Hippothoa calcicola, 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 : 123-124

Hippothoa calcicola sp. nov.

( Fig. 15 ; Table 13 )

Hippothoa distans: Marcus 1941: 60 , fig. 9.

z1, length of dilated portion of autozooid; o 2, orifice of autozooid.

Material examined. Holotype: MZUSP 701, BIOTA Stn 212iA, Ilhabela, São Paulo, Brazil, 17 December 2001, on shell. Paratypes: MZUSP 702, BIOTA Stn 212iA, Ilhabela, São Paulo, Brazil, 17 December 2001, on shell; MZUSP 734, Biota Stn 211; VMNH 70022, BIOTA Stn 209.

Etymology. From Latin calx, calcis, lime, because of its preference for grains of calcium carbonate, such as fragments of mollusk shell.

Diagnosis. Calcareous sand-grain encruster. It can be distinguished from the other known sand-dwelling species, Hippothoa balanophila Winston & Håkansson, 1986 , by its smaller, keeled zooids and by the shape and position of female zooids, as well as their ovicell and orifice shape.

Description. Colony uniserial, encrusting shell grains. Zooids elongate-oval, frontal shield imperforate, with a rugged keel of calcification marking the midpoint of each zooid. Each is connected to the next by a relatively short cauda, the stolonlike proximal extension of the zooid. Two kinds of zooids, autozooids and female zooids occur. Autozooids have a keyhole-shaped orifice, with transversely oval anter, short rounded condyles, and a narrower Ushaped sinus. Female zooids branch from the center of lateral wall of an autozooid and are oriented in the opposite direction to it. They are shorter than autozooids, but show the same ridged midline keel extending up to the edge of the orifice, which has an elongate transverse-D shape, with similar rounded condyles and a very slightly sinuate poster. Ooecia are transversely oval in shape with a few vertical striations and a central less-calcified spot.

Remarks. Marcus (1941) used the name Hippothoa distans MacGillivray, 1869 for the São Paulo specimens. Hippothoa distans was described from Australia and is distinguished from Brazilian colonies, here described as Hippothoa calcicola sp. nov., in possessing female zooids with a broad U-shaped sinus and denticles (Morris 1980). Hippothoa calcicola resembles Hippothoa balanophila from the Florida bryozoan sand fauna, and like it, is highly cryptic in habit, occurring in crevices and sheltered next to calcified polychaete tubes. Hippothoa calcicola differs in its zooid size, being larger than that of H. balanophila , and by its more flattened orifice. Hippothoa flagellum (Manzoni, 1870) has a similar female zooid, but the autozooidal orifice is deeper and narrower than that of Hippothoa calcicola (see Hayward & McKinney 2002).

Distribution. São Paulo state, Brazil.

Figures

FIGURE 15. Hippothoa calcicola sp. nov.: A, colony curving around a serpulid tube. B, area with two female zooids and an autozooid. C, close-up of autozooidal orifice. D, close-up of female zooidal orifice. Scale bars: A, 0.3 mm; B, 0.1 mm; C, 0.02 mm; D, 0.01 mm.

Tables

TABLE 13. Measurements (in mm) of Hippothoa calcicola sp. nov..

	Lz 1	Wz 1	Lo 2	Wo 2	Lov	Wov
N	10	10	10	10	6	6
Mean	0.294	0.163	0.062	0.051	0.134	0.143
SD	0.011	0.021	0.004	0.004	0.012	0.008
Min	0.279	0.121	0.051	0.047	0.116	0.130
Max	0.316	0.195	0.070	0.056	0.149	0.153