[Paleontology • 2023] Burgessomedusa phasmiformis • A Macroscopic Free-swimming Medusa (Cnidaria: Medusozoa) from the middle Cambrian Burgess Shale

Burgessomedusa phasmiformis

Moon, Caron & Moysiuk, 2023

 DOI: 10.1098/rspb.2022.2490

Artwork by C. McCall.

Abstract

Cnidarians are regarded as one of the earliest-diverging animal phyla. One of the hallmarks of the cnidarian body plan is the evolution of a free-swimming medusa in some medusozoan classes, but the origin of this innovation remains poorly constrained by the fossil record and molecular data. Previously described macrofossils, putatively representing medusa stages of crown-group medusozoans from the Cambrian of Utah and South China, are here reinterpreted as ctenophore-grade organisms. Other putative Ediacaran to Cambrian medusozoan fossils consist mainly of microfossils and tubular forms. Here we describe Burgessomedusa phasmiformis gen. et sp. nov., the oldest unequivocal macroscopic free-swimming medusa in the fossil record. Our study is based on 182 exceptionally preserved body fossils from the middle Cambrian Burgess Shale (Raymond Quarry, British Columbia, Canada). Burgessomedusa possesses a cuboidal umbrella up to 20 cm high and over 90 short, finger-like tentacles. Phylogenetic analysis supports a medusozoan affinity, most likely as a stem group to Cubozoa or Acraspeda (a group including Staurozoa, Cubozoa and Scyphozoa). Burgessomedusa demonstrates an ancient origin for the free-swimming medusa life stage and supports a growing number of studies showing an early evolutionary diversification of Medusozoa, including of the crown group, during the late Precambrian–Cambrian transition.

Keywords: cnidarian, cambrian explosion, medusae

 

Systematic palaeontology

 Phylum Cnidaria Verrill, 1865

 Subphylum Medusozoa Peterson, 1979

 Burgessomedusa phasmiformis gen. et sp. nov.

Diagnosis: Medusoid with a tetraradial bell-shaped umbrella with width reaching approximately 40% of umbrella height. Over 90 finger-like tentacles along the oral margin, reaching approximately 15% of umbrella height in length. Stomach cavity located at apex of the umbrella, occupying approximately 30% of the body area. Manubrium extending up to two-thirds the length of the umbrella. Gonads elongate and ovoid, occupying approximately 45% of the umbrella height, located along umbrella corners, but internally positioned approximately halfway between umbrella margins and manubrium.

 Etymology: Genus is a compound name with Burgess referring to the locality, the Burgess Shale, and medusa (Latin) referring to the clade Medusozoa. Species is a compound name with phasma (Greek) and forma (Latin), in reference to the ghostly figure of the umbrella.

  Life reconstruction showing a cluster of Burgessomedusa phasmiformis gen. et sp. nov. swimming above the benthos. This reconstruction is based on the Raymond Quarry Burgess Shale community with clusters of Vauxia sponges represented in the foreground.

Artwork by C. McCall.

Justin Moon, Jean-Bernard Caron and Joseph Moysiuk. 2023. A Macroscopic Free-swimming Medusa from the middle Cambrian Burgess Shale. Proc. R. Soc. B. 29020222490. DOI: 10.1098/rspb.2022.2490

 https://phys.org/news/2023-08-oldest-species-jellyfish.html

[Paleontology • 2021] Cambrian Comb Jellies from Utah illuminate the early Evolution of Nervous and Sensory Systems in Ctenophores

in Parry, Lerosey-Aubril, Weaver & Ortega-Hernández, 2021. 

DOI: 10.1016/j.isci.2021.102943

Highlights

• Two species of rare fossil ctenophores are described from the Cambrian of Utah

• Fossil ctenophores preserve remains of nervous tissue and sensory structures

• Neurological structures include an oral nerve ring and giant longitudinal axons

• Cambrian ctenophores had a more complex neuroanatomy than living species

Summary

Ctenophores are a group of predatory macroinvertebrates whose controversial phylogenetic position has prompted several competing hypotheses regarding the evolution of animal organ systems. Although ctenophores date back at least to the Cambrian, they have a poor fossil record due to their gelatinous bodies. Here, we describe two ctenophore species from the Cambrian of Utah, which illuminate the early evolution of nervous and sensory features in the phylum. Thalassostaphylos elegans has 16 comb rows, an oral skirt, and an apical organ with polar fields. Ctenorhabdotus campanelliformis has 24 comb rows, an oral skirt, an apical organ enclosed by a capsule and neurological tissues preserved as carbonaceous films. These are concentrated around the apical organ and ciliated furrows, which connect to a circumoral nerve ring via longitudinal axons. C. campanelliformis deviates from the neuroanatomy of living ctenophores and demonstrates a substantial complexity in the nervous system of Cambrian ctenophores.

