Pyriporoides aviculata, Gordon, Dennis P. & Taylor, Paul D., 2017

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 : 211-212

Pyriporoides aviculata n. sp.

( Fig. 7 )

Material examined. Holotype: NIWA 98178 , NIC Wellington, Stn TAN 1503 /68, 42.7895° S, 179.9207° W – 42.7888° S, 179.9223 W, 932–1005 m, Diabolical Seamount, Graveyard Seamounts, Chatham Rise , New Zealand, 4 April 2015. Paratype: NIWA 98179 , same data as for holotype.

Etymology. Alluding to the presence of well-developed avicularia.

Description. Colony comprising encrusting uniserial runners, zooids having a cruciform budding pattern with a daughter zooid produced from a pore-chamber on either side of the widest point of the zooidal dilatation, more or less at right angles (or budding is suppressed); no other lateral pore-chambers; total colony spread c. 12 mm. Autozooids elongate-pyriform–claviform, with a proximally tapered portion about a third to a half of total zooid length [ZL 621–889 (766); DL 489–578 (542); CL 121–334 (223); DW 321–389 (346)], the gymnocyst proximally and laterally extensive, sloping to the substratum. Opesia and cryptocystal shelf surrounded by a raised elongateoval cryptocystal rim that is evenly horizontal and minutely tubercular on the inner face [CrL 221–312 (269); CrW 167–212 (190)]. Proximal cryptocystal shelf less than a third of the length of the oval cryptocystal rim, flat, gently sloping towards opesia, narrowing on each side towards opesial constriction, surface smooth. Opesia more or less dumbbell-shaped, constricted in middle part by blunt or rounded projections that have a weakly tubercular surface; lower edge of distal opesial rim more or less straight, proximal opesial rim generally evenly rounded [OpL 110– 167 (144)]. Operculum flap-like, occupying area of opesia distal to constriction. Articulated spines pericryptocystal, 13–17 in total, the two distal spine pairs thin and more or less erect; the next two proximal pairs stoutest, slightly curved, directed frontalwards, the remaining spines all arching over the opesia, the most proximal ones slightly overlapping. No additional spines borne on the gymnocyst. Ooecium almost as wide as long, smoothsurfaced, with only a thin median suture line, its opening apparently not closed by zooidal operculum [OoL 232; OoW 224]. Ooecial heterozooid always avicularian, with very long, tapering, narrow rostrum that projects beyond edge of cystid; foramen longitudinally oval, rostral tip slightly rounded but mandibular tip acute. Occasional avicularia within the linear chains of zooids, the rostrum not always protruding beyond distal margin of cystid [AvL 367–556 (469); AvW 156–211 (187)]. Ephebic zooids may have a contained kenozooid that forms a closure plate; a subcentral foramen may have a hooded cover. Ancestrula elongate-oval, like later zooids but lacking a cauda, with 15 pericryptocystal spines [AnL 456; AnW 244]; distal daughter zooid with 14 spines; proximal daughter zooid with 13 spines.

Remarks. This species is very close to P. libita , which it resembles in having a smooth cryptocystal shelf, tubercular (weakly so) opesial projections, and an ooecium with only a thin median suture line. It differs most obviously in having a larger number of spines (which completely overarch the opesia), interzooidal avicularia, and ooecial heterozooids that are always avicularian, never kenozooidal.

Distribution. Endemic to the Chatham Rise, where it is known only from the Graveyard Seamount complex at depths of 932–1005 m.

Figures

FIGURE 7. Pyriporoides aviculata n. sp. A – D, F, G, holotype, NIWA 98178; E, paratype, NIWA 98179: A, colony with ancestrula (an), interzooidal avicularium (av) and other zooids including one that is ovicellate; B, laterally budded interzooidal avicularium; C, ovicellate zooid with associated avicularian heterozooid; D, E, zooids with and without spines, respectively showing spine disposition and the opesia and cryptocyst; F, ancestrula, the closure plate with a tiny hooded pore; G, proximal zooid budded from ancestrula, with kenozooidal closure. Scalebars: A, 1 mm; B, D, E, G, 100; C, F, 200 µm.