[Cnidaria • 2026] Hemicorallium osmanthogemmum • A New Species of Hemicorallium (Anthozoa: Octocorallia: Coralliidae), along with a revised identification key to species of the genus

Hemicorallium osmanthogemmum

Koido, 2026 

 

DOI: doi.org/10.3897/zookeys.1277.184620 

 

Abstract

A new precious coral species, Hemicorallium osmanthogemmum sp. nov. (Scleralcyonacea, Coralliidae), retrieved from a depth of 550 m in Kochi Prefecture, Japan, is described, and an updated identification key for the genus Hemicorallium is provided. The new species is confirmed as belonging to the genus Hemicorallium based on the presence of nonretractile but contractile autozooids with an ovate-cylindrical shape and sclerites comprising elongated rods, 6–8-radiates and double clubs, with elongated rods present exclusively in the tentacles. Moreover, the species is distinct from all its congeners in that it has orange coenenchyme and a pink axis, with autozooids distributed only on the front side of the branch, forming clusters at the branch tips. These morphological features differ from those of all previously described species of Hemicorallium, and molecular analysis of mitochondrial sequences (16S, ND1, ND2, ND3, ND6, COI, MSH, and IGR1) further corroborates the validity of this new species. This is the first report of Hemicorallium off the coast of Kochi Prefecture, Japan.

Key words: Cnidaria, deep-sea corals, precious coral, Scleralcyonacea, Western Pacific

 

Hemicorallium osmanthogemmum sp. nov. (Holotype: KBF-OA-00436).
 A. ‘‘Front’’ and ‘‘back’’ of colony; B. Branch, showing autozooid (AZ); C. Exposed axis with the coenenchyme removed; D, E. Surface detail of branch, showing autozooid (AZ), siphonozooid (SZ), burrows (Bu), cluster of autozooids (CL), warts on coenenchyme surface (W), and commensal polychaete (Po).

 Scale bars: 50 mm (A); 10 mm (B–E).

Class Octocorallia Haeckel, 1866

Order Scleralcyonacea McFadden, van Ofwegen & Quattrini, 2022

Family Coralliidae Lamouroux, 1812

Genus Hemicorallium Gray, 1867

Hemicorallium osmanthogemmum sp. nov. 

 New Japanese name. Kinmokusei-mizo-sango.

Diagnosis. The colony branches in one plane, and anastomoses are present only where broken branches come into contact with other branches. Autozooids are contracted but not retracted, and they are distributed only on one side of the colony. Spacing is almost absent on the twigs, and clusters are formed at the tips. The axis has no pits beneath the autozooids and is pale pink to pink in colour. Sclerites are predominantly radiate, and double clubs are rare. Warty rods are present only in the tentacles.

 

Tatsuki Koido. 2026. A New Species of Hemicorallium (Anthozoa, Octocorallia, Coralliidae), along with a revised identification key to species of the genus. ZooKeys. 1277: 339-354.  DOI: doi.org/10.3897/zookeys.1277.184620 [20 Apr 2026]

[Cnidaria • 2026] Paraplexaura binyuani • A New Gorgonian (Octocorallia: Acanthogorgiidae) from the Huaguang Atoll, Xisha Islands, South China Sea

 

Paraplexaura binyuani 

You, Xia & Liu, 2026. 

斌源似丛柳珊瑚  ||  DOI: doi.org/10.3390/d18030166 

Abstract

A new shallow-water gorgonian coral species in the family Acanthogorgiidae, Paraplexaura binyuani sp. nov., is described from a specimen collected at Huaguang Atoll in the South China Sea at a depth of 22 m. The new species is distinguished from its congeners by abundant polyp sclerites, predominantly flattened rods, and by the coenenchyme bearing numerous large spindles reaching up to 0.6 mm in length, which are approximately two to three times longer than those reported for most described species of Paraplexaura. Phylogenomic analyses based on ultraconserved elements (UCEs) recover Paraplexaura as monophyletic and place P. binyuani sp. nov. as sister to P. cryptotheca, consistent with its morphological distinctiveness and supporting its recognition as a separate species.

Keywords: Malacalcyonacea; shallow-water coral; taxonomy; morphology; ultraconserved elements

 The external morphology and polyps of Paraplexaura binyuani sp. nov. Holotype, GXTCMU-2025-HT005.
(A,C) in situ; (B) After collection; (D) Frontal view of a branch; (E) Polyps under SEM.

 Scale bars indicate 1 cm in (B), 5 mm in (D), 100 μm in (E).

Paraplexaura binyuani sp. nov.

Etymology. The new species is named after Dr. Binyuan He, principal investigator of the Guangxi Academy of Oceanography, and for his great contribution to benthos research of Guangxi. The Chinese name of the new species is “斌源似丛柳珊瑚”

Distribution and habitat. Known only from the subtidal zone of the Huaguang Atoll on the Chinese coast of the South China Sea with a water depth of 22 m. Colony attached to a rocky substrate.

