Parasmittina alba Ramalho, Muricy & Taylor, 2011 Introduced

Ruiz-Velasco, Sofía, Ros, Macarena, Guerra-García, José M. & López-Fé, Carlos M., 2025, Fouling bryozoans in recreational marinas of the Canary Islands (North-Eastern Atlantic) with new records of non-indigenous and cryptogenic species, Zootaxa 5656 (1), pp. 1-63 : 37

Parasmittina alba Ramalho, Muricy & Taylor, 2011 Introduced

( Fig. 18 ; Table 18)

Parasmittina alba Ramalho, Muricy & Taylor, 2011: 769 , fig. 2; Souto et al. 2016: 980, fig. 3.

Figured material. Morro Jable (27/06/23) (4C on buoy) ( MNCN 25.03/4466),

Other material examined. Las Galletas (19/06/23) (1C on buoy), Taliarte (26/06/23) (1C on buoy), Gran Tarajal (28/06/23) (1C on buoy), Corralejo (28/06/23) (3C on buoy).

Description. Colonies whitish and encrusting, unilaminar or multilaminar ( Fig. 18A ). Rectangular autozooids ( Fig. 18B, C ), with a linear pattern in young colonies.Primary orifice wider than long with a proximolateral peristome, disrupted in the proximal area forming a V-shaped pseudosinus, with one or usually two oral spines distally ( Fig. 18D ). Round distal edge with two curved condyles, pointing to a wide lyrula ( Fig. 18D ). Usually one adventitious avicularium per zooid, positioned latero-proximally to the orifice and showing two different morphologies: (1) small triangular avicularia with serrated margins ( Fig. 18E ); (2) small oval avicularia, longer than wide ( Fig. 18F ). Ovicellate zooids show two symmetrical notches in the distal margin of the orifice ( Fig. 18G ). Ovicell hyperstomial, with a globular ooecium, which shows multiple and variable pores in the ectooecium ( Fig. 18G ).

Remarks. Souto et al. (2016) mentioned some differences between P. alba specimens from Madeira and the original material from Brazil. The specimens from the Canary Islands are more similar to those of Madeira than to the Brazilian ones. The specimens from Madeira showed smaller pores in the ectooecium in comparison to the Brazilian samples.Also, large adventitious spatulate avicularia were absent in Canary specimens and rare in Madeira ones. Indeed, avicularia were not very frequent in the collected colonies, and only two avicularium types (oval and triangular) were observed. In this sense, our material resembles Parasmittina protecta ( Thornely 1905) usually with two oral spines, orifice broader than long, pointed condyles and similar avicularia morphology ( Harmelin et al. 2009). In fact, Farias et al. (2024) questions if the P. protecta of Harmelin et al. (2009) could be referring to P. alba . Parasmittina protecta has been recorded in Madeira ( Canning-Clode et al. 2013a) and the Canary Islands ( Arístegui 1984b). The morphological characteristics observed by Arístegui (1984b) in the material depicted as P. protecta is similar to the description of P. alba , except for the secondary calcification of the ovicell with the shape of a “visor” and the absence of the symmetrical notches in the proximal border of the ovicell. The material of P. protecta from Harmelin et al. (2009) also seems to lack those characteristic symmetrical notches on the ovicell, which are observed in our material, in Ramalho et al. (2011) and Souto et al. (2016). Furthermore, the pattern of pores seems to differ, and the length of the orifice seems shorter in our material.

Nevertheless, it seems that intracolonial and astogenetic variability may be hindering the identity of P. alba and other congeneric species. Souto et al. (2016) suggested a further examination of intracolonial variability of specimens assigned to P. alba and Parasmittina betamorphaea Winston, 2005 , due to the possibility of these species being synonyms. Furthermore, Farias e t al. (2024) mentioned that these two species could be assigned to astogenetic variations of Parasmittina lavela Soule & Soule, 2002 , namely that P. betamorphaeae could correspond to younger colonies without ovicells and scarce avicularia, and P. alba to well-developed colonies including ovicells and all types of avicularia. All three species occur in the Western Atlantic (WoRMS 2024). In addition, the previously discussed P. protecta (species that has already been recorded in the Canary Islands and other Macaronesian archipelagos, and that is widely distributed in the Indo-Pacific) could also be included in this synonymy ( Farias et al. 2024). These potential synonymies should be further clarified to properly assign this species identity.

Distribution and status. Parasmittina alba was originally described from Brazilian coasts ( Ramalho et al. 2011). Individuals attributed to this species were later detected in the North Atlantic Ocean, arriving in Madeira ( Souto et al. 2016), where it has only been recorded in marinas or the area surrounding them ( Souto et al. 2016; Ferrario et al. 2020; Png-Gonzalez et al. 2021). Despite the need for clarification of these potential synonymies, all the species occur in the Western Atlantic ( P. alba , P. betamorphaea and P. lavela ) or the Mediterranean and Indo-Pacific region ( P. protecta ). The present study constitutes the first record of P. alba for the Canary Islands and for Spain.

Figures

FIGURE 18. Parasmittina alba Ramalho, Muricy & Taylor, 2011 (MNCN25.03/4466). A. View of bleached colony through stereomicroscope and B. through SEM. C. Group of zooids. D. Primary orifice. E. F. Avicularia with different morphology. G. Ovicell. Scale bars: A = 300 µm; B = 200 µm; C, G = 100 µm; D = 60 µm; E, F = 20 µm.