Calyptotheca wasinensis ( Waters, 1913 )

Cumming, Robyn L. & Tilbrook, Kevin J., 2014, Six species of Calyptotheca (Bryozoa, Cheilostomata, Lanceoporidae) from the Gulf of Carpentaria and northern Australia, with description of a new species, Zootaxa 3827 (2), pp. 147-169 : 149-152

Calyptotheca wasinensis ( Waters, 1913)

( Figure 1 , Table 1 )

Schizoporella nivea var. wasinensis Waters, 1913: 504 , 535, pl. 70, fig. 1.

Calyptotheca wasinensis: Harmer 1957: 1017 , pl. 68, figs 15, 20, 21, 24, 32, 33; Winston & Heimberg 1986: 18, figs 41, 42; Amui & Kaselowski 2006: 16, figs 15, 16; Liu et al. 2001: 157, pl. 63, figs 4–6.

Not Calyptotheca wasinensis: Hirose 2010: 117 , pl. 201, figs A–E (? Calyptotheca conica ).

Material examined. Bryomol Reef: MTQ G26409, 16°31.653' S, 139°54.589' E, 36.5 m.

South-eastern GoC: MTQ G26410, 16°36.925' S, 140°33.559' E, 19.5 m; MTQ G26411, 16°36.667' S, 140°33.959' E, 22 m.

Beagle Gulf, Northern Territory: MAGNT G130, between Channel Point and North Peron Island, 13.154° S, 130.092° E, 3 October 1993, gravel encrusted with barnacles, 20 m.

Description. Colony originally encrusting, forming a foliaceous, anastomosing network of bilaminar, wavy sheets, colour cream when dried or in ethanol. Autozooids usually rectangular, sometimes irregularly polygonal, in alternating series (c. 0.4 × 0.25 mm; Table 1 ). Frontal shield flattened to slightly convex, with rounded pseudopores (average 19 per zooid), each separated by more than width of a pseudopore, sometimes quite sparse, extending to zooid margins, absent proximal to orifice. Interzooidal boundaries marked by thin, continuous, sinuous sutures that may be obscured by marginal avicularia.

Primary orifice rounded, slightly wider than long (c. 0.11 × 0.12 mm), lunula restricted to distal edge of orifice, poster with wide, shallow sinus, condyles small, rounded, not serrate. Distinct suboral umbo, most pronounced on ovicellate zooids.

Adventitious avicularia small, oval to rounded-subtriangular (c. 0.07 × 0.05 mm), marginal, appearing to lie on interzooidal boundaries and in both distal and both proximal angles of each zooid, directed medially, proximomedially or distomedially; those in proximal angles sometimes slightly larger and wider distally, angled frontally and directed toward, sometimes impinging on, orifice of preceding zooid; opesia semi-elliptical proximally, semicircular distally, crossbar complete. Vicarious avicularia absent.

Ovicell subimmersed, wider than long (c. 0.3 × 0.4 mm), with pseudopores of similar size to those of frontal shield but in greater density, usually crossed by Y-shaped suture lines. Orifice dimorphism, ovicellate orifice wider than autozooid orifice (c. 0.14 vs 0.12 mm; Table 1 ).

Remarks. Calyptotheca wasinensis is distinguished by its bilaminate foliaceous growth form and zooids with small, oval avicularia along the zooidal margins in each angle. The often alternating series of zooids leads to the appearance of each zooid having four avicularia along each side. Calyptotheca wasinensis is most similar to C. conica , which also has numerous oval avicularia along the margins but is unilaminar, its growth form encrusting or conical, with large, bilobed condyles, large vicarious avicularia and hooks projecting basally. Calyptotheca fossulata Harmer, 1957 from Indonesia also has numerous marginal avicularia, which may form nearly continuous rows, but its zooids are approximately three times larger (c. 1.25 × 0.65 mm), with much larger orifices, only slight orificial dimorphism and no suboral umbo ( Harmer 1957).

Busk (1884) described Schizoporella nivea as unilaminar, foliaceous, milk-white in colour, and noted ‘elevations’ at each distal angle—i.e. the adventitious avicularia. We examined SEM images of two of Busk’s (1884) S. nivea specimens (courtesy of M. Spencer-Jones, NHMUK), including one from the type locality off South Africa (NHMUK 1887.12.9.652 [Cape of Good Hope], NHMUK 1887.12.9.663 [Simons Bay]). These differ from C. wasinensis from the GoC in the following characters: zooids almost twice the dimensions (c. 0.7 × 0.5 mm), much larger orifices (c. 0.15 × 0.20 mm) and umbones either small or absent. Whilst zooid size can vary within colonies, orificial size and shape are relatively invariant characters.