 

Li You, Fei Xia and Xinming Liu. 2026. A New Gorgonian Paraplexaura binyuani sp. nov. (Cnidaria, Octocorallia, Acanthogorgiidae) from the Huaguang Atoll, Xisha Islands, South China Sea. Diversity. 18(3), 166. DOI: doi.org/10.3390/d18030166 [9 March 2026]

[Cnidaria • 2026] Chironex blakangmati • Chironex box jellyfishes (Cubozoa: Chirodropida) in Singapore: New Species, and Range Extension of C. indrasaksajiae

Chironex blakangmati

Iesa, Ames, Yap & Huang, 2026 

 RAFFLES BULLETIN OF ZOOLOGY. 74

Abstract

 Two venomous box jellyfish species of the genus Chironex Southcott, 1956 (Cnidaria: Cubozoa: Chirodropida) were collected from Singapore’s coastal waters: Chironex indrasaksajiae Sucharitakul, 2017 and a novel species described herein as Chironex blakangmati, new species. Chironex indrasaksajiae was collected from both the Johor and Singapore Straits around mainland Singapore. Chironex blakangmati, new species, was collected from Sentosa Island along the Singapore Strait and is the fourth species described in the genus. While C. blakangmati’s volcano-shaped pedalial canal and tentacle number are similar to C. yamaguchii Lewis & Bentlage, 2009, its elongated, sharp-tipped velarial canals and DNA sequences distinguish it from other Chironex species. Comparisons of Chironex blakangmati, new species, with C. yamaguchii and C. fleckeri reveal novel morphological differences at the terminal end of the perradial lappet along the velarium edge, where C. blakangmati, new species, lacks velarial canals extending from the perradial lappet terminus. Juvenile Chironex yamaguchii specimens were examined and ontogenetic variations of velarial canals are herein reported. Preliminary cnidome analysis reveals eight types of nematocysts observed in C. blakangmati, new species, five types in C. indrasaksajiae, and five types in C. yamaguchii. Molecular phylogenetic reconstruction places C. blakangmati, new species, in a clade distinct from its congeners, as sister group to C. yamaguchii based on 16S rRNA gene analysis but diverging earlier than the clade comprising C. yamaguchii and C. indrasaksajiae based on cytochrome c oxidase subunit I gene analysis for which sequence data are comparatively limited. Understanding the biodiversity and seasonality of venomous cubomedusae will help mitigate the risk they pose to human health and safety during maritime activities. 

Key words. 16S rRNA, COI barcoding, marine biodiversity, phylogenetic analysis, Southeast Asia, venomous

Chironex blakangmati, new species, from Singapore.
A, live individual (paratype, ZRC.CNI.1462), lateral perradius view; B, live individual (holotype, ZRC.CNI.3014), lateral perradius view; C, cockscomb gastric saccule (sac); D, gastric cirri (gc); E, rhopalial niche front view; F, rhopalial niche side view (paratype, ZRC.CNI.1462); G, rhopalial niche side view (holotype, ZRC.CNI.3014); H, tentacle contracted with alternating brown dark bands; I, tentacle stretched; J, preserved tentacle with hollow cross section (arrow); K, pedalium with volcano pedalial canal bend (pcb) marked by arrow; L, U-shaped alternating tentacle pattern with gap marked by an arrow; M, adradial positions (ad) marked by arrows, and rhopalial niche at perradial position (per); N, gastric saccules (sac) surrounding cruciform manubrium (man); O, velarium at perradial position with frenulum (fre) arrowed, lappet terminating in simple triangular tip; P, velarium with candelabrum velarial canal pattern (holotype, ZRC.CNI.3014). rh = rhopalium, rhO = rhopalial ostium, co = convex boundary.

Chironex blakangmati, new species 

Diagnosis. Chironex with conical to cuboidal bell. Seven tentacles per pedalium, branching U-shaped alternating. Pedalial canal bend volcano shaped. Tips of velarial canals sharp towards velarial margin (Fig. 11D), with simple triangular tip at edge of velarium in perradial position (Fig. 3O & Fig. 12). Absence of velarial canals at perradial position where frenulum tapers off (Fig. 12D). 

Etymology. This species is named using Bahasa Melayu, the Austronesian language spoken in the region and the national language of Singapore, for Sentosa Island from which the animal was collected. Sentosa Island was historically referred to as “Pulau Blakang Mati”, meaning “Island of Death Behind” and, as such, “blakangmati” in denoting the geographic location is a noun in apposition. 

Iffah Iesa, Cheryl Lewis Ames, Nicholas Wei Liang Yap and Danwei Huang. 2026. Chironex box jellyfishes (Cnidaria: Cubozoa: Chirodropida) in Singapore: Chironex blakangmati, new species, and range extension of C. indrasaksajiae. RAFFLES BULLETIN OF ZOOLOGY. 74: 383–402. DOI: 10.26107/RBZ-2026-0026 [15 May 2026]

[Cnidaria • 2026] Chrysogorgia pugnioides, Iridogorgia acutisclerita, I. levisquama • Systematics and Biogeography of Chrysogorgiidae (Anthozoa: Octocorallia) from the Indian Ocean: discovery of New Species on Deep-sea Ridges

Iridogorgia acutisclerita Ge, Zhang & Xu,

in Ge, N. Xu, Hu, Tian, Li, Y. Xu, Wang, Zhang et Q. Xu, 2026. 

