Short Communication |
Corresponding author: Mark J. Gibbons ( mgibbons@uwc.ac.za ) Academic editor: Stephanie Stainbank
© 2022 Gillian M. Mapstone, Craig N. Foster, Mark J. Gibbons.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Mapstone GM, Foster CN, Gibbons MJ (2022) First occurrence of the rare siphonophore Lilyopsis Chun, 1885 (Hydrozoa, Siphonophora, Prayinae) in South Africa. African Invertebrates 63(2): 121-130. https://doi.org/10.3897/afrinvertebr.63.94095
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A colony of the rare hydrozoan siphonophore Lilyopsis Chun, 1885, was observed for the first time in shallow water in False Bay, South Africa, swimming amongst kelp. A study of a high-quality image of this individual found it to share some characters with the prayine prayid L. fluoracantha Haddock, Dunn & Pugh, 2005, so far known only from Monterey Bay, California, in the eastern Pacific. No Lilyopsis species has previously been reliably identified from either the South Atlantic or the Indian Ocean, so this record represents an expansion of the known worldwide distribution for this genus.
Agulhas Current, Benguela ecosystem, Calycophorae, community science, diversity, photo identification, Prayid
Siphonophores can be abundant members of coastal and oceanic zooplankton (e.g.
A specimen of a siphonophore was photographed by CF taken on 10 May 2018, at a depth of 1.5 m from within a kelp bed along the western shore of False Bay (34°12.484'S, 018°27.662'E, Fig.
Bathymetric chart of False Bay (From
Glossary of terminology used in this paper:
Basigaster – proximal thickened region of gastrozooid where nematocysts are produced.
Bract – protective asexual zooid of cormidium, typically rounded in prayids with lobed distal margin but in Lilyopsis extending into a spur on one side.
Calyconula larva – later larval stage of a calycophoran siphonophore.
Cormidium – serially repeated (iterative) group of zooids on the main stem, or siphosome, each including a gastrozooid, one or more gonophores and typically a bract.
Cormidial bell – a special nectophore in the cormidia of Lilyopsis, some other prayines and some other siphonophores.
Gastrozooid – asexual feeding zooid in a cormidium, with tentacle arising from proximal end.
Nectophore – asexual swimming bell present in most siphonophores, having a muscular nectosac for locomotion opening distally via an aperture termed the ostium.
Siphosome – posterior part of the stem, bearing cormidia in all siphonophores.
Tentilla – specialized side branches on a siphonophore tentacle comprising a complex nematocyst battery.
The specimen illustrated in Fig.
There are two species currently identified as belonging to the genus Lilyopsis: L. medusa (Metschnikoff & Metschnikoff, 1871) and L. fluoracantha, Haddock, Dunn and Pugh 2005. Lilyopsis medusa was first introduced as Praya diphyes by
Lilyopsis medusa was last studied in detail by Carré as L. rosea, based on specimens collected at Villefranche in the Mediterranean, including drawings and photographic images of the siphosome and of male and female cormidia (
The siphosome of the present colony from False Bay (Fig.
Some characters of the present colony from South Africa fit well with those of both Lilyopsis medusa and L. fluoracantha (large transparent nectophores and closely spaced siphosomal cormidia, each with a cormidial bell), although nectophore details could not be directly compared since in the False Bay image only one of the two nectophores was visible, and in posterior view (Fig.
Lilyopsis fluoracantha was described from just five specimens collected, or captured on video, between 1998 and 2004 near Monterey Bay, California, at depths between 327 and 476 m (
So far Lilyopsis fluoracantha has only been observed or collected in deep water from Monterey Bay where the water temperature varied between ~6.5 and 8.5 °C (pers. comm. from Kyra Schlining at MBARI, July 2020). In contrast, reliable records for L. medusa show that it typically inhabits shallower and warmer water worldwide, between, for example, 14 and 24 °C in Villefranche Bay (
In general, our specimen shares more characters with L. fluoracantha than it does with L. medusa, but the bright green basigasters of the gastrozooids do seem to be unique, although may not be a robust character for species separation. Perhaps, therefore, it represents a third Lilyopsis species, or maybe a variant of L. fluoracantha, since in both species the bracts have elongate spurs. It will be necessary to collect a specimen in the future for genetic analysis if this is ever possible, which could confirm its identity as L. fluoracantha. Meanwhile, we assign our specimen to the genus Lilyopsis Chun, 1885, in the subfamily Prayinae Chun, 1897, of the calycophoran family Prayidae Kolliker, 1853.
We thank Kyra Schlining of Monterey Bay Aquarium Research Institute for information about observations and samples of Lilyopsis fluoracantha from the Monterey Bay area. GMM thanks The Natural History Museum, London for access to literature and other facilities as an NHM Scientific Associate. We are grateful to Bert Hoeksema and Dhugal Lindsay for their comments on the manuscript, which have helped to clarify the text.