Cigclisula arborescens

Vieira, Leandro M., Gordon, Dennis P., Souza, Facelucia B. C. & Haddad, Maria Angélica, 2010, New and little-known cheilostomatous Bryozoa from the south and southeastern Brazilian continental shelf and slope, Zootaxa 2722, pp. 1-53 : 29-32

Cigclisula arborescens ( Canu & Bassler, 1928a) n. comb.

( Figures 67–72 , Table 14 )

Rhynchozoon (?) arborescens Canu & Bassler, 1928a: 89 , pl. 7, figs 4–10.

Rhynchozoon arborescens: Souza, 1989: 502 ; Vieira et al., 2008: 33 (checklist).

Material examined. Lectotype (chosen here). USNM 8565, Bahia, Brazil. Paralectotype (chosen here). USNM 542389, Bahia, Brazil. Additional material. MZUSP 0 315, Brazil, project REVIZEE South SCORE, RV ‘Prof. Wladimir Besnard’, station 6662. MZUSP 0 316, station 6674 MZUSP 0 317, station 6678.

Redescription. Colony robust, erect, bilaminar, with stout base, dichotomously branching, yellowishbrown in colour; mostly in one plane, with occasional short branches developing at right angles frontally from a branch surface. Zooids recumbent with subterminal orifice at branch tips but becoming suberect with a central orifice owing to secondary calcification proximal to branch tips. Shape oval to diamond-shaped or irregularly polygonal, separated by deep furrows in which there is an inconspicuous raised wall. Frontal shield convex, the surface smooth to granular, typically centrally imperforate with several areolar septular pores along each lateral margin, these sometimes branching within the wall calcification to appear more frontal in position. Orifice relatively large, subcircular with a deep round poster that is nearly as large as the anter; the two parts of the orifice separated by a pair of stout, inwardly projecting round-tipped condyles. Secondary calcification of the frontal shield around the primary orifice results in its partial concealment by a peristome and sometimes by associated tubercles. No oral spines. A suboral avicularium with crossbar occurs transversely within the peristome of some zooids, frontally concealed, with the D-shaped rostrum and palate facing into the peristomial shaft; 1–3 very small circular avicularia may occur frontolaterally in some zooids and on ovicells, with crossbar complete. Large spatulate vicarious avicularia rarely found between autozooids; crossbar complete. Ovicelled zooids larger than ordinary autozooids, the ovicell a flattened hood; developing ovicells cucullate at growing margin, becoming incorporated in secondary calcification in mature zooids, the frontal surface smooth; ovicell opening into the peristome above the level of the operculum, with skeletal processes partly blocking the entrance; proximal rim of peristome of maternal zooid with a stout tubercle. Interzooidal communication via mural septular pores; no pore-chambers.

Remarks. The characters of this species have necessitated transfer from Rhynchozoon Hincks, 1895 (Phidoloporidae) , from which it differs in characters of the frontal shield, peristomial complex, and ovicell, to Cigclisula . This genus was established by Canu & Bassler (1927) monotypically for Escharoides occlusa Busk, 1884 (type locality Zamboanga, Philippines, c. 18 m depth; pers. comm. Mary Spencer Jones). The precise number of additional Recent species attributable to the genus is uncertain, perhaps six, comprising five Indo-Pacific and one recently described from Barbados by Winston and Woollacott (2009). An erect, bilamellar colony form, whether branched or unbranched, is normal. During development, the ovicell becomes cucullate, sometimes with a median fissure that, depending on the species, becomes completely or partially closed (see Harmer 1957, pl. 69). Hence, following Canu & Bassler (1927) who coined the name from “Greek: cigclis, grating”, alluding to the ovicell, Hastings (1932) noted the “fissured ovicell” as characteristic of Cigclisula [see C. cautium Hastings, 1932 , illustrated by Livingstone 1926, pl. 8 as Porella areolata ] and also reported that a peristomial avicularium is found in several species.

