Utinga castanea ( Busk, 1884 )

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 : 169-170

Utinga castanea ( Busk, 1884)

( Figs 5G , 7F )

Mucronella castanea Busk, 1884: 157 , pl. XIX, fig. 6. Utinga castanea: Marcus, 1949: 21 , figs 26–29; Vieira et al., 2008: 30; Almeida et al., 2015a: 5; Bastos et al., 2018: table 1.

Material examined. Abrolhos Bank, Bahia State, Brazil: MNRJ-Bry1339, Parcel dos Abrolhos , 15 m depth, February 2014, col. R. Moura, G. Amado-Filho & A . Bastos ; MNRJ-Bry1346, California Reef, 25 m depth, March 2015, col. F.C. Moraes, R. Moura, G. Amado-Filho & A . Bastos ; MNRJ-Bry1363, California Reef, 25 m depth, March 2015, col. F.C. Moraes, R. Moura, G. Amado-Filho & A . Bastos ; MNRJ-Bry1370, California Reef, 25 m depth, March 2015, col. F.C. Moraes, R. Moura, G. Amado-Filho & A. Bastos.

Description. Flat colonies, forming unilamellar plates. Dark brown colour preserved after collection and storage ( Fig. 7F ). Autozooids large, longer than wide (830–957–1180 µm long x 428–540–654 µm wide), polygonal with distal corner usually rounded. Frontal wall porous, coarsely tuberculate. Orifice coarctate, large (250–288–342 µm long x 224–255–281 µm wide), with two triangular hinge-teeth and prominent condyles situated below the midline, proximal rim with a rounded and large crescent lyrula ( Fig. 5G ). Two types of avicularia present, disposed laterally to the orifice, suboral or on the frontal shield: (1) large, triangular and sword-like avicularia (314–378–419 µm long) with rostrum slightly curved to one side, located on one or both sides of the orifice, rarely on the frontal surface (one, two, or rarely, three avicularia per autozooid), directed distally or sometimes slightly curved to orifice; crossbar complete; (2) small, rounded avicularia (97–119–134 µm long), directed distally and located more proximally of the orifice; rostrum rounded and crossbar complete; frequently two small avicularia (96–102–108 µm long) present at the frontal corners; similar to the small lateral avicularia, rostrum rounded and directed to proximal region, crossbar complete ( Fig. 5G ). Ovicell globose, longer than wide (430–460–495 µm long x 388–415–430 µm wide), extending onto the distal zooid; ooecial surface perforated by tiny pores disposed in deep depressions, absent proximally; aperture opening inside the maternal orifice.

Geographic distribution. Alagoas, Bahia, and Espírito Santo states ( Busk 1884; Marcus 1949; Vieira et al. 2008; Almeida et al. 2015a; Bastos et al. 2018; present study).

Remarks. This species has been recorded previously in northeastern and southeastern Brazil ( Busk 1884; Marcus 1949; Almeida et al. 2015a). Marcus (1949) described Utinga castanea from Alagoas State but did not mention the presence of the two different types of avicularia (large and acute, and small and rounded). However, Busk (1884) showed them in his plates of material collected from Bahia State, leaving no doubt about the presence of both kinds of avicularia. The material of Marcus (1949) has the following dimensions: zooid 1–1.2 mm long x 500–700 µm wide; orifice up to 280 µm long x 220 µm wide; large avicularia 370 µm long. Some colonies from Abrolhos show avicularia in different positions (suboral, on the frontal shield) and greater in number (up to four per zooid). Utinga is represented by a single living species, plus two species described from the middle Miocene of Egypt: U. habisensis Abbas & El-Senoussi, 1979 and U. rakhamensis Abbas & El-Senoussi, 1979 .

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.

FIGURE 7. In situ underwater photographs of six bryozoan species recorded from Abrolhos Bank, Brazil. A, B. Steginoporella magnilabris. C. Reptadeonella bipartita. D. Celleporaria atlantica. E. Stylopoma variabilis n. sp. F. Utinga castanea. G. Arthropoma cecilii. Photos by Áthila Bertoncini/Rede Abrolhos.