DOI: doi.org/10.3897/zse.102.182492 

Abstract

Species of the family Chrysogorgiidae are distributed worldwide in deep-sea environments. However, most recorded species of this family were from the Atlantic and Pacific Oceans, with only a few reports from the Indian Ocean, particularly from ridge regions. This study describes three new species and reports two known species from Indian Ocean ridges, integrating morphological and molecular analyses (mtMutS and 28S rDNA). Chrysogorgia pugnioides Ge, Hu & Xu, sp. nov. is characterized by fist-like polyps; warty spindles in tentacles; flat and irregular spindles and elongate scales in the polyp body wall; and slender and smooth scales with toothed to irregular edges in the coenenchyme. Iridogorgia acutisclerita Ge, Zhang & Xu, sp. nov. resembles I. splendens but differs by possessing needles and pointed elongate scales in the polyp body wall. Iridogorgia levisquama Ge, Zhang & Xu, sp. nov. is differentiated from the congeneric I. squarrosa by slender and smooth scales with sharp ends in the polyp body wall and needles with fine wartiness in the tentacles. Parachrysogorgia chryseis and Metallogorgia melanotrichos are reported as new records for the Indian Ocean ridges. These findings expand the known biodiversity and biogeographic range of Chrysogorgiidae in the Indian Ocean ridges.

Key Words: Carlsberg Ridge, Chrysogorgiidae, Ninetyeast Ridge, phylogeny, taxonomy

Chrysogorgia pugnioides Ge, Hu & Xu, sp. nov.  

Iridogorgia acutisclerita Ge, Zhang & Xu, sp. nov. 

Iridogorgia levisquama Ge, Zhang & Xu, sp. nov.

The external morphology of Iridogorgia acutisclerita Ge, Zhang & Xu, sp. nov.
 A. Holotype FIO-IND72-JLBEN22309 in situ; B. Paratype FIO-IND72-JLBEN22402 in situ; C–E. Holotype FIO-IND72-JLBEN22309, paratype FIO-IND72-JLBEN22402, and FIO-IND72-JLBEN225511 after collection;
F. Single polyp under a light microscope; G. Single polyp under SEM; H. A part of the tentacle under SEM; I. A part of the branch under a light microscope; J. A part of the branch with epidermal tissue removed under SEM; K. A part of the branch with epidermal tissue under SEM.

Scale bars: 20 cm (C–E); 1 mm (F, I); 500 μm (G, K); 250 μm (H, J).

 Meiling Ge, Ningxia Xu, Xuying Hu, Xin Tian, Xinlong Li, Yu Xu, Zongling Wang, Xuelei Zhang and Qingzeng Xu. 2026. Systematics and Biogeography of Chrysogorgiidae from the Indian Ocean: discovery of New Species on Deep-sea Ridges. Zoosystematics and Evolution. 102(2): 621-647.  DOI: doi.org/10.3897/zse.102.182492 [07 Apr 2026]

[Cnidaria • 2026] Rhytisma acoronatum, R. calyaceum, R. karibu, ... • Phylogenomics-guided Revision of the Genus Rhytisma Alderslade, 2000 (Octocorallia: Malacalcyonacea: Lemnaliidae), with Descriptions of Six New Sspecies

 

(a, b) Rhytisma karibu sp. nov., 

(c, d) R. acoronatum sp. nov. 

(e, f) R. oblongum sp. nov.

 (c) R. inaequale sp. nov., with expanded polyps 

(d) R. calyaceum sp. nov., with partially expanded polyps 

(e) R. sperkolae sp. nov., polyps partly expanded

Samimi-Namin, Benayahu, Durkin, Ekins, Quattrini & McFadden, 2026

DOI: doi.org/10.1071/IS25068 

Photographs by Y. Benayahu, and M. Ekins.

 

The genus Rhytisma Alderslade, 2000 (Octocorallia: Malacalcyonacea: Lemnaliidae), formerly comprising four nominal species (R. fulvum, R. fuscum, R. monticulum and R. rubiginosum), is revised using an integrative approach. We combine morphological and phylogenomic data for newly collected and historical specimens. A neotype is designated for R. fulvum and a lectotype for R. fuscum to stabilise the application of these names. Six new species are described from the Indo-Pacific: R. acoronatum sp. nov., R. calyaceum sp. nov., R. oblongum sp. nov., R. inaequale sp. nov., R. karibu sp. nov. and R. sperkolae sp. nov. Species delimitation is supported by discrete combinations of morphological characters – particularly those of the tentacle and polyp sclerites – as well as multi-locus DNA barcoding and phylogenomic analyses of conserved elements (UCE and exon loci). Our findings highlight the diagnostic value of tentacle sclerites and reveal extensive species-level diversity that was previously obscured by insufficient morphological examination. The revised genus currently comprises 10 valid species, many of which display restricted geographic distributions, reflecting patterns of regional endemism in Indo-Pacific octocoral assemblages. These results underscore the importance of integrative taxonomy in uncovering hidden biodiversity.

 

Keywords: biogeography, DNA barcoding, endemism, Indo-Pacific, integrative taxonomy, neotype, soft corals, species delimitation, taxonomic revision, ultraconserved elements

Underwater images of Rhytisma species in their respective type localities.
(a, b) Rhytisma fulvum yellow colour and grey colour morphs, polyps partly expanded
(c) R. inaequale sp. nov., with expanded polyps (d) R. calyaceum sp. nov., with partially expanded polyps
(e) R. sperkolae sp. nov., mat morphology reflects underlying irregular reef substrate, polyps partly expanded. (f) R. monticulum with expanded polyps.

Photographs by (a–c, e) Y. Benayahu, (d, f) M. Ekins.

