylor, Paul D., 2009, Taxonomy of the fouling cheilostome bryozoans Schizoporella unicornis (Johnston) and Schizoporella errata (Waters), Journal of Natural History 43 (35 - 36), pp. 2227-2243 : 2234-2238

Schizoporella errata ( Waters, 1878)

( Figures 3A–F , 4A–F )

Eschara spongites Pallas, 1766 (partim), p. 45.

Lepralia spinifera Busk, 1854 (partim), p. 69, pl. 91, figs 1,2.

Lepralia spinifera c) L. serialis Heller, 1867, p. 104 .

Lepralia spinifera d) L. spongites Heller, 1867, p. 104 .

Lepralia errata Waters, 1878, p. 11 , pl. 1, fig. 9.

Lepralia errata, Stadium Hemeschara Waters, 1879, p. 39 , pl. 10, fig. 5.

Schizoporella unicornis (Johnston) : Waters, 1909 (partim), p. 143, pl. 12, figs 12, 13. Schizoporella errata (Waters) : Calvet, 1902, p. 23; Gautier, 1962, p. 149, fig. 151; Ryland, 1965, p. 64, fig. 31a,b; Hastings, 1967, p. 336; Hayward and Ryland, 1999, p. 212.

Schizoporella unicornis var. errata (Waters) : Calvet, 1927, p. 16.

Schizopodrella violacea Canu and Bassler, 1930, p. 40 , pl. 4, figs 1–14.

Schizopodrella errata (Waters) : Canu and Bassler, 1930, p. 39; Barroso, 1935, p. 373, figs 1, 2.

Material

Lectotype (here chosen). MM H1186.3113 , Bay of Naples , specimen labelled ‘ Stadium Hemeschara , boiled in potash’, figured by Waters (1879, p. 39, pl. 10, fig. 5) ( Figure 3A–F herein).

Other material (topotypic). NHM 2009.1.26.1, ( Figure 4A ). Bleached, Nisida Harbour, Naples, Italy and NHM 2009.1.26.2, ( Figure 4B–F ). Bleached, Nisida Harbour, Naples, Italy.

Description

Colony encrusting, multiserial, unilamellar or multilamellar as the result of frontal budding, sometimes tubular (“hemescharan”) growing around arborescent epibiota such as hydroids. Colour varying from white (at growth tips) to red and purple/ brown in the older, multilamellar regions.

Basal autozooids longer than wide, 381–558 µm (mean 494 µm, SD 43 µm, n = 31) long by 263–508 µm (mean 371 µm, SD 71 µm, n = 31) wide, almost as wide as long at row bifurcations, surrounded by a distinct suture line; areolar pores deep. Frontally budded autozooids less consistent in shape, often more rounded. Frontal shield in basal zooids slightly convex, more so in frontally budded zooids. Pseudopores present everywhere apart from area distal of primary orifice, polygonal in early ontogeny ( Fig. 4D ), later reduced by secondary calcification, becoming occluded before frontal budding. Primary orifice broad, 125–172 µm (mean 147 µm, SD 11 µm; n = 25) long by 125–181 µm (mean 154 µm, SD 15 µm; n = 26,) wide. Anter broad, D-shaped, sinus (poster) U-shaped, broader than deep. When the operculum is removed, the edge of primary orifice adjacent to the condyles runs slightly distally from sinus to proximolateral corners (i.e. slopes upwards). Condyles small with acute tips.

Adventitious avicularia generally single, developing proximolaterally to the primary orifice and orientated distolaterally from midline, small (mean 137 µm, SD 19 µm, n = 10). Rostrum pointed distally with concave sides and hooked tip. Opesia rounded, deeply D-shaped, no columella. Mandible with curved tip. Avicularia occasionally develop proximal to orifice and occupy a large proportion of frontal shield. Larger than regular adventitious avicularia but with similarly shaped rostrum and opesium. Mandible orientated proximally.

Ovicells not present in type specimen. In topotype material ovicells are globular, rounded, recumbent on the distal zooid, and have surfaces completely covered by pores but lacking radial ridges.

Remarks

Like S. unicornis , the introduction of S. errata is somewhat confused. Waters (1878) first mentioned the name in a study of cheilostome opercula. A more thorough and recognizable description was subsequently provided by Waters (1879), in which reference was made to a particular specimen described as “Stadium, Hemeschara ” (i.e. with a tubular colony-form). It is very likely that Waters was referring to the same material in both publications. Hastings (1967) revised the synonymy of S. errata and attempted to designate a lectotype. However, she listed this putative lectotype under the Manchester Museum catalogue number HII86, a catalogue number prefix used for the entire Waters Collection at the museum. Fortunately, a specimen matching the descriptions of Waters (1879) and Hastings (1967) was found in the MM and has been examined by SEM.

