Hemismittoidea asymmetrica, 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 : 166-167

Hemismittoidea asymmetrica n. sp.

( Fig. 4E, F )

Hemismittoidea sp. nov.: Bastos et al., 2018: table 1.

Material examined. Abrolhos Bank, Bahia State, Brazil: Holotype: MNRJ-Bry1342, Parcel dos Abrolhos, 4 m depth, February 2014, col. R. Moura, G. Amado-Filho & A . Bastos ; Paratype: MNRJ-Bry1379, Parcel dos Abrolhos, 15 m depth, February 2014, col. R. Moura, G. Amado-Filho & A . Bastos ; MNRJ-Bry1389, California Reef, 25 m depth, March 2015, col. F.C. Moraes, R. Moura, G. Amado-Filho & A. Bastos.

Etymology. From the Latin ' asymmetricus, -a, -um', meaning 'unequal, asymmetrical', referring to the asymmetrical shape of the sinus formed by the development of the peristome.

Diagnosis. Multilamellar colony. Autozooid rectangular to irregularly polygonal, with an almost circular orifice having six or seven distal spines; peristome well developed proximally, forming a larger protuberance on one of the sides; sinus U-shaped, asymmetrical, with a pair of prominent and fringed condyles, and a large, broad anvil-shaped lyrula; a single, large, triangular avicularium located adjacent to the peristomial sinus, directed proximo-laterally; ovicell almost immersed, with few small circular pores on the ooecial surface and a single row of larger areolar pores.

Description. Encrusting colonies, forming more than one layer, frequently overgrown by other bryozoan species (e.g. Stylopoma variabilis n. sp. and Parasmittina distincta n. sp.). Autozooids rectangular to irregularly polygonal, distally rounded, longer than wide (344–390–436 µm long x 290–336–376 µm wide) with coarsely tuberculate frontal wall, imperforate except for a few scattered circular areolar pores (13–16) ( Fig. 4E ). Orifice almost circular, slightly longer than wide (81–108–118 µm long x 87 –96–103 µm wide), with six (sometimes seven) distal spines; peristome low distally and laterally but well developed proximally forming a protuberance, more developed on one of the sides; wide U-shaped sinus, asymmetrical due to the peristomial protuberance; a pair of prominent and fringed condyles; a large and broad anvil-shaped lyrula, usually partially hidden by the protuberance formed by the peristome on one side ( Fig. 4E, F ).

Single, large, triangular avicularium (84–109–141 µm long) proximo-laterally directed and located adjacent to the peristomial sinus; rostrum triangular, ending on a sharp tip, palate with a large pore; crossbar complete and ligula present ( Fig. 4E ). Ovicell almost immersed, wider than long (191–204–213 µm long x 218–242–260 µm wide), large, extending onto the distal zooid for half the length of the frontal shield or almost reaching the orifice; ooecial surface perforated by a few small, circular pores and a single row of larger areolar pores which become obscured by calcification ( Fig. 4F ).

Geographic distribution. Abrolhos Bank, Bahia State, Brazil ( Bastos et al. 2018; present study).

Remarks. Eight species of Hemismittoidea are known worldwide. Most are extant (except H. waiorensis Guha & Gopikrishna, 2007 from the Miocene of India) and described from the Pacific Ocean (bryozoa.net; accessed 0 1.0 3.2018). None were previously known from Brazil. The most similar species are H. corallinea Soule & Soule, 1973 , described from Hawaii, and H. hexaspinosa ( Uttley & Bullivant, 1972) , from New Zealand, which shows 6– 7 oral spines and a triangular avicularium. Hemismittoidea corallinea has avicularia that are slightly more elongate (120–122–130 µm long), located medially or almost medially and directed proximally, and an orifice with strong condyles hooked proximally and smooth.

Hemismittoidea hexaspinosa can be distinguished from H. asymmetrica n. sp. by the narrower, rounded and central sinus, distally constricted, and the more elongated, narrow avicularia with finely serrated rostra.

Figures

FIGURE 4. Scanning electron micrographs of three bryozoan species. A–D. Parasmittina abrolhosensis n. sp. A. Detail of some autozooids showing the orifice, lyrula, condyles and three or four oral spine bases, and a lateral elongate avicularium. B. Detail of an elongate lateral avicularium with serrated rostrum. C. Detail of an autozooid showing the orifice with anvil, tall lyrula and a pair of condyles, and a large and spatulate avicularium. D. Detail of a fragment showing some fertile autozooids. E, F. Hemismittoidea asymmetrica n. sp. E. Detail of some autozooids showing the orifice with six and seven distal spines, large anvil-shaped lyrula, large and triangular avicularia, and a perforated ooecium. F. Detail of a fertile zooid showing a perforated ooecium and orifice with a pair of spines others, hidden by the ooecium. G, H: Stylopoma variabilis n. sp. G. Detail of a fragment showing autozooids and two elongate, spatulate interzooidal avicularia. H. Detail of the distal region of an autozooid showing the orifice with U-shaped sinus, condyles and small triangular lateral avicularium.