Underwater images of Rhytisma species in their respective type localities.
(a, b) Rhytisma karibu sp. nov., growing on seagrass blades and reef substrate (c, d) R. acoronatum sp. nov. (e, f) R. oblongum sp. nov. 

Photographs by (a, b, e, f) Y. Benayahu, and (c, d) M. Ekins.

Rhytisma acoronatum sp. nov., R. calyaceum sp. nov., 

R. oblongum sp. nov., R. inaequale sp. nov., 

R. karibu sp. nov. and R. sperkolae sp. nov. 

Kaveh Samimi-Namin, Yehuda Benayahu, Kathleen M. Durkin, Merrick Ekins, Andrea M. Quattrini and Catherine S. McFadden. 2026. Phylogenomics-guided Revision of the Genus Rhytisma Alderslade, 2000 (Octocorallia: Malacalcyonacea: Lemnaliidae), with Descriptions of Six New Sspecies. Invertebr Syst. 40(3); IS25068. DOI: doi.org/10.1071/IS25068   [30 March 2026]

[Paleontology • 2026] Paleocanna tentaculum • Thecate stem medusozoan polyp (Cnidaria: Anthozoa) from the Upper Ordovician of Québec, Canada

  

Paleocanna tentaculum  

 Ramirez-Guerrero, Alghaled, Bateman, Cournoyer & Cameron, 2026

 

 DOI: doi.org/10.1017/jpa.2025.10211

 

Abstract

The fossil record of medusozoan cnidarians is relatively sparse and, in some cases, contentious. Here, we describe a new genus and species of a well-preserved, soft-bodied, tubicolous polyp, Paleocanna tentaculum n. gen. n. sp., from the Upper Ordovician (Katian) Neuville Formation in Québec. These fossils, preserved as carbonaceous compressions, were found in association with typical shelly assemblages. Fifteen slabs of shaly limestone containing ~ 135 specimens of Paleocanna tentaculum n. gen. n. sp. were examined. Individual polyps occupied upright tubes, which occur either solitarily or in clusters. Some tubes exhibit a striated periderm near their base. The polyp is elongated, with a rounded aboral end and a consistent ring of tentacles protruding distally from the tube. A phylogenetic analysis of 69 taxa and 236 discrete morphological characters indicated that the species is more closely related to the extant crown group than it is to the other stem-group medusozoans, e.g., conulariids and carinachitids. The uniform orientation of specimens on single slabs suggests rapid burial. Paleocanna tentaculum n. gen. n. sp. represents an exceptionally preserved member of an Ordovician deposit exhibiting Burgess Shale-type soft-tissue preservation.

Paleocanna tentaculum n. gen. n. sp., holotype, MPEP713.4.
 (1) General view of the organism taken under cross-polarized light; accompanying line drawing illustrates the outline of the tube and tentacles. (2) Detail of the left set of tentacles. (3) Detail of the basal part of the tube. (4) Detail of the tube. Scale bars = 1 cm (1, 3), 0.5 cm (2, 4).

Systematic paleontology

Phylum Cnidaria Verrill, Reference Verrill1865

Subphylum Anthozoa Ehrenberg, Reference Ehrenberg1834

Genus Paleocanna new genus

Etymology: Paleocanna: palaios, meaning old or ancient, plus canna, meaning flute or pipe.

 Paleocanna tentaculum new species

Diagnosis: Cylindrical tubicolous periderm with fine, parallel, transverse annulations; polyp with anterior tentacle crown extending from aperture.

Occurrence: Upper Neuville Formation of the Saint Lawrence Lowlands of Québec, Canada (Clark, Reference Clark1959).

 Interpretive drawings of Paleocanna tentaculum n. gen. n. sp. as living organisms.
(1) Oral view showing a circle of tentacles. (2) Lateral perspective of the tube, highlighting the tube aperture and annular striations. (3) Depiction of individuals living in single tubes, as well as clusters of two or three tubes attached together.

Greta Ramirez-Guerrero, Huda Alghaled, Louis-Philippe Bateman, Mario Cournoyer and Christopher B. Cameron. 2026. Thecate stem medusozoan polyp from the Upper Ordovician of Québec. Journal of Paleontology. First View. DOI: doi.org/10.1017/jpa.2025.10211 [13 February 2026]

[Cnidaria • 2025] Endolobactis simoesii (Cnidaria: Actiniaria) • A New Species of Sea Anemone from the Yucatán Peninsula, Mexico

Endolobactis simoesii

 González-Muñoz, Rodríguez, Durán-Fuentes & Acuña, 2025

DOI: doi.org/10.11646/zootaxa.5722.3.5

Abstract

A new genus and species of sea anemone belonging to the family Actiniidae, Endolobactis simoesii gen. et sp. nov., is described. A comprehensive description is provided, including information on its external and internal anatomical features, cnidome, and size ranges and distribution of cnidae, accompanied by images of live specimens and their histological characteristics. The most distinctive feature of E. simoesii gen. et sp. nov. is the frond-like marginal projections located on exclusively endocoelic lobes. This contrasts with other genera in Actiniidae that exhibit similar marginal projections, which are commonly referred to as a “marginal ruff.” In addition, E. simoesii gen. et sp. nov. has more mesenteries proximally than distally. These and other differences between E. simoesii gen. et sp. nov. and other genera within Actiniidae with similar features are discussed in detail. With the inclusion of E. simoesii gen. et sp. nov., the number of documented sea anemone species along the Mexican Atlantic coast increases to 24.

