Corresponding author: Julian Uribe-Palomino (
Academic editor: J. Reimer
Two new species of small hydromedusae were found during routine monitoring in coastal waters of eastern Australia and are here described. The first,
Uribe-Palomino J, Pausina S, Gershwin L-a (2018) Two new species of Hydromedusae from Queensland, Australia (Hydrozoa, Leptothecata). ZooKeys 783: 17–36.
Increasing global scientific attention on jellyfish has focused mostly on large and conspicuous species; however, approximately 90% of jellyfish species are small and rarely noticed (
Around Australia, gelatinous zooplankton are now routinely monitored along with other plankton, under the umbrella of the Australian Plankton Survey, a collaboration between the Integrated Marine Observing System (
Seven species of the genus
Here, we describe two new species from Queensland coastal waters, the first,
Specimens were collected as part of four separate studies in Queensland, Australia, three in the subtropics and one in the tropics. The locations where the specimens were found and the distribution of their congeners is shown in Figure
Study 1: University of Queensland PhD project (Sarah Pausina), four specimens December 2010 to April 2011. Specimens were collected as part of a study on the zooplankton community dynamics within Moreton Bay, a shallow subtropical embayment. Stations along a salinity and nutrient gradient were sampled from the eutrophic Brisbane River mouth to the oligotrophic, oceanic-influenced Rous Channel. A 0.2 m mouth diameter, 100 µm mesh net fitted with a non-filtering cod-end (0.75 L) was towed horizontally within 1 m of the surface at approximately 1 m s-1 for 3-5 minutes during daylight hours.
Study 2:
Study 3:
Study 4:
Samples collected from the different projects were fixed and preserved in 10% formalin.
All specimens were examined in a preserved state. Bulk samples were sorted under a Leica M165C stereo microscope. Specimens were photographed with a Canon EOS-5D camera adapted to the microscope by a 2.5x Leica optical tube. High quality images of the specimens were produced by stacking multiple pictures from different depth planes with Helicon focus 6.7.1 software.
Nematocyst slides from
Distribution maps were produced using the packages ‘map’ and ‘mapdata’ for the statistical computing and graphics software R 3.3.3 (R-Project) and the application RStudio 1.1.136 (RStudio).
Non-English descriptions were converted to text with OnlineOCR (
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QM G335903, very poor condition, BD ca. 2 mm (Not figured), Moreton Bay, Queensland, Australia,
QM G335902, Male, BD ca. 2.4 mm, hemi-gonad: 0.8-0.9 mm x 0.3 mm, tentacle bulbs seven (five well developed, plus two small ones), base ca. 0.6 mm (Figure
QM G335900, Male, flattened specimen, BD ca. 2 mm. (Not figured); Moreton Bay, Queensland, Australia,
QM G335901, Female, flattened specimen, eigth tentacles, BD ca. 2 mm (Figure
QM G335905, QM G335906, microscope slide nematocyst preparations, Moreton Bay, Queensland, Australia,
Umbrella isosceles trapezoid-shaped in lateral view, aborally flattened, with the margin curving inwards at the edges, possibly due to preservation (Figure
Tentacles eight, six fully developed and two incompletely developed; hollow; coiled; more or less evenly located around the bell margin (Figure
Cordyli club-shaped with a swollen end and slender stalk, almost half as long as the tentacle bulbs (Figure
Between adjacent cordyli typically lies another structure different in form, here interpreted as a statocyst. Compared to the tapered stalk of the cordylus, this structure is more evenly columnar or thimble-shaped with straight sides and a rounded distal end (Figure
Stomach amorphously round-ish, broad, nearly 1/2 BD in width (Figure
Radial canals eight, relatively broad, straight-sided throughout length, clearly visible from the stomach to the ring canal (best illustrated in Figure
Gonads in eight pairs of oval hemi-gonads straddling each radial canal adjacent to the stomach, occupying the proximal third of each radial canal (Figure
Colour not noted in living specimen, but preserved specimen has a transparent bell with brown gonads, tentacle bulbs and stomach.
