Ammatophora arenacea, 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 : 107-108

Ammatophora arenacea sp. nov.

( Fig. 5 ; Table 3 )

Material examined. Holotype: MZUSP 713 ( Fig. 5 A–C,), measured specimen #1, BIOTA Stn 205. Paratypes: MZUSP 685, specimen #14, near BIOTA Stn 205, 15 m; MZUSP 686, #15 [4 colonies], near BIOTA Stn 205, 15 m; MZUSP 715 ( Fig. 5 D), BIOTA Stn 205; MZUSP 716, measured specimen #2, BIOTA Stn 211; VMNH 70007, measured specimen #3, BIOTA Stn 205; VMNH 70008, BIOTA Stn 211. Additional material: MZUSP 708, BIOTA Stn 205.

Supplementary video. http://cifonauta.cebimar.usp.br/taxon/ammatophora-arenacea/

Etymology. From Latin arenaceus, of sand, for its habit of encrusting small substrata in sand-bottom areas.

Diagnosis. Characterized by small zooid size, large tubercles at proximal edges of zooids, broad ooecia, and closely connected zooids with tubules between them.

Description. Colony encrusting, unilaminar. Zooids oval in outline, closely connected by tubules, which are sometimes hidden by gymnocystal development. Inside lateral rim of zooids is a beaded cryptocyst. Cryptocyst extending over proximal half of zooid and around the lateral edges of the triangular to bell-shaped opesia which occupies most of the distal half of the zooid. Irregularly shaped calcified tubercles develop at the proximal ends of zooids. Ooecia imperforate, with a convex proximal rim, endooecium not exposed; short in length, but equal to or greater than zooids in width. Polypides with 11 tentacles. Ancestrula similar to later zooids, the proximal margin crenulated.

Remarks. Ammatophora arenacea sp. nov. was found encrusting shell grains and larger pieces of broken mollusk shells in interstitial habitats. The encrusting unilaminar colonies of small zooids with a depressed cryptocyst and large nodular kenozooids, as well as the flattened imperforate ooecium seem to place this species in the genus Ammatophora , along with Ammatophora nodulosa , an Eastern Atlantic species which, according to Hayward & Ryland (1998, p. 200), occupies a similar habitat on offshore shell gravels “where it forms part of a characteristic community of cheilostomate bryozoans adapted for living on the smallest shell substrata.”

The short, often hidden tubules connecting the zooids might indicate a relationship with Mollia . However, unlike Mollia species, the zooids are not attached to the substratum by rhizoids, but are directly attached by the basal wall (although holes, like those for rhizoids are present in the basal wall and can be seen in the broken zooids in Fig. 5 B).

Only one morphologically similar species has been recorded from Brazil (Vieira et al. 2008). Mollia elongata was described by Canu & Bassler (1928b) from deeper-water stations. It has much larger zooids and more voluminous ooecia immersed in the zooid (see Marcus 1949, fig. 18), distinct from other Mollia species. Souto et al. (2010) also noted confusion between some characters of specimens assigned to Mollia and to other Calloporidae , suggesting the need for reexamination of Mollia elongata , which may be more closely related to Ammatophora arenacea .

Distribution. São Paulo state, Brazil.

Figures

FIGURE 5. Ammatophora arenacea sp. nov.: A, part of a colony showing ovicelled zooids and tubercles. B, group of three ovicelled zooids, two of the ovicells with small holes, probably bored by a predator. C, close-up of a single ovicelled zooid and tubercles. D, close up of ancestrula showing the crenulated proximal margin. Scale bars: A, 0.5 mm; B, 0.2 mm; C, D, 0.1 mm.

Tables

TABLE 3. Measurements (in mm) of Ammatophora arenacea sp. nov..

	Lz	Wz	Lop	Wop	Lov	Wov
N	18	18	18	18	8	8
Mean	0.469	0.262	0.223	0.140	0.146	0.263
SD	0.056	0.025	0.292	0.018	0.018	0.033
Min	0.360	0.198	0.108	0.108	0.126	0.216
Max	0.576	0.306	1.386	0.162	0.180	0.306