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| Atolla reynoldsi Matsumoto, Christianson, Robison, Haddock & Johnson, 2022 |
Abstract
We have observed and collected unusual specimens of what we recognize as undescribed types of the genus Atolla over the past 15 years. Of these, there appear to be three potentially different types. One of these has now been genetically sequenced and compared both morphologically and molecularly with five other Atolla species that have been found in the eastern Pacific. This new variant is so morphologically distinct from other previously described Atolla species that we believe it can be described as a new species, Atolla reynoldsi sp. nov. This species along with two additional types may comprise a new genus. It is also clear that a more accurate and diagnostic morphological key for the genus Atolla needs to be developed. This paper will also provide some potential starting points for a new key to the genus.
Keywords: Atolla; new species; Pacific; coronate; Scyphozoa; ROV; trawl
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| Images of Atolla reynoldsi sp. nov. from T960 on 4 April 2006. (a) Laboratory photo. Diameter from margin to margin (excluding lappets) is 8.5 cm and tentacles were coiled in situ. (photo by Rob Sherlock) (b) In situ image. The spikes and spike ridges on the lappets and the coiled tentacles are visible. |
Systematics
Class Scyphozoa Götte, 1887
Subclass Coronamedusae Calder, 2009
Order Coronatae Vanhöffen, 1892
Family Atollidae Hickson, 1906
Genus Atolla Haeckel, 1880
Atolla reynoldsi sp. nov.
Diagnosis: Atolla reynoldsi sp. nov. can have from 26–39 tentacles and rhopalia. The overall shape is flattened although the center zone is a rounded dome, albeit not very tall (Figure 1). The tentacles in situ are usually coiled and a hypertrophied tentacle has not been observed. There are ~nine lateral ridges along the pedalia that have some spikes of various heights (Figure 5b–d). The gut has a distinctive Greek-cross morphology (Figure 6c). Diagnostic characters separating this new species from extant Atolla species include the spiked ridges and papillae on the exumbrellar surface of the rhopaliar pedalia, the ability to coil the tentacles, the Greek-cross gut morphology, and the lack of a hyptertrophied tentacle. The gonads are oval when immature but become large and horseshoe-shaped when mature. The radial septa are straight or slightly divergent and extend beyond the coronal muscle.
Etymology: Named after the first volunteer at the Monterey Bay Aquarium (Jeff Reynolds) who guarded a beached whale on Del Monte Beach overnight so that the Aquarium could retrieve it and prepare it for eventual overhead display.
Systematic remarks: The order Coronatae is identified by the separation of the exumbrella into two concentric zones by a circular coronal groove. The central zone is a circular disc or dome while the marginal zone is divided by radiating grooves into thickened pedalia, with peripheral lappets. The presence of more than eight rhopalia place it into the family Atollidae, which is currently monogeneric.
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| Figure 2. Atolla species A (a) Laboratory photo of D1399 taken in the lab (photo by SHDH) of the specimen collected on 30 October 2021. Diameter from margin to margin (excluding lappets) is 8.5 cm. (b) In situ image of D1402 photographed on 14 November 2021 at a depth of 1913 m, 5.4 cm in diameter. Figure 3. Atolla species B (a) Laboratory photo of T1088 of the specimen collected on 14 April 2007. (photo by Rob Sherlock) (b) In situ image of T1088 photographed on 14 April 2007 at a depth of 2570 m. |
George I. Matsumoto, Lynne M. Christianson, Bruce H. Robison, Steven H. D. Haddock and Shannon B. Johnson. 2022. Atolla reynoldsi sp. nov. (Cnidaria, Scyphozoa, Coronatae, Atollidae): A New Species of Coronate Scyphozoan Found in the Eastern North Pacific Ocean. Animals. 12(6); 742. DOI: 10.3390/ani12060742
Simple Summary: This paper describes an unusually large and distinctive deep-sea red medusa with coiled tentacles in the family Atollidae. This family is monogeneric with ten presently accepted species in the genus Atolla. The new medusa is molecularly and morphologically distinct from the five species that we have been able to sample and morphologically distinct from all ten previously described species. We have also observed and collected samples from another two potentially new species. The ocean provides over 98% of the available living space on our planet and we still do not know who is living there or how they interact with one another. This paper adds to the increasing number of new deep-sea species being described as we increase our exploration, and as advances in undersea technology and genetic sequencing become more available.
Atolla reynoldsi sp. nov. has 26–39 tentacles that are coiled in situ, a Greek-cross gut morphology with smooth edges, spiked ridges and papillae on the rhopaliar pedalia and no trailing tentacle.