The description by Waters (1879: 39) of this species reads:

“(A)n encrusting piece, measuring 9 × 10 mm. It consists of a regular layer of straightsided zooecia over which two successive layers of superficial zooecia are spreading. The superficial zooecia are larger, irregular in shape and orientation and more rounded in outline...”

This description draws attention to the notable differences in zooidal morphology at different astogenetic and ontogenetic stages. This has no doubt been a cause of taxonomic confusion in past descriptions, which have often focused on zooids from any of the following three growth stages: (1) basal zooids of the unilaminar “primogenial” stage; (2) frontally budded zooids at early ontogenetic stages with minimal secondary calcification; or (3) frontally budded zooids at late ontogenetic stages with heavy secondary calcification of the frontal shield.

The true identities of S. errata- like specimens from places distant from the type locality remain open to question. The ability of S. errata to foul man-made structures, such as gas rigs ( Relini et al. 1998) and ships ( Ryland 1965; Gordon and Mawatari 1992) has no doubt mediated its transfer to ports around the world, where it has become highly invasive ( Hayward and McKinney 2002). Furthermore, the opening of the Suez Canal in 1869 may have played a role in its transfer between the Mediterranean and the Red Seas ( Eitan 1972). However, as highlighted by Winston (2005), it is possible that S. errata is part of a species complex that includes S. pungens (Canu and Bassler, 1928) and S. isabelleana (d’Orbigny, 1842) . To complicate this issue further a subspecies called S. unicornis floridana (Osburn, 1914) has been recognized in a number of works ( Maturo 1957; Banta 1971, 1972; Soule at al. 1995). The origin of this species complex may have predated anthropogenic exchange, with species morphologically similar to S. errata being present in the Pliocene deposits of North Carolina and Jamaica ( Taylor and Foster 1998). Redescription of the type material here should aid in deciding whether fossil material and that of S. pungens belongs to the same species. Fossil material of S. errata has not been found in any of the European deposits during the course of our investigation. Therefore, it may be the case that this species has been introduced anthropogenically or otherwise into the Mediterranean in recent times. However, because of high levels of intracolonial morphological plasticity, it is likely that the true identity of the Recent S. errata complex will only be confirmed using molecular techniques.

Compared to S. unicornis , S. errata differs in the shape of the primary orifice. In S. unicornis the edge of the primary orifice adjacent to condyles is directed proximally from the sinus towards the proximolateral corners of the orifice, whereas in S. errata it is directed slightly distally. In addition, the structure of the pseudopores differs, forming within shallow polygonal, almost octagonal, recesses in the early ontogeny of S. errata but not S. unicornis . Also diagnostic of S. unicornis are the scalloped ridges around the edges of the ovicells and imperforate central region. Schizoporella unicornis does not undergo frontal budding, unlike S. errata .

No ancestrulae were apparent in either the lectotype or associated material. However, according to Ryland (1965) and Hayward and Ryland (1999), these are tatiform and have eight oral spines.

Figures

Figure 3. (A–F) Lectotype of Schizoporella errata (MM H1186.3113). (A) Growing edge of colony in primogenial unilamellar mode. (B) Portion of colony showing development of frontally budded zooids in intial phase of multilamellar growth. (C) Various stages of the development of the frontal shield of frontally budded autozooids. (D) Frontal shield of zooids in early astogeny with wide areolae and polygonal shaped border surrounding pseudopores. (E) Primary orifice and adventitious avicularia with operculum intact. The sinus is a wide U-shape with the proximal border of the orifice directed distally from the sinus. The avicularium bears an acutely pointed mandible with a hooked tip. (F) Primary orifice with operculum absent. Condyles small with acute tips. Scale bars: 1 mm (A, B); 500 µm (C); 250 µm (D); 50 µm (E, F).

Figure 4. (A, B) Topotype of Schizoporella errata (NHM 2009.1.26.1). (A) Primogenial autozooids growing in unilamellar form. Later astogeny with secondary calcification of frontal shield. (B) Frontally budded autozooid in the process of budding a daughter zooid. Later astogeny with secondary calcification of the frontal shield. (C–F) Topotype (NHM 2009.1.26.2). (C) Frontally budded zooid in early astogeny with a polygonal shaped border around each pseudopore. (D) Detail of the primary orifice with its small condyles and the distolaterally directed adventitious avicularium. (E) Ovicells in various stages of development, with a completely porous surface. (F) A group of autozooids undergoing frontal budding. The frontal shield has been removed in some cases to reveal the occluded primary orifice of the basal zooid. Scale bars: 250 µm (A, B, E, F); 150 µm (C); 100 µm (D).