Crassimarginatella winstonae, Ramalho & Taylor & Moraes & Moura & Amado-Filho & Bastos, 2018

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 : 158-159

Crassimarginatella winstonae n. sp.

( Fig. 2C, D )

Crassimarginatella aff. tuberosa: Bastos et al., 2018 : table 1.

Material examined. Abrolhos Bank, Bahia State, Brazil: Holotype: MNRJ-Bry1362, Parcel dos Abrolhos, 15 m depth, February 2014, col. R. Moura, G. Amado-Filho & A. Bastos.

Etymology. Named in honour of Dr Judith E. Winston for her significant contributions to the study of bryozoans from Brazil.

Diagnosis. Colony encrusting, multilamellar. Zooids elliptical, gymnocyst short, cryptocyst finely crenulated; a pair of oral spines. Interzooidal avicularium as long as an autozooid and with a parallel-sided rostrum ending in a spatulate tip.

Description. Encrusting colonies occurring within the reef framework and on its surface, multilamellar, forming several layers fouling the bryozoan Celleporaria atlantica .

Zooids elliptical, longer than wide (462–513–579 µm long x 310–391–454 µm wide) with narrow finely tuberculate/crenulate cryptocyst, sometimes slightly more developed laterally and proximally; gymnocyst short; opesia elongate, elliptical (363–418–494 µm long x 230–286–322 µm wide) ( Fig. 2C, D ). A pair of oral spines, often conspicuously developed ( Fig. 2D ). Avicularium interzooidal as large as an autozooid (518 µm long), crossbar incompletely calcified, a pair of strong denticles separating a proximal, circular opesiae from the rostrum which has parallel sides ending in a slightly spatulate tip (246 µm wide) ( Fig. 2D ). Ovicells not observed.

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

Remarks. Only one species of Crassimarginatella have been recorded in Brazilian waters: C. exilimargo Canu & Bassler, 1928a , described from Rio de Janeiro State. This species differs from the Abrolhos specimens in its larger, figure of 8-shaped avicularia and larger autozooids (600–700 µm long x 440 µm wide), as well as the absence of oral spines, which are very frequent and prominent in the Abrolhos material. Canu & Bassler (1928b) described C. tuberosa (as Aplousina tuberosa ) from the Gulf of Mexico and it has since been reported from West Africa ( Cook 1968) and the Caribbean ( Winston 1984); the material from Abrolhos is very similar to that described from the Gulf of Mexico which has slightly larger autozooids (600 µm long x 400 µm wide) and avicularia with more rounded spatulate tips. The material from the Caribbean and West Africa also has slightly larger zooids (up to 637 µm in length) and avicularia (592–828 µm long), and the avicularia are more spatulate (mandible: 246–319 µm wide) (see Winston 1984, fig. 12). Despite the absence of ovicells in the Abrolhos specimens, the differences found in avicularium shape and autozooid size are considered sufficient to erect a new species. Other Atlantic species have different-shaped avicularian rostra: rounded in C. crassimarginata ( Hincks, 1880) and C. harmeri Fransen, 1986 ; curved in C. falcata Cook, 1968 ; triangular in C. similis Cook, 1968 ; and elongate in C. quadricornuta ( Waters, 1918) (avicularia are apparently absent in C. latens Cook, 1968 ).

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.