Trypostega ilhabelae, 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 : 124-125

Trypostega ilhabelae sp. nov.

( Fig. 16 ; Table 14 )

Material examined. Holotype: MZUSP 735 ( Fig. 16 A, B, D–F), Biota Stn 211. Paratypes: MZUSP 682, #12 [2 colonies], near BIOTA Stn 205, 15 m; MZUSP 681, specimen #11, near BIOTA Stn 205, 15 m; MZUSP 736 (figured in Winston & Migotto 2005), Biota Stn 211; MZUSP 737, measured specimen #1, BIOTA Stn 205; MZUSP 738, measured specimen #2, BIOTA Stn 205; VMNH 70023, measured specimen #3, BIOTA Stn 211. Additional material: MZUSP 683, #13a [1 colony], near BIOTA Stn 205, 15 m.

Etymology. Named for the large island of Ilhabela near which three of the BIOTA sand-fauna collections were obtained.

Diagnosis. Sand-grain encrusting, having both autozooids and female zooids with similar orifices, keyhole shaped, with sinus a rounded V-shape. Zooeciules found both on ovicells and between zooids.

Description. Colony encrusting on sand grains, particularly in hollows or crevices in shell grains. Zooids of three types, autozooids, female zooids with ovicells and zooeciules. Zooids oval, rhombic, or irregularly polygonal. Frontal walls smooth, evenly perforated by large round pores, except for central portion which, proximal to orifice is raised into a large imperforate tubercle. Autozooidal orifice keyhole shaped, with a round anter and a shallow rounded V-shaped sinus. Female zooids and ovicells with similar frontal wall structure. Orifice of ovicelled zooids similar to that of autozooids but slightly broader and with a wider sinus. Ooecia rounded, with a zooeciule embedded in distal center of each. Zooeciule orifice very small and hoof-shaped with a very shallow sinus. Additional zooeciules may occur between zooids.

Remarks. This species is very similar to the Trypostega species found in the Florida sand fauna. However, in that species, ovicelled zooids have a sinus that is a broad shallow U in contrast to the deeper narrower U shaped sinus of autozooids, whereas the orifice sinus in ovicelled zooids of Trypostega ilhabelae sp. nov. is a shallow Vshape. Zooeciules, except those upon ovicells, may be lacking.

Distribution. São Paulo state, Brazil.

Figures

FIGURE 16. Trypostega ilhabelae sp. nov.: A, colony encrusting shell fragment. B, edge of colony showing two female zooids and several zooeciules. C, female zooid showing ovicell and suboral tubercle in profile. D, autozooidal orifice. E, female zooidal orifice. F, orifice of zooeciule. Scale bars: A, 1 mm; B, 0.5 mm; C, 0.2 mm; D – F, 0.05 mm.

Tables

TABLE 14. Measurements (in mm) of Trypostega ilhabelae sp. nov..

	Lz	Wz	Lo	Wo	Lov	Wov	Lzl	Wzl
N	18	18	18	18	14	14	18	18
Mean	0.349	0.218	0.058	0.043	0.171	0.186	0.134	0.098
SD	0.033	0.020	0.009	0.007	0.031	0.028	0.027	0.018
Min	0.306	0.180	0.045	0.036	0.126	0.144	0.090	0.072
Max	0.414	0.252	0.072	0.054	0.234	0.234	0.180	0.126