Although Sir Sidney Harmer died in 1950, work on what would become his 1957 monograph was nearly completed and printing of the plates already underway much earlier. According to Anna Hastings who saw the volume through to completion ( Harmer 1957, p. xiii), Harmer’s oversight of it was interrupted first by “the German invasion of Holland ” (10 May 1940) and then by Harmer’s failing health. This explains why the genus Trematooecia Osburn, 1940 , with Lepralia turrita Smitt, 1873 as type species, was not mentioned in the volume. Harmer (1957) included L. turrita in Cigclisula (cf. also Winston 1982; d’Hondt & Mascarell 2004) which is not surprising as the two genera overlap in zooidal, peristomial, and ovicellular characters. As in Cigclisula occlusa , the ovicells have a distinctive porous area, but the pores are smaller and more numerous. Unlike C. occlusa , which has an erect branching colony, T. turrita has tiny spot-like colonies (unilamellar to multilamellar) that do not exceed more than a few millimetres in diameter. Additionally, orificial peristomes are surrounded by robust peristomial tubercles. The frontal shield has tiny pores, but it is not clear if these are pseudopores or derived from areolar septular pores. Because of these differences, especially that of colony morphology, species attributed to the two genera have been consistently placed in different families ― Cigclisula in Stomachetosellidae (e.g. Canu & Bassler 1927; Bassler 1934, 1953; Harmer 1957; Ryland & Hayward 1992; Hayward & Ryland 1995) or Celleporidae ( Zabala & Maluquer 1988; Winston & Woollacott 2009), Trematooecia in Celleporidae (e.g. Osburn 1940; Bassler 1953; Winston & Håkansson 1986; Winston 2005 [as Celleporinidae ]; Winston & Woollacott 2009), Celleporariidae (d’Hondt 1979; Ristedt & Hillmer 1985), or Hippoporidridae ( Tilbrook 2006; Ayari et al. 2008).

The type species of Stomachetosella has an evenly pseudoporous lepralioid shield and an ovicellular skeletal surface that resembles the frontal shield. The type and other genera of the family Stomachetosellidae , except Cigclisula , are appropriately placed in the Schizoporelloidea. Cigclisula and Trematooecia are clearly very closely related and perhaps only a molecular study will clarify the inter-relationships of their respective species, but it is obvious from the taxonomic history of Trematooecia that this genus has been consistently included in families belonging to the superfamily Celleporoidea. We agree with this placement but would argue that the ovicellular and other characters of Trematooecia and Cigclisula mediate against inclusion in any of the celleporoidean families suggested by previous authors. Instead, we choose to ally these two genera with Colatooecia Winston, 2005 . The type species, Porina serrulata Smitt, 1873 , has erect, branching bilamellar colonies. Zooids have coarse frontal perforations that are not small like conventional pseudopores but appear to be areolar in origin [the interior of the frontal shield has not been examined so their exact nature is not certain], a peristomial spiramen, and the ovicell has a perforated frontal area that, while much more uniformly cribriform in structure than ovicells in Cigclisula and Trematooecia species, at least conforms to the “grating-like” ovicell remarked upon by Canu & Bassler (1927). Indeed, these authors actually included P. serrulata in Cigclisula (see Canu & Bassler 1928b). Accordingly, we would expand the definition of Colatooeciidae (superfamily Celleporoidea) to comprise Colatooecia , Cigclisula , and Trematooecia . Winston (2005) also included the Early Miocene species Adeona porosa Canu & Bassler, 1919 in Colatooecia ; inter alia, the authors described the ovicell as having symmetrical “areolar pores”. Although a number of species of Colatooeciidae , as here redefined, have porous frontal shields, it is clear that the Celleporoidea has to be expanded in concept to accommodate them. This has been demonstrated by Winston (2005) for Pourtalesella and by Berning and Kuklinski (2008) for some species of Buffonellaria Canu & Bassler, 1917 (which may include Pourtalesella Winston, 2005 ).

The sole known species from Atlantic waters, Cigclisula gemmea Winston & Woollacott, 2009 , is characterized by large interzooecial avicularia on the outer edges of branches, a hoof-shaped orifice with shallow poster, and ovicells with a shallow sinus. Brazilian Cigclisula arborescens differs in its subcircular orifice with deeper poster, a peristome with 4–7 rounded tubercles, and only 1–3 small frontal avicularia .

Distribution. Brazil: off Bahia ( Canu & Bassler 1928a), Rio de Janeiro and São Paulo states (present study), 49– 135 m.

Figures

FIGURES 67 – 72. Cigclisula arborescens (Canu & Bassler, 1928 a) n. comb. 67 – 69, USNM 8565 (lectotype specimen of Rhynchozoon arborescens), off Bahia, Brazil. 67, Distal end of colony; 68, close-up of ovicelled zooid with small avicularia; 69, close-up of orifice. 70 – 72, MZUSP 0 315 (part of specimen), off São Paulo, Brazil. 70, Distal end of colony; 71, distal view of autozooids; 72, close-up of ovicelled autozooid with two small avicularia.

Tables

TABLE 14. Measurements (in mm) of Cigclisula arborescens (Canu & Bassler, 1928 a) n. comb.

	n min–max	mean SD
Autozooid length	20 0.618–0.716	0.664 0.034
Autozooid width	20 0.395–0.543	0.468 0.037
Orifice length	20 0.130–0.161	0.147 0.009
Orifice width	20 0.130–0.161	0.144 0.008
Avicularium length	20 0.371–0.432	0.391 0.029
Avicularium width	20 0.358–0.494	0.408 0.061
Ovicell length	3 0.062–0.099	0.089 0.011
Ovicell width	3 0.049–0.086	0.068 0.011