Parasmittina amazonensis 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 : 14-16

Parasmittina amazonensis Ramalho & Moraes n. sp.

( Fig. 7A–D )

Material examined. Holotype: MNRJBRY-1451: Brazil, Maranhão state (Sta #7, 00°14.742’S – 044°54.089’W), 23 m, on rhodoliths, 29 September 2014, collected by Fernando Moraes & Rodrigo Moura (NHo Cruzeiro do Sul ).

Etymology. Referring to the type locality, the reef system off the Amazon River mouth.

Diagnosis. Colony encrusting, initially forming circular patches and later becoming multilaminar; frontal shield ventricose, imperforate; peristome well developed laterally with median U-shaped pseudosinus; orifice with broad anvil-shaped lyrula and six, robust oral spines; latero-oral avicularium oval with serrated rostrum; frontal avicularium elliptical; ovicell with tubular pseudopores.

Description. Colony encrusting, multiserial, initially forming unilamellar, circular patches ( Fig. 7A ), later becoming multilaminar. Autozooids polygonal, slightly longer than wide [L 275–363–439 (SD 50, N 15); W 180– 304– 456 µm (SD 30, N 15)]; frontal shield ventricose, imperforate except for 11–17 circular, marginal areolar pores varying in size ( Fig. 7A ). Peristome well developed laterally, forming a median U-shaped pseudosinus ( Fig. 7B ). Primary orifice circular and hidden by peristome, with a broad anvil-shaped lyrula, occupying almost the entire proximal margin of the orifice and with a straight edge; six oral spines (rarely five) on non-ovicellate zooids and only two spines visible when ovicell is present ( Fig. 7A, B ); spine bases robust [24–27– 31 µm in diameter (SD 2, N 17)]. Single or paired oval, latero-oral avicularia [L 43–48– 61 µm (SD 5, N 14)] with rostrum tip serrated, directed distolaterally towards the orifice, with complete crossbar ( Fig. 7 B, D ). An additional avicularium present on frontal shield of some zooids, randomly oriented, similar in shape to latero-oral avicularia, but larger [L 74–79– 84 µm (SD 5, N 3)] and more elliptical ( Fig. 7A ). Ovicell hyperstomial, slightly wider than long [L 135–150–172 (SD 13; N 8); W 152–165– 177 µm (SD 10, N 8)], ooecial surface perforated by about 20 small and tubular pseudopores ( Fig. 7A, D ).

Remarks. Eight Parasmittina species have been recorded from Brazil ( Ramalho et al. 2018), all with only four thin oral spines. The two most similar congeners of P. amazonensis Ramalho & Moraes n. sp. are: P. fraseri Osburn, 1952 , from the Pacific Ocean, and P. talismani ( Calvet, 1906) , from the Atlantic Ocean. Reverter-Gil & Fernández-Pulpeiro (2007), who studied the paratypes of P. talismani and images of P. fraseli , mentioned that the two species share several characters, such as the broad lyrula with straight edge, well developed peristome, avicularium supported by peristome and up to five oral spines. These authors recommended a taxonomic revision to confirm the identification and distribution of these two species. Some of these characters are also shared with P. amazonensis Ramalho & Moraes n. sp. (i.e., broad lyrula, ovicell perforated by circular, tubular pseudopores, and avicularia lateral to the orifice), but P. fraseri differs in having 3–5 oral spines, a single long-pointed frontal avicularium (absent in the new species), and peristomial avicularia with smooth, rounded to elliptical rostrum (serrated in the new species), while P. talismani differs in having 4–5 oral spines, ovicell almost immersed in the distal zooid, and lateral and frontal avicularia similar in size (lateral avicularia are smaller than frontal ones in the new species). Another similar species is P. tubula ( Kirkpatrick, 1888) described from Mauritania, which has six oral spines, broad lyrula, very small frontal avicularium, lacks avicularia lateral to orifice, and the peristome is not as well developed as in the new species.

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.