Rhynchozoon coalitum n. sp.

(Figures 77–82, Table 16)

Material examined. Holotype. MZUSP 0 333, Brazil, project REVIZEE South SCORE, RV ‘Prof. Wladimir Besnard’, station 6665 (alcohol 70%). Paratypes. MZUSP 0334–0335, Brazil, project REVIZEE South SCORE, RV ‘Prof. Wladimir Besnard’, station 6661. MZUSP 0 336, station 6686. Additional material. MZUSP 0 337, Brazil, project REVIZEE South SCORE, RV ‘Prof. Wladimir Besnard’, station 6661. MZUSP 0 338, station 6666. MZUSP 0 339, station 6673 (alcohol 70%). MZUSP 0 340, station 6678.

Diagnosis. Colony encrusting, unilaminar; autozooids elongate, with smooth frontal shield and few marginal pores; orifice obscured by mucro and suboral avicularium; 2–4 oral spines, only 2 spines in ovicelled zooids; hyperstomial ovicell imperforate, with U-shaped aperture formed by frontal labellum extending basally.

Etymology. Latin coalitus, alluding to the shape of the proximal peristome formed by the fusion of the mucro and suboral avicularium.

Description. Colony encrusting, unilaminar. Zooids elongate, recumbent, subrectangular at the colony edge and irregularly hexagonal in older colonies. Frontal shield smooth with few rounded marginal areolarseptular pores; suboral mucro strong, developed on one side, partially joined with suboral avicularium and forming a pseudospiramen/labial pore. Orifice with beaded distal rim, the shallow poster obscured by a mucro and suboral avicularium; lateral condyles triangular, small, inconspicuous. Secondary orifice rounded distally, the proximal edge straight, sometimes with irregular crenulation. Two to four oral spines; only 2 spines in ovicelled zooids. Suboral avicularium with larger triangular rostrum, orientated laterally, merged proximally with mucro, crossbar with small columella and well-developed palate; mandible triangular with rounded distal end. Frontal avicularia absent. Ovicell hyperstomial, subglobular, flat frontally, imperforate, with U-shaped aperture formed by frontal labellum extending basally.

n min–max mean SD Autozooid length 20 0.445–0.642 0.546 0.052 Autozooid width 20 0.247–0.457 0.369 0.049 Orifice length 20 0.074–0.105 0.091 0.009 Orifice width 20 0.124–0.154 0.139 0.011 Avicularium length 20 0.093–0.167 0.128 0.024 Ovicell length 20 0.167–0.235 0.202 0.018 Ovicell width 20 0.173–0.201 0.188 0.011 Remarks. Vieira et al. (2008) listed five species from Brazilian waters: Rhynchozoon arborescens Canu & Bassler, 1928a (now Cigclisula arborescens), Rhynchozoon bispinosum (Johnston, 1847), Rhynchozoon phrynoglossum Marcus, 1937, Rhynchozoon rostratum (Busk, 1856) and Rhynchozoon verruculatum (Smitt, 1873). Both R. bispinosum, described from British waters, and R. rostratum, from the Pacific coast of Mexico, require reexamination and probably represent distinct species. Rhynchozoon phrynoglossum, described from shallow water in southeastern Brazil, is characterized by the presence of large vicarious avicularia, a primary orifice with two long condyles and a peristome sometimes surrounded by three projections. Rhynchozoon verruculatum, originally described from Florida (USA), differs in having a large diamond-shaped avicularium below and beside the peristome, as well on frontal walls. The new Brazilian species R. coalitum is distinguished by the lack of frontal avicularia and in having the mucro merging with a relatively large suboral avicularium to form the proximal peristome.

Distribution. Brazil: off São Paulo and Paraná states, 99–380 m (present study).