Diplulmaris antarctica Maas, 1908

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

Diplulmaris antarctica Maas, 1908

Materials

Type status: Other material. Occurrence : individualID: MCMEC2019_ Diplulmaris _antarctica_a; lifeStage: adult; associatedMedia: "http://morphobank.org/permalink/?P3993", "https://youtu.be/qKnd53wZVZo"; Taxon : scientificName: Diplulmaris antarctica; kingdom: Animalia ; phylum: Cnidaria ; class: Hydrozoa ; order: Semaeostomeae ; family: Ulmaridae ; genus: Diplulmaris ; 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: 2019-11-16; Record Level: type: StillImage, Video; language: en; rightsHolder: Emiliano Cimoli Type status: Other material. Occurrence : individualID: MCMEC2019_ Diplulmaris _antarctica_b; lifeStage: juvenile; associatedMedia: "https://youtu.be/q9pcie-ri9M", "https://youtu.be/33EccdfSTh8", "https://youtu.be/kki0KyhFdUc"; Taxon : scientificName: Diplulmaris antarctica; kingdom: Animalia ; phylum: Cnidaria ; class: Hydrozoa ; order: Semaeostomeae ; family: Ulmaridae ; genus: Diplulmaris ; 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: 2019-11-30; Record Level: type: StillImage; language: en; rightsHolder: Emiliano Cimoli Type status: Other material. Occurrence : individualID: MCMEC2019_ Diplulmaris _antarctica_c; lifeStage: juvenile; associatedMedia: "http://morphobank.org/permalink/?P3993", "https://youtu.be/pLlGoqwDZMs", "https://youtu.be/4PbHRjs4JVQ", "https://youtu.be/fh1rmQ_piZ8", "https://youtu.be/9MZ2BrZBLvE", "https://youtu.be/ce7Rvhf_8rw", "https://youtu.be/4XyQIQw04vs", "https://youtu.be/qDyH3_mnVBs", "https://youtu.be/NYDEDKs8PR0", "https://youtu.be/6EMBHjnJ7cU"; Taxon : scientificName: Diplulmaris antarctica; kingdom: Animalia ; phylum: Cnidaria ; class: Hydrozoa ; order: Semaeostomeae ; family: Ulmaridae ; genus: Diplulmaris ; 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: 2019-12-01; Record Level: type: StillImage, Video; language: en; rightsHolder: Emiliano Cimoli

Distribution

Southern Ocean: off Anvers Island, Antarctic Peninsula ( Maas 1908), Ross Sea (USNM 53827, 58897) ( Larson 1986, Browne 1910) and north of Ross Sea (62.408°S, 159.608°W, USNM 58895), Bellingshausen Sea ( Larson 1986), Davis Sea ( Larson 1986), off Dumont d’Urville ( Thiebot et al. 2016, Toda et al. 2014), Gauss Station (as Ulmaropsis drygalskii , Vanhöffen 1908), off cape Adare ( Browne 1910) and in Prydz Bay ( Australian Antarctic Data Centre 2018a, Hosie 1999b, Hosie 1999a). Although also reported from Madagascar ( Richmond 1997) and the Indo-Pacific ( van der Land 2008), these records are deemed unreliable and were probably misidentifications of Diplulmaris malayensis Stiasny, 1935.