 

Keywords: Ctenophora, Marjum Formation, Cambrian, Nervous system, Metazoa

 Ctenorhabdotus campanelliformis (top) and
Thalassostaphylos elegans (bottom).

Reconstruction by Holly Sullivan

Systematic Paleontology 

Phylum: Ctenophora Eschscholtz 1829 

Holotype fossil specimen of Thalassostaphylos elegans from the mid-Cambrian Marjum Formation in Utah.
Light photograph (left), interpretative drawing (right), and magnification of polar fields (bottom left).

Genus: Thalassostaphylos gen. nov 

Etymology: Genus name from Greek Thalassa (sea) and staphylos (grape). 

 Type species: Thalassostaphylos elegans nov. 

 Diagnosis: Ctenophore with rounded body outline in lateral view with broad comb rows that 16 abut each other laterally. Comb rows terminate at the margin of an extensive oral skirt surrounding a large mouth opening. Oral skirt has a scalloped oral margin, with eight lobes present around its circumference. Apical sense organ with paired polar fields.

Thalassostaphylos elegans sp. nov. 

Etymology: From Latin elegans (elegant), in reference to the skirt and its scalloped margin. 

 Type material: UMNH.IP.6086 (holotype and only known specimen). 

Locality and Horizon: House Range of western Utah, USA (see methods for locality details). Drumian strata (lower Ptychagnostus punctuosus Zone) of the middle part of the Marjum Formation, Miaolingian, Cambrian (see Methods below). 

Fossil specimen of Ctenorhabdotus campanelliformis from the mid-Cambrian Marjum Formation in Utah.
Light photograph (left), elemental map showing nervous system as carbon films (right), and interpretative drawing (bottom left).

Genus: Ctenorhabdotus Conway Morris and Collins 1996 

 Type species: Ctenorhabdotus capulus (Conway Morris and Collins, 1996). 

Ctenorhabdotus campanelliformis sp. nov. 

Etymology: From Latin campanella (small bell) and formis (shape), in reference to the bell-shaped outline of the body. 

Type material: UMNH.IP.6125 (holotype and only known specimen). 

Locality and Horizon: House Range of western Utah, USA (see methods for locality details). Most likely recovered from the Drumian strata (lower Ptychagnostus punctuosus Zone) of the middle part of the Marjum Formation, Miaolingian, Cambrian (see Methods below). 

Diagnosis: Ctenophore with bell-shaped body outline in lateral view with 24 comb rows. Comb rows terminate at the margin of an extensive oral skirt surrounding a large mouth opening.  Aborally, comb rows merge with trifurcating ciliary grooves arising from the apical organ. Apical sense organ enclosed in a capsule.

 

Luke A. Parry, Rudy Lerosey-Aubril, James C. Weaver and Javier Ortega-Hernández. 2021. Cambrian Comb Jellies from Utah illuminate the early Evolution of Nervous and Sensory Systems in Ctenophores. iScience. 102943. DOI: 10.1016/j.isci.2021.102943

[Invertebrate • 2020] Duobrachium sparksae • A New Genus and Species of Benthopelagic Ctenophore (Ctenophora: Tentaculata: Cydippida) seen at 3,910 m Depth off the Coast of Puerto Rico

 Duobrachium sparksae  

Ford, Bezio & Collins, 2020

 DOI 10.3800/pbr.15.296 

 fisheries.noaa.gov 

 

