Calyptotheca australis ( Haswell, 1880 )

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 : 152-155

Calyptotheca australis ( Haswell, 1880)

( Figure 2 ; Table 2 )

Hemeschara australis Haswell, 1880: 41 , pl. 2, figs 7, 8.

Schizoporella australis: Harmer 1902: 266 , 303, pl. 17, fig. 47.

Schizomavella australis: Hastings 1932: 417 , pl. 1C; Harmer, 1957: 1031, pl. 66, figs 5, 9. Calyptotheca australis: Tilbrook 2006: 224 , pl. 49A, B.

Material examined. Bryomol Reef: MTQ G26418, 16°29.091' S, 139°55.366' E, 34 m; MTQ G26419, G26420, 16°30.404' S, 139°56.970' E, encrusting Adeonella , 35.5 m; MTQ G26421, G26422, 16°30.404' S, 139°56.970' E, encrusting Celleporaria , 35.5 m; MTQ G26423, G26424, G26425, G26427, G26428, 16°29.310' S, 139°56.513' E, 39 m; MTQ G26429, 16°31.566' S, 139°52.587' E, 24.5 m; MTQ G26430, 16°31.566' S, 139°52.587' E, encrusting gorgonian, 24.5 m; MTQ G26431, 16°29.306' S, 139°53.191' E, encrusting Adeonella , 42.5 m; MTQ G26432, G26501, 16°29.306' S, 139°53.191' E, 42.5 m; MTQ G26433, G26434, 16°31.812' S, 39°56.424' E, 31.5 m; MTQ G26441, G26442, G26443, G26444, G26445, G26446, 16°28.819' S, 139°55.419' E, 32.5 m; MTQ G26447, 16°28.819' S, 139°55.419' E, encrusting Triphyllozoon , 32.5 m; MTQ G26448, 16°28.819' S, 139°55.419' E, encrusting Celleporaria , 32.5 m; MTQ G26449, 16°26.06' S, 139°55.861' E, 31.5 m; MTQ G26450, G26451, 16°26.721' S, 139°54.028' E, encrusting anascan, 33.5 m; MTQ G26452, G26453, G26454, 16°26.312' S, 139°52.748' E, encrusting Adeonella , 34.5 m; MTQ G26455, 16°26.780' S, 139°52.034' E, 34.5 m; MTQ G26456, 16°27.343' S, 139°52.712' E, encrusting Steginoporella , 41 m; MTQ G26457, G26458, 16°27.627' S, 139°51.171' E, 26.5 m; MTQ G26459, G26460, G26461, G26462, 16°28.929' S, 139°54.340' E, 41.5 m; MTQ G26463, 16°31.653' S, 139°54.589' E, encrusting Triphyllozoon , 36.5 m; MTQ G26464, G26465, 16°31.653' S, 139°54.589' E, 36.5 m.

Southeastern GoC: MTQ G26412, 16°50.029' S, 140°11.999' E, 23 m; MTQ G26413, 16°50.904' S, 140°29.998' E, 19.5 m; MTQ G26414, 16°30.160' S, 140°34.068' E, 21 m; MTQ G26415, 16°33.347' S, 140°45.127' E, 17 m; MTQ G26416, G26417, 16°40.914' S, 140°12.092' E, encrusting Cigclisula , 33 m; MTQ G26435, 15°23.983' S, 140°11.084' E, encrusting Triphyllozoon , 43.5 m; MTQ G26436, G26437, G26438, G26439, 15°23.983' S, 140°11.084' E, 43.5 m; MTQ G26440, 15°23.983' S, 140°11.084' E, encrusting base of Adeonella , 43.5 m; MTQ G26466, G26467, 16°10.176' S, 140°12.169' E, 33 m; MTQ G26468, 16°30.052' S, 140°11.994' E, encrusting Adeonella , 29 m; MTQ G26469, seabed surrounding submerged coral reef, 15°15.561' S, 140°22.905' E, encrusting Triphyllozoon , 49 m; MTQ G26470, seabed surrounding submerged coral reef, 15°20.782' S, 140°22.902' E, encrusting Triphyllozoon , 45.5 m; MTQ G26471, reef margin, submerged coral reef, 15°16.938' S, 140°17.127' E, 39.5 m; MTQ G26499, 16.1438° S, 139.841015° E, 5 March 2003, encrusting Adeonella .

GBR: AM U:483.001, G:8468, Holbourne Island, 19°44' S, 148°22' E (estimate). AM U:1382, U:2205, Port Denison, Queensland, 20°02' S, 148°15' E (estimate).

Central GoC: MTQ G26494, G26495, 15.52393° S, 137.79065° E, 10 March 2005; MTQ G26496, 15.707845° S, 138.08176° E, 7 March 2005, encrusting calcareous worm tubes; MTQ G26497, 15.707845° S, 138.08176° E, 7 March 2005, encrusting shell; MTQ G26498, 15.935433° S, 139.169233° E, 1 April 2005, encrusting Adeonella .

Beagle Gulf, Northern Territory: MAGNT G000053, G000119, between Channel Point and North Peron Island, 13.154° S, 130.092° E, 3 October 1993, gravel encrusted with barnacles, 20 m, coll. S.K. Horner; MAGNT G000120, north-east of Charles Point, 12.316° S, 130.679° E, 13 October 1993, sandy mud and gravel, 23 m, coll. R.S. Williams.