Notes

Original description after Maas (1908) (Fig. 8 A,Fig. 9 A): medusa with 16 rhopalia, 16 tentacles and 32 marginal lappets, regularly alternating, with narrow canals, ramified at the periphery, connected through a circular canal. Early stage (15 mm diameter) (Fig. 8 A): short manubrium, with quadrangular basal part more developed than its lips, the latter with little incisions, interradial arcs carrying the gastric filaments highly visible, also indicating the radius of the gonads, recognisable by a notch of the sub-umbrella with ectoderm and endoderm. Gastro-vascular system not consisting of pockets, but of real canals, due to the width of the merging anastomoses (i.e. “cathamnes” in the original French version). Two types of canals extend from the coronal base of the stomach (i.e. "basigaster coronaire"), distinctively separated at their origin: the canals in the radius of the 16 rhopalia and those in the radius of the tentacles, the former being separated close to their origins by anastomoses into a larger principal radial canal and into two lateral canals. The canals in the radius of the tentacles are divided into eight larger canals, similar to the canals in the axis of the rhopalia, with these eight canals being narrower in the axis of the less-developed tentacles compared to those in the axis of the largest tentacles. All those radial canals are reunited by a narrow continuous circular canal, which does not extend into the lappets themselves. The 16 statocysts are typically club-shaped and regularly placed. Of the 16 tentacles, eight are large and of equal size, the other eight are smaller and of inequal size. The bell margin is incised into 16 large primary lappets at the radius of the tentacles, with these incisions being the deepest in the radius of the eight large tentacles, whereas the eight other incisions at the smaller tentacles are shallower and more unequal, with some barely incised at all. The 16 incisions in the radius of the statocysts are shallower, but of equal depth, dividing each primary lappet into two secondary ones. Adult stage (35-40 mm diameter, description based on one quadrant) (Fig. 9 A): the incisions are more or less equal and the difference in size amongst tentacles is less marked. The disc grew mainly in the area located between the stomach and the periphery of the lappets. The canals were elongated and became single lanes of communication between the central sinus and the peripherical network, the latter being formed due to the increased complexity of the canal branches without significant growth, the mesh becoming, therefore, more irregular. Gonads more distinct. Type locality: Antarctica, off Anvers Island (during the French Antarctic Expedition with the " Français " vessel).

Additional information from specimens from the Southern Ocean: from Gauss Station as Ulmaropsis drygalskii ( Vanhöffen 1908), description matching with the original of Maas (1908), 96 bases of canals leaving the stomach. Meta-ephyra stage: for medusa of 15 mm diameter, the beginning of the formation of lateral canals emerging from the canal in the axis of the rhopalia can be observed, at 17 mm diameter, these lateral canals are more defined and, by 22 mm diameter, two pairs of lateral canals are present, although the anastomoses for these canals are still missing; from the Ross Sea ( Browne 1910) (Fig. 8 B), ephyra stage (smallest 4-5 mm in diameter), with 16 fairly long arms divided into two flat lobes, 32 straight unbranched radial canals, 16 of which directly run from the stomach to the rhopalia and alternating with 16 in the axis of the tentacles, the latter developed slightly later than the rhopalial canals. Tentacles in rudimentary stage, either as bulb-like buds, tapering elongated buds or minute tentacles. In the smallest ephyra, only four of those tentacular buds present and an additional 12 buds develop, in irregular intervals and without any definite order, as the medusa grows. Stomach small and circular, with four gastric filaments (number increasing as medusa grows), with one filament in each group much longer than the others in the early developmental stages. Mouth simple large opening, without any definite lips or arms, which appear later. Ex-umbrella covered with small clusters of nematocysts, which, in later stages, will be confined to the aboral side of the marginal lobes. Circular canal formed by outgrowths from the radial canals and formed before the branches of the rhopaliar canals begin to develop. Meta-ephyra stage (15-25 mm diameter) similar to Maas (1908). Adult stage (three specimens of diameter between 60-75 mm, none of which were complete), umbrella thin, margin of the mouth studded with warts and short protuberances containing nematocysts, stomach is a flat circular cavity (size 2/3 of umbrella diameter), covered in a moderately thick layer of mesoglea on its lower side. Radial canals as described by Maas (1908). Gonads narrow band on the outer side of the gastric filaments, protruding from the stomach and hanging down from the sub-umbrella and becoming broader and sinuously folded when further developed. Tentacles hollow and laterally compressed, especially in their basal portions, but the distal portion is rounder and tapers off to a slender tip. Along the whole inner side of the tentacle runs a band, closely studded with nematocyst clusters. In fully-grown tentacles, the inner cavity has transverse folds. Number of rhopalia and tentacles same as Maas (1908). Rhopalia not well-protected, situated on the wall of the niche formed by the marginal lobes and pointing upwards to the aboral side of the umbrella. Rhopaliar canal, leading from the circular canal to the sense organs, broad and flat. Over the rhopaliar canal and on the surface of the umbrella, a small patch of darkly-coloured cells is present, forming a rudimentary dorsal sensory pit, which is occasionally absent. Ex-umbrella side of marginal lobes covered in numerous warts containing nematocysts. Lobes show slight variation in shape and fill up the space between the sense organs and the tentacles; from the Bellingshausen Sea, Ross Sea and Davis Sea ( Larson 1986) (Fig. 9 B-D), adult stage (bell diameters 90-180 mm), umbrella mesoglea thin, ex-umbrella smooth, rounded or pointed marginal lappets, 16 rhopalia alternating with 1-3 marginal tentacles. Tentacles (number between 16 and 48), laterally compressed, with abaxial nematocyst warts along their length. Four oral arms, frilled, curtain-like, length ca. equal to bell diameter, lip margin studded with nematocyst papillae. Four gonads, everted and sac-like. Gastrovascular canals between 32-96. Rhopaliar canals 16, with 1-5 interjacent tentacular canals between each rhopalium. All canals proximally unbranched for inner 1/2- 2/3 of length, distally anastomosing in an irregular network. Ring canal near umbrella margin. Colour: umbrella colourless, tentacles whitish, gastrodermis of stomach and of oral arms reddish-orange.

