Rhynchozoon phrynoglossum Marcus, 1937a, MARCUS, 1937

Almeida, Ana C. S., Souza, Facelucia B. C., Farias, Jamile, Alves, Orane F. S. & Vieira, Leandro M., 2018, Bryozoa on disarticulated bivalve shells from Todos os Santos Bay, northeastern Brazil, with the description of two new species, Zootaxa 4434 (3), pp. 401-428: 418-419

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Rhynchozoon phrynoglossum Marcus, 1937a


Rhynchozoon phrynoglossum Marcus, 1937a  

( Fig. 9A –D View FIGURE 9 ; Table 11)

Rhynchozoon phrynoglossum MARCUS, 1937   A: P. 115, PL. 23, fIg. 61A, PL. 22, fIg. 61B, C.

Rhynchozoon phrynoglossum   : MARCUS, 1955: P. 304.

Rhynchozoon phrynoglossum   : VIEIRA et al., 2008: P. 33.

Rhynchozoon phrynoglossum   : ALMEIDA et al., 2015A: P. 5.

Material examined. UFBA 1650, UFBA 3388, on valve of Dallocardia muricata   .

Redescription. Colony encrusting, uni- to multilaminar. Zooids subrectangular at the growing edge ( Fig. 9A View FIGURE 9 ),

arranged in linear horizontal rows, separated by slightly raised lateral walls; with increasing calcification, becoming somewhat oblong and irregularly organized, with zooidal boundaries indistinct. Frontal wall smooth, with 6–12 marginal pores. Primary orifice ( Fig. 9B View FIGURE 9 ) small relative to zooidal length, almost obscured by secondary orifice; distal edge with 12–16 rounded denticles; proximal edge with broad, shallow median sinus; condyles small, rectangular, located at proximal corners of orifice. No oral spines. Secondary orifice well developed, formed by 1– 3 tubercles (two lateral and one median); median tubercle commonly with acute tip. Suboral avicularium ( Fig. 9B View FIGURE 9 ) single, located lateral to median orificial tubercle, oblique and directed distolaterally; rostrum subtriangular, with hooked tip and complete crossbar; foramen triangular. Frontal avicularia small, 1 or 2 per autozooid, similar in outline to suboral avicularium but without hooked tip, located near zooidal margins, variable in orientation. Large vicarious avicularia ( Fig. 9C View FIGURE 9 ) occur, smaller than autozooids, rostrum nearly rectangular, narrower in proximal third, proximal edge rounded and distal edge nearly straight; foramen nearly oval; calcified palate occupying about half the rostrum length. Ovicell ( Fig. 9A, D View FIGURE 9 ) prominent, becoming immersed with increasing calcification; ooecia semicircular and frontally flat; ectooecium non-calcified frontally, leaving a large, semicircular tabula of completely calcified entooecium.

Remarks. This is the first description of R. phrynoglossum   based on SEM images since the original description by Marcus (1937a). The species differs from congeners in having 1–3 tubercles around the primary orifice, with a large suboral avicularium, frontal avicularia similar to the suboral avicularium, large subrectangular avicularia and semicircular ooecia.

Rhynchozoon phrynoglossum   is found on hard substrata, commonly encrusting shells (Marcus 1937a, 1955).

Distribution. Western Atlantic: Brazil ( Rocas Atoll, Bahia, Espírito Santo and São Paulo) ( Vieira et al. 2008; Almeida et al. 2015a).