Beania mirabilissima Vieira, Migotto & Winston, 2010, n. sp.

Beania mirabilissima n. sp.

(Figs 12, 13, 22, 23; Table 1)

Beania mirabilis: Osburn 1914: 189; 1940: 398; Marcus 1937: 60, pl. 12, fig. 29; Winston 1982: 133, fig. 45; 1986: 5; López-Gappa 2001: 73, figs 1, 2, 9; Vieira et al. 2008: 18 (checklist); Ramalho et al. 2010: 503, fig. 3.

Non Beania mirabilis Johnston, 1840: 272, fig 1, 2; 1847: 372, figs 69–70; Busk 1852b: 32, pl. 24, figs 4–5; Hincks 1880: 96, pl. 4, figs 8–10; Hayward & Ryland 1998: 244; Hayward & McKinney 2002: 26, figs 10C,D.

Material examined. Holotype: MZUSP 405. Paratype: MZUSP 406. Additional material: MZUSP 407–414; UFAL 0 49, Maceió, Alagoas state, 27.iv.2006, on hydroids; VMNH 2992.00, Beania mirabilis, Walton Rocks, South Hutchinson Island, St Lucie County, Florida, USA, coll. J. E. Winston 15.vii.2002, intertidal on hydroid stolon; VMNH 3116.00, Beania mirabilis, Fort Pierce Inlet, USA, coll. J. E. Winston, 14.vii.2003, beach drift on aluminum can, with Aetea sp.

Description. Colony uniserial, branched, lightly attached to substratum, translucent white in color. Zooids oblong, suberect, with an erect boat-shaped portion and a long and slender connective tube. Erect portion inclined, convex basally with a flat, expanded membranous frontal surface. Connective tube proximal, about 0.05 mm in diameter, joined to basal part of zooid. Orifice about 0.06 mm long and 0.12 mm wide. Two pairs of short distal spines around operculum and 5–8 (often 6) pairs of small spines overarching the frontal membrane; sometimes the proximal spines are slightly longer than the distal ones. Tubular basal radicles present in all zooids, between connective tubes. Avicularia and ovicells absent. Polypides with 18–20 tentacles.

Remarks. Johnston (1840) described a new British genus and species, Beania mirabilis, found loosely attached to shell. The species has been characterized by several authors as having slender zooids with 5–11 pairs of lateral spines in addition to the four distal spines. It has been considered to be a species with a worldwide distribution in warm and temperate waters (e.g. Winston 1982; Ramalho et al. 2010). However, Cook (1985) suggested that B. mirabilis may represent a species complex in the warm waters of the Atlantic and Indo-Pacific oceans. Later, López-Gappa (2001) observed slight differences (zooid length, number and position of spines) between British and Patagonian specimens of putative B. mirabilis, but did not introduce a new species name for the southwestern Atlantic material. Recently, Ramalho et al. (2010) remarked that specimens from Rio de Janeiro (Brazil) had fewer spines, but considered that the number of spines of those specimens fell within the range for the species.

Tilbrook et al. (2001) redescribed Johnston’s material of Beania mirabilis, characterized by zooids about 0.70 mm long, connective tubes 1.5 times longer than the boat-shaped portion, two pairs of oral spines and 9– 10 pairs of lateral spines overarching the frontal membrane; neanic colonies identified by Johnston from the type locality have only 2–6 spines. Tilbrook et al. (2001) also noted that several specimens previously attributed to B. mirabilis represent undescribed species. Later, Hayward and McKinney (2002) described and figured specimens of Beania mirabilis from the Adriatic; they are similar to Johnston’s specimens.

These descriptions have made it possible to compare precisely the Brazilian colonies with material from North Atlantic and Adriatic. Both English and Adriatic ephebic specimens differ from those found in shallowwater localities of the West Atlantic in the presence of 10 pairs of short, short-spaced lateral spines, and deeper (about 0.2 mm), wider zooids (about 0.28 mm wide) connected by longer proximal tubes. Beania mirabilis sensu strict is probably restricted to the northeastern Atlantic (Johnston 1840; Busk 1852b; Hincks 1880), Red Sea (Dumont 1981) and Mediterranean-Adriatic (Gautier 1962; Zabala & Malquer 1988; Hayward & McKinney 2002).

The material from Vanuatu previously identified as Beania cf. mirabilis (Tilbrook et al. 2001) was recently redescribed by Tilbrook (2006) as Beania lagenula, also characterized by a large gap between marginal and oral spines, but differing from those found in the western Atlantic in the shape of the zooid and the presence of 6–8 pairs of marginal spines that overlap each other in the midline.

Beania mirabilissima n. sp., which name alludes to the morphological likeness with Beania mirabilis Johnston, 1840, is characterized by oblong, shallower zooids (about 0.17 mm deep) joined by a shorter proximal connective tube (about 1.1 times longer than the boat-shaped portion), 5–8 pairs of lateral spines overarching the frontal membrane but not reaching its midpoint, and a large gap between the marginal and oral spines. Two small colonies from deep water off Brazil deposited at the MZUSP (MZUSP 0 40, 088) are readily distinguished from B. mirabilissima by their smaller, deeper zooids (about 0.21 mm deep) connected by a longer proximal connective tube (ca 1.5–2.5 times longer than the boat-shaped portion) and 8–10 shorterspaced pairs of lateral spines with slightly curved distal tips; these resemble European B. mirabilis and the eastern Atlantic colonies described by Cook (1985) but have slightly shorter zooids (about 0.4 mm). We suggest molecular genetics and further morphometric studies will resolve the identity and morphological variations of different populations of B. mirabilis with 8–11 spines in Atlantic waters.

Biological notes. Colonies of B. mirabilissima were found on rocky shores from the intertidal to 20 m deep, epiphytic on algae including Halimeda sp. and Sargassum sp., and epizoitic on bryozoans (e.g. Amathia sp.) and hydroids (Table 6). It was previously recorded in the West Atlantic by several authors (Osburn 1914; Marcus 1937; Winston 1982; Ramalho et al. 2010) as Beania mirabilis, growing on rocks, shells, other bryozoans and hydroid stems. It was previously recorded from Caribbean at 9–36 m deep (Osburn 1914, 1940). According to Winston (1982), embryos probably develop inside the zooids, and as she remarked, there is still no information available on its reproduction. Specimens collected in São Paulo state, Brazil, have about 18–20 tentacles while African specimens of B. mirabilis collected on shells have 12–14 (Cook 1985) and probably represent an undescribed species.

Distribution. Western Atlantic: Argentina (López-Gappa 2001); Brazil: Santa Catarina (present study), Paraná (present study), São Paulo (Marcus 1937; present study), Rio de Janeiro (Ramalho et al. 2010) and Alagoas (Vieira et al. 2007; present study); USA: Tortugas Island (Osburn 1940) and Florida (Winston 1982; present study).