Additional information from specimens from outside the Southern Ocean: to our knowledge, no specimens have been described outside the Southern Ocean. The records from Madagascar ( Richmond 1997) and the Indo-Pacific ( van der Land 2008), are not accompanied by photographs or morphological descriptions and, although the sketch/illustration of " Diplulmaris antarctica " in Richmond (1997) shows the characters of the genus, both records are deemed mis-identifcations of Diplulmaris malayensis Stiasny, 1935, or another presently undescribed congener. Expatriation of Southern Ocean species is not unknown, so further surveys in southern Africa, Chile or New Zealand should carefully investigate the species-specific characters.

Comments on observed material: N = 3 in 2019 [two juveniles (Fig. 8 G-H) and one adult specimen (Fig. 9 E-F), based on the ramification of peripheral canals]. Bell diameter of one juvenile specimen, ca. 50 mm; ex-umbrella covered in warts and cnidocysts, these warts being large and pointy in young medusa and smaller and rounder in the adult specimen; dorsal surface of marginal lappets covered in cnidocysts; transparent tubular gastric filaments rooted at the four corners of the manubrium; gastrodermis of adult orange; oral arms transparent, length ca. same as bell radius, with frilled edges; tentacles white with yellow segmented dorsal side; hyperiids attached to ex-umbrella; small transparent Beroe sp. in stomach of adult specimen.

Figures

Figure 8. Juvenile Diplulmaris antarctica. A. Drawing from the original description (modified from Maas 1908) of a juvenile specimen (diameter 15 mm), oral view, from off Anvers Island, Antarctica; B. Drawing of a specimen in an early (left) and more advanced (right) ephyra stage from the Ross Sea, Antarctica (modified from Browne 1910); C-E. Juvenile specimen MCMEC 2019 _ Diplulmaris _ antarctica _ b observed on 30 / 11 / 2019: apico-lateral view (C), lateral view (D), apico-lateral view when contracted (E) and apical view (F). G-H Juvenile specimen MCMEC 2019 _ Diplulmaris _ antarctica _ c observed on 1 / 12 / 2019: apical view (G) and oral-lateral view (H). C-H photos courtesy: E. Cimoli.

Figure 9. Adult Diplulmaris antarctica. A. Drawing from the original description by Maas (1908) of a bell portion of an adult specimen (diameter 35 - 40 mm), oral view, from off Anvers Island, Antarctica; B. Photography of sub-umbrella view of the gastrovascular canals of a specimen (diameter 18 cm) from McMurdo Sound (Operation Deep Freeze II station 61 - D) (Larson 1986); C-D. Drawing of the sub-umbrella view of a specimen (diameter 10 cm) from McMurdo Sound (Operation Deep Freeze II station 61 - D) (Larson 1986); E-F. Sub-umbrella (E) and apicular (F) views of an adult specimen MCMEC 2019 _ Diplulmaris _ antarctica _ a observed on 16 / 11 / 2019 eating a Beroe sp. Gv: gastrovascular canal, rc: ring canal, rh: rhopalium, te: tentacle. E-F photos courtesy: E. Cimoli.