Parasmittina, Osburn, 1952

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 : 16

Parasmittina sp.

( Figs 7E, F ; 8A, B )

Material examined. MNRJBRY-1518: Brazil, Maranhão state (Sta #7, 00°14.742’S – 044°54.089’W), 23 m, on rhodoliths, 29 September 2014; MNRJBRY-1421: Brazil, Amapá state (Sta#3, 03°35.4267’N – 049°07.6028’W), 90 m, on rhodoliths, 26 September 2014; collected by Fernando Moraes & Rodrigo Moura (NHo Cruzeiro do Sul ).

Description. Colony encrusting, multiserial, unilaminar. Autozooids approximately rectangular, longer than wide [L 411–564–750 (SD 111, N 13); W 245–298– 357 µm (SD 33, N 13)]; frontal shield abraded, seemingly smooth with circular to elliptical marginal areolar pores, varying in size [18–29– 49 µm diameter (SD 10, N 18)] ( Fig. 7E, F ). Peristome short, apparently more developed laterally (frequently broken in the studied colonies), forming a shallow, median, U-shaped pseudosinus ( Figs 7F , 8A, B ). Primary orifice almost circular [L 100–111–125 (SD 7, N 11); W 99–108– 115 µm (SD 5, N 11)], with a pair of thin, pointed triangular condyles slightly curved downwards, and a median anvil-shaped lyrula occupying about one-third of the orifice proximal margin; 1–2 oral spines (rarely three) on the non-ovicellate zooids; spines not visible in ovicellate zooids ( Fig. 7F , 8A, B ). One spathulate avicularium [L 109–115– 127 µm (SD 6, N 7)] proximo-lateral to orifice and oriented proximally; rostrum smooth, sometimes asymmetrical at the tip, crossbar complete ( Figs 7F , 8A ); a similar avicularium observed placed more medially on the frontal shield of only one zooid ( Fig. 8A , see arrow). Another latero-oral avicularium, larger (L 307 µm), with elongate triangular rostrum, broken at the tip, proximally oriented ( Figs 7A , 8B ). Ovicell rounded in outline, usually broken, ooecial surface with large and irregular pseudopores, occupying mainly the central region and highly variable in number from 5 to 20 ( Figs 7E, F , 8A ).

Remarks. The studied specimens resemble Parasmittina alba Ramalho et al., 2011 described from Rio de Janeiro state ( Brazil) in the shape of the primary orifice, in having the majority of the zooids with two oral spines and spatulate avicularia. However, P. alba differs in having a giant spatulate avicularium, and triangular frontal avicularia with serrated rostrum and ovicell with ectooecium perforated by pseudopores or a fenestra. Another similar species is P. distincta Ramalho et al., 2018 , which shares with the Amazon species the circular shape of the primary orifice and the presence of spatulate avicularia lateral to the orifice, but differs in having also triangular avicularia on the side of the orifice, laterally or proximally directed, 2–4 spines (in Parasmittina sp. two spines are more frequent), and beaded distal margin of the primary orifice. The studied specimens were poorly preserved preventing accurate species level identification.

Figures

FIGURE 7. A–D. Parasmittina amazonensis Ramalho & Moraes n. sp. (Holotype MNRJBRY-1451). A. Part of a circular colony. B. Detail of the orifice with six oral spines and latero-oral avicularium. C. Detail of an avicularium with serrated rostrum. D. Two fertile zooids with only two oral spines visible. E, F. Parasmittina sp. (MNRJBRY-1518). E. General view showing the arrangement of the zooids, fertile and infertile. F. Detail of some zooids. Scale bars: A, E, 500 µm; B, D, 100 µm; C, 50 µm; F, 200 µm.

FIGURE 8. A, B. Parasmittina sp. (MNRJBRY-1518). A. Part of the colony showing zooids with lateral and frontal (arrowed) avicularia B. Autozooids, one with a large, triangular avicularium (arrowed). C–F. Stylopoma hastata Ramalho et al., 2018 (MNRJBRY-1495). C. Colony with one ovicell bearing a small triangular avicularium on the frontal surface, and large interzooidal avicularia. D. Colony with several ovicells with or without avicularia, and some autozooids with calcified orifices. E. Ovicell bearing a small, triangular avicularium. F. Detail of the large interzooidal avicularia. Scale bars: A, B, D, F, 200 µm; C, 500 µm; E, 50 µm.