Hippomonavella lingulata, 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 : 121

Hippomonavella lingulata n. sp.

( Fig. 8 A–E, Table 7)

zoobank.org/ 895C8035-EB64-418E-90E5-71BD671C358B

Material examined. Holotype: SAMC-A029050 (in ethanol), station AFR273 A31624 (33°48’24”S, 25°56’48”E), Algoa Bay , Southeast Coast, South Africa, South Coast Demersal Survey, trawl, depth 45 m, 21 April 2011 . Paratype: SAMC-A028993 (in ethanol), AFR273 A31624, see station data above. Additional comparative material: Hippomonavella formosa , SAMC-A028621 , Bakoven (33°56’S, 18°22’E), West of Cape Peninsula, South Africa, collected by W. Florence, depth 8 m, 5 May 1999 ; SAMC-A028622 , Saldanha Bay (33°01’S, 17°59’E), West Coast, South Africa, collected by W. Florence, depth 10 m, 25 February 2001 .

Etymology. From the Latin, referring to the tongue-shaped avicularium.

Diagnosis. Colony encrusting. Autozooids with imperforate frontal shield except conspicuous marginal areolae. Orifice with proximally slanted condyles and flaps developing laterally. Distal oral spine present, not visible in ovicelled zooids. Avicularia adventitious, sub-lingulate. Ovicell hyperstomial; ooecium formed by the distal autozooid, smooth and pseudoporous.

Description. Colony encrusting. Autozooids oval, rectangular to irregularly polygonal, about 0.78 mm long by 0.50 mm wide, separated by raised sutures. Frontal shield imperforate, nearly smooth or unevenly textured, with a single series of about 17–23 (N T = 8) conspicuous marginal areolae. Orifice circular to roundly subquadrate, with slight median concave proximal rim and a pair of proximally slanted condyles. A pair of distal oral spine bases usually present, except in ovicelled autozooids; a pair of flaps developing lateral to the orifice. Avicularium median, proximal to orifice, sub-lingulate, small opesia, long palatal shelf, rounded rostrum proximally raised, almost one third of the total length of autozooid, directed proximally, with complete crossbar or, less frequently, condyles. Ovicell hyperstomial; ooecium formed by the distal autozooid, longer than wide, flattened frontally, smooth with about 38 (N T = 1) rounded or irregular shaped frontal pseudopores; secondary calcification of distal zooid(s) covering distal part of ovicell. Mural pore chambers in lateral walls. Ancestrula not observed.

Remarks. This species is confidently placed in Hippomonavella based on the presence of conspicuous marginal areolae, hippoporine orifice and adventitious suboral avicularia. Globally, about 19 Hippomonavella species are known, of which more than half are extinct (www. bryozoa.net, accessed 06 June 2020). In South Africa, H. formosa MacGillivray, 1887 has been reported from the West Coast ( Florence et al. 2007). Hippomonavella lingulata n. sp. differs from H. formosa in having a straight proximal orificial rim and a median suboral avicularium. In fact, the other known extant Hippomonavella species, including H. pellucidula Hayward & Ryland, 1991 , H. gymnae Gordon, 1984 , H. ramosae López de la Cuadra & Garcia-Gomez, 2000 and H. brasiliensis Ramalho, Muricy & Taylor, 2008 , differ from H. lingulata n. sp. in the position and size of avicularia, orifice shape and smaller marginal pores.

The new species closely resembles H. flexuosa Hutton, 1873 from New Zealand in having sub-lingulate median avicularium, in the number of conspicuous marginal areolae, and the paired oral spines ( Gordon 1989), but it lacks the proximal median convexity of the orifice and the sizeable avicularium. Particularly, the median avicularium covers almost one third of the total autozooid length in H. lingulata n. sp. as opposed to almost one sixth of the total autozooid length in H. flexuosa .

No ancestrula was observed in H. lingulata n. sp. and therefore has not been described. The ancestrula and early astogeny of a species of Hippomonavella were only recently described for the first time ( López-Gappa et al. 2020). Hippomonavella charrua López-Gappa, Liuzzi & Pereyra, 2020 has tatiform ancestrula with nine, delicate, cylindrical spines surrounding a circular opesia, and a band of proximal cryptocyst, budding three periancestrular zooids with five spines.

Hippomonavella lingulata n. sp. was found at Algoa Bay, on Southeast Coast, at 45 m depth.

Figures

FIGURE 8. A–E. Hippomonavella lingulata n. sp. (SAMC-A029050) A. Group of autozooids (scale bar = 0.4 mm, magnified x35). B. Close-up of autozooids (scale bar = 0.2 mm, magnified x75). C. Close-up of the orifice, showing condyles and two oral spine bases (scale bar = 0.1 mm, magnified x200). D. Developing ooecium (scale bar = 0.2 mm, magnified x100). E. Ovicelled zooid (scale bar = 0.1 mm, magnified x150).