Abstract

On April 10, 2015, three individuals of an undescribed species of ctenophore were observed moving just above the seafloor in the Arecibo Amphitheater inside the Guajataca Canyon, north-northwest of Puerto Rico at a depth of approximately 3,900 m. The ctenophore is distinctive; having two prominent tentacle arms, a body that is rectangular when observed laterally along the tentacular plane, and rounded when observed laterally along the stomodeal plane. The tentacle arms each give rise to an extensible tentacle bearing short tentilla of uniform length and distribution. One ctenophore appeared to be anchored to the seafloor by its two long flexible tentacles, as well as by two filaments exiting its oral end. The overall form of the ctenophore suggests classification within the problematic, non-monophyletic order Cydippida, but the robust tentacle arms are more reminiscent of benthic species of Platyctenida, particularly those of families Lyroctenidae and Ctenoplanidae. Whereas most platyctenid ctenophores do not possess ctene rows in their adult forms, features that are possessed by the new species described herein, species of Ctenoplanidae retain comb rows as adults and are capable of limited swimming. The species described herein is easily distinguishable from all other known species of Ctenophora and may trace its origin to a lineage diverging near the origin of Platyctenida.

Keywords: Aricebo Amphitheater, Ctenophora, Duobrachium sparksae gen nov. & spec. nov., Puerto Rico, Cydippida

Still captured from video observation of  Duobrachium sparksae n. gen. n. sp.
  Second sighting (USNM 1607332) showing regular tentilla of tentacles and large embryos/eggs within gonads, highlighting the quality of the HD video. 17:37:36 UTC.

Digital illustration of the habit of  Duobrachium sparksae n. gen. n. sp.
 A. tentacular view B. stomodeal view.

Illustrations by Nicholas Bezio.

Phylum Ctenophora Eschscholtz, 1829 

Class Tentaculata Eschscholtz, 1825 

Order Cydippida Gegenbaur, 1856 

Family Cydippida incertae sedis 

Genus Duobrachium gen. nov. 

Diagnosis. Tentaculate cydippid ctenophores with two thick, aboral, conical tentacle arms. Tentacle arms emerge from the center of the body and extend aborally. Body rectangular in the tentacular plane, oblong in the stomodeal plane. The tentacle arms are as long as the body is tall. Tentacles retractile, with simple tentilla of uniform length. Filaments can exit orally, anchoring it to the sediment. Stomodeum darkly pigmented. Gonads globular, not extending the length of the meridional canals. 

 

Etymology. From the Latin “two-arms”, a name reflecting the two prominent arms. The Latin “brachium” is of common gender, but shall be treated as feminine, in accordance with ICZN article 30.1.4.2.

Line drawing schematic of Duobrachium sparksae n. gen. n. sp.
 A. Tentacular view of the main body of the animal. B. Oral view. C. Aboral view.

ct - ctene row, g - gonads, m - mouth, ta - tentillum, tent - tentacle, stat - statocyst, sto - stomodeum.

 Illustrations by Nicholas Bezio.

 Duobrachium sparksae spec. nov.

Etymology. The specific epithet “sparksae” honors Elizabeth Ann Sparks, the wife of Michael Ford. Common name. Sparks’ two-armed ctenophore. 

Distribution. Only known from Guajataca Canyon, north-northwest of Puerto Rico at a depth of approximately 3,900 m, within meters of the seafloor 

 

Michael Ford, Nicholas Bezio and Allen Collins. 2020. Duobrachium sparksae (incertae sedis; Ctenophora: Tentaculata: Cydippida): A New Genus and Species of Benthopelagic Ctenophore seen at 3,910 m Depth off the Coast of Puerto Rico. Plankton and Benthos Research. 15(4); 296-305. DOI 10.3800/pbr.15.296  

 

NOAA Scientists Virtually Discover New Species of Comb Jelly Near Puerto Rico

fisheries.noaa.gov/feature-story/noaa-scientists-virtually-discover-new-species-comb-jelly-near-puerto-rico

twitter.com/RebeccaRHelm/status/1330927733677895681

[Invertebrate • 2020] Vampyroctena delmarvensis (Vampyroctenidae, fam. nov.) • A Mesopelagic Ctenophore representing A New Family, with Notes on Family-level Taxonomy in Ctenophora

Vampyroctena delmarvensis Townsend, Damian-Serrano & Whelan

in Townsend, Tassia, Damian-Serrano, et al., 2020.

