Discoporella gemmulifera, 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 : 112-114

Discoporella gemmulifera sp. nov.

( Fig. 9 , Table 7 )

Discoporella umbellata: Marcus & Marcus 1962: 290 .

Material examined. Holotype: MZUSP 718 ( Fig. 9 A), BIOTA Stn 208. Paratypes: MZUSP 675, #5 [22 colonies], near BIOTA Stn 205, 15 m; MZUSP 719 ( Fig. 9 B, C), BIOTA Stn 208. MZUSP 720, measured specimen #2, BIOTA Stn 209; MZUSP 721, measured specimen #3, BIOTA Stn 206iB (from macrofauna sample), 23°34’936” S, 45°16’54” W, Ubatuba, São Paulo, Brazil; VMNH 70010, measured specimen #1, BIOTA Stn 208; VMNH 70011, BIOTA Stn 208; VMNH 70012, colony fragments, BIOTA Stn 208; VMNH 70013, juvenile colony, BIOTA Stn 205; VMNH 70014, juvenile colony, BIOTA Stn 211. Additional material: MZUSP 700, #31 [5 colonies], Itassucê, São Sebastião, São Paulo, Brazil, 7 m; MZUSP 705, BIOTA Stn 211.

Supplementary video. http://cifonauta.cebimar.usp.br/taxon/discoporella-gemmulifera/

Etymology. From the diminitive, gemmula, of the Latin, gemma, bud and – fer, Latin suffix, meaning bear or carry, carrying little buds.

Diagnosis. Discoporella with relatively flat bowl shape, red to brownish pink in life; granular cryptocyst with distal semicircular opesia and 6–9 small opesiules; polypides with 13 tentacles.

Description. Free-living colonies a few mm in size and, if intact, bowl-shaped, with outer surface convex, undersurface concave, red to brownish pink in life. Colonies undergoing fragmentation may have more irregular or angular shapes, with several subcolonies forming at colony edges. Zooids rhomboidal, about 0.42 mm in length and 0.30 mm in width, arranged in a regular pattern. The frontal surface is a granular cryptocyst with a distal semicircular opesia, about 0.11 mm by 0.12 mm, a little larger than the operculum, and a proximal area containing 6 or more small opesiules. At the distal end of each zooid is a vibraculum with a chamber about 0.12 mm long and 0.10 mm wide. It has a long curved mandible about 0.62 mm in length and 0.03 mm wide at the base, but tapering to a sharp point). These serve to move the colony through the sediment, and to clean its surface. Polypides with about 13 tentacles. Brooding internal in autozooids; no ovicells occur. Non-feeding larvae settle in a short time on a grain of sand, produce an ancestral triad and continue to bud new zooids until the grain is enveloped.

Remarks. The Brazilian specimens are distinguished from Eastern Atlantic Discoporella umbellata (DeFrance, 1823) in the number of cryptocystal opesiules (8–14 in D. umbellata vs 6–9 in D. gemmulifera sp. nov.) and number of polypide tentacles (14–16 in D. umbellata (Cook 1985) vs 13 in D. gemmulifera ). Discoporella gemmulifera also differs from the Caribbean Discoporella studied by Herrera-Cubilla et al. (2008). Two of them, D. scutella Herrera-Cubilla, Dick, Sanner & Jackson, 2008 and D. peltifera Herrera-Cubilla, Dick, Sanner & Jackson, 2008 , have larger zooids and determinate growth, although D. peltifera can regenerate from fragments. Discoporella triangula Herrera-Cubilla, Dick, Sanner & Jackson, 2008 has very small conical colonies with determinate growth, and Discoporella terminata Herrera-Cubilla, Dick, Sanner & Jackson, 2008 has a flat discoidal colony with determinate growth. The most similar species in terms of zooid size and growth pattern is Discoporella bocasdeltoroensis Herrera-Cubilla, Dick, Sanner & Jackson, 2008 . It has a wider range in number of opesiules (3–10), very spiny opesiule edges, larger avicularian zooids, a conical colony shape and, like the others, showed no evidence of the colonial budding seen in D. gemmulifera .

The biology of the Brazilian species was studied by Marcus & Marcus (1962). Discoporella gemmulifera has an amazing ability to reproduce asexually by fragmentation, with subcolonies developing at the edges of parent colony then splitting off from it. Discoporella colonies, like those of other free-living species, are so well integrated that their behavior is that of a cormidium and like a unitary organism. Vibracula move in coordination to row the colony from place to place or unbury it from sediment. The species’ distribution and ecology in Brazil has also been studied by Braga (1967) and Tommasi et al. (1972). Discoporella gemmulifera prefers very fine sand with relatively stable conditions and full marine salinity. It is found in s and-bottom habitats on the continental shelf from a few meters to about 150 m depth.

Distribution. The Brazilian species, previously reported from Amazonas River mouth, Bahia, Rio de Janeiro, São Paulo and Paraná, is part of the Discoporella umbellata species complex, with members known from both sides of the Atlantic, the Mediterranean and the eastern Pacific.

Figures

FIGURE 9. Discoporella gemmulifera sp. nov.: A, upper surface of a large colony. B, lower surface of a smaller colony with buds developing at corners. C, detached bud, a new asexually produced colony. D, E, zooids and vibracular chambers. F, closeup of a vibraculum and zooid. Scale bars: A, B, 1 mm; C, 0.4 mm; D, E, 0.2 mm; F, 0.1 mm.

Tables

TABLE 7. Measurements (in mm) of Discoporella gemmulifera sp. nov..

	Lz	Wz	Lop	Wop	Lav	Wav
N	18	18	18	18	18	18
Mean	0.426	0.314	0.112	0.123	0.136	0.114
SD	0.034	0.040	0.008	0.013	0.020	0.018
Min	0.378	0.252	0.099	0.108	0.108	0.090
Max	0.504	0.396	0.126	0.144	0.180	0.144