Trypostega richardi, Boonzaaier-Davids & Florence & Gibbons, 2020

Boonzaaier-Davids, Melissa K., Florence, Wayne K. & Gibbons, Mark J., 2020, Novel taxa of Cheilostomata Bryozoa discovered in the historical backlogs of the Iziko South African Museum, Zootaxa 4820 (1), pp. 105-133 : 114-115

Trypostega richardi n. sp.

( Fig. 5 A–F, Table 4)

zoobank.org/ BD4246A9-2A68-4343-A821-91462E8F426E

Material examined. Holotype: SAMC-A 028985 (dry), station AFR273 A31666 (34°58’51”S, 21°36’52”E), south of Cape Infanta, South Coast, South Africa, Africana South Coast Demersal Survey, trawl, depth 95–97 m, 5 May 2011. Additional comparative material: Trypostega venusta (= T. richardi n. sp.), SAMC-A 026788, station SM 164 (33°04.6’S, 28°06.6’E), off East London, Southeast Coast, South Africa, RV Meiring Naude Survey, heavy dredge, depth 90 m, 26 May 1978. Trypostega venusta , SAMC-A 026809, station SM 163 (33°04.6’S, 28°06.6’E), off East London, Southeast Coast, South Africa, heavy dredge, depth 90 m, 26 May 1978.

Etymology. Named after the first author’s father, Richard Lawrence Boonzaaier (b. 1953). As school teachers and former principals under the difficult circumstances and education system of the ‘Apartheid’ Era and post-‘apartheid’, both her parents have shown remarkable levels of commitment and motivation in teaching children in South Africa. His courage and endurance, and patience, love and support throughout her study career and life is hereby acknowledged.

Diagnosis. Colony encrusting, unilaminar. Autozooids with hyaline, evenly pseudoporous frontal shield; pseudopores aligned in an arch distally. Orifice dimorphic, cleithridiate with narrow U-shaped sinus, broader and shallower in ovicelled zooids. Suboral umbo absent. Zooeciules placed distal to most autozooids, sometimes in clusters. Ovicell subimmersed; ooecium formed by the distal kenozooid, ectooecium with scattered pseudopores.

Description. Colony encrusting, unilaminar, forming thin sheets; colour greyish to creamy white in dried material. Autozooids rounded rhomboidal or irregularly polygonal, elongate, separated by distinct sutures. Frontal shield smooth, slightly convex or flat, hyaline, evenly perforated by 55–100 (N T = 7) circular pseudopores; pseudopores distal to the orifice aligned in an arch. Orifice dimorphic, keyhole-shaped with prominent condyles (cleithridiate), longer than wide; rounded anter, separated from a narrow U-shaped sinus, broader and shallower in ovicelled zooids, by a pair of short, proximally directed condyles; slightly raised rim bordering the orifice. No suboral umbo. Zooeciules, of varying size and shape, placed distally to most autozooids or between two adjacent autozooids, either single, twinned or in clusters of up to seven; evenly pseudoporous similar to autozooid frontal shield; small, elliptical or rounded opening, bordered by a slightly raised rim. Ovicell subimmersed, cleithral; ooecium formed by the distal kenozooid associated with the terminal zooeciule, ectooecium with evenly scattered pseudopores. Ancestrula not observed.

Remarks. Only part of the colony (less than 20 autozooids) was detached from the original substrate (scleractinian coral) and examined using SEM.

Although all cleithridiate, the orifice of Trypostega richardi n. sp. differ from those of T. dorothysouleae Tilbrook, 2006 , T. johnsoulei Tilbrook, 2006 , T. venusta Norman, 1864 and T. maculata Tilbrook, Hayward & Gordon, 2001 . In the new species the sinus is narrow and U-shaped, while the species above-mentioned all possess a broader and shallower U-shaped or horseshoe-shaped sinus. Additional features that distinguish T. richardi n. sp. from other known species, including the most similar T. henrychaneyi Tilbrook, 2006 , are the irregularly shaped zooids and the frequency of zooeciules. The zooeciules are sporadic and mostly placed distally to autozooids, but they may also form clusters of up to seven.

Hayward and Cook (1983, p. 86) reported a few colonies of the widespread T. venusta on the Southeast and East Coast of South Africa, which differ from T. richardi n. sp. in having shallow, horseshoe-shaped sinus, and also much less frequent zooeciules. Upon examining some of the voucher specimens of T. venusta in the SAMC collection, one of the colonies (SAMC-A026788) determined as T. venusta is, in fact, T. richardi n. sp. ( Fig. 5 A–D). Trypostega richardi n. sp. was sampled off Cape Infanta on the South Coast of South Africa at 95–97 m depth.

Figures

FIGURE 5. A–F. Trypostega richardi n. sp. A. Group of ovicelled and non-ovicelled autozooids and zooeciules (SAMC- A026788) (scale bar = 0.2 mm, magnified x250). B. Close-up of two zooids, one ovicelled. Note the dimorphic orifice in the ovicelled zooid (SAMC-A026788) (scale bar = 0.2 mm, magnified x400). C. Close-up of an ovicell with circular opening of the associated zooeciule (SAMC-A026788) (scale bar = 0.1 mm, magnified x1.0K). D. Cleithridiate orifice with operculum (SAMC-A026788) (scale bar = 0.05 mm, magnified x1.8K). E. Cleithridiate orifice from an angle showing detail of condyles (SAMC-A028976) (scale bar = 0.05 mm, magnified x350). F. Close-up of two zooeciules (SAMC-A028976) (scale bar = 0.1 mm, magnified x200).