Rhynchozoon aff. rostratum (Busk, 1856)

(Fig. 6D–F)

Rhynchozoon sp.: Reis et al., 2016: supplementary table.

Rhynchozoon rostratum: Bastos et al., 2018: table 1.

Material examined. Abrolhos Bank, Bahia State, Brazil: MNRJ-Bry1338, Parcel dos Abrolhos, 15 m depth, February 2014, col. R. Moura, G. Amado-Filho & A . Bastos; MNRJ-Bry1374, Parcel dos Abrolhos, 4 m depth, February 2014, col. R. Moura, G. Amado-Filho & A. Bastos.

Short description. Colonies encrusting, multilamellar; zooids initially orderly but becoming irregularly arranged. Frontal wall tuberculate with areolar pores only (Fig. 6D). Primary orifice with distinct rounded sinus, hidden by the development of the peristome; tubercles sometimes present, varying in number and size (Fig. 6D, E). Oral and frontal avicularia of similar shape and size, crossbar complete, the frontal avicularium triangular, diamond-shaped and distolaterally or laterally directed (Fig. 6E); oral avicularium single (Fig. 6F) directed laterally. Ovicells not observed.

Geographic distribution. Indonesia, E. Pacific, Caribbean and Gulf of Mexico (Busk 1856; Winston & Heimberg 1986); Abrolhos Bank, Bahia State (Reis et al. 2016; Bastos et al. 2018; present study).

Remarks. Rhynchozoon verruculatum (Smitt, 1873) is very similar to R. rostratum, but it differs from the latter in having larger zooids, a shallow U-shaped sinus, more elongated diamond-shaped frontal avicularia, and ovicells that are completely immersed. Rhynchozoon brasiliensis Almeida et al., 2017, also known from Bahia State, has a primary orifice with a V-shaped sinus, the peristomial avicularium is absent, and the frontal avicularium is variously oriented. Two other Brazilian Rhynchozoon species are distinct: R. coalitum Vieira et al., 2010 has only a suboral avicularium and lacks vicarious avicularia, while R. phrynoglossum Marcus, 1937 has large vicarious avicularia with truncate or tongue-shaped mandibles. The colonies found in the studied cores were poorly preserved, making a more precise identification difficult.