Steginoporella magnilabris ( Busk, 1854 )

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 : 157-158

Steginoporella magnilabris ( Busk, 1854)

( Figs 2A , 7A–B )

Membranipora magnilabris Busk, 1854: 62 (part), 113.

Steganoporella magnilabris: Marcus, 1955: 284 , fig. 25; Cook, 1964: 53, figs 2, 4.

Steginoporella magnilabris: Winston, 1986: 10 ; Winston, 2005: 29, figs 73–75; Winston & Woollacott, 2009: 252, fig. 11; Winston et al., 2014: 150, fig. 6; Almeida et al., 2015a: 4; Winston, 2016: 8, fig. 2; Vieira et al., 2016: 77, fig. 16l; Bastos et al., 2018: table 1.

Material examined. Abrolhos Bank, Bahia State, Brazil: MNRJ-Bry1336, California Reef, 25 m depth, March 2015, col. F.C. Moraes, R. Moura, G. Amado-Filho & A . Bastos ; Abrolhos Archipelago, Bahia State, Brazil: MNRJ-Bry323 ( Fig. 2A ), MNRJ-Bry324, Redonda Island, April 2000, col. C.E.L. Ferreira.

Short description. Fragments of colonies erect and frondose ( Fig. 7A, B ); beige in colour. Autozooids rectangular, arranged quincuncially ( Fig. 2A ); A-zooids of smaller size, rectangular, orifice D-shaped ( Fig. 2A ) with a pair of prominent condyles on the proximal corners; B-zooids larger in size ( Fig. 2A ), operculum almost square, sclerite inverted Y-shaped, with numerous strong and curved teeth decreasing in size towards lateral border. Cryptocyst perforated by small pores, slightly concave, forming a depressed median process with an associated polypide tube ( Fig. 2A ).

Geographic distribution. Caribbean (Winston 1986). Brazil: Rio de Janeiro, Espírito Santo, Bahia, Alagoas States ( Busk 1854; Marcus 1955; Winston et al. 2014; Almeida et al. 2015a; Vieira et al. 2016; Bastos et al. 2018; present study).

Remarks. Four species of Steginoporella have been described from Brazil: S. magnilabris Busk, 1852 , S. buskii Harmer, 1900 (as S. transversalis by Canu & Bassler 1928a), S. connexa Harmer, 1900 , and S. evelinae Marcus, 1949 ( Busk 1854; Canu & Bassler 1928a; Marcus 1938, 1949, 1955; Cook 1964; Braga 1968, Winston et al. 2014; Almeida et al. 2015a; Vieira et al. 2016).

Steginoporella magnilabris was recorded from the AB by Busk (1854) (NHM 1854.11.15.222), Almeida et al. (2015a) and Bastos et al. (2018). It can be distinguished from S. buskii , which has A-zooid and B-zooid of similar size, and the operculum of the B-zooids has numerous, small or sometimes vestigial teeth. Steginoporella connexa has a cryptocyst pierced by two narrow opesiules on each side, while S. evelinae has two large projecting tubercles adjacent to the orifice and the edges of the opesiules bear small sharp pointed denticles.

Figures

FIGURE 2. Scanning electron micrographs of six bryozoan species. A. Steginoporella magnilabris, part of the colony showing the shape and disposition of the autozooids. B. Labioporella tuberculata, part of the colony with some autozooids. C, D. Crassimarginatella winstonae n. sp., general view of the colony with autozooids and one avicularium. E. Detail of the colony showing an interzooidal avicularium. E. Exechonella sp., general view of a colony fragment. F. Reptadeonella bipartita, general view of colony part showing some autozooids with elliptic orifice, median avicularium and ascopore. G, H. Celleporaria atlantica, detail of some zooids showing orifices, and suboral avicularia on umbos. H. Detail of an autozooid showing an avicularium at the base of the umbo.

FIGURE 7. In situ underwater photographs of six bryozoan species recorded from Abrolhos Bank, Brazil. A, B. Steginoporella magnilabris. C. Reptadeonella bipartita. D. Celleporaria atlantica. E. Stylopoma variabilis n. sp. F. Utinga castanea. G. Arthropoma cecilii. Photos by Áthila Bertoncini/Rede Abrolhos.