 

Coelenterata, Actiniidae, sea anemone, Endolobactis simoesii

 Endolobactis simoesii gen. et sp. nov.

Ricardo GONZÁLEZ-MUÑOZ, Estefanía RODRÍGUEZ, Jefersón DURÁN-FUENTES and Fabián H. ACUÑA. 2025. Endolobactis simoesii gen. et sp. nov. (Cnidaria: Actiniaria), A New Species of Sea Anemone from the Yucatán Peninsula, Mexico.  Zootaxa. 5722(3); 391-407. DOI: doi.org/10.11646/zootaxa.5722.3.5 [2025-11-20]

[Cnidaria • 2025] Pavona giannii • A New Reef-dwelling Coral (Hexacorallia: Scleractinia: Agariciidae), with an overview of the skeletal morphology of the type specimens of the genus Pavona

 

Pavona giannii  

Benzoni, 2025 

 

DOI: doi.org/10.3897/zookeys.1260.167263

Abstract

Hard coral species in the agariciid genus Pavona are common in shallow and mesophotic coral reef communities across the Indo-Pacific, but their taxonomy has long been overlooked. Pavona giannii sp. nov. is here described based on newly collected material across the Indian Ocean, and historical museum specimens. In vivo and skeletal morphological features are described, diagnostic characters measured, and comparison with congeners performed. The new species forms an encrusting corallum devoid of raised ridges on its surface. Its corallites are flush with the surface, not inclined, and less than half a corallite diameter apart. Corallites arrangement is thamnasteroid and series can form locally. Where they occur, the radial elements run over the shared walls to the adjacent series’ corallites creating a ladder-like arrangement similar to that observed over the ridges in congeners like Pavona varians and Pavona chiriquiensis. Despite the lack of ridges, P. giannii sp. nov. has morphological affinities with these two species. However, based on previously published morphometrics and meristics, P. giannii sp. nov. corallites are larger and more crowded, and the primary septa are longer and more numerous. In vivo, the new species is distinguished by fully extended white to beige tentacles during the daytime, giving it a white-bearded appearance. Despite the ecological relevance of Pavona corals, a taxonomic revision of the genus is overdue, and the existing molecular studies indicate that it is polyphyletic. Here, the proposed placement of P. giannii sp. nov. in the genus is based on morphological evidence alone and phylogenomic analyses are currently in progress.

Key words: Morphometrics, museum collections, reef-building coral, skeletal morphology, taxonomy

Holotype of Pavona giannii sp. nov. MNHN-IK-2012-14233
A. the whole colony in situ at Hyllanyia Island, Bir Ali, Yemen, prior to sampling and B. corallum of the sampled fragment. C. Top view of the corallum showing corallite arrangement and the position of some of the corallite series boundaries (dashed pink lines) marked by the presence of parallel radial elements running over and across them, and D. side view showing its even surface given by equally high and flat top margins of S1 and S2 septa, and the deep-seated fossae. Scale bars: 1 cm (B); 5 mm (C, D).

Pavona giannii sp. nov. in situ.
A. Typically white extended tentacles in the colony, from which specimen UNIMIB BAL252 was collected, encrusting a submassive Porites (living portion at the top right-hand side) at Balhaf, Yemen; B. Colony of UF 17957, Mirbat, Oman; C. Fully extended white tentacles covering the whole surface of the colony of UNIMIB SO078 at Socotra Island, Yemen; D. Colony with partially retracted tentacles allowing the polyps’ white oral disks to show, Mahé Island, Seychelles; E. Colony of UNIMIB MY069 at Mayotte Island; F. Colony with white tentacles and grey oral disks Balhaf, Yemen; G. Close-up of the polyps of colony UNIMIB BU049 with beige tentacles and white oral disks at Burum, Yemen.

 Francesca Benzoni. 2025. A New Reef-dwelling Coral, Pavona giannii sp. nov. (Scleractinia, Agariciidae), with an overview of the skeletal morphology of the type specimens of the genus Pavona. ZooKeys. 1260: 123-147. DOI: doi.org/10.3897/zookeys.1260.167263

[Cnidaria • 2025] Physalia mikazuki (Hydrozoa: Siphonophorae) blown into Japan’s northeast (Tohoku) at the whim of Marine Ecosystem Change

 Physalia mikazuki Yongstar, Ochiai & Lewis Ames, 
collected from Gamo Beach, Sendai City, Miyagi Prefecture, Japan.  

in Yongstar, Ochiai, Nugraha, Tan, Totsu, Sato-Okoshi et Lewis Ames. 2025. 

DOI: doi.org/10.3389/fmars.2025.1653958 

The discovery of Physalia mikazuki sp. nov. from the temperate waters of Gamo Beach, Sendai Bay (Miyagi Prefecture) in the Tohoku (northeast) region of Japan, represents a significant addition to the taxonomic and ecological understanding of this genus. Morphological analysis reveals key diagnostic traits, distinguishing it from all known Physalia species. Phylogenetic analyses of the 16S rRNA gene and COI (cytochrome c oxidase subunit 1) regions further confirm its classification as a distinct species, forming a well-supported monophyletic clade separate from other Physalia species. Oceanographic data and Lagrangian particle trajectory simulations suggest that P. mikazuki may have dispersed northward via the recent 100 km northward extension of the Kuroshio Current (KE) in tandem with record-breaking sea surface temperature changes (SST) of more than 2°C in the Tohoku region between 2022 and 2024. Long-term monitoring confirmed no previous reports of Physalia at the type locality of Gamo Beach, Sendai City (Tohoku) prior to 2023, indicating a likely recent introduction. Molecular barcode sequences matching samples from both Pakistan and Mexico indicate a broad Indo-Pacific connectivity for the new species. The occurrence of P. mikazuki sp. nov. in the Tohoku region poses potential ecological and public health concerns, particularly due to its predation on fish larvae and risk of envenomation during beach recreation. This study underscores the importance of integrative experimental design combining taxonomy, molecular data, and oceanographic modeling to understand species range shifts and cryptic diversity in a changing ocean.