DOI: 10.1007/s12526-020-01049-9

  twitter.com/planktomancer

Abstract

The stunning diversity of midwater ctenophores is well-known to veterans of oceanographic cruises and ROV operations, but many species lack formal descriptions, leading to taxonomic confusion and a systematic underestimation of the biodiversity of the mesopelagic zone. Here, we present a description of a novel genus and species of one such ctenophore, Vampyroctena delmarvensis gen. nov. sp. nov. This cydippid ctenophore, the sole described representative of Vampyroctenidae fam. nov. (Class Tentaculata, Order Cydippida), was collected in mesopelagic waters off the coast of Delaware in the northwest Atlantic Ocean and has a characteristic bright red mesoglea, large paragastric diverticulae, deep red macrocilia, and a darkly pigmented gut. A molecular phylogenetic analysis of Ctenophora based on transcriptomic data places V. delmarvensis gen. nov. sp. nov. as the closest known relative to Euplokamis dunlapae Mills, 1987 (Euplokamididae), in a clade that is sister to all other ctenophore lineages.

Keywords: 18S, Atlantic Ocean, Delmarva, Molecular phylogeny, New species, Transcriptome, Tucker trawl

 Vampyroctena delmarvensis gen. nov. sp. nov. anatomy.
Schematic representation of V. delmarvensis gen. nov. sp. nov. anatomy based on accumulated photographs, video, and notes.

 Vampyroctena delmarvensis gen. nov. sp. nov. anatomy.
 b Representative photograph of V. delmarvensis gen. nov. sp. nov. in the stomodeal plane; c Close-up of aboral organ depression and surrounding meridional canals; d Close-up of comb rows, showing the underlying light orange meridional canal; e Close-up view of paragastric diverticulae; f Detail showing the tentacle sheaths, which open into a broad groove spanning ~ 30% of the animal’s total body length.

Systematics

Vampyroctenidae fam. nov. Townsend, Damian-Serrano & Whelan

Vampyroctena gen. nov. Townsend, Damian-Serrano & Whelan

Etymology: Compound feminine noun derived from the French “vampyre” and Greek κτεíς, κτενóς, “comb.” This metaphorical comparison to mythological creatures refers to the dark gut pigmentation, which may serve as a “cloak” enabling them to hide bioluminescence emitted from captured prey, and the blood red pigmentation of the epithelium, comb plates, and mesoglea.

Diagnosis: Tentaculate ctenophores with bright red mesoglea and an elongate, cylindrical body. Adults with large, darkly pigmented stomodaeum. Comb rows with large, pigmented ctenes. Orange canals, tentacle bulbs, and tentacles which bear tentilla.

Vampyroctena delmarvensis sp. nov. Townsend, Damian-Serrano & Whelan

Etymology: Compound noun from “Delmarva,” the colloquial name for the peninsula nearest to the type locality, derived from the three states that occupy it: Delaware, Maryland, and Virginia.

 Vampyroctena delmarvensis gen. nov. sp. nov. anatomy.

 a Schematic representation of V. delmarvensis gen. nov. sp. nov. anatomy based on accumulated photographs, video, and notes; 

b Representative photograph of V. delmarvensis gen. nov. sp. nov. in the stomodeal plane; c Close-up of aboral organ depression and surrounding meridional canals; d Close-up of comb rows, showing the underlying light orange meridional canal; e Close-up view of paragastric diverticulae; f Detail showing the tentacle sheaths, which open into a broad groove spanning ~ 30% of the animal’s total body length.

  twitter.com/planktomancer

James P. Townsend, Michael G. Tassia, Alejandro Damian-Serrano, Nathan V. Whelan, Kenneth M. Halanych and Alison M. Sweeney. 2020. A Mesopelagic Ctenophore representing A New Family, with Notes on Family-level Taxonomy in Ctenophora: Vampyroctena delmarvensis gen. nov. sp. nov. (Vampyroctenidae, fam. nov.). Marine Biodiversity. 50: 34.  DOI: 10.1007/s12526-020-01049-9

  twitter.com/planktomancer/status/1258113609579855872

[Invertebrate • 2016] Census of Cnidaria (Medusozoa) and Ctenophora from South American Marine Waters

