Pyrostephos vanhoeffeni Moser, 1925

Verhaegen, Gerlien, Cimoli, Emiliano & Lindsay, Dhugal, 2021, Life beneath the ice: jellyfish and ctenophores from the Ross Sea, Antarctica, with an image-based training set for machine learning, Biodiversity Data Journal 9, pp. 69374-69374 : 69374

Pyrostephos vanhoeffeni Moser, 1925

Materials

Type status: Other material. Occurrence : individualID: MCMEC2019_ Pyrostephos _vanhoeffeni_a; lifeStage: adult; associatedMedia: "http://morphobank.org/permalink/?P3993", "https://youtu.be/R5E_HAW49DM", "https://youtu.be/o0XGpFavjyo", "https://youtu.be/QAADM0MERIo", "https://youtu.be/zEA6-7-qcYI", "https://youtu.be/SbuAA2nEVnU"; Taxon : scientificName: Pyrostephos vanhoeffeni; kingdom: Animalia ; phylum: Cnidaria ; class: Hydrozoa ; order: Siphonophorae ; family: Pyrostephidae ; genus: Pyrostephos ; Location: continent: Antarctica; waterBody: McMurdo Sound; maximumDepthInMeters: 1; decimalLatitude: -77.637; decimalLongitude: 166.401; Identification: identifiedBy: Dhugal Lindsay; Event: samplingProtocol: Sony Alpha 7 III camera equipped with a FE 90mm F2.8 Macro G OSS lens; eventDate: 2019-11-25; Record Level: type: StillImage, Video; language: en; rightsHolder: Emiliano Cimoli Type status: Other material. Occurrence : individualID: MCMEC2019_ Pyrostephos _vanhoeffeni_b; lifeStage: adult; associatedMedia: "http://morphobank.org/permalink/?P3993", "https://youtu.be/tW2Ko92f3Bo", "https://youtu.be/2rrQCybEg0Q", "https://youtu.be/G9tev_gdUvQ", "https://youtu.be/NfJjKBRh5Hs", "https://youtu.be/1-aLzxLpzWs", "https://youtu.be/HnaIASH9yM0", "https://youtu.be/OSTJ3ldg63w", "https://youtu.be/d7OPyXn 64g 4", "https://youtu.be/YE50FZg8mpU", "https://youtu.be/csUoJl5Mapc", "https://youtu.be/uc6cP0YSrwc"; Taxon : scientificName: Pyrostephos vanhoeffeni; kingdom: Animalia ; phylum: Cnidaria ; class: Hydrozoa ; order: Siphonophorae ; family: Pyrostephidae ; genus: Pyrostephos ; Location: continent: Antarctica; waterBody: McMurdo Sound; maximumDepthInMeters: 1; decimalLatitude: -77.637; decimalLongitude: 166.401; Identification: identifiedBy: Dhugal Lindsay; Event: samplingProtocol: Sony Alpha 7 III camera equipped with a FE 90mm F2.8 Macro G OSS lens; eventDate: 2018-11-29; Record Level: type: StillImage, Video; language: en; rightsHolder: Emiliano Cimoli

Distribution

Antarctica: Ross Sea from under the ice ( Totton 1965), from the Antarctic convergence to the south of the Bellingshausen and Weddell Seas ( Mackintosh 1934), Croker Passage in the Antarctica Peninsula ( Hopkins 1985, Panasiuk-Chodnicka et al. 2014, Panasiuk-Chodnicka and Żmijewska 2010), Drake Passage ( Panasiuk et al. 2018), South Georgia Island ( Alvariño 1981, Hardy and Gunther 1935), Weddell Sea ( Pagès and Kurbjeweit 1994, Pagès and Schnack-Schiel 1996, Pagès et al. 1994, Panasiuk et al. 2018, Pugh et al. 1997), Falkland Islands ( Alvariño 1981), Lützow-Holm Bay ( Toda et al. 2010), Gauss Station ( Moser 1925), D’Urville Sea ( Grossmann 2010, Toda et al. 2014), Cosmonaut and Cooperation Seas ( Margulis 1992), off the southern Victoria Land coast (71°2'S, 166°24'E) ( Alvarino et al. 1990), east Antarctic (90°E) ( Totton 1965); north of the Antarctic Convergence (54°6'S, 119°54'W) ( Alvarino et al. 1990); Southern Chilean Fjords ( Palma 2006); South Atlantic Ocean ( Panasiuk et al. 2018), Argentina continental shelf ( Araujo et al. 2013) and San Matias Gulf ( Guerrero et al. 2013); New Zealand ( Cairns et al. 2009).

Notes

Original description after Moser (1925) (Fig. 7 A-B): The original description is convoluted with much misapplied terminology, which was clarified and represented by Totton (1965), whose description we present below. Syntypes locality: Gauss Station (66.03°S, 89.63°E), Antarctica.