Description. Colony initially encrusting, developing large, anastomosing networks of unilaminar tubes, zooids opening outwards, colour off-white/cream in ethanol. Autozooids rectangular to irregularly polygonal, in irregularly arranged series (c. 0.5 × 0.4 mm; Table 2 ). Frontal shield typically flat with rounded, regularly spaced pseudopores (average 55 per zooid), each separated by more than the width of a pseudopore, extending to zooid borders, absent between orifice and avicularium. Interzooidal boundaries marked by thin raised lines of calcification. Lateral walls with evenly spaced uniporous mural septula.

Primary orifice rounded, slightly wider than long (c. 0.10 × 0.09 mm), anter rounded, lunula extending to lateral margins, poster with a deep, U-shaped sinus about half orificial width, condyles prominent, semicircular, serrate.

Adventitious avicularia suboral, medial, one per zooid, sometimes absent, narrowly triangular proximally, with bluntly triangular opesia, elongate-oval and tapering slightly distally, with oval opesia, widest mid-length with complete crossbar; dimorphic in size, smaller type common (mean length 0.13 mm), varying in orientation from distolateral to proximal in either direction, many with slight rostral curvature resulting in asymmetry, especially those oriented distolaterally and curving toward orifice; enlarged type directed proximally or proximolaterally and extending to zooid border, mean length 0.3 mm, uncommon but can occur in aggregations. Vicarious avicularia absent.

Ovicell subimmersed, wider than long (c. 0.3 × 0.2 mm), initially distinct with fewer pores than in frontal shield, becoming almost indistinguishable with thicker calcification, not crossed by suture lines. Orificial dimorphism not distinctive, but ovicellate orifices slightly wider than autozooidal orifices (0.10 mm vs 0.11 mm; Table 2 ).

Remarks. Calyptotheca australis is characterised by its erect, tubular growth form, a deep U-shaped sinus with large serrate condyles, adventitious avicularia that vary in size, shape and orientation throughout the colony, and occasional enlarged avicularia that occupy the entire frontal shield ( Fig. 2 A, D, E). Tilbrook (2006) recorded differences in tube diameter, orifice shape and prevalence of large avicularia between locations, with the Solomon Islands specimens having large avicularia in approximately 50% of zooids. In the GoC, Beagle Gulf and GBR specimens large avicularia are infrequent, and the sinus appears narrower and deeper than in the Solomon Islands specimen illustrated by Tilbrook (2006). Some specimens possess the full variety of avicularia ( Fig. 2 E) but most have a predominance of either distolaterally oriented avicularia, curved toward the orifice ( Fig. 2 D), or proximolaterally or proximally oriented avicularia ( Fig. 2 A, C). C. australis is either a considerably variable species with a relatively wide geographic distribution or a complex of closely related species.

Distribution. Calyptotheca australis occurs from East Asia to Melanesia, with records from the GBR ( Haswell 1880; Hastings 1932), Torres Strait ( Harmer 1902), Beagle Gulf and Port Darwin ( Gordon 2009; Hastings 1932; this study), Singapore, Indonesia and Papua New Guinea ( Hastings 1932; Harmer 1957), Japan and northwestern Australia ( Hastings 1932), the Solomon Islands (Tilbrook 2006) and the GoC.

Calyptotheca australis is one of the commonest bryozoan species, and the commonest Calyptotheca species in the MTQ GoC bryozoan collection. It is one of the three-dimensional habitat-providing species that harbours other bryozoans, sessile invertebrates and mobile invertebrates, particularly crustaceans, ophiuroids and polychaetes. Encrusting colonies of C. australis were commonly attached to the habitat-providing bryozoans Steginoporella spp., Adeonella spp., Cigclisula spp. and Triphyllozoon spp. and also shells and rocks, at depths of 17– 49 m. C. australis occurred in soft-sediment areas, Bryomol Reef and the margin and surrounding seabed of a submerged coral reef.

Figures

FIGURE 2. Calyptotheca australis (Haswell, 1880). A – D, Gulf of Carpentaria specimens. A, MTQ G 26501, autozooids, one with enlarged avicularium; B – C, MTQ G 26460, B, primary orifice, C, autozooids and two ovicellate zooids, with laterally and proximolaterally oriented avicularia; D, MTQ G 26438, two ovicellate zooids (top), one with an enlarged avicularium, and autozooids with distolaterally oriented avicularia; note the rare zooid without an avicularium; E, specimen from Beagle Gulf (unregistered), two ovicellate zooids, top left, and autozooids—note the distolaterally and proximolaterally orientated avicularia occurring on the same colony.

Tables

TABLE 2. Measurement (mm) and count data for Calyptotheca australis (MTQ G 26501, MTQ G 26439, MTQ G 26438, MTQ G 26460 & MTQ G 26428).

Zooid length	Mean 0.497	Standard Deviation 0.106	Range N 0.341–0.647 15
Zooid width Autozooid orifice length Autozooid orifice width	0.385 0.093 0.103	0.095 0.007 0.007	0.234–0.495 15 0.083–0.101 12 0.088–0.113 12
Adventitious avicularium length Adventitious avicularium width Large adventitious avicularium length	0.135 0.039 0.290	0.026 0.006 0.017	0.097–0.201 25 0.027–0.049 25 0.275–0.315 5
Large adventitious avicularium width Diameter of perforations in frontal shield Number of perforations in frontal shield	0.059 0.014 55.5	0.007 0.003 9.49	0.053–0.071 5 0.011–0.021 20 39–80 15
Ovicell length Ovicell width Ovicellate orifice length	0.229 0.287 0.094	0.021 0.037 0.009	0.198–0.258 8 0.242–0.341 8 0.086–0.110 5
Ovicellate orifice width	0.108	0.012	0.093–0.125 5