Reptadeonella bipartita ( Canu & Bassler, 1928a )

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 : 160

Reptadeonella bipartita ( Canu & Bassler, 1928a)

( Figs 2F , 7C )

Adeona bipartita Canu & Bassler, 1928a: 37 , fig. 2; Marcus 1949: 25, figs 37–39;

Reptadeonella bipartita: Winston, 1986: 24 , fig. 50; Almeida et al., 2015b: 353, figs 6–9; Bastos et al., 2018: table 1. Additional synonymies in Almeida et al., (2015b).

Material examined. Abrolhos Bank, Bahia State, Brazil: MNRJ-Bry1364, Parcel dos Abrolhos, 15 m depth, February 2014, col. R. Moura, G. Amado-Filho & A. Bastos.

Description. Colony encrusting, forming extensive layers inside and on the external surface of the cores. Autozooids rhomboidal, longer than wide (450–567–648 µm long x 364–404–435 µm wide) with an elliptical transverse orifice (63–69–76 µm long x 90 –103–117 µm wide); peristome not developed; frontal shield finely crenulate, one line of circular to oval areolar pores around the margin and sometimes a second line of smaller pores close to the avicularium and above the orifice. Spiramen crescentic, inside the deep circular pore located just below the avicularium. Single, suboral, median avicularium (155–193–209 µm long) located between the orifice and spiramen, directed distally; rostrum triangular with point resting on the proximal border of the peristome; short condyles.

Geographic distribution. Caribbean ( Almeida et al. 2015b); Brazil: Alagoas, Bahia, Espírito Santo states ( Almeida et al. 2015a, b; Bastos et al. 2018; present study).

Remarks. Almeida et al. (2015b) mentioned that the number of Reptadeonella species from Brazil is uncertain due to historical taxonomic mistakes attributing records of this genus to R. violacea ( Johnston, 1847) . In their paper, these authors redescribed R. bipartita and R. costulata Canu & Bassler, 1928 , and added R. granulosa Winston & Vieira, 2013 , R. brasiliensis , R. cucullata , R. leilae and R. aspera Almeida et al., 2015b ( Marcus 1939, 1949; Almeida et al. 2015b). In addition to R. bipartita , there are some other species with suboral avicularia directed longitudinally to the orifice: R. aspera and R. brasiliensis have a shorter suboral avicularium than R. bipartita , and R. violacea has a rounded spiramen and sometimes an avicularium directed obliquely to the orifice (absent in Brazilian material). Features of R. bipartita collected from Abrolhos Bank are very similar to the type material ( Canu & Bassler 1928a), including the position and shape of the avicularia, spiramen and orifice. However, the type material has longer autozooids (600–700 µm; cf. 450–648 µm at Abrolhos) but this difference is insufficient to separate these as different species, especially in view of the fact that environmental factors, such as food supply and water temperature, are known to influence zooid size in other bryozoan species (e.g. Lombardi et al. 2006; O’Dea et al. 2007).

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.