Moreton Bay, Queensland, Australia.
One specimen (QM G335901) has lumpy gonads with obvious ova (Figure
Three of the specimens (two in lot QM G335904, and one in QM G335902) are each missing one tentacle bulb; these are not variants in merosity, but rather, they are octamerous with one bulb simply absent (Figure
Paratypes have a transparent and colourless bell and cordyli, pale yellowish gonads, and darkly pigmented tentacle bulbs. A black ocellus is found at the base of each tentacle and cordylus (Figure
On the tentacles, the larger size class is nearly 19 μm long by 10 μm wide, and bears a conspicuous barb on the free (= aboral) end of the undischarged shaft; we interpret this type as a stenotele. The smaller size class is approximately half the size of the larger, and bears a conspicuous v-shaped notch on the free (= aboral) end; we interpret this type as a microbasic
On the cordyli, nematocysts are scattered throughout the tip in a distal cap. The cordyli nematocysts are similar in shape but smaller in size (8 μm) than the small size class on the tentacles. However, we were unable to observe internal structures and were unable study them directly (Figure
The specific epithet,
Summary of main features from each one of the known species of
Species | BD | Bell shape | Stomach | Mouth | Gonads | Tentacles | Cordyli | Ocelli | Cirri | Locality |
---|---|---|---|---|---|---|---|---|---|---|
46 mm | Flatter than hemisphere, with thick jelly | Short | 8 short crenulated lips | Linear along length of RC | 24 | 3–5 between adjacent tentacles | On each cordylus | More # than cordyli | Adriatic sea | |
10 mm | Flat to hemispherical; jelly thin | Flat, or in a long narrow manubrium | Quadratic, drawn into 4 or 8 short lips | Foliaceous along most of RC, thicker in middle half | 8, with thick conical base | 3 between adjacent tentacles | On tentacles and cordyli | (Not indicated) | Canary Islands | |
32 mm | Flat | Very flat | 8-lobed | Linear on proximal 1/3 of RC, slender, tapering | >160, with slight bulbous swelling | At irregular intervals between tentacles | ~ 5–6 per octant at base of some tentacles | Sparser than cordyli | Malay Archipelago | |
7 mm | Flatter than hemisphere; with moderately thin walls | Flat | 8 short, simple lips | Somewhat sinuous, upon the middle half of RC | 16, with long, hollow, tapered bulbs | 16 | 32 | (Not indicated) | Tortugas, Florida | |
11 mm | Flatter than hemisphere; fairly thick jelly | Flat and broad | 8 faintly indicated lips with a smooth margin | Wavy, lateral bands with about 5 extensions, on distal 2/5 of RC | 17, with heart-shaped bulb | 1–3, mostly 2, between adjacent tentacles | Black, on base of tentacles and cordyli | (Not indicated) | Green Island, Great Barrier Reef | |
7 mm | Watch-glass shaped, very thick in centre | Flat, half as wide as BD | 8 lanceolate lips with thick wavy margins | Linear on outer half of RC in 3 continuous lumps | 8, short stumpy, with large conical bulbs | 4–6 in each octant | 12–14 dark ocelli per octant | (Not indicated) | Trivandrum coast, India | |
10 mm | (Not indicated) | 1/3 BD | Formed into 8 folds | Foliaceous, almost as long as RC | 40 | 40 | At base of tentacles and cordyli | (Not indicated) | Papua New Guinea | |
2 mm | Isosceles trapezoid | Flat and broad, about half BD | 8-lobed, with smoothly-rounded lips | 8 pairs of oval hemi-gonads close to stomach | 8, with heart-shaped bulbs | ~ 2 between tentacles, plus a statocyst between | Black, at base of tentacles and cordyli | Not observed | Moreton Bay, Queensland |
Compared to the other species with eight tentacles, namely
Finally,
One may wonder about the relationship between
With the specimens of
Curiously,
We recognise
Umbrella bell- to barrel-shaped, broadest about 2/3 of the way down, truncate to slightly indented aborally (Figure
Tentacles two, opposite, on voluminous, triangular perradial basal bulbs, approximately 250 μm across the base (Figures
