Cranosina gilbertoi Ramalho & Moraes, 2021

Ramalho, Laís V., Moraes, Fernando C., Salgado, Leonardo T., Bastos, Alex C. & Moura, Rodrigo L., 2021, Bryozoa from the reefs off the Amazon River mouth: checklist, thirteen new species, and notes on their ecology and distribution, Zootaxa 4950 (1), pp. 1-45 : 4-5

Cranosina gilbertoi Ramalho & Moraes n. sp.

( Fig. 2A–C )

Material examined. Holotype: MNRJBRY-1457: Brazil, Pará state (Sta #6, 00°45.359’N – 046°38.49’W), 50 m, on rhodolith, 28 September 2014, collected by Fernando Moraes & Rodrigo Moura (NHo Cruzeiro do Sul ).

Etymology. In honour of Gilberto Menezes Amado-Filho, a dear friend and leading Brazilian marine scientist who dedicated his last years to study the Amazon Reef System.

Diagnosis. Small colonies with large and oval autozooids; 11–14 spines around the opesia; large avicularium placed distally of each autozooid with rostrum ending in an open tip; ovicell endozooidal.

Description. Colony encrusting, multiserial, unilaminar; only small, incomplete, fragments found, showing a spiral growth pattern ( Fig. 2A ). Autozooid large, oval, longer than wide [L 464–518–594 (SD 45, N 18); W 280– 355– 414 µm (SD 34, N 23)], separated by narrow grooves, with a distinct tuberculate cryptocyst varying in width, bearing 11 to 14 spines (visible as spine bases) around the opesia [L 349–399–472 (SD 30, N 23); W 173–217– 297 µm (SD 28, N 25)]; large pore chambers on the lateral and distal walls ( Fig. 2B, C ). Interzooidal avicularia [L 125–146–159 (SD 11, N 14); W 61–80– 90 µm (SD 8, N 14)] located distally of each autozooid, directed laterally or proximo-laterally with rostrum ending in an open tip, somewhat trapezoidal in shape, with strong and incomplete condyles ( Fig. 2B, C ); mandible not observed. Ovicell endozooidal; fertile autozooids show a slight elevation and thickening of the distal rim ( Fig. 2C ).

Remarks. The genus Cranosina comprises 10 known species, half of them fossil. This is the first record of a living Cranosina in the Atlantic Ocean ( Bock 2020, accessed 13 November 2020). The two most similar species are C. coronata ( Hincks, 1881) from the Indo-West Pacific, which lacks spines around the opesia, and has interzooidal avicularia always directed laterally ( Hincks 1881; Tilbrook et al. 2001; Tilbrook 2006); and C. colombiana Osburn, 1950 from the East Pacific, which has fewer spines (8–10) surrounding mainly the proximal half of the opesia, narrower cryptocyst, square avicularium chamber (150 µm in all dimensions), and slightly longer and narrower (L 500–550–650, W 250–300– 400 µm) autozooids.Another species described from the Pacific Ocean, C. spiralis Chimonides & Cook, 1994 has similar budding pattern (left or right-handed spiral series in the same colony) and distal avicularia, but lacks spines, has larger zooids (510–820 x 320–500 µm), and longer avicularium rostrum (150–310 µm) with thick condyles.

Figures

FIGURE 2. Cranosina gilbertoi Ramalho & Moraes n. sp. (Holotype MNRJBRY-1457).A. Colony showing spiral growth pattern. B. Detail of zooids and interzooidal avicularia. C. Detail of an ovicellate zooid. Scale bars: A, 500 µm; B, C, 250 µm.