Rosulapelta rosetta, Winston, Judith E. & Vieira, Leandro M., 2013

Winston, Judith E. & Vieira, Leandro M., 2013, Systematics of interstitial encrusting bryozoans from southeastern Brazil, Zootaxa 3710 (2), pp. 101-146 : 121

Rosulapelta rosetta sp. nov.

( Figs 14 , 25 D–F; Table 12 ) Material examined. Holotype: MZUSP 676, specimen #6, near BIOTA Stn 205, 15 m. Paratypes: MZUSP 677, #7 [5 colonies], near BIOTA Stn 205, 15 m; MZUSP 729 (figured), BIOTA Stn 211; MZUSP 730 (figured), specimen #2, BIOTA Stn 211; MZUSP 731 (figured), specimen #3, BIOTA Stn 205; MZUSP 372, specimen #1, BIOTA Stn 205; VMNH 70020, measured specimen #3, BIOTA Stn 211; VMNH 70021, BIOTA Stn 205. Additional material: MZUSP 678, #8 [several colonies], near BIOTA Stn 205, 15 m; MZUSP 733, BIOTA, between São Sebastião and Ubatuba, São Paulo, Brazil.

Supplementary video. http://cifonauta.cebimar.usp.br/taxon/rosulapelta-rosetta/

Etymology. From Latin rosa, via French/English rosette, a small circular flower-like decoration.

Diagnosis. Zooids with 6 oral spines, 2 slender and 4 thick and curved, a raised costal shield reduced to a rosette, a small porous area surrounded by a circular rim and costae only faintly visible or lost with increasing secondary calcification.

Description. Colonies encrusting sand grains. Zooids oval, lateral walls very high, gymnocyst expanded to cover most of zooid surface; slitlike marginal pores may be visible at margin of lateral and frontal wall calcification. A central circular to oval ring of calcification surrounds the very reduced and fused costal area. In newly developed zooids the raised central area can be seen to be composed of a fused first pair of costae and several irregularly spaced costae and pores below that area. As zooids age this area becomes more calcified and the central area fills in to become a “rosette”. Zooidal orifice hoof-shaped, surrounded by 2 delicate distal and 4 thick lateral outward curving hollow spines, broken off in most specimens. Proximal edge of orifice marked by fused vertical plates or spines, thickly calcified and distinctly raised. No avicularia. Ovicells hyperstomial, smooth. Ancestrula with a larger, more proximally convex orifice, faint impression of first pair of costae and 6 orificial spines similar to those of autozooids. Polypides with 9 translucent white tentacles ( Fig. 25 D–F).

Remarks. This species most closely resembles interstitial Reginella repangulata Winston & Håkansson, 1986 from Atlantic Florida, but has more orificial spines, six vs two, and an even more raised and reduced costal shield in which costae are distorted and fused together. Arnold and Cook (1997) noted differences between frontal-shield morphology in R. repangulata and Reginella furcata (Hincks, 1882) , the type species of Reginella . They also suggested that a new genus should be introduced to accommodate the Atlantic material. Despite similarities between the Floridan and Brazilian specimens, Rosulapelta rosetta sp. nov. is readily distinguished from Rosulapelta repangulata comb. nov. by its much-reduced costal shield and the presence of smooth ovicells.

Distribution. São Paulo state, Brazil.

Figures

FIGURE 14. Rosulapelta rosetta sp. nov.: A, colony on a shell grain. B, another colony, live when collected, with four long oral spines, and two small slender spines distal to them. C, outer zooid, showing frontal wall “ rosette ” and orifice shape. D, orifice region. E, close-up of ovicell. F, close-up of frontal shield. Scale bars: A, 0.5 mm; B, 0.2 mm; C – E, 0.1 mm; F, 0.07 mm.

FIGURE 25. A, sample of sand from Stn 205; the small units on the ruler are millimeters. B, live colony of Disporella calcitrapa sp. nov. encrusting the edge of a quartz grain; tentacles are visible. C, live colony of Reptadeonella granulosa sp. nov. D – F, three frames from a digital video of Rosulapelta rosetta sp. nov., showing a lophophore tentacle curving in towards the mouth during feeding. Scale bars: B, 0.2 mm; C, 1 mm; D – F, 0.1 mm.

Tables

TABLE 12. Measurements (in mm) of Rosulapelta rosetta sp. nov..

	Lz	Wz	Lo	Wo	Lov	Wov
N	15	15	15	15	1	1
Mean	0.275	0.203	0.078	0.059	0.108	0.144
SD	0.030	0.037	0.011	0.007	n/a	n/a
Min	0.216	0.126	0.054	0.054	0.108	0.144
Max	0.306	0.270	0.090	0.072	0.108	0.144