Parasmittina alba, Ramalho & Muricy & Taylor, 2011

Ramalho, Laís V., Muricy, Guilherme & Taylor, Paul D., 2011, Taxonomic revision of some lepraliomorph cheilostome bryozoans (Bryozoa: Lepraliomorpha) from Rio de Janeiro State, Brazil, Journal of Natural History 45 (13 - 14), pp. 767-798 : 769-772

Infraorder ASCOPHORA Levinsen, 1909

‘Grade’ LEPRALIOMORPHA Gordon, 1989 Superfamily SMITTINOIDEA Levinsen, 1909 Family SMITTINIDAE Levinsen, 1909 Genus Parasmittina Osburn, 1952 Parasmittina alba sp. nov.

( Figure 2 )

Material examined

Arraial do Cabo: Holotype: MNRJ-077, 24 May 2002, Pedra Vermelha, Cabo Frio Island , collected by L. V. Ramalho , depth 5 m. Paratype: MNRJ-079, 27 February 2003, Pedra Vermelha, Cabo Frio Island, collected by L. V. Ramalho and R. Melo , depth 5 m. Parasmittina raigioidea : holotype: 95BFS0820-6 1995 (18 ◦ 11 ′ N, 109 ◦ 21 ′ E), depth 4 m.

Etymology

The name alba refers to the white colour of the colonies.

Diagnosis

Colony encrusting, unilamellar, frontal wall granular with marginal areolar pores; primary orifice rounded with prominent condyles turned downwards; lyrula well developed; peristome may be elevated proximally, forming two projections; secondary orifice with pseudosinus; oral spines numbering one or two; avicularia comprising one interzooidal type and up to three adventitious types (large with rostrum elongated and spatulate; small with rostrum rounded and smooth; small with rostrum slightly triangular and serrated), only one type occurring on each zooid. Ovicell with ectooecium perforated by pores or fenestra.

Description

Colony encrusting, variable in shape and size, unilamellar, white ( Figure 2A,B ). Autozooids rectangular, longer than wide (451 µm long, range 392–490 µm, by 305 µm wide, range 265–383 µm), disposed in linear series on young colonies ( Figure 2A ), linear pattern obscured on older colonies or colonies growing on irregular substrata ( Figure 2B,C ); the two daughter zooids after a bifurcation are relatively small and narrow ( Figure 2A ). Frontal wall granular without pseudopores but having marginal areolar pores ( Figure 2C,D ). Primary orifice rounded with prominent condyles turned downwards and lyrula. Secondary orifice with pseudosinus, well developed ( Figure 2D ); peristome slightly elevated laterally and sometimes strongly elevated proximally, hiding the lyrula, sometimes forming two proximal projections ( Figure 2C–H ). Oral spines numbering two, thin, non-articulated, often broken, leaving only a scar; rarely only one medial oral spine is present ( Figure 2D–F ). Ovicell prominent, large, wider than long (274 µm long by 323 µm wide). Ectooecium membranous frontally, revealing the perforate, calcified entooecium ( Figure 2B,H ).

Avicularia adventitious and interzooidal. Adventitious avicularia of three types but only one per autozooid: (1) large avicularia generally placed next to orifice, but sometimes randomly, turned proximally and slightly oblique, rostrum elongated (353 µm long by 137 µm wide), spatulate, smooth and more dilated at the tip (166 µm wide), covering almost all the frontal wall of the autozooid ( Figure 2C,G ); (2) small avicularia adjacent to the orifice or placed more lateromedially, oriented proximally and slightly towards the lateral zooidal margin, with mandible and rostrum rounded, smooth and more dilated at the proximal end ( Figure 2C,F–H ); (3) small avicularia (109 µm long, range 98–118 µm, by 83 µm wide, range 69–98 µm) with rostrum slightly triangular having small teeth on the border, placed almost randomly, tending to be oriented proximally and slightly towards the lateral zooidal margin ( Figure 2C,E ). Interzooidal avicularia large, with triangular rostrum, border asymmetrical, the margin of one side curved; cross-bar complete ( Figure 2C ).

Habitat

Colonies found growing directly on rocks, 5 m deep.

Geographical distribution

Colonies collected only at Arraial do Cabo (Pedra Vermelha).

Remarks

Among the Brazilian species of Parasmittina , P. evelinae ( Marcus, 1937) has five oral spines, large interzooidal avicularia are absent, and the lyrula is wide with acute or bicuspate tips. Barbosa (1964) noted five “varieties” of a species she attributed to the European P. trispinosa : P. trispinosa vars. ligulata, loxa, munita, nitida and spathulata. All of these bear three oral spines, unlike P. alba sp. nov. Several other species of Parasmittina worldwide share some characteristics with P. alba sp. nov.

Although P. betamorphaea Winston, 2005 occurs in Brazil, and was previously mentioned as Smittina trispinosa var. nitida by Marcus (1937: 104), it may be distinguished from P. alba sp. nov. in having more than one avicularium per autozooid, lacking a serrated rostrum in the small avicularia, possessing giant avicularia with more rounded rostra, and by the different disposition and shape of the pores on the ovicells. Another species that is close to P. alba sp. nov. is P. raigioidea Liu et al., 2001 . However, P. raigioidea lacks avicularia with serrated rostra and the small avicularia have mandibles directed distally. While P. winstonae Liu et al., 2001 has several different types of avicularia, like P. alba , there may be more than one avicularium on each autozooid and none of them have serrated rostra. The oral lateral avicularia are large, directed obliquely distally and have rostra with less dilated tips. The triangular avicularia are small, placed on one side of the peristome or elsewhere on the frontal wall, with oblique and distally directed rostra. Ovicells in P. winstonae have small pores and P. parsevalioidea Liu et al., 2001 has two oral spines, avicularia without serrated rostra and the peristome is laterally elevated. In P. galerita Ryland and Hayward, 1992 there are one or two oral spines and the avicularia vary in shape. However, condyles are rounded and thinly serrated on their free parts, more than one avicularium may be borne by each autozooid, some of them with mandibles obliquely directed distally, and the ovicell has small pores.

Figures

Figure 2. Parasmittina alba sp. nov. (A) Group of zooids without frontal budding; (B) old part of colony; (C) zooids arrangement and different types of avicularia; (D) autozooids with orifices and lyrulae; (E) detail of two autozooids showing small triangular avicularia and distal spines; (F) autozooids showing small avicularia with rounded distal tips; (G) giant avicularium with elongate spatulate rostrum and small avicularia with round and smooth rostrum; (H) ovicellate autozooid. Scale bars: A, C, E–H: 100 µm; B: 400 µm; D: 200 µm; A: MNRJ-077 and others: MNRJ-079.