Stephanotheca triangulata , Reverter-Gil, Oscar, Souto, Javier & Fernández-Pulpeiro, Eugenio, 2012

Reverter-Gil, Oscar, Souto, Javier & Fernández-Pulpeiro, Eugenio, 2012, A new genus of Lanceoporidae (Bryozoa, Cheilostomata), Zootaxa 3339, pp. 1-29: 22-23

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Stephanotheca triangulata

n. sp.

Stephanotheca triangulata  n. sp.

( Figs 50–56View FIGURES 50 – 56; Table 7)

Schizomavella ochracea (Hincks)  : Hayward & Thorpe 1995: 674 (in part), pl. 5, fig. c.

Material examined. Holotype: NHMUKAbout NHMUK 1899.7.1.2342: Mediterranean, Coll. McAndrew. Paratypes: NHMUKAbout NHMUK 1899.7.1.2346: Mediterranean, Coll. McAndrew; NHMUKAbout NHMUK 1939.7.4.12: Malta.

Etymology. The name of the species refers to the roughly triangular shape of both the orifice and avicularium.

Description. Colony encrusting, multilaminar, forming broad sheets. Autozooids in irregular series, subrectangular to irregularly polygonal, separated by raised sutures. Frontal shield slightly convex; covered by small rounded nodules; surface evenly perforated by small circular pseudopores; periorbital and suboral areas imperforate, slightly raised; marginal pores elongate and more conspicuous in older zooids. Primary orifice subtriangular; anter projecting distally; poster with a narrow V-shaped sinus, occupying most of the proximal edge; condyles large, almost entirely denticulate. Oral spines absent. Avicularia in almost every zooid, triangular, placed medially in the proximal part of the zooid, proximally directed. Ovicell endozooidal with brooding cavity deeply immersed in the succeeding zooid; a flat crescentic pseudoporous area, sometimes even centrally covered by a net of secondary calcification; central area surrounded by a low nodular crown of secondary calcification. Orifice in ovicellate zooids dimorphic, larger and with shallower sinus. Ovicell opening closed by the zoecial operculum. Ancestrula unknown.

SD, Standard deviation; N, number of measurements.

Remarks. The material here ascribed to S. triangulata  n. sp. has been previously cited by Hayward & Thorpe (1995) as Schizomavella ochracea  . In fact, although its primary orifice is very similar it is significantly larger and tends to show a general shape that is rather triangular owing to its narrower proximal edge and V-shaped sinus. It also differs in shape, size and position of the avicularium, without intermediate forms between both species. Stephanotheca triangulata  n. sp. also lacks gigantic avicularia such as occur in S. ochracea  . Moreover, the autozooids of S. triangulata  n. sp. show a suboral imperforate area that is not present in the zooids of S. ochracea  lacking a suboral avicularium. The ovicell is particularly characteristic of this species, being endozooidal with a flat ectooecium clearly wider than long; its crescent pseudoporous area is similar to that in some specimens of S. monoecensis  . However, in the latter species the nodular crown is more prominent, is lacking proximally, and its pseudoporous area is wider and round.

This species is known from only three samples, one collected in Malta and the others from unrecorded Mediterranean localities.

TABLE 7. Measurements (in mm) of Stephanotheca triangulata n. sp. (paratype: NHMUK 1899.7.1.2346).

  Mean SD Minimum Maximum N
Autozooid length 0.532 0.0393 0.467 0.611 13
Autozooid width 0.421 0.0891 0.261 0.538 13
Orifice length 0.136 0.0114 0.115 0.152 13
Orifice width 0.132 0.0041 0.125 0.141 13
Adventitious avicularium length 0.145 0.0070 0.126 0.152 13
Adventitious avicularium width 0.081 0.0075 0.066 0.092 13
Ovicell orifice length 0.153 0.0078 0.148 0.162 3
Ovicell orifice width 0.154 0.0055 0.148 0.158 3
Ovicell length 0.330 0.0014 0.329 0.331 2
Ovicell width 0.419 0.0000 0.412 0.426 2
Pseudorous area length 0.206 0.0082 0.206 0.206 2
Pseudorous area width 0.303 0.0099 0.296 0.310 2

Natural History Museum, London














Stephanotheca triangulata

Reverter-Gil, Oscar, Souto, Javier & Fernández-Pulpeiro, Eugenio 2012


Schizomavella ochracea

Hayward 1995: 674