Mecynoecia cf. delicatula ( Busk, 1875 )

Ramalho, L. V., Muricy, G. & Taylor, P. D., 2009, Cyclostomata (Bryozoa, Stenolaemata) from Rio de Janeiro State, Brazil, Zootaxa 2057, pp. 32-52 : 44

Mecynoecia cf. delicatula ( Busk, 1875)

( Fig. 7A–F)

Pustulopora delicatula Busk, 1875: 20 .

Entalophora delicatula: Marcus 1937: 24 .

Mecynoecia delicatula: Buge 1979: 221 .

Material examined. MNRJ-364, Baía da Guanabara, Rio de Janeiro city, 10 April 2002, collector J.E.A. Gonçalves, depth 2 m.

Description. Colony erect, almost 11 mm long in single available example, dichotomously branched ( Fig. 7A), white, basal portion broken, branch diameter 380–(460)–517 µm. Autozooids opening around entire branch, 8–10 in one circumference, frontal wall transversely wrinkled, pseudopores small (about 7 µm in diameter). Peristomes (356–(418)–630 µm long x 100–(110)–120 µm wide) gently curved frontodistally, mostly broken off ( Fig. 7A, B), with few pseudopores distally ( Fig. 7B–D). Aperture circular (80–(84)–100 µm diameter), sometimes bicuspate. Laminar layer of internal wall formed by flattened, distally imbricated crystallites ( Fig. 7E–F). Gonozooid not observed.

Remarks. Two species of Mecynoecia have been recorded from Brazil, M. delicatula ( Busk, 1875) and M. cf. smitti (Pergens, 1887) (see Marcus 1937; Buge 1979). Mecynoecia smitti differs from M. delicatula in having six to seven zooids around the branch circumference (cf. 8–10), longer peristomes (1500 µm cf. <700 µm) and wider branches (300–380 µm diameter, cf. 380–517 µm), but generally smaller apertures (75–85 µm, cf. 80–100 µm).

Another species, M. buski ( Borg, 1944) , was recorded from South America by Buge (1979). This has longer zooids (850–1400 µm), thicker branches (900–1200 µm) and larger apertures (150–190 µm) than M. cf. delicatula .

Mecynoecia delicatula was previously described from São Paulo and Pernambuco states ( Marcus 1937; Buge 1979). The Rio de Janeiro specimen is very similar to this material in all respects but, unfortunately, gonozooids are lacking, raising some doubts over the identity of the species (and even the genus).

Ecology. Colonies found on artificial plates in a harbour, together with the cheilostome Bugula neritina (Linnaeus, 1753) , in shallow (2 m) and calm water.

Geographic distribution. Gulf of Mexico, Saint Helena, East Africa, Japan and Australia ( Marcus 1937; Buge 1979). Brazil: São Paulo (Santos) and Pernambuco (Recife) States ( Marcus 1937; Barbosa 1964; Buge 1979); Rio de Janeiro State (Baia da Guanabara, Rio de Janeiro city) (this study).