Hippopleurifera confusa, Ramalho, Laís V., Távora, Vladimir A., Tilbrook, Kevin J. & Zágoršek, Kamil, 2015

Ramalho, Laís V., Távora, Vladimir A., Tilbrook, Kevin J. & Zágoršek, Kamil, 2015, New species of Hippopleurifera (Bryozoa, Cheilostomata) from the Miocene Pirabas Formation, Pará state, Brazil, Zootaxa 3999 (1), pp. 125-134 : 130

Hippopleurifera confusa sp. nov.

( Figs 3 A–F)

Material examined. Holotype: MG–6302–I–c, Atalaia Beach, Salinópolis, Pará state, Brazil. Paratypes: MG– 6302–I–a, b, d, from same locality as holotype.

Diagnosis. Colony encrusting, unilaminar. Autozooids short, frontal shield with 1–3 rows of areolar pores and smooth central region proximal to orifice. Orifice with 6–8 small spine bases and variably developed small median lyrulate process. Suboral avicularium and 1–2 asymmetrical lateral avicularia present.

Description. Colony encrusting, unilaminar. Autozooids short, hexagonal, slightly longer than wide (460–704 [568] µm x 427–691 [522] µm). Frontal shield with 1–3 rows of areolar pores and an imperforate area proximal to the orifice frontally. Interior of frontal shield with 3 rows of areolar pores and an imperforate umbonuloid area proximal to orifice.

Orifice longer than wide (147–220 [193] µm x 163–205 [185] µm); anter rounded, bordered by 6–8 small spine bases, the most proximal of which are located near the short condylar projections; poster concave with a small, median lyrulate projection.

A single suboral avicularium on a raised cystid; rostrum subtriangular, directed frontally, usually poorly preserved or broken with cystid apparent only as a large hole; distal end of avicularium terminating at proximal border of orifice. Single, or paired asymmetrical lateral avicularia present; rostrum elongate (143–317 µm long), directed frontally or angled toward adjacent frontal wall; well-preserved rostral tips flared, extending beyond interzooidal boundary ( Fig. 3 D–E).

Ooecium not observed.

Etymology. The specific epithet alludes to the confusion caused by the similarity of this species to H. barbosae sp. nov.

Remarks. Despite the lack of ooecia in the colony fragments examined, we believe Hippopleurifera confusa sp. nov. belongs to this genus because of the presence of the reduced umbonuloid area in the frontal shield, the lateral suboral avicularia and the presence of a suboral umbo or avicularium. Hippopleurifera confusa is very similar to H. barbosae sp. nov. (see above) in having a median suboral avicularium and similarly shaped lateral avicularia. It may be discriminated from H. barbosae by its shorter zooids with a shorter orifice, greater spine number (six to eight), more-proximally positioned lateral avicularia and fewer rows of areolar pores. Hippopleurifera semicristata ( Reuss, 1847) also resembles this species, but it too has fewer rows of areolar pores (two, rarely three), there is no suboral umbo or avicularia, the frontally smooth suboral area is larger and the lateral avicularia are also larger. Hippopleurifera confusa sp. nov. is known only from the Pirabas Formation.

Figures

FIGURE 3. Hippopleurifera confusa sp. nov. Specimens: A, C, E, specimen MG – 6302 – I – a; B, D, F, specimen MG – 6302 – I – c. A, B, general view of colony fragments showing autozooids, frontal shields with areolar pores, lateral avicularia and orifices with suboral avicularia. C, detail of an orifice with oral-spine bases, lateral condyles and a simple lateral avicularium. D, another orifice, with distal spine bases, broken cystid of a suboral avicularium and a pair of asymmetrical lateral avicularia. E, orifice with a small lyrulate process, lateral condyles and a long, spatulate, lateral avicularium with a flared rostral tip. F, frontal-shield interiors showing openings of areolar pores and reduced umbonuloid areas. Scale bars: A, B, 500 µm; C, E, 150 µm; D, 100 µm; F, 250 µm.