Description after Totton (1965) of specimens at longitude 90°E, just off the Antarctic continent and from the Ross Sea from under the ice: we updated the terminology to describe Siphonophorae as in Pugh (2019). Pneumatophore: apex not pigmented. Nectosome: relatively long, two rows of nectophores. Nectophores: minimum 20 mm in length, carried on narrow muscular lamellae, which are inserted into a long bow-shaped mantle (i.e. “pallial”) canal that lies in a groove on the pedicular side (i.e. "adaxial side" in original description) of the nectophore. The pedicular canal (i.e. "adaxial canal") bifurcates almost at once to form the upper (i.e. “dorsal”) and lower (i.e. “ventral”) radial canals. The two lateral radial canals arise separately from the upper canal and take an outward and ascending course on the pedicular nectosac-wall to cross over on to the lateral wall of the same. Here, each form first a small downward loop and then the main downward, lateral loop. After crossing under a fold in the lateral wall, each makes a final downward loop to run to the circular canal round the ostium. The lower radial canal is generally straight, but may have a few small bends. The upper canal usually has three or four more marked bends on the upper part of the nectosac. Nectosac has inpushing of the proximal (i.e. adaxial) side of its median part, absence of musculature from the median wall part similar to Bargmannia spp. or Marrus spp. Siphosome: dioecious (single-sexed), gonophores budding from one another to form small bunches, with male gonophores sausage shaped (size at maturity 1.3 × 0.5 mm) or female gonophores ovoid (0.5 mm in diameter), containing three to five eggs arranged meridionally and giving external appearance of the seams of a football. Continuous ventral line of budding gastrozooids (on the unsegmented stem), with young gastrozooids having an almost cylindrical basigaster and a conventional tentacle arising from a point very close to the junction of the basigaster with the pedicel (or pedicle). Mature gastrozooids (15 × 2 mm) spindle-shaped, consisting of three sections: the basigaster, the main stomach and a proboscis. Endodermal wall of the stomach vacuolated and consisting of four main types of cells. Each vacuole (ca. 0.07 mm in diameter) surrounded by 4-5 smaller more irregular vacuolated cells and forming transparent patches visible through the stomach wall. Small darker conical-shaped secretory cells (smaller than the large vacuoles) present in endoderm, located at the intersection of several cell boundaries, with their hemispherical surfaces projecting into the lumen of the gastrozooid and carrying stiff cilia (ca. 0.01 mm in length), similar to those described in the palpons of Apolemia by Willem (1894). Tentilla, up to 50 per tentacle. Hypertrophy of axial canal develops thickened mesogloeal walls and appears to form the extensile part of the cnidobattery, which has not been noted in any other species. It probably acts as an extensor on activation of the mechanism when the proximal end of the cnidoband breaks away from the pedicel and the whole cnidoband turns end to end and is flung on to the prey. In an early growth stage, the axial canal of a tentillum runs uniformly from the tentacle axis to the tip of the straight and short terminal filament. From the proximal end of this terminal filament, a diverticular canal of the axial canal runs back towards the pedicel alongside the proximal part of the axial canal. The epidermis on the opposite side to the axial canal of this diverticular canal forms the cnidoband. As growth proceeds, the lumen of the diverticular canal that lies under the cnidoband, comes to exceed the diameter of the axial canal and forms the cavity of the saccus. Five to seven lateral ovoid nematocysts (0.28 × 0.04 mm), located at the base of the tentillum’s saccus (i.e. "cnidosac"), which do not enter the wall of the saccus through the pedicel until the terminal filament, still in its straight uncoiled condition, reaches almost 0.5 mm in length. These nematocysts contain a large central structure which is probably the shaft with spines. The bracts (after Moser 1925) up to 23 × 14 mm in size, very thick, flat underneath, convex above,and proximally coming to a long point much broadened distally and irregularly toothed. The bracteal canal is slender, drawn out and ends some distance from the distal end, the latter seems to be three pointed. In early growth stages, a shallow horizontal pocket is found on the upper side between the lateral pair of points. The palpons (i.e. oleocysts) seem to be arranged at the dorsal edges of the ventral tract of siphosomal appendages, as if to buoy up the stem. Colour: stem orange in adults, vermilion in juveniles; nectophores wine red in adults, pink in juveniles; ostia carmine; gastrozooids golden red with fiery red mouth; cnidosacs fiery red.

Description of and comments on observed material (Fig. 7 C-H): N = 3 in 2018, N = 4 in 2019. Pneumatophore: non-retractable transparent tube (Fig. 7 F). Nectosome: up to 12 pairs of nectophores (Fig. 7 C), lacking axial wings. A colony was observed jetting backwards (https://youtu.be/YE50FZg8mpU, https://youtu.be/uc6cP0YSrwc) by angling the ostial velum of the nectophores to deflect extruded water anteriorally (Fig. 7 E). A similar velum alteration during forward and reverse swimming was previously observed in the physonect Nanomia bijuga ( Mackie 1964, Costello et al. 2015). Ostium colourless (Fig. 7 D). Siphosome (Fig. 7 G-H): gastrozooids elongated, transparent and pink, oleocysts spherical to fusiform, oleocyst cavity transparent and bright red, the colour red being the brightest at the stem end of the oleocyst. Distal ridges of the bracts appear to be lined with nematocysts. Tentacles either contracted between the bracts or hanging down the siphosome with numerous white tentilla per tentacle. The number of pairs of nectophores vs. the minimum number of cormidia were counted for four individuals: 3p/31, 10p/27, 8p/12 and 12p/45.

Figures

Figure 7. Pyrostephos vanhoeffeni. Drawing from the original account by Moser (1925) of a juvenile specimen (length ca. 25 mm) missing the pneumatophore and distal end (A) and a piece (length 6 mm) of another specimen including the nectosome with pneumatophore, but missing nectophores and a part of the siphosome (B), from Gauss Station, Antarctica. C-F. Specimen MCMEC 2019 _ Pyrostephos _ vanhoeffeni _ b observed on 29 / 11 / 2019: whole specimen (C), apex nectosome (D), part of nectosome when contracting (E) and pneumatophore (F). G-H. Siphosome of specimen MCMEC 2019 _ Pyrostephos _ vanhoeffeni _ a observed on 25 / 11 / 2019. Abbreviations: g., gastrozooids; nc., nectophore; ne., nematocysts; os., ostium; os. v., ostial velum; ol., oleocyst; pn., pneumatophore; s. b. z., siphosomal budding zone; t, tentacles. C-H photos courtesy: E. Cimoli.