Stephanotheca ambita ( Waters, 1889 )
treatment provided by
|Stephanotheca ambita ( Waters, 1889 )|
Stephanotheca ambita ( Waters, 1889) n. comb.
( Figs 24–25View FIGURES 24 – 25; Table 2)
Schizoporella ambita Waters, 1889: 11 (part: only material from Green Point). Not Schizoporella ambita Waters, 1889: 11 (part: material from Naples and Victoria). Not Schizoporella ambita Waters : Calvet 1902: 46, pl. 2, figs 1, 2.
Material examined. Lectotype (designated here): MM 2938. Green Point, Port Jackson, New S. Wales, Waters Coll. Paralectotypes (designated here): MM 2927, MM 2936; same locality as lectotype.
Description. Colony encrusting, unilaminar, forming broad irregular crusts. Autozooids arranged in alternating series; rhomboid to subrectangular, large, separated by fine sutures. Frontal shield slightly convex, evenly perforated by numerous pseudopores situated in deep depressions. Primary orifice orbicular, as long as wide, with a wide shallow sinus and two small oval condyles, not denticulated. Oral spines absent. Small suboral avicularium, close to the primary orifice and inclined at an angle; oval, with slender, complete crossbar; semi-elliptical mandible proximally directed. Ovicell frontally flattened, subimmersed, with a large, flat, circular area of ectooecium with rounded pseudopores, surrounded by low nodular rim of secondary calcification, incomplete proximally. Opening in ovicellate zooids dimorphic, larger and with shallower sinus; formed by the proximolateral margin of the ovicell and the poster of the primary orifice. Ovicell cleithral. Ancestrula unknown.
SD, Standard deviation; N, number of measurements.
Remarks. Waters (1889) described Schizoporella ambita from material collected at Green Point ( Australia). In the original description, the author remarked he also had material from the same species from Port Western (Victoria, Australia) and from Naples. We revised the material from the Waters Collection labelled as S. ambita , kept in the Manchester Museum, which actually consists of three species. Three colonies are labelled as originating from Green Point / Port Jackson, so we consider they match the type series of S. ambita . This species differs from the material collected in Victoria ( Australia) as well as from the Mediterranean material reported as Schizomavella ambita by several authors, as it will be discussed below.
The shape of the ovicell, its closure, and the shape of the primary orifice suggests that S. ambita belongs to the genus Stephanotheca . However, this species is the only one in the genus with smooth condyles. Also, the pseudoporous area in the ovicell is extremely large, occupying almost all the ooecial roof.
|Adventitious avicularium length||0.034||0.0044||0.028||0.042||17|
|Adventitious avicularium width||0.054||0.0053||0.046||0.064||17|
|Ovicell orifice length||0.112||0.0066||0.094||0.121||9|
|Ovicell orifice width||0.128||0.0048||0.120||0.133||9|
|Pseudorous area diameter||0.216||0.0195||0.179||0.250||12|
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