Stephanotheca ipsum, Cumming, Robyn L., 2015

Cumming, Robyn L., 2015, Two tropical species of Stephanotheca (Bryozoa, Cheilostomata, Lanceoporidae) from the Gulf of Carpentaria, Australia, Zootaxa 3948 (2), pp. 279-286 : 280-283

publication ID 10.11646/zootaxa.3948.2.8

publication LSID


persistent identifier

treatment provided by


scientific name

Stephanotheca ipsum

sp. nov.

Stephanotheca ipsum n. sp.

( Figure 1 View FIGURE 1 , Table 1 View TABLE 1 )

Material Examined. Holotype: MTQ G26766, southeastern GoC, 16°40.914’ S, 140°12.092’ E, encrusting Cigclisula sp., 33 m. Paratypes: MTQ G26767, encrusting Cigclisula , same data as for holotype; MTQ G26768, eastern GoC, seabed surrounding submerged coral reef, 15°15.561’ S, 140°22.905’ E, encrusting Steginoporella sp., 49 m.

Etymology. From the Latin ipsum for button, for the button-like roundness of the primary orifice, the sinus and the adventitious avicularia.

Description. Colony encrusting; autozooids irregularly hexagonal (c. 0.4 x 0.3 mm; Table 1 View TABLE 1 ); frontal shield flattened to slightly convex; pseudopores relatively small (c. 0.008 mm diameter) and widely spaced, separated by more than two pseudopore diameters (c. 43 per zooid), rounded to elongate, extending to zooid margins; interzooidal boundaries marked by thin grooves and occasional elongate sutural pores; walls between zooids with 3–4 uniporous septula.

Primary orifice as wide as long (c. 0.10 x 0.10 mm); anter round; lunula restricted to distal half of orifice; sinus a wide rounded arc; condyles large, elongate, serrate.

Each zooid with a single, small, round, suboral, medial adventitious avicularium (c. 0.04 mm diameter), cystid raised proximally, directed proximofrontally; proximal opesia and rostral foramen oval; mandible semicircular; crossbar complete; sometimes one, rarely two, additional avicularia of same shape and size proximally, adjacent to orifice of an adjacent zooid, directed distolaterally; vicarious avicularia not observed.

Ooecium wider than long (c. 0.3 x 0.2 mm), immersed, bordered by ridge of calcification that is sometimes complete, sometimes restricted to distal edge, not crossed by suture lines; orifice dimorphic, the ovicellate orifice significantly wider than autozooidal orifice (c. 0.12 vs 0.10 mm; 1-tailed t-test: p<0.001; Table 1 View TABLE 1 ).

Remarks. Stephanotheca ipsum n. sp. is distinguished by its rounded orifice with semicircular sinus, small, round avicularia suborally and proximally, and the extensively pseudoporous ooecium with a low ridge of peripheral calcification. It shares with other Stephanotheca species an encrusting growth form and a proximally directed, medial adventitious avicularium. No other Stephanotheca species have more than one adventitious avicularium per zooid, except S. romajoyae n. sp.

Stephanotheca ipsum n. sp. is provisionally placed in Stephanotheca View in CoL on the basis of the ridged ooecium, which differs from the fully pseudoporous ooecium of Calyptotheca View in CoL and resembles the crowned ooecium of Stephanotheca View in CoL in having a porous area surrounded by an imperforate area. On the one hand, it resembles S. perforata Reverter-Gil, Souto & Fernández-Pulpeiro, 2012 , from the Mediterranean, which also has a ridged ooecium instead of the crowned ooecium typical of European Stephanotheca View in CoL , but only one ooecium was present in the material and the morphological variability is unknown ( Reverter-Gil et al. 2012). On the other hand, it resembles C. inclusa ( Thornely, 1906) View in CoL , an Indo-Pacific species, which has a single, near-circular, suboral medial avicularium on each zooid and ooecia with a ridge [called a “calcareous arch” by Thornely (1905, p. 116, plate, fig. 2, as Schizoporella avicularis )]. However, Harmer (1957, p. 1029, pl. 66, fig. 4) noted C. inclusa View in CoL specimens were only “sometimes bordered by a smooth, semicircular ridge”. This feature has not appeared in subsequent descriptions and illustrations of C. inclusa View in CoL by Ristedt & Hillmer (1985), Winston & Heimberg (1986), Hayward (1988), Scholz (1991), Ryland & Hayward (1992) and Tilbrook (2006). Stephanotheca perforata differs from C. ipsum n. sp. in having a much larger orifice (0.15 x 0.15 mm vs 0.10 x 0.10 mm), more numerous and more closely spaced pseudopores in the frontal shield (approx. 75 vs mean 43), and only a single, oval avicularium, often wanting, whereas S. ipsum has up to three round avicularia on each zooid, one suborally and one or two proximally. Calyptotheca inclusa View in CoL differs from S. ipsum n. sp. by its pear-shaped orifice with deeper, narrower sinus, larger, more oval suboral avicularia with trifoliate distal opesia, no proximal adventitious avicularia, and occasional vicarious avicularia.