DOI:  10.11646/zootaxa.4194.1.1 

Abstract

We have compiled available records in the literature for medusozoan cnidarians and ctenophores of South America. New records of species are also included. Each entry (i.e., identified species or still as yet not determined species referred to as “sp.” in the literature) includes a synonymy list for South America, taxonomical remarks, notes on habit, and information on geographical occurrence. We have listed 800 unique determined species, in 958 morphotype entries: 5 cubozoans, 905 hydrozoans, 25 scyphozoans, 3 staurozoans, and 20 ctenophores. Concerning nomenclatural and taxonomical decisions, two authors of this census (Miranda, T.P. & Marques, A.C.) propose Podocoryna quitus as a nomen novum for the junior homonym Hydractinia reticulata (Fraser, 1938a); Euphysa monotentaculata Zamponi, 1983b as a new junior synonym of Euphysa aurata Forbes, 1848; and Plumularia spiralis Milstein, 1976 as a new junior synonym of Plumularia setacea (Linnaeus, 1758). Finally, we also reassign Plumularia oligopyxis Kirchenpauer, 1876 as Kirchenpaueria oligopyxis (Kirchenpauer, 1876) and Sertularella margaritacea Allman, 1885 as Symplectoscyphus margaritaceus (Allman, 1885).

Keywords: Distribution, Faunistics, Hydroids, Hydromedusae, Scyphozoans, Siphonophores

Oliveira, Otto M. P., Thaís P. Miranda, Enilma M. Araujo, Patricia Ayón, Cristina Cedeño-Posso, Amancay A. Cepeda-Mercado, Pablo Córdova, Amanda F. Cunha, Gabriel N. Genzano, Maria A. Haddad, Hermes Mianzan, Alvaro E. Migotto, Lucília S. Miranda, André C. Morandini, Renato M. Nagata, Karine B. Nascimento, Miodeli N. Júnior, Sergio Palma, Javier Quiñones, Carolina S. Rodriguez, Fabrizio Scarabino, Agustín Schiariti, Sérgio N. Stampar, Valquiria B. Tronolone and Antonio C. Marques.  2016. Census of Cnidaria (Medusozoa) and Ctenophora from South American Marine Waters.

 Zootaxa. 4194(1); 1–256.  DOI:  10.11646/zootaxa.4194.1.1

[Paleontology • 2015] A Vanished History of Skeletonization in Cambrian Comb Jellies (Ctenophora)

Fig. 3. Idealized three-dimensional models of Cambrian skeletonized ctenophores. (A to C) Side views of Gemmactena actinala gen. et sp. nov, Batofasciculus ramificans, and Thaumactena ensis gen. et sp. nov., respectively. (A′ to C′) Oblique aboral views corresponding to (A) to (C).

DOI: 10.1126/sciadv.1500092

Abstract

Ctenophores are traditionally regarded as “lower” metazoans, sharing with cnidarians a diploblastic grade of organization. Unlike cnidarians, where skeletonization (biomineralization and sclerotization) evolved repeatedly among ecologically important taxa (for example, scleractinians and octocorals), living ctenophores are characteristically soft-bodied animals. We report six sclerotized and armored ctenophores from the early Cambrian period. They have diagnostic ctenophore features (for example, an octamerous symmetry, oral-aboral axis, aboral sense organ, and octaradially arranged ctene rows). Unlike most modern counterparts, however, they lack tentacles, have a sclerotized framework, and have eight pairs of ctene rows. They are resolved as a monophyletic group (Scleroctenophora new class) within the ctenophores. This clade reveals a cryptic history and sheds new light on the early evolution of this basal animal phylum. Skeletonization also occurs in some other Cambrian animal groups whose extant members are exclusively soft-bodied, suggesting the ecological importance of skeletonization in the Cambrian explosion.

Keywords: Cambrian, Chengjiang biota, Ctenophora, skeleton

Fig. 4. Phylogenetic relationship of fossil and extant ctenophores based on a comprehensive cladistic analysis (tables S2 and S3).
The skeletonized ctenophores from the Chengjiang biota form a clade here described as the new class Scleroctenophora. The cladogram is a strict consensus of the three most parsimonious trees. Apomorphies (character number and state above and below nodes, respectively) are mapped on the cladogram. Tree length = 53; consistency index = 0.9231; retention index = 0.9394; rescaled consistency index = 0.8671. Illustrated taxa are marked in bold.

DOI: 10.1126/sciadv.1500092

Qiang Ou, Shuhai Xiao, Jian Han, Ge Sun, Fang Zhang, Zhifei Zhang and Degan Shu. 2015. A Vanished History of Skeletonization in Cambrian Comb Jellies.  Science Advances. 1(6); e1500092. DOI: 10.1126/sciadv.1500092