Stephanotheca kutyeri, Cumming & Sebastian, 2018

Cumming, Robyn L. & Sebastian, Pascal, 2018, New encrusting species of Lanceoporidae (Bryozoa, Cheilostomata) from the southern Great Barrier Reef, Australia, Zootaxa 4500 (1), pp. 104-114 : 110-112

Stephanotheca kutyeri n. sp.

( Fig. 3 , Table 3)

Material examined. Holotype: MTQ G101185, southern GBR, inter-reefal, east of Southampton Reef, Hydrographers Passage , 20° 35' 46.093" S, 150° 28' 36.318" E, 28 May 2004, 71 m, coll. Seabed Biodiversity Project.

Paratype: MTQ G101187, southern GBR, inter-reefal, west of Warland Reef , Hydrographers Passage, 20° 37' 57.112" S, 150° 19' 38.806" E, 28 May 2004, 34 m, coll. Seabed Biodiversity Project.

Other material: MV F224562 , central Bass Strait , 38 km south-west of Cape Paterson, Victoria, Australia, 38° 55' 30" S, 145° 16' 58.8" E, 12 November 1981 , 70 m; MV F238894 & MV F238895 , Great Australian Bight east of Albany, Western Australia, 35º S, 119º E, 27 July 1995, 149 m.

Etymology. The epithet is an Australian aboriginal word meaning thin, referring to the shape of the pseudopores in the frontal shield.

Description. Colony encrusting, unilaminar. Autozooids neatly rectangular to hexagonal (c. 0.4 x 0.3 mm; Table 3); frontal shield flattened, pseudopores mostly long and narrow (length c. 0.02 mm), regularly-spaced, numerous (average 53 per zooid), oriented in all directions, extending to zooid borders; developing zooids at edge of colony with approximately round pseudopores; interzooidal boundaries marked by thin suture lines and long thin areolae.

Primary orifice oval, wider than long (c. 0.11 x 0.09 mm), poster with deep U-shaped sinus; condyles large, rounded, weakly serrate.

Adventitious avicularia small, approximately round (c. 0.3 mm diameter), suboral, medial, one per zooid, directed proximally, distance to orifice more than one avicularium length, and occasional additional marginal avicularia, directed medially; cystid slightly raised; proximal opesia and rostral foramen transversely oval to semicircular, crossbar central, complete. Vicarious avicularia absent.

Ovicell immersed; ooecium wider than long (c. 0.3 x 0.2 mm), with narrow imperforate border and large, slightly convex area with numerous rounded, approximately evenly spaced pseudopores, cormidial, as indicated by Y-shaped suture lines; distinct orifice dimorphism, ovicellate orifice wider than autozooid orifice (c. 0.14 vs. 0.11 mm), sinus shallow, condyles large, rounded, serrate.

Occasional dimorphic zooids ( Fig. 3A , lower left) with larger orifice, wider than long (c. 0.14 x 0.08 mm), and a shallow sinus, similar in size to those of ovicellate zooids; condyles serrate.

Remarks. Stephanotheca kutyeri n. sp. is the only known Stephanotheca species with long, narrow, slit-like pseudopores in the frontal shield, but shares the trait with fellow lanceoporid Calyptotheca triquetra . The three southern Australian specimens, one from Victoria and two from Western Australia, have slightly larger orifices than the type specimen, both autozooid (width c. 0.12 mm, n= 12) and ovicellate (width c. 0.15 mm, n= 8), but agree with the type in other characters.

Stephanotheca kutyeri n. sp. is closest to the temperate Australian species Stephanotheca ambita from New South Wales, which shares a similar ooecium morphology (a large pseudoporous area and abundant round pseudopores) and a relatively small primary orifice. But its frontal shield pseudopores are large and rounded, the primary orifice is not transversely oval and has smooth condyles, and the suboral avicularium is larger and not round (i.e. transversely oval and twice as large as that of S. kutyeri n. sp.). The relatively small primary orifice of S. kutyeri n. sp. is shared only by S. ambita , S. ipsum and S. romajoyae , all Australian species. Stephanotheca kutyeri n. sp. also shares with S. ipsum and S. romajoyae the occasional occurrence of extra avicularia, whereas other Stephanotheca species have one per zooid. Stephanotheca ipsum shares the small, approximately round avicularia, but has a distinctly round orifice, round pseudopores and different ooecium morphology. Stephanotheca romajoyae has subtriangular avicularia, large dimorphic avicularia and different ooecium morphology.

The occasional dimorphic zooids ( Fig. 3A , lower left) have orifices that resemble those of maternal zooids in size (width 0.14; length 0.08), shape (wider than long, shallow sinus) and condyles (similar shape and size, serrate).

Gordon (2014, p. 13) mentioned viewing SEM micrographs of an unnamed species from Bass Strait that fits the description of Stephanotheca kutyeri n. sp. He observed the suboral avicularium, developing zooids at the colony margin with approximately round pseudopores, and the “chaotic orientation” of the slit-like pseudopores in all directions.

Distribution. Stephanotheca kutyeri n. sp. is known from the Hydrographers Passage region, east of Mackay, GBR (depth range 34–72 m), and two temperate localities: Bass Strait, Victoria, and the Great Australian Bight east of Albany, Western Australia (depth range 70–149 m). Thus S. kutyeri n. sp. appears to have a wide distribution in Australian waters and to be unusual amongst Australian lanceoporids in occurring in both tropical and temperate locations.

SD, standard deviation

Figures

FIGURE 3. Stephanotheca kutyeri n. sp. Holotype (MTQ G101185). A. Autozooids, ovicellate zooids and dimorphic zooid (lower left), note the Y-shaped suture lines on ooecium (far right). B. Primary orifice. C. Ovicellate orifice. D. Ovicellate zooid, note the marginal avicularia. E. Marginal avicularia.