Pyriporoides uniserialis ( Waters, 1904 )

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, Zootaxa 4242 (2), pp. 201-232 : 204-206

Pyriporoides uniserialis ( Waters, 1904)

( Fig. 2 )

Membranipora uniserialis Waters, 1904: 32 , pl. 2, fig. 2.

Pyriporoides uniserialis: Hayward & Thorpe 1989: 914 , fig. 1A; Hayward 1995: 73, fig. 64.

Material examined. Lectotype: RBINS BRY.392, RBINS, Brussels, SY Belgica Stn 570, 70.3833° S, 82.7833° W, 480 m, Bellingshausen Sea, 8 October 1898 (part of Waters’s figured material). Other material : NHMUK 1995.5.23.4–5, Discovery Stn 190, off Graham Land, Palmer Archipelago, 64.9333° S, 65.5833 W, 93–130 m, 24 March 1927 .

Redescription. Colony comprising encrusting uniserial runners, zooids having a cruciform budding pattern, with a lateral daughter zooid produced more or less at right angles (or shallower) from one or both of the distolateral pore-chambers, rarely from proximolateral pore-chambers (evident in some zooids), or budding is suppressed. Autozooids elongate-pyriform–claviform, with a proximally tapered portion of variable length [ZL 631–920 (805); DL 555–787 (653); CL 60–236 (152); DW 381–498 (439)], the gymnocyst proximally and laterally extensive, sloping to the substratum. Opesia and cryptocystal shelf surrounded by a raised elongate-oval cryptocystal rim that has linear granulations on the edge and inner face [CrL 307–504 (391); CrW 207–293 (257)]. Proximal cryptocystal shelf extensive, flat, evenly granular, the granules becoming a little more pustular at the edge of the opesia, the shelf attenuating distad to the opesiular constriction. Opesia about twice as long as wide, weakly dumbbell-shaped, being constricted by rounded projections that have a tubercular surface; distal (lower edge) and proximal opesial rims gently rounded, the proximal rim sometimes obliquely so [OpL 218–227 (223)]. Operculum flap-like, occupying area of opesia distal to constriction. Articulated spines perioral, six in total, more or less erect, not arching; no accessory gymnocystal spines. Ooecium hyperstomial, frontally a little longer than wide, smoothsurfaced with a short longitudinal peak that contains a small foramen [OoL 200–228 (214); OoW 225–252 (239)]; the distalmost pair of oral spines is so closely appressed to the sides of the ooecium as to leave a crease or furrow on each side when the spine is missing. Ooecial kenozooid projecting beyond ooecium, with a frontal cryptocystal area surrounding a foramen. No avicularia. Occasional kenozooids, usually roundly triangular, within the linear chains of zooids, typically (but not always) forming as a consequence of a developing zooid unable to complete its growth owing to collision with another zooid.

Remarks. Additional material discovered since the first description of the species has provided more metric data for autozooidal variation, as well as information on geographical distribution. Importantly, examination of the lectotype colony figured herein establishes the nature of the ooecium and the presence of an ooecial heterozooid. The longitudinal expression of the frontal crest of the ooecium in Waters’ (1904, pl. 2, fig. 2a) illustration shows it to be proportionally much longer than shown herein in Fig. 2 D, indicating variability of this character. Also, in the lectotype colony figured here, the ooecial kenozooid seems to bear a spine ( Fig. 2 D). The base of the spine is not in evidence, however (or may be concealed), and the possibility cannot be ruled out that a spine from an autozooid has come to lie in this position; in the only other such heterozooid encountered ( Fig. 2 E) there is no hint of a spine or spine base. However, one or a pair of spines is variably seen on the heterozooid in P. circularis ( Fig. 5 C) and P. murdochi n. sp. ( Fig. 8 B). The heterozooid in P. uniserialis also has a lateral pair of pore-chambers.

Waters’ (1904, pl. 2, fig. 2A) depiction of the perioral spines in one zooid shows five pairs, whereas his description (ibid. p. 32) states “there are three or four spines on each side.” Hayward & Thorpe (1989) and Hayward (1995) state that there are only six such spines, confirmed by us, although one zooid in the lectotype material shows what also looks like an additional spine base in a left-proximal position ( Fig. 2 F).

Distribution. Waters’ (1904) specimens encrusted stones and pebbles at depths of 436–480 m in the Bellingshausen Sea west of the Antarctic Peninsula. Additional material from off Graham Land, Palmer Archipelago, occurred at 93– 130 m.

Figures

FIGURE 2. Pyriporoides uniserialis (Waters, 1904), A – D, F, lectotype, RBINS BRY. 392 (unbleached); E, G, NHMUK 1995.5.23.4 – 5 (unbleached): A, part of a colony showing caudate zooids, one of them ovicellate; B, autozooids showing the variable shape of the opesia in each; C, a kenozooid with a pair of autozooids, the one at left apparently budded reparatively from the one at right; D, ooecium with distal expression of the associated heterozooid; E, a broken ooecium with its heterozooid; F, autozooid showing the disposition of oral-spine bases and details of the opesia and cryptocyst; G, autozooid with the membranous frontal wall in place, clearly showing the hinge line of the opercular area. Scalebars: A, 1 mm; B, 400 µm; C, 300 µm; D, E, 100 µm; F, G, 200 µm.

FIGURE 5. Pyriporoides circularis (Gordon, 1989), NIWA 95680: A, profile of zooids with broken ooecia; B, close-up of proximofrontal ooecial fenestra; C, D, frontal views of two ooecia, showing the narrow peripheral extension of the ooecial kenozooid, that in C with a single spine-base. Scalebars: A, 500 µm; B, 50 µm; C, D, 100 µm.

FIGURE 8. Olisthella plana n. gen., n. sp., holotype, NIWA 95617: A, part of colony with autozooids and ovicellate zooid (arrows indicate tiny spine-bases on lateral gymnocysts); note the distal exposure of the ooecial kenozooid, with an extensive cryptocystal area. Pyriporoides murdochi n. sp. B – D, holotype, NIWA 136; E, unregistered: B, ovicellate zooid (note the spined ooecial kenozooid and the paired distal spines on the lateral gymnocyst of the maternal zooid); C, autozooids, showing short caudae; D, disposition of autozooidal spines; E, ancestrula. Scalebars: A, 500 µm. B – D, 200 µm; E, 100 µm.