Waters (1909) described Schizoporella nivea var. millanensis from the Red Sea with two very small circular avicularia at the distal angles and a broad ‘spathulate’ avicularium at one of the proximal angles. Dumont (1981) noted several such specimens from the Sudanese Red Sea, including one in which the avicularium covered most of the frontal shield. Harmer (1957) considered the large spatulate avicularium to be a ‘slightly enlarged’ ‘sutural’ avicularium, not indicative of a separate species, and placed S. nivea var. millanensis into junior synonymy with Calyptotheca wasinensis . Some of the proximal avicularia in the GoC specimens are indeed slightly larger than others ( Fig. 1 ), but none approach the very large size of those of the Red Sea specimens, and we have not seen evidence of an intermediate form. Schizoporella nivea var. millanensis is therefore here taken out of synonymy with C. wasinensis ( Waters, 1913) .

Several characters appear to be quite variable within and between colonies of C. wasinensis : colony growth form (encrusting vs bilaminar, wavy sheets), autozooid size and shape, presence and size of the suboral umbo and the number of avicularia per zooid. Harmer (1957) noted considerable variation in some of these characters within single colonies, in particular that younger zooids were sometimes longer and flatter, with no umbo and only two avicularia, while older zooids tended to be smaller and more convex with an umbo and numerous lateral avicularia on the sutural lines. Harmer (1957) reported the growth form as loosely encrusting, becoming wavy bilaminar plates when fully developed, with a ‘hemescharan’ (unilaminar) form also common on hydroids and other objects, at first encrusting and later tubular. He noted a strong suboral umbo on a small proportion of fertile orifices only, whereas Waters (1913) considered the strong umbo as a distinctive feature of var. wasinensis .

Winston & Heimberg (1986, p. 18) described a specimen from Indonesia with encrusting growth form, longer zooids (0.5–0.6 mm vs 0.3–0.4 mm) and larger orifice than the GoC specimens (0.14 × 0.14 vs 0.11 × 0.12 mm), small suboral umbo and only two avicularia, one in each distal angle. Amui & Kaselowsky (2006, p.16) described a specimen from the Red Sea with encrusting growth form, longer zooids (0.5–0.7 mm) and similar orifice dimensions to the GoC specimens (0.10 × 0.12 mm), two distal avicularia and sometimes a third proximal oval avicularium. Waters (1913, pl. 70, fig. 1) figured a specimen from Wasini Island, Kenya, with a tall umbo and proximal avicularia in each angle. The GoC specimens therefore appear to resemble those from Wasini more closely than those from Indonesia or the Red Sea.

Distribution. Calyptotheca wasinensis was originally described from Wasini Island, Kenya, East Africa. Harmer (1957) listed records from across the Indian Ocean—Amirante Islands ( Seychelles), Sri Lanka, Andaman Islands, Southeast Asia including Indonesian West Papua—and it has subsequently been reported from Bali ( Winston & Heimberg 1986) and the Gulf of Aden ( Amui & Kaselowsky 2006). The present record is the first from Australian territorial waters. In southeastern GoC, C. wasinensis was found at Bryomol Reef at 36.5 m, and softsediment areas at 19.5 and 22 m.

Figures

FIGURE 1. Calyptotheca wasinensis (Waters, 1913) (MTQ G 26409). A, general view of autozooids and ovicellate zooids; B, autozooid; C, autozooids and one ovicellate zooid—note the suboral umbo more pronounced on ovicellate zooids, and the slightly larger proximal avicularia; D, primary orifice.

Tables

TABLE 1. Measurement (mm) and count data for Calyptotheca wasinensis (MTQ G 26409).

Zooid length	Mean 0.384	Standard Deviation 0.040	Range N 0.318–0.437 10
Zooid width Autozooid orifice length Autozooid orifice width	0.257 0.109 0.122	0.023 0.006 0.003	0.229–0.300 10 0.010–0.120 10 0.117–0.126 10
Adventitious avicularium length Adventitious avicularium width Diameter of perforations in frontal shield	0.067 0.054 0.013	0.010 0.009 0.002	0.056–0.084 10 0.042–0.065 10 0.011–0.015 10
Number of perforations in frontal shield Ovicell length Ovicell width	18.70 0.279 0.364	4.24 0.012 0.014	12–27 10 0.265–0.300 10 0.341–0.382 10
Ovicellate orifice length Ovicellate orifice width	0.099 0.140	0.009 0.004	0.093–0.106 2 0.134–0.147 10