Malakosaria atlantica, Vieira, Leandro M., Gordon, Dennis P., Souza, Facelucia B. C. & Haddad, Maria Angélica, 2010

Vieira, Leandro M., Gordon, Dennis P., Souza, Facelucia B. C. & Haddad, Maria Angélica, 2010, New and little-known cheilostomatous Bryozoa from the south and southeastern Brazilian continental shelf and slope, Zootaxa 2722, pp. 1-53 : 27-29

Malakosaria atlantica n. sp.

( Figures 64–66 , Table 13)

Material examined. Holotype. MZUSP 0 312, Brazil, project REVIZEE South SCORE, RV ‘Prof. Wladimir Besnard’, station 6686. Paratypes. MZUSP 0 313, Brazil, project REVIZEE South SCORE, RV ‘Prof. Wladimir Besnard’, station 6661 (alcohol 70%). MZUSP 0 314, station 6666.

Diagnosis. Colony erect, dichotomously branching; elongate autozooids, longer than Malakosaria sinclairii , back to back in overlapping alternating pairs, tapering proximally.

Etymology. Name alluding to the first record of the genus at Atlantic waters.

Description. Colony erect, dichotomously branching, attaining 80 mm height. Zooids elongate, arranged back to back in overlapping alternating pairs; zooids at bifurcations medially constricted. Frontal-shield calcification smooth, cryptocystidean with minimal development of the hypostegal coelom, imperforate except for a crescentic toothed ascopore and six shallow, subrectangular to oval excavations around the semicircular orifice, of which two occur between ascopore and orifice; between each pair of pore-chambers a much smaller circular pore. No oral spines or other processes. Ovicells not present in the available material.

n min–max mean SD Autozooid length 20 0.877–1.173 0.877 0.069 Autozooid width 20 0.272–0.309 0.294 0.012 Orifice length 20 0.105–0.130 0.116 0.006 Orifice width 20 0.148–0.191 0.163 0.010 Remarks. Malakosaria atlantica n. sp. resembles the Pacific type species Malakosaria sinclairii ( Busk, 1857) in colony morphology but differs in branch width, proportionality of zooidal dimensions, and zooid shape. Busk (1857) noted that M. sinclairii was collected by Andrew Sinclair from New Zealand. Based on Sinclair’s known travels, which were fairly extensive in the North Island, it is not certain where his material came from but the shores of Cook Strait are not improbable; M. sinclairii grows as shallow as 11 m depth on rock walls near the entrance to Wellington Harbour, where many beach-cast bryozoan species can be abundant after strong southerly storms. We have closely compared M. atlantica with M. sinclairii from New Zealand, both by direct visual comparison by laying branches of each species alongside each other under the same microscope, and by measurements of zooidal parameters. M. sinclairii has wider branches (0.47–0.58 mm) and consistently shorter zooids (0.57–0.78 mm) while the Brazilian species is 0.272–0.309 mm wide and 0.877-1.173 mm long. Other dimensions overlap, but the elongate zooids of M. atlantica taper proximally whereas those of M. sinclairii are nearly of equal width throughout their length. Since M. sinclairii in New Zealand occurs from only shallow water to shelf depths, it is likely that published records from the south Indian Ocean and from the deep sea (see synonymy in Gordon 1989) are not conspecific.

Distribution. Brazil: off São Paulo and Paraná states, 147–380 m (present study).

Figures

FIGURES 64 – 66. Malakosaria atlantica n. sp., MZUSP 0 312 (part of the holotype specimen), off Paraná, Brazil. 64, Detail of colony; 65, close-up of branching zooid; 66, close-up of orifice with associated pore-chambers and ascopore.