[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 • 2024] Zancleopsis grandis & Melicertum tropicalis • Additional Observations on Hydromedusae during Night Dives in the Gulf Stream

Zancleopsis grandis 

Schuchert & Collins, 2024

 

DOI: 10.35929/RSZ.0113

Abstract

This work is a supplement of our previous study (Schuchert & Collins, 2021) on hydromedusae observed and collected during night-time dives in the Gulf Stream off Florida. Close-up photos and collection of selected specimens for DNA extraction and 16S barcode sequencing permitted us to distinguish 49 distinct morphotypes or species of hydromedusae. Eighteen of them are new additions to the ones reported in our 2021 paper. Seven potential species of the 49 were only identified to the genus level, one to the family level. Two new species are described: Zancleopsis grandis sp. nov. and Melicertum tropicalis sp. nov. 16S sequences permitted us to identify the previously unknown subadult medusa of Podocoryna martinicana Galea & Ferry, 2013. Three species are new records for the Northwest Atlantic: Leuckartiara adnata Pagès, Gili & Bouillon, 1992, Corymorpha valdiviae (Vanhöffen, 1911), and Cnidocodon leopoldi Bouillon, 1978. The 16S data indicated the potential presence of cryptic species in Thecocodium quadratum (Werner, 1965), Laodicea undulata (Forbes & Goodsir, 1853), Orchistoma pileus (Lesson, 1843), and Pseudaegina rhodina (Haeckel, 1879).

KEYWORDS: 16S DNA barcodes, blackwater diving, Cnidaria, Florida, Hydrozoa, taxonomy

Zancleopsis grandis sp. nov. Holotype, BFLA4559, total height size 29 mm. The brownish objects are crustaceans.
 Structural details: green arrows – the same individual capitulum; red arrows – filiform tentacles, blue arrows – broken ends of the long tentacles, yellow arrows – developmental zone of the side-branches, purple arrow – gonad folds.
(A) Lateral view. (B) Manubrium in lateral view. (C-D) Tentacle details. (E-F) Partially relaxed filiform and branched tentacles, the axis of the medusa is horizontal. 

Zancleopsis grandis sp. nov. Paratype, BFLA4561, size 25 mm, tentacles and capitula relaxed; green arrows indicate branched tentacles, blue arrows the shorter, filiform tentacles.
(A) Lateral view. (B) View on velar opening, the green arrow points to incipient side-branches of a long tentacle. (C) Long tentacle region with large capitula. (D) Higher magnification of capitula. Photos by Linda Ianniello.

Zancleopsis grandis sp. nov.

 

Zancleopsis dichotoma. – Bigelow, 1938: 102, figs 1-2. [not Zancleopsis dichotoma (Mayer, 1900)].

  

Type locality: USA, Florida, about 10 km east of Palm Beach; ...; depth 10 m.

Etymology: The specific epithet “grandis” refers to the relatively large size of this medusa and to the very large capitula of the tentacular side branches.

Diagnosis: Zancleopsis medusa with total bell height up to 29 mm, with large apical process, with two long tentacles with abaxial side branches, the latter ending in very large capitula, much larger than marginal bulbs, spherical or ovoid depending on state of contraction, other two tentacles relatively long, tapering, without swollen end or capitulum; gonads in vertical folds.

Peter Schuchert and Richard Collins. 2024. Additional Observations on Hydromedusae during Night Dives in the Gulf Stream. Revue suisse de Zoologie. 131(1):43-120. DOI: 10.35929/RSZ.0113

[Cnidaria • 2020] Plumularia roxanae • A New Epiphytic Hydroid (Hydrozoa: Plumulariidae) from the Indo-Pacific

Plumularia roxanae

Galea, 2020

DOI:  10.35929/RSZ.0026 

 Abstract 

A new epiphytic, small-sized species of Plumularia Lamarck, 1816, P. roxanae sp. nov., is described based on fertile material from Bali, Indonesia. Its deep hydrothecae are characteristically narrowed distally through a distinctive hypertrophy of the free portion of their adaxial wall. Its minute gonothecae, however, are comparable in shape and size to those of the well-known, circumtropical P. floridana Nutting, 1900.

