Stylopoma hastata, Ramalho & Taylor & Moraes & Moura & Amado-Filho & Bastos, 2018

Ramalho, Laís V., Taylor, Paul D., Moraes, Fernando Coreixas, Moura, Rodrigo, Amado-Filho, Gilberto M. & Bastos, Alex C., 2018, Bryozoan framework composition in the oddly shaped reefs from Abrolhos Bank, Brazil, southwestern Atlantic: taxonomy and ecology, Zootaxa 4483 (1), pp. 155-186 : 168-169

Stylopoma hastata n. sp.

( Fig. 5C–E )

Stylopoma sp. 2: Reis et al., 2016: supplementary table; Bastos et al., 2018: table 1.

Material examined. Abrolhos Bank, Bahia State, Brazil: Holotype: MNRJ-Bry1357, Parcel dos Abrolhos, 4 m depth, February 2014, col. R. Moura, G. Amado-Filho & A . Bastos ; Paratype: MNRJ-Bry1367, Parcel dos Abrolhos, 15 m depth, February 2014, col. R. Moura, G. Amado-Filho & A. Bastos.

Etymology. From the Latin ' hastatus, -a, -um ', meaning 'spear-shaped, armed with a spear', used in reference to the shape of one of the interzooidal avicularia.

Diagnosis. Stylopoma with almost circular orifice with U-shaped sinus and small, ball-shaped condyles; single or paired small triangular lateral oral avicularia; two types of large interzooidal avicularia: spear-shaped, usually positioned parallel to autozooids; and elongated, directed transversely to the growth axis of the colony.

Description. Encrusting colonies, multilamellar ( Fig. 5C ). Autozooids rectangular, longer than wide (410– 508–580 µm long x 259–345–428 µm wide); frontal wall perforated by numerous small circular pores (54–67) inserted in depressions, slightly convex; circular to elongate areolar pores around the perimeter ( Fig. 5C ). Orifice wider than long (77–86–94 µm long x 99 –107–116 µm wide), displaced from the median axis of the zooid, with a thick and crenulate region without pores around the orifice, distal border smooth, proximal border with U-shaped sinus, and a pair of small ball-shaped condyles at the corners ( Fig. 5D ). Single or, rarely, a pair of small lateral oral avicularia (60–71–83 µm long), located proximally near the sinus or laterally to orifice, never terminally distal, directed distally and slightly laterally; rostrum triangular, almost equilateral, raised distally from the frontal shield, crossbar complete. Oral avicularium may be absent ( Fig. 5C, D ). Two different types of large vicarious avicularia ( Fig. 5C, E ): (1) avicularia oriented parallel to the autozooids or slightly inclined, directed distally, rostrum elongate (425–450–481 µm long), tip pointed or slightly rounded (lanceolate), crossbar complete (sometimes broken) ( Fig. 5C ); (2) avicularia oriented transversely to the autozooids on a salient chamber, larger than previous type (562–617–739 µm long), covering two or three autozooids, rostrum elongated and curved, tip rounded, crossbar complete ( Fig. 5C, E ). Ovicells not observed.

Geographic distribution. Abrolhos Bank, Bahia State, Brazil ( Reis et al. 2016; Bastos et al. 2018; present study) and Espírito Santo State, Brazil (18°40’S, 38°28’W - MNRJ-Bry398, 7 May 1974).

Remarks. The presence of two types of large interzooidal avicularia (lanceolate and elongate), plus a small triangular lateral oral avicularium and a circular orifice with U-shaped sinus and small ball-shape condyles, differentiates the new species from almost all other species of Stylopoma . The Abrolhos specimens are similar to Stylopoma s pongites ( Pallas, 1766) in having two types of large vicarious avicularia, but the avicularia differ in shape, one type having a spatulate rostrum and the other, larger avicularium on a raised cystid with a long and parallel-sided rostrum, terminally pointed and laterally directed, the orifice is as long as wide, the anter has a sparsely denticulate inner rim and the poster a slit-like deep sinus, condyles are smooth, deep and wide with distinct processes pointing medially. Two other species recorded from Brazil have small condyles in the orifice – S. aurantiacum Canu & Bassler, 1928a and S. carioca Winston et al., 2014 – but in both species the umbo is raised at the centre of the zooid; the first species has no vicarious avicularia, and the second has an orifice longer than wide, and vicarious avicularia with spatulate mandibles.

Figures

FIGURE 5. Scanning electron micrographs of five bryozoan species. A, B. Stylopoma variabilis n. sp. A. Detail of a small fragment showing some zooids and an ooecium. B. Frontal view of one ooecium showing the crescent-shaped aperture and the fused and asymmetrical labellum. C–E. Stylopoma hastata n. sp. C. Detail of part of the colony showing zooids and different kinds of avicularia: small and triangular lateral oral avicularia, two large and spear-shaped interzooidal avicularia, and a giant elongated and curved avicularium. D. Detail of the distal part of a zooid showing the orifice with U-shaped sinus, small condyles, and a triangular lateral avicularium. E. Detail of a giant avicularium with curved, elongate rostrum. F. Hippaliosina imperfecta, detail of two zooids with a pair of elongate distal avicularia. G. Utinga castanea, detail of the colony showing zooids with different kinds of avicularia and ooecia with a pair of small avicularia. H. Arthropoma cecilii, detail of fertile and infertile zooids showing orifices, perforate frontal walls and smooth ooecia.