Antarctothoa ballia Gordon 2020, n. sp.
Antarctothoa ballia n. sp. (Fig. 9 A–J) Etymology. Alluding to Ballia callitricha (C.Agardh) Kütz., the red-algal substratum on which the species grows. Material examined. Holotype: NIWA 144833, 40.6199° S, 176.4151° E, on beach-cast dried Ballia callitricha, Akitio, North Island, coll. D.P. Gordon,...
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| Format: | Other/Unknown Material |
| Language: | unknown |
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2020
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| Online Access: | https://zenodo.org/record/3717924 https://doi.org/10.5281/zenodo.3717924 |
| Summary: | Antarctothoa ballia n. sp. (Fig. 9 A–J) Etymology. Alluding to Ballia callitricha (C.Agardh) Kütz., the red-algal substratum on which the species grows. Material examined. Holotype: NIWA 144833, 40.6199° S, 176.4151° E, on beach-cast dried Ballia callitricha, Akitio, North Island, coll. D.P. Gordon, 31 December 2019. Paratype: NIWA 144834, same data as holotype. Other material: NIWA 144835, same data as holotype. Description. Colony encrusting axis of finely branched red-alga, initially biserial for 4–5 zooid generations (Fig. 9A), then becoming pluri-multiserial, up to 8–10 zooidal series wide (Fig. 9B), unilaminar, to 10 mm long, 2.5 mm maximum breadth. Autozooids averaging more than twice as long as wide, of varying length, those at bifurcation of zooid rows being generally a little shorter. Lateral margins straight or, more generally, slightly convex, widest midlength or just proximal to orifice. Distal margin truncate or gently rounded; proximal margin truncate if budded directly from autozooid, typically tapered if budded from zooidal bifurcation. Gymnocystal shield opaque in most zooids, with occasional transverse growth lines. No median carina or series of tubercles; instead, a very stout elevated blunt umbo proximal to and generally slightly curving over the sinus; orifice flanked by 1–2 shorter such prominences (Fig. 9C, F). ZL 500±87, 389–702 (20); ZW 215±14, 177–243 (20). Orifice widest about midlength; sinus deep and wide, not quite parallel-sided (Fig. 9D), ‘shoulders’ of orifice correspondingly short. Condyles small, pointed, variable, set on edge of sinus entrance. OL 114±13, 89–134 (20); OW 97±8, 81–109 (20). Female cystids mostly shorter than autozooids, budded from autozooids or ooecial kenozooids directly or at bifurcation of zooid rows, with a shorter suboral umbo and no lateral prominences. Ovicell prominent, terminal, cleithral; ooecium formed by distal (ooecial) kenozooid and averaging as long as wide, with c. 7–12 scattered pseu- dopores of variable size (Fig. 9C). Dimorphic combined ... |
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