Stephanotheca ochracea ( Hincks, 1862 ) Hincks, 1862

Reverter-Gil, Oscar, Souto, Javier & Fernández-Pulpeiro, Eugenio, 2012, A new genus of Lanceoporidae (Bryozoa, Cheilostomata), Zootaxa 3339, pp. 1-29 : 17-19

Stephanotheca ochracea ( Hincks, 1862) n. comb.

( Figs 3 , 36–39 ; Table 5 )

Lepralia ochracea Hincks, 1862: 206 , pl. 12, fig. 3.

Schizoporella auriculata var. ochracea: Hincks 1880: 260 , pl. 29, fig. 7.

Schizomavella ochracea (Hincks) : Hayward & Thorpe 1995: 674 (in part: only holotype), pl. 5, figs a, b; Hayward & Ryland 1999: 288, fig. 132 A, C.

Schizomavella rudis ( Manzoni, 1869) : López de la Cuadra 1991: 232, pl. 27, figs F–H.

Material examined. NMHUK 1899.5.1.977: Schizomavella ochracea . Holotype. Cornwall.

Description. Colony encrusting, unilaminar, forming a broad spreading sheet. Autozooids in regular series, subrectangular to irregularly polygonal, separated by raised sutures. Frontal shield slightly convex, initially smooth, but soon covered by small rounded nodules; surface evenly perforated by about 45 small, circular pseudopores; marginal pores elongate and more conspicuous in older zooids; periorbital area imperforate and slightly raised. Primary orifice orbicular, slightly longer than wide; anter forming a wide arch projecting distally, with proximolateral edges oblique and rather straight; poster with a wide V-shaped sinus occupying most of the proximal edge; a pair of large, oval condyles with serrate median and proximal edges. Oral spines absent. Avicularia not developed in all autozooids, dimorphic; either small, subrectangular to lanceolate, with complete slender crossbar and oval palatal foramen; or gigantic, subrectangular, occupying almost all the length of the frontal shield, with complete crossbar and variably sized palatal foramen. Both types proximally directed. Ovicell observed once. Globular, prominent, closed by the autozoecial operculum. Exposed ectooecial area circular, with rounded pseudopores larger at the periphery, encircled by a nodular ridge of secondary calcification of the distal zooid. Opening of ovicell wider than long, inclined at an angle, formed by the concave proximal margin of the ooecium, overarching the primary orifice, and extending to its proximolateral corners. Ovicell cleithral. Ancestrula unknown.

Remarks. This species was considered as a variety of S. auriculata for a long time until Hayward & Thorpe (1995) redescribed the holotype and other material. However, their description needs to be amended; on the one hand, the material used by these authors presents four different morphologies, considered here to belong to four different species ( S. ochracea , S. barrosoi , and two new species); on the other hand, the ovicell was not described, which is, however, present in the uncoated portion of the holotype (see Reverter Gil & Fernández Pulpeiro 1995, and fig. 39 in the present paper). The ovicell has also been figured by López de la Cuadra (1991: pl. 27, fig. H, as S. rudis ) in this case seeming more immersed and exhibiting a nodular crown of secondary calcification that is well developed but interrupted proximally; however, its primary orifice and its avicularia are like the holotype, including the gigantic avicularia.

The shape of the ovicell, its closure, and the shape of the primary orifice and the condyles suggest that S. ochracea belongs to the genus Stephanotheca . Yet this species is the only one in the genus exhibiting dimorphic avicularia. The orifice in this species is different from that in S. watersi , being slightly longer than wide and also exhibiting a more triangular sinus and larger condyles; moreover, the frontal avicularium is larger, more frequent, and placed further away from the orifice. These features bring it closer to S. barrosoi , which differs from S. ochracea in the different shape of the orifice and the condyles, in exhibiting vicarious avicularia, and in lacking the frontal gigantic avicularium.

Stephanotheca ochracea is also the only species of the genus collected in the Atlantic Ocean, specifically southeast of the British Isles and in the Strait of Gibraltar. Its Mediterranean records probably correspond to other species of the genus (see remarks of S. barrosoi and below).

SD, Standard deviation; N, number of measurements.

Figures

FIGURES 1 – 8. Ovicell development in Stephanotheca. 1, communication pore between the ooecium-producing zooid and the coelomic cavity of the ooecium (arrow) (S. barrosoi n. sp.). 2, calcification of ectooecium and beginning of the calcification of entooecium (S. watersi n. sp.). 3, calcified ooecial floor (S. ochracea n. comb.). 4, developing ooecia (S. watersi n. sp.). 5, developing ooecium (S. monoecensis n. comb.). 6, central suture of the ectooecium (arrow) (S. barrosoi n. sp.). 7, complete ovicell, ooecial floor, and a partially broken ovicell showing ectooecial pseudopores (S. watersi n. sp.). 8, secondary calcification growing over the central porous area (S. monoecensis n. comb.).

FIGURES 36 – 39. Stephanotheca ochracea (Hincks, 1862) n. comb. (holotype: NMHUK 1899.5.1.977). 36, zooids with gigantic avicularia; 37, primary orifice and small suboral avicularium; 38, primary orifice; 39, ovicellate zooids.

Tables

TABLE 5. Measurements (in mm) of Stephanotheca ochracea (Hincks, 1862) n. comb. (holotype: NMHUK 1899.5.1.977).

	Mean	SD	Minimum	Maximum	N
Autozooid length	0.536	0.0506	0.470	0.632	13
Autozooid width	0.353	0.0558	0.277	0.481	13
Orifice length	0.124	0.0082	0.106	0.134	13
Orifice width	0.119	0.0085	0.105	0.137	13
Adventitious avicularium length	0.096	0.0103	0.079	0.111	9
Adventitious avicularium width	0.058	0.0061	0.047	0.065	9
Gigantic avicularium length	0.351	0.0403	0.288	0.396	5
Gigantic avicularium width	0.162	0.0132	0.144	0.177	5
Ovicell length	0.316	-	-	-	1
Ovicell width	0.334	-	-	-	1
Ovicell orifice length	0.128	-	-	-	1
Ovicell orifice width	0.148	-	-	-	1
Pseudorous area diameter	0.182	-	-	-	1