Pachycerianthus fiordlandensis, Stampar & Mills & Keable, 2020

Stampar, Sérgio N., Mills, V. Sadie & Keable, Stephen J., 2020, Ceriantharia (Cnidaria) from Australia, New Zealand and Antarctica with Descriptions of Four New Species, Records of the Australian Museum 72 (3), pp. 81-100 : 83-85

Pachycerianthus fiordlandensis sp. nov.

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Figs 2–4 , Table 1

Cerianthus bollonsi Wing, 2003 (p. 247, in image caption); Wing, 2008 (p. 35 in image caption and p. 46), nomen nudum. (The name is cited, but there is no formal description of the species or designation of type material so it does not meet the criteria for acceptance as defined by the ICZN).

Holotype. NIWA Invertebrate Collection ( NIC)— NIWA 139391 New Zealand, off Moeraki , Otago, 45.30°S 170.80°E (vii/1970), depth 82 m. Paratypes. New Zealand— NIWA 139397 Doubtful Sound, Fiordland, New Zealand Oceanographic Institution ( NZOI) Station O 869, 45.44°S 167.12°E (07/iii/1985), depth 5–35 m, (1 specimen) ; NIWA 139400 Milford Sound, Fiordland , NZOI Station W27, 44.66°S 167.91°E (13/xi/1985), depth 3–26 m, (1 specimen) ; NIWA 56235 Great Exhibition Bay , Northland , RV Tangaroa Station TAN0906/140, 34.57°S 173.20°E to 34.57°S 173.21°E (13/vii/2009), depth 117–120 m, (1 specimen) ; NIWA 35103 Milford Sound, Fiordland, 44.58°S 167.78°E (03/ix/1996), depth 20–25 m (3 specimens) .

84 Records of the Australian Museum (2020) Vol. 72 Diagnosis. Marginal tentacles brown to light brown. Six mesenteries attached to siphonoglyph, very long P2 mesentery, long m mesenteries and presence of directive labial tentacle.

Variation. Slightly long (up to 110 mm long) and thin (20–25 mm width) cerianthid; 60–88 brown to light brown ( Fig. 1 ) marginal tentacles (110–120 mm in preserved specimens), arrangement 1243.2314.2314…, with more than 6 pores per tentacle, 56–72 dark brown labial tentacles (up to 50 mm long in preserved specimens), arrangement (2)312.1321.3213…, unpaired labial tentacle present; pleated stomodeum extending over 1/4 of total body length, hyposulcus 4–6 mm long, hemisulci distinct; siphonoglyph rather narrow, connected to directives, P2 and P3 (6 mesenteries); free parts of sterile directive mesenteries 1/3 of length of siphonoglyph, without mesenterial filaments. Second protomesenteries long, 2/3 of gastral cavity, fertile, bearing ciliated tracts with bundles of craspedonemes, with short (1/5 of mesentery length) cnido-glandular tract and long (~90% of the mesentery) craspedion tract. Third protomesenteries sterile, three times longer than directives, with short craspedonemes. M and m-metamesenteries long, fertile; M1 and M2 reaching almost aboral pore (M2 shorter than M1), with bundles of craspedonemes; B and b-mesenteries, steriles, B longer than b; see Fig. 3 for schematic arrangement of mesenteries. The cnidome of the species ( Fig. 4 ) is composed of spirocysts, atrichs, microbasic b-mastigophores (four types) and ptychocysts distributed as shown in Table 1.

Holotype description ( NIWA 139391). Somewhat elongated polyp, 9.6 cm long, 25 mm diameter just below marginal tentacles and 20 mm near aboral end. Marginal tentacles 88, arranged in four pseudocycles, 110–120 mm long and 2 mm in diameter near the base, light brown. The space between cycles of marginal and labial tentacles brown colored. Labial tentacles 72, about 50 mm long, dark brown, directive labial present, arrangement of marginal tentacles 1243.2314.2314… and labial tentacles (2)312.1321.3213… Oral disk 25 mm wide, stomodeum 24 mm long, dark brown, siphonoglyph narrow and elongate with 6 mesenteries attached, hyposulcus 3 mm long with short hemisulci 1.5 mm long. Free parts of directive mesenteries without mesenterial filaments. Second protomesenteries with 2/3 of gastral cavity, fertile, bearing ciliated tract with bundles of craspedonemes. Third protomesenteries sterile, three times longer than directives, with short craspedonemes. M1 and M2 reaching almost aboral pore (M2 shorter than M1), with bundle of craspedonemes; B and b-mesenteries, sterile, B longer than b.

Remarks. Specimens of this species have previously been recorded in photographs by divers ( Fig. 2A,B ) and discussed in some general books on marine biodiversity for the coastal region of New Zealand (e.g., Cairns et al., 2009; Grange et al., 1981 (as Cerianthus sp.); Grange & Brook, 2010; Wing, 2003, 2008 [as Cerianthus bollonsi ]). It is noted by divers for its long flowing tentacles and very rapid “disappearing act” when disturbed (Francis, pers. comm.; Wing, 2008). The species ranges from shallow areas from about 15 m to around 100 m deep. This wide range is not very common in Ceriantharia , except for a few species such as Ceriantheopsis americana and Pachycerianthus borealis ( Shepard et al., 1986) . It is usually found in an upright position with its tube buried in coarse sediments or shell hash on sand slopes or sediment filled ledges in the deep rock wall zones in the fiords (Grange et al., 1981; Wing, 2003; Woods, pers. comm.). All specimens had well developed gonads with deep orange oocytes. This has also been observed in other species of the genus, such as Pachycerianthus schlenzae (Stampar et al., 2014) and may be linked to high levels of egg yolk.

Distribution. New Zealand and adjacent areas (from shallow waters to 120 m).

Etymology. The specific name “ fiordlandensis ” is based on the area of occurrence, Fiordland, New Zealand, in which specimens are commonly observed.

Figures

Figure 1. Specimens of Pachycerianthus delwynae in New South Wales, Australia. (A, B) Tentacles with longitudinal lines and (C, D) banded tentacles. Images: Tony Strazzani.

Figure 2. Specimens of Pachycerianthus fiordlandensis sp. nov. (A) Dusky Sound specimen, Fiordland, New Zealand, photo by Malcolm P. Francis; and (B) Milford Sound specimen, Fiordland, NZ, photo by Chris Woods; (C, D) holotype, NIWA 139391.

Figure 3. Graphical representation of the arrangement of mesenteries of Pachycerianthus fiordlandensis sp. nov. Abbreviations: M.C., multiplication chamber; dm, directives; T.P., terminal pore; S, siphonoglyph; B, betamesenteries (convoluted mesentery); M, metamesenteries (double filament); P, protomesenteries.

Figure 4. Cnidome of Pachycerianthus fiordlandensis sp. nov. based on two specimens (NIWA 139391; 139400).