Calyptotheca inclusa View in CoL belongs to a group of similar species with a single, oval or round, suboral, medial avicularium on each zooid. Of these, C. immersa ( Powell, 1967) View in CoL , C. lardil Cumming & Tilbrook, 2014 , C. reniformis Tilbrook, 2006 View in CoL and C. rugosa Hayward, 1974 View in CoL (p. 379, fig. 5a) have the fully perforated ooecia of Calyptotheca View in CoL , but ooecial details are not known for C. kapaaensis Dick, Tilbrook & Mawatari, 2006 View in CoL , C. subimmersa (MacGillivray, 1879) View in CoL , Schizomavella collina Cook, 1965 View in CoL and S. incompta Hayward, 1988 View in CoL (p. 315, pl. 7e), in most cases because ooecia were not present in the material. It remains possible that some of these latter species have ridged ooecia. Only one of these, S. incompta View in CoL , has additional proximal avicularia, but unlike those of C. ipsum n. sp., they are dimorphic, the proximal avicularia being triangular and larger.

The ooecia of the two southern Australian Stephanotheca View in CoL species, S. ambita Reverter-Gil, Souto View in CoL & Fernández- Pulpeiro, 2012 and S. victoriensis Reverter-Gil, Souto & Fernández-Pulpeiro, 2012 , also vary from the typical crowned ooecium of the European species. Those of S. ambita View in CoL have a relatively larger perforated area and smaller, lower nodular rim of calcification, which is nevertheless larger than the ridge of S. ipsum n. sp. and S. perforata . Those of S. victoriensis are neither crowned nor ridged, but instead have a wide arch of pseudopores, and a few pseudopores scattered frontally. Stephanotheca victoriensis is only provisionally placed in the genus ( Reverter-Gil et al. 2012). Stephanotheca ambita View in CoL shares with S. ipsum n. sp. a relatively small round orifice with wide, shallow sinus, and small, suboral, proximofrontally directed avicularia, but differs in having non-serrate condyles, oval rather than round avicularia, only one avicularium per zooid, and different ooecial morphology. Stephanotheca victoriensis has a wider, distinctly oval orifice, a single, oval, much larger avicularium distant from the orifice and almost in the centre of the zooid, and different ooecial morphology.

Distribution. Stephanotheca ipsum n. sp. is known only from the GoC. Two colonies are from the same site east of Mornington Island in the southeastern GoC, encrusting the foliaceous habitat-providing bryozoan Cigclisula sp. at 33 m. The third colony is from the seabed surrounding a submerged coral reef in the eastern GoC, encrusting the platelike habitat-providing bryozoan Steginoporella sp. at 49 m.

TABLE 1. Measurements (mm) and counts for Stephanotheca ipsum n. sp. Zooid, orifice, avicularia and ovicell measurements on holotype (MTQ G 26766), pseudopore measurements on MTQ G 26768.

  Mean Standard deviation Range N
Zooid length 0.446 0.060 0.369–0.558 10
Zooid width 0.256 0.063 0.190–0.353 10
Autozooid orifice length 0.096 0.004 0.090–0.101 10
Autozooid orifice width 0.100 0.003 0.094–0.104 10
Adventitious avicularium length 0.040 0.003 0.035–0.045 10
Adventitious avicularium width 0.039 0.001 0.038–0.042 10
Diameter of pseudopores in frontal shield 0.008 0.001 0.007–0.010 10
Number of pseudopores in frontal shield 43.4 4.648 36–49 10
Ooecium length 0.218 0.027 0.188–0.247 5
Ooecium width 0.274 0.062 0.211–0.376 5
Ovicellate orifice length 0.087 0.003 0.085–0.090 3
Ovicellate orifice width 0.117 0.007 0.113–0.126 3














Stephanotheca ipsum

Cumming, Robyn L. 2015

C. lardil

Cumming & Tilbrook 2014

S. perforata Reverter-Gil, Souto & Fernández-Pulpeiro, 2012

Reverter-Gil, Souto & Fernandez-Pulpeiro 2012

S. victoriensis Reverter-Gil, Souto & Fernández-Pulpeiro, 2012

Reverter-Gil, Souto & Fernandez-Pulpeiro 2012

C. reniformis

Tilbrook 2006

C. kapaaensis

Dick, Tilbrook & Mawatari 2006

S. incompta

Hayward 1988

C. rugosa

Hayward 1974

C. immersa (

Powell 1967

Schizomavella collina

Cook 1965

C. inclusa (

Thornely 1906

C. subimmersa

MacGillivray 1879
GBIF Dataset (for parent article) Darwin Core Archive (for parent article) View in SIBiLS Plain XML RDF