Keywords: Portuguese man-of-war, new species, ecosystem change, Kuroshio Extension (KE), distribution range

Phylum Cnidaria Verrill, 1865

Subphylum Medusozoa Peterson, 1979

Class Hydrozoa Owen, 1843

Subclass Hydroidolina Collins, 2000

Order Siphonophorae Eschscholtz, 1829

Family Physaliidae Brandt, 1835

Genus Physalia Lamarck, 1801

 Morphological characteristics of Physalia mikazuki sp. nov. collected from Gamo Beach, Sendai City, Miyagi Prefecture, Japan. Type 112960 (Tohoku University Museum).; Central image: Entire colony displaying the gas-filled pneumatophore and trailing tentacles (scale bar = 5 cm).;
 (A) Lateral view of the pneumatophore with a well-defined wrinkled crest and transparent, sail-shaped float.; (B) Close-up of the dorsal surface beneath the pneumatophore, highlighting clusters of gonodendra, tentacular palpons, and gastrozooids with yellow-tipped oral regions.; (C) Multiple principal tentacles exhibiting characteristic coiled morphology.; (D) Zooid clusters divided into the posterior zone (right), containing six zooid clusters (I–VI) and a protozooid (PZ), and the main zone (left), with densely packed tripartite zooid groups extending aborally. Colony orientation is indicated (anterior, posterior, dorsal, ventral).; (E) Close-up view of the gastrozooids elongate with distally swollen, balloon-like yellow tips, highlighting their feeding structures. Photographs taken of live specimens under natural and aquarium lighting to preserve color and morphology.

Physalia mikazuki sp. nov. Yongstar, Ochiai & Lewis Ames 

Diagnosis: Physalia mikazuki sp. nov. Yongstar, Ochiai & Lewis Ames is distinguished from other members of the genus Physalia by a combination of morphological traits: Pneumatophore length range 9.25–72.4 mm, with maximum known size smaller than that reported for P. physalis (8.1–134 mm) but overlapping with P. utriculus. Coloration of the crest is bluish with deep blue to purple hues and membrane is a translucent bluish-green (vs. dark green/carmine in P. physalis, blue and clear-glassy in P. utriculus, transparent with green patch at anterior apex in P. minuta). Up to six zooid clusters are present in the ...

Distribution: Tohoku and Kanto regions of Japan; Pakistan and Mexico.

Type locality: Gamo Beach, Sendai City, Miyagi Prefecture, Japan.

Etymology: The Japanese word “mikazuki” refers to the “crescent moon” shape of the warrior helmet worn by Samurai Masamune Date (1567 – 1636) of the Tohoku region who founded Sendai City. Vernacular “mikazuki no eboshi” (Japanese), “crescent helmet man-of-war” (English).

Chanikarn Yongstar, Yoshiki Ochiai, Muhammad Izzat Nugraha, Kei Chloe Tan, Ayane Totsu, Waka Sato-Okoshi and Cheryl Lewis Ames. 2025. Physalia mikazuki sp. nov. (Phylum Cnidaria; Class Hydrozoa) blown into Japan’s northeast (Tohoku) at the whim of Marine Ecosystem Change. Front. Mar. Sci. 12:1653958. DOI: doi.org/10.3389/fmars.2025.1653958 [30 October 2025]

https://www.tohoku.ac.jp/en/press/researchers_in_japan_discover_new_jellyfish_species_deserving_of_a_samurai_warrior_name.html

[Cnidaria • 2025] Iridogorgia curva & I. chewbacca • Unexpected Diversity of the Genus Iridogorgia in the tropical western Pacific with Descriptions of Two New Species [Studies on western Pacific Gorgonians (Anthozoa: Octocorallia: Chrysogorgiidae). Part 2]

 

Iridogorgia chewbacca 

Y. Xu, Watling, Zhan & K. Xu, 2025

  

DOI: doi.org/10.11646/zootaxa.5689.3.3 

manoa.hawaii.edu

Abstract

Species of the genus Iridogorgia Verrill, 1883 are typical deep-sea organisms, characterized by monopodial and spiral axis with a brilliant iridescence. Utilizing an integrated morphological-molecular approach, twelve specimens of Iridogorgia obtained from the tropical western and central Pacific were described as two new species I. curva sp. nov. and I. chewbacca sp. nov., and four known species. Additionally, I. fontinalis Watling, 2007 and I. splendens Watling, 2007 are two new recorded species in the Western Pacific Ocean. Iridogorgia verrucosa Xu, Zhan & Xu, 2021 and I. squarrosa Xu, Zhan, Li & Xu, 2020 are described again. There are currently fourteen species of Iridogorgia with twelve species in the Pacific. Among them, ten species were found in the tropical western Pacific, showing a high diversity. This study indicates the direction of growth (clockwise or counter-clockwise) is not a useful taxonomic character for Iridogorgia species identification. Phylogenetic analyses, based on both mtMutS-cox1 and 28S rDNA sequences, substantiated the taxonomic designation of the new species, I. chewbacca sp. nov. However, the mtMutS and mtMutS-cox1 showed very limited usefulness for species delimitation and inner relationship inference of most Iridogorgia species, while the 28S rDNA showed much higher level of genetic variation.

