Disporella pila Marcus, 1955

Ramalho, L. V., Muricy, G. & Taylor, P. D., 2009, Cyclostomata (Bryozoa, Stenolaemata) from Rio de Janeiro State, Brazil, Zootaxa 2057, pp. 32-52 : 47

Disporella pila Marcus, 1955

( Fig. 9A–F)

Disporella pila Marcus, 1955: 277 ; Buge 1979: 243.

Material examined. MNRJ-191, MNRJ-365: Arraial do Cabo Farol beach, Cabo Frio Island, 1 March 2002, collector L. V. Ramalho, depth 5 m.

Description. Colony almost circular, encrusting, small, up to 5 mm diameter, white; basal lamina free, sometimes elevated from substratum, growing edge thick ( Fig. 9A). Autozooids tubular, apertures circular (50–(63)–80 µm), grouped in uniserial rows ( Fig. 9A, B); orientated at low angle to colony surface, their tubular walls clustered into radial ridges, some central autozooids growing freely and irregularly; apertures bicuspate, opening laterofrontally, mostly close to growing edge ( Fig. 9A–C). Calcification entirely cryptocystal ( Fig. 9C). Alveoli polygonal (62–(78)–100 µm diameter), interspersed among autozooids, their apertures larger than autozooidal apertures in central region, usually forming uniserial rows between autozooids in outer parts of colonies ( Fig. 9C–D), containing mural spinules with star-shaped crowns ( Fig. 8E). Basal lamina with flattened, distally imbricated crystallites ( Fig. 9A–B, F). Gonozooid not observed.

Remarks. The taxonomy of lichenoporids is more problematical than that of most other groups of cyclostomes because very little is known about variations in skeletal morphology in relation to the age and reproductive state of colonies. Species of Disporella from the Atlantic and Mediterranean were revised by Alvarez (1992, 1994, 1995) but D. pila was not considered in these publications. Disporella pila differs from other species in the acute angle of the autozooidal tubes to the colony surface, with the result that the apertures open laterofrontally, almost parallel to the substratum. The Rio de Janeiro material differs from D. pila as described by Marcus (1955) and Buge (1979) from the Espírito Santo coast, which have fewer rows of autozooids and a more frequently elevated basal lamina. These differences are minor, however, and the Rio de Janeiro material is identified as D. pila .

Ecology. Colonies found encrusting the alga Sargassum at 5 m depth; Marcus (1955) also collected D. pila on non-calcareous algae.

Geographic distribution. Espírito Santo (Vitória) and 21°10’ – 21°38’S, 40°42’ – 40°45’W ( Marcus 1955; Buge 1979); Arraial do Cabo (Cabo Frio Island), Rio de Janeiro State (present study).