Other marginal structures: opposite the radial canal associated with one of the tentacle bulbs bearing cirri, there exists a small gelatinous “thorn” projecting outward (Figures
Stomach small, cruciform at base (Figure
Radial canals four, straight sided throughout length clearly visible from the stomach to the ring canal, approximately 30 μm in diameter and expanded proximally to create mesentery-like connections with the stomach (Figure
Gonads four, spindle-shaped, starting approximately half way from the stomach toward the margin, covering 2/5 of the entire length of the radial canal, absent on the distal fifth of the radial canal (Figure
Near the shipwreck
No nematocyst preparation was made because the only available specimen is the holotype and it is too small to take sections from without destroying it. Therefore, the following description of nematocysts is based on in situ observation only. Bell nematocysts are mostly in roughly circular clusters up to 30 μm in diameter on the subumbrellar surface. Each cluster consists of 4–20 nematocysts. The nematocysts are oval in shape and approximately 12 μm long and half as wide (Figure
The specific name
The specimen was collected in a vertical drop net from the surface to 28 m in an area of maximum 30 m depth; we therefore do not know its exact location in the water column. The sea surface temperature at the time was 27.5 °C.
Like its congeners,
Whereas
Summary of main features from each of the known species of
Species | BH | Body shape | Stomach | Mouth | Gonads | Tentacles | Cirri | Sense organs | Locality |
---|---|---|---|---|---|---|---|---|---|
|
1.4 mm | Deep bell, piriform | Short | 4 lips, with a quadrangular manubrium | Voluminous, cylindrical, occupying central ¾ of RC | 2 opposing, on large, conical, bulbous bases | 2 opposing clusters of 6, on bulbs smaller than those bearing tentacles | Statocysts and ocelli absent | Papua New Guinea |
~ 2 mm | Deep bell, piriform | Large, broad | Not described | Voluminous, cylindrical, extending along each RC from the stomach nearly to the margin | 2 opposing, on large, conical, bulbous bases | 2 opposing clusters of up to 12 | Statocysts absent; ocelli not specified | Taiwan Strait, China | |
1.4 mm | Short bell, truncated apex; with subumbrellar nematocyst clusters | Short, cruciform | Mouth perfectly quadrangular, with a short quadrangular manubrium | Voluminous, spindle-shaped, in distal half of RC, well separated from the margin | 2 opposing, with large broad bulbs | 2 opposing clusters of 10–12 solid straight cirri | Ocelli absent; statocysts open, on broad conical base | Great Barrier Reef, Australia |
The cirri of
The cirri are worthy of discussion.
Interestingly,
Similarly, the conical statocyst-like structure in
We recognise the value of providing DNA sequences as molecular evidence to support the description of new species when it is practical. In the present case, all the specimens were preserved in formalin, making successful extraction of DNA unlikely. Moreover, with so few specimens of
Finally, while we believe that the fully-developed gonads for both species suggest that they are mature specimens, this hypothesis may be tested using DNA sequencing in future research.
We are grateful to the following people for helping in sample collection: Study 1: We thank DSITI Aquatic Ecosystem Health for assistance with sample collection. Water quality data was provided by the Ecosystem Health Monitoring Program and Healthy Waterways Ltd. This study was funded by the Australian Research Council Linkage Grant LPO883663.
Study2: (in alphabetical order) Geoff Carlin, Nagur Cherukuru, Phillip Ford, Jim Franklin, Gary Fry, Andrew Lowe, Sean Maberly, Kadija Oubelkheir, Peter Ralph and Andy Steven.
Study 3: (in alphabetical order) Frank Coman, Claire Davies, Felipe Gusmao and Mark Tonks.
Thank you Frank Coman and Claire Davies for checking the manuscript and we are also grateful to the two reviewers for their constructive comments, Merrick Ekins and James Reimer.