Apiophragma hyalina Waters 1904
Creators: name: Gordon, Dennis P.
name: Taylor, Paul D.
Publisher: name: Zenodo
Year: 2017
Subjects: Biodiversity
Taxonomy
Animalia
Bryozoa
Gymnolaemata
Cheilostomatida
Microporidae
Apiophragma
Apiophragma hyalina

description: Apiophragma hyalina (Waters, 1904)
(Fig. 14)
Megapora hyalina Waters, 1904: 39, text-fig. 1, pl. 2, figs 13a, b.
Apiophragma hyalina: Hayward & Ryland 1993: 120, fig. 1; Hayward 1995: 154, fig. 120E, F.
Material examined. NIWA 23005, NIC Wellington, Stn TAN 0402 /73, 72.0613° S, 173.2455° E – 72.0647° S, 173.2632° E, 620–622 m, NW Ross Sea off Cape Adare, Antarctica, 13 February 2004.
Redescription. Colony encrusting, small, spot-like, maximum spread up to 4.5 mm. Autozooids arranged contiguously in quincunx, communicating via basal pore-chambers, of which two lateral pairs and one mid-distal are visible in zooids at colony margin [ZL400–661 (561); ZW 343–544 (468)]. Gymnocyst continuous around zooid, narrow to moderately well developed. Cryptocyst and opesia surrounded by a distinct pyriform rim constricted at level of proximalmost oral spines [CrL 298–412 (360); CrW 239–350 (317)]. Cryptocystal shelf extensive, flat, with a pair of suboval opesiules. Opesia generally a little wider than long, distal margin rounded and tubercular, straight proximally, constricted in proximal third; articular surface smooth, rounded, operculum occupying c. three-quarters of opesial length [OpL 110–145 (122)]. Six articulated spines, perioral only, all of which are retained in ovicellate zooids, arranged in arc around operculum; 0–2 additional tiny spines on each lateral gymnocyst. No avicularia. Ooecium hyperstomial, acleithral, smooth with longitudinal carina in proximal half, carina occupied by elongate slit or smaller excavation [OoL 217–232 (226); OoW 233–245 (239)]. Ooecial kenozooid protruding a little distally, with small opesial foramen surrounded by semicircular cryptocyst, subgranular to smooth, flanked by pair of smaller pore-chambers. Ancestrula resembling later zooids but with slightly longer opesia and nine pericryptocystal spines [AnL 335–431 (383); AnW 223–305 (264)].
Remarks. Waters (1904) did not describe the ooecium, which meant that his illustration of it was ambiguousis the longitudinal feature on the front a carina or an excavation? This question could not be answered by Hayward & Ryland (1993) as their material was infertile. In the event, it is now seen to be both, viz a carina in which there is an elongate slit or shorter excavation. On the other hand, Waters described and illustrated the tiny gymnocystal spines that were not remarked upon by Hayward & Ryland. Hayward (1995) showed a presumed ancestrula but it had only six oral spines; it is clear from the larger, original SEM photograph in Hayward & Ryland (1993, fig. 1A) [from which figure 120E in Hayward (1995) was cropped] that this was not the actual ancestrula but a daughter zooid.
None of these authors mentioned the ooecial kenozooid in A. hyalina, which is a character also exhibited by Pyriporoides, Olisthella n. gen., Bryobrownius n. gen. and Megapora, suggesting that all of these genera could be phylogenetically related. Waters (1904) and Hayward & Ryland (1993) neglected to suggest a family for A. hyalina, but Waters’ inclusion of the species in Megapora shows that he regarded it as ‘membraniporine’. Hayward (1995) included it in Microporidae, no doubt on the basis of the cryptocystal opesiules. Significantly, Hayward & Ryland (1993) coined the name Apiophragma from “ apios (Gr.), a pear, and phragma (Gr.), a wall, referring to the shape of the mural rim,” which is one of the diagnostic characters of Pyrisinellidae (Di Martino & Taylor 2012). Interestingly, one autozooid in the present material shows a very thin suture line from each opesiule to the opesia. Such a line is to be expected to result developmentally as the cryptocyst calcifies around each opesiular locus (insertion of a parietal muscle), but it may also be indicative of origination of Apiophragma from an ancestor having a larger opesia and lacking opesiules.
Distribution. Antarctica (Ross Sea, Bellingshausen Sea, South Shetland Islands) from 60° to 72° S at 436–622 m depth on pebbles and dead stylasterid hydrocoral.
description: Published as part of Gordon, Dennis P. & Taylor, Paul D., 2017, Resolving the status of Pyriporoides and Daisyella (Bryozoa: Cheilostomata), with the systematics of some additional taxa of Calloporoidea having an ooecial heterozooid, pp. 201-232 in Zootaxa 4242 (2) on pages 223-225, DOI: 10.11646/zootaxa.4242.2.1, http://zenodo.org/record/376356