Plumularia roxanae sp. nov.
(A) Portion of cormoid. (B) Detail of a portion of stem with proximal parts of four successive cladia. (C) Detail of a stem internode, showing centrally an apophysis and the proximal part of the corresponding cladium. (D) Proximal most hydrotheca. (E) Distalmost hydrotheca, note the absence of the distal part of its corresponding internode. (F) Portion of fertile stem with rows of gonothecae. (G) Gonotheca. (H) More detailed view of a gonotheca, showing apical aperture (arrowhead).

 Scale bars: 50 µm (H), 100 µm (C-E, G), 200 µm (B, F), 500 µm (A).

Plumularia roxanae sp. nov.  

  

Diagnosis: Small-sized, epiphytic Plumularia arising from stolon with perisarcal spurs, giving rise to monosiphonic stems divided homomerously by transverse nodes into rather short, collinear internodes, each with a subterminal cladial apophysis provided with an inconspicuous adaxial mamelon and a pair of axillar nematothecae; cladia heteromerously segmented by alternating straight and oblique nodes into short, ahydrothecate internodes occasionally provided with a nematotheca, and up to three, comparatively longer hydrothecate internodes accommodating a centrally-placed hydrotheca and its three associated nematothecae; hydrotheca deep, saccate, partly adnate, distal portion distinctly constricted through the hypertrophy of the free adaxial wall that adopts a triangular shape, considerably reducing the thecal lumen; abaxial wall slightly convex; gonothecae in two closely-set, parallel rows along the stem, borne on the cladial apophyses, minute, ovoid, thick-walled.

 Etymology: It is my great pleasure to dedicate this new species to the memory of my late mother, Roxana S. Galea (née Florescu, 5 Oct. 1946 – 18 Jan. 1994), a Romanian biologist, who passed on to me her interest for natural sciences.

Horia R. Galea. 2020. Plumularia roxanae, A New Epiphytic Hydroid (Cnidaria: Hydrozoa: Plumulariidae) from the Indo-Pacific. Revue suisse de Zoologie. 127(2); 367-376. DOI:  10.35929/RSZ.0026 

[Cnidaria • 2019] Benthic Hydroids (Hydrozoa) from the Weddell Sea (Antarctica)

Campanularia hicksoni Totton, 1930

in Àngel & Cantero, 2019.  

DOI: 10.11646/zootaxa.4570.1.1   

Abstract

Hydrozoans are a conspicuous component of Antarctic benthic communitites. Recent taxonomic effort has led to a substantial increase in knowledge on the diversity of benthic hydroids from some areas of the Southern Ocean, including the Weddell Sea, the largest sea in the Antarctic region. However, the study of many hydrozoan taxa are still pending, and the diversity in this huge region is expected to be higher than currently known. In order to contribute to the knowledge of taxonomy, ecology and distribution of these cnidarians, a study of unpublished material collected by several German Antarctic expeditions aboard the RV Polarstern in the eastern sector of the Weddell Sea has been conducted. A total of 77 species belonging to 22 families and 28 genera of benthic hydroids have been inventoried, constituting the most prolific collection hitherto analyzed. Most species (81%) belong to Leptothecata, but the observed share of Anthoathecata (19%) is higher than in previous Antarctic hydrozoan studies. Symplectoscyphidae was the most speciose family with 16 representatives (22%), followed by Haleciidae with 10 (14%) and Staurothecidae with 8 (11%). The number of species known in the area was increased with 27 new records, including several species rarely documented. As a result, the Weddell Sea becomes the second Antarctic region in terms of hydrozoan diversity, with 89 species known to date. Novel data on the use of substrate, reproductive phenology, and bathymetric range are provided for the inventoried species.

Keywords: Coelenterata, Biodiversity, Checklist, Cnidome, Hydrozoan, New Records, Southern Ocean

Campanularia hicksoni Totton, 1930,
general view of the colony.

Joan J. Soto Àngel and Álvaro L. Peña Cantero. 2019. Benthic Hydroids (Cnidaria, Hydrozoa) from the Weddell Sea (Antarctica). Zootaxa. 4570(1); 1–