deep sea, morphology, phylogeny, seamount, taxonomy

Iridogorgia chewbacca 

YU XU, LES WATLING, ZIFENG ZHAN and KUIDONG XU. 2025. Studies on western Pacific Gorgonians (Anthozoa: Octocorallia: Chrysogorgiidae). Part 2: Unexpected Diversity of the Genus Iridogorgia in the tropical western Pacific with Descriptions of Two New Species. Zootaxa. 5689(3); 451-486. DOI: doi.org/10.11646/zootaxa.5689.3.3  [2025-09-04]

Chewbacca coral: New deep-sea species spotted in waters off Hawai‘i, Mariana Trench

https://manoa.hawaii.edu/news/article.php?aId=14141

[Cnidaria • 2025] Neoanthomastus stellatus, Anthomastus sphaericus, Pseudoanthomastus ornatus, ... • Mushroom Soft Corals (Octocorallia: Coralliidae) From Seamounts in the Tropical Northwestern Pacific: Morphology and Phylogenetic Analysis Reveal a New Genus and Six New Species

 

Neoanthomastus stellatus gen. et sp. nov., N. elongatus gen. et sp. nov., 
Anthomastus sphaericus sp. nov., A. tongi sp. nov., 
Pseudoanthomastus ornatus sp. nov., and P. applanatus sp. nov.

Y. Li, J. Li & Xu, 2025 

DOI: doi.org/10.1155/jzs/4177670

Abstract

Mushroom soft corals in the subfamily Anthomastinae are among the most remarkable octocorals found in the deep sea, characterized by their capitate or mushroom-shaped red colonies and large autozooids. To date, their species diversity remains largely unknown due to limited research, and their phylogenetic relationships have yet to be explored. Based on samples collected from four seamounts in the tropical Northwestern Pacific, we establish a new genus and six new species within Anthomastinae: Neoanthomastus stellatus gen. et sp. nov., Neoanthomastus elongatus gen. et sp. nov., Anthomastus sphaericus sp. nov., Anthomastus tongi sp. nov., Pseudoanthomastus ornatus sp. nov., and Pseudoanthomastus applanatus sp. nov. We transfer four species of Anthomastus with the siphonozooids extending into the stalk to the new genus Neoanthomastus, and four additional species of Anthomastus to Pseudoanthomastus. A dichotomous key to all five known genera and 43 species of Anthomastinae is provided. Meanwhile, we utilize the concatenated nucleotides of 13 mitochondrial protein-coding genes (PCGs), the full-length coding regions of the mitochondrial MutS gene (mtMutS) and the barcodes of partial mtMutS to elucidate the phylogenetic relationships among all the five genera (Anthomastus, Bathyalcyon, Heteropolypus, Pseudoanthomastus, and Neoanthomastus gen. nov.) and available species of Anthomastinae. The phylogenetic trees constructed from the three types of sequences suggest a hierarchical relationship where Neoanthomastus gen. nov. and Pseudoanthomastus form a clade that clusters with Bathyalcyon, which in turn with Heteropolypus, and finally with Anthomastus, all with high nodal supports. We also identify a second species in octocorals that lack the unique mtMutS. The study reveals a high diversity of mushroom soft corals and underscores the need for further systematic and zoogeographic research.

Keywords: Anthomastus, Anthomastinae, deep sea, mitochondrial DNA, mtMutS, new taxa

Morphology of Neoanthomastus gen. nov. and six new species of Anthomastinae.
(A–C) A. sphaericus sp. nov., same specimen in situ (A) and in preservation (B, C). (D, E) A. tongi sp. nov. in situ and in preservation.
(F, G) N. stellatus gen. et sp. nov. in situ and in preservation. (H, I) N. elongatus gen. et sp. nov. in situ and in preservation.
(J–M) P. ornatus sp. nov., same specimen in situ (J) and in preservation (K–M), arrows indicate small autozooids of capitulum margin. (N–P) P. applanatus sp. nov., same specimen in situ (N, O) and in preservation (P). au, autozooids; o, oocytes; si, siphonozooids.

 Scale bars = 10 mm (B, C, E), 20 mm (G, I, K, M), 5 mm (L), and 50 mm (P).

 

Neoanthomastus stellatus gen. et sp. nov., N. elongatus gen. et sp. nov., 

Anthomastus sphaericus sp. nov., A. tongi sp. nov., 

Pseudoanthomastus ornatus sp. nov., and P. applanatus sp. nov. 

Yang Li, Junyuan Li, Kuidong Xu. 2025. Mushroom Soft Corals (Octocorallia: Coralliidae) From Seamounts in the Tropical Northwestern Pacific: Morphology and Phylogenetic Analysis Reveal a New Genus and Six New Species. Journal of Zoological Systematics and Evolutionary Research. DOI: doi.org/10.1155/jzs/4177670 [30 March 2025] 

[Cnidaria • 2025] Parasphaerasclera mcfaddenae • A New Soft Coral Species (Octocorallia: Scleralcyonacea: Parasphaerascleridae) from the Gulf of Mexico

 Parasphaerasclera mcfaddenae

Quattrini, Morrissey & McCartin, 2025.  

