Akatopora leucocypha (Marcus, 1937)

Winston, Judith E. & Vieira, Leandro M., 2013, Systematics of interstitial encrusting bryozoans from southeastern Brazil, Zootaxa 3710 (2), pp. 101-146 : 110-111

Akatopora leucocypha (Marcus, 1937)

( Figure 7 , Table 5 )

Crassimarginatella leucocypha Marcus, 1937: 46 , pl. 8, fig. 20A, pl. 9, figs 20B–C; 1938: 20, pl. 3II, figs 8A–B. Conopeum reticulum (part): Osburn 1940: 351.

Antropora leucocypha: Shier 1964: 613 ; Winston 1982: 123, fig. 36; Winston & Håkansson 1986: 9, figs 14–16.

Material examined. MZUSP 0 25, Crassimarginatella leucocypha, E. Marcus coll., 14 January 1938, Sangava, São Paulo, Brazil, 20 m. MZUSP 674, #4 [2 colonies], near BIOTA Stn 205, 15 m; MZUSP 698, #29 [several colonies], Itassucê, São Sebastião, São Paulo, Brazil, 7 m; MZUSP 712 ( Fig. 7 ), measured specimen #3, BIOTA Stn 208; VMNH 70005, measured specimen #1, BIOTA Stn 211; VMNH 70006, BIOTA Stn 208.

Description. Colonies encrusting shells of living and dead gastropods. Interstitial specimens encrusting shells of very small gastropods or shell grains. Zooids oval to irregular in outline, depending on shape of underlying substratum. Lateral walls composed of thickened gymnocyst with scattered tubercles. Frontal membrane underlain by cryptocystal rim with rows of granules, rim narrowed distally but orifice outline not skeletally marked. Basal walls well calcified, fortified internally with thick vertical ridges. Triangular or rounded kenozooids with a similar cryptocyst occurring between autozooids, occasionally replaced by small avicularia with semicircular mandibles (e.g. Fig. 7 C). Ooecia indicated by a narrow thickened distal crescent of calcification.

Remarks. Marcus (1937) described Akatopora leucocypha (as Crassimarginatella ) from Santos, São Paulo state, Brazil, and noted similarities between his specimens and Antropora tincta (Hastings, 1930) . Tilbrook (1998) suggested that A. leucocypha may be a junior synonym of Antropora tincta or Antropora minor (Hincks, 1880) . Gordon (1986) had previously suggested that both A. leucocypha and A. tincta should be included in Akatopora ; both resemble the type species, Akatopora clausentina Davis, 1934 , in having a much-reduced cryptocyst (hence a relatively large opesia) and small kenozooids in the angles between autozooids. The latter species is characterized by a pinkish color, rather than grayish to white as in A. leucocypha . Akatopora leucocypha is also distinguished by the lack of avicularian condyles and in having a semicircular mandible (as shown in Marcus 1937, pl. 8, fig. 20A). Antropora minor , also reported from Brazil (Vieira et al. 2008) is distinguished by a wider proximal cryptocyst and the presence of large vicarious avicularia (Tilbrook 1998). Although it has a somewhat reduced cryptocyst, it has many small avicularia at the interzooidal angles and probably should be retained in Antropora .

Although A. leucocypha colonies are more abundant on larger substrata, we include the species here because it is common on sand- to gravel-size shells (e.g. those of very small gastropods) and shell fragments. As in Alderina smitti , the Brazilian specimens are larger in size than Floridan specimens (Winston & Håkansson 1986). Opesia measurements are comparable, indicating a more extensive cryptocyst in Brazilian zooids.

Distribution. Cape Hatteras to Brazil, Caribbean and Gulf of Mexico.

Figures

FIGURE 7. Akatopora leucocypha (Marcus, 1937): A, portion of colony showing a number of zooids with interspersed kenozooids and thick and pillared calcification of side and basal walls. B, more highly magnified view of several zooids; the central zooid had been damaged and a smaller replacement zooid has grown inside the skeleton of the earlier zooid. C, close-up of a zooid surrounded by triangular kenozooids and an avicularium. Scale bars: A, 0.3 mm; B, C, 0.1 mm.

Tables

TABLE 5. Measurements (in mm) of Akatopora leucocypha (Marcus, 1937).

	Lz	Wz	Lop	Wop	Lov	Wov	Lkz	Wkz
N	18	18	18	18	1	1	18	18
Mean	0.350	0.224	0.211	0.140	0.054	0.108	0.117	0.100
SD	0.022	0.023	0.033	0.025	n/a	n/a	0.027	0.022
Min	0.306	0.180	0.144	0.090	0.054	0.108	0.072	0.054
Max	0.396	0.270	0.270	0.198	0.054	0.108	0.162	0.144