Metrarabdotos, Canu, 1914

Ramalho, Laís V., Taylor, Paul D., Moraes, Fernando Coreixas, Moura, Rodrigo, Amado-Filho, Gilberto M. & Bastos, Alex C., 2018, Bryozoan framework composition in the oddly shaped reefs from Abrolhos Bank, Brazil, southwestern Atlantic: taxonomy and ecology, Zootaxa 4483 (1), pp. 155-186 : 163-164

Metrarabdotos sp.

( Fig. 3B )

Material examined. Abrolhos Bank, Bahia State, Brazil: MNRJ-Bry1344, Parcel dos Abrolhos, 15 m depth, February 2014, col. R. Moura, G. Amado-Filho & A. Bastos.

Description. Fragments of erect bifoliate colonies with zooids opening on both sides. Zooids rectangular (608–711–753 µm long x 277–308–354 µm wide), frontal shield smooth with 13–18 areolar pores. Secondary orifice circular (179–202–241 µm long x 137–151–167 µm wide), bidenticulate, with a small U-shaped sinus ( Fig. 3B ). Ordinary avicularia paired, located distally to orifice; rostrum triangular, proximally directed ( Fig. 3B ). No entire ovicells observed.

Geographic distribution. Abrolhos Bank, Bahia State, Brazil ( Bastos et al. 2018; present study).

Remarks. All colony fragments recovered from the cores were poorly preserved and lacked ovicells, which are important for taxonomic identification to species level. Neither the avicularia nor the orifice showed distinctive features, precluding species-level identification of this bryozoan.

Figures

FIGURE 3. Scanning electron micrographs of four bryozoan species. A. Metrarabdotos aff. jani, detail of some autozooids showing orifice with small, slit-shaped sinus and lateral, elongate avicularium. B. Metrarabdotos sp., general view of the fragment showing some autozooids with almost circular orifice and a pair of lateral distal avicularium. C–G. Parasmittina distincta n. sp. C. General view of a fragment showing autozooids with two oral spine bases and different kinds of avicularia: shoe-shaped, triangular and elongate. D. General view of a fragment showing autozooids with almost circular orifice, large lyrula, three or four oral spine bases and shoe-shaped avicularium. E. Detail of orifice showing four oral spine bases, large anvil-shaped lyrula and prominent condyles. F. Detail of two autozooids with two and three distal oral spines and short and large triangular lateral avicularium. G. General view of a fragment showing autozooid with two oral distal spines, lyrula and a putative ooecium. H. Parasmittina abrolhosensis n. sp., general view of a fragment showing some autozooids with different kinds of avicularia, orifice circular with three to four oral spine bases and tall and narrow lyrula.