 

DOI: doi.org/10.11646/zootaxa.5601.3.8

 

Abstract

A new species of soft coral, Parasphaerasclera mcfaddenae (Octocorallia: Scleralcyonacea: Parasphaerascleridae), is described from mesophotic hardbottom habitats of the Gulf of Mexico, western North Atlantic Ocean. Previously, this family was only known from the tropical Indo-Pacific and South Africa; therefore, we extend the distribution of the family Parasphaerascleridae into the North Atlantic Ocean. This diminutive species differs from other parasphaerasclerids by a capitate growth form, non-retractile polyps, and presence of tuberculated spindles. Notably, this species was also detected in environmental (e)DNA samples from locations where it was not physically collected, highlighting the importance of both eDNA for biodiversity surveys as well as specimen collections for building comprehensive reference databases for eDNA analyses.

Coelenterata, Parasphaerasclera, Scleralcyonacea, North Atlantic Ocean, eDNA, mesophotic reef

 Parasphaerasclera mcfaddenae sp.  nov. 
A) in situ image of two colonies,  B) in situ image of  the holotype prior to ROV collection, and C) image of holotype under the microscope with a 1 cm scale bar.

Parasphaerasclera mcfaddenae sp. nov. 

Andrea M. QUATTRINI, Declan MORRISSEY and Luke J. MCCARTIN. 2025. A New Soft Coral Species from the Gulf of Mexico (Octocorallia: Scleralcyonacea: Parasphaerascleridae). Zootaxa. 5601(3); 545-557. DOI: doi.org/10.11646/zootaxa.5601.3.8 [2025-03-10]

[Cnidaria • 2024] Pseudopterogorgia nanjiensis • A New gorgonian (Octocorallia: Gorgoniidae) from the Nanji Islands, China

 Pseudopterogorgia nanjiensis Sun, Xu & Zhan,

in Sun, Y. Xu, K. Xu, Chen, Xie et Zhan, 2024.  

DOI: 10.3897/zookeys.1213.126841

Abstract

Members of the genus Pseudopterogorgia Kükenthal, 1919 are widely distributed in shallow water of the Indo-West Pacific. During an investigation of benthic biodiversity in the subtidal zone surrounding the Nanji Islands in the East China Sea, two specimens of Pseudopterogorgia were collected and described as a new species based on an integrated morphological-molecular approach. Pseudopterogorgia nanjiensis sp. nov. is most similar to P. fredericki Williams & Vennam, 2001 in the irregular branching form and indistinct scaphoids, but differs by the coenenchymal sclerite content of distinct capstans and a few warty spindles and radiates (vs. mostly warty spindles and a few capstans), and a purplish colony (vs. white, pink to deep rose). Molecular phylogenetic analyses, based on the mtMutS-COI gene sequences, delineated a monophyletic clade encompassing all assessed Pseudopterogorgia species. Within this clade, P. nanjiensis sp. nov. showed a close phylogenetic affinity with both P. fredericki and P. australiensis Ridley, 1884.

Key words: Anthozoa, COI, Malacalcyonacea, morphology, mtMutS, new species, phylogeny, taxonomy, 28S rDNA

Phylum Cnidaria Hatschek, 1888

Subphylum Anthozoa Ehrenberg, 1834

Class Octocorallia Haeckel, 1866

Order Malacalcyonacea McFadden, van Ofwegen & Quattrini, 2022

Family Gorgoniidae Lamouroux, 1812

Genus Pseudopterogorgia Kükenthal, 1919

The external morphology and polyps of Pseudopterogorgia nanjiensis sp. nov.
  A holotype in situ B holotype after collection C paratype after fixation D part of branch under a light microscope E single polyp aperture under a light microscope F sclerites under a light microscope G coenenchyme under SEM H single dissolved polyp aperture under a light microscope.

Scale bars: 2 cm (B); 3 cm (C); 2 mm (D); 0.2 mm (E); 0.1 mm (F, G, H).

 Pseudopterogorgia nanjiensis Sun, Xu & Zhan, sp. nov.

 

Diagnosis: Colony non-pinnate and purplish. Branches divided dichotomously and irregularly, nearly in one plane. Polyp retracted and forming a small and oval-shaped protrusion. Sclerites in polyps small flat rodlets, colorless and rare to absent in numbers. Sclerites in coenenchyme red, mostly capstans, a few radiates and warty spindles, and rare scaphoids. Capstans have two whorls of tubercles and blunt ends with irregular arrangements of complex tubercles. Radiates and immature sclerites with two whorls of projections, spindles with 4–8 whorls of tubercles, and scaphoids with similar ornamentation of tubercles on both convex and concave sides.

Tingzai Sun, Yu Xu, Kuidong Xu, Shun Chen, Shangwei Xie and Zifeng Zhan. 2024. A New gorgonian Pseudopterogorgia nanjiensis sp. nov. (Cnidaria, Octocorallia, Gorgoniidae) from the Nanji Islands, China. ZooKeys. 1213: 237-249. DOI: doi.org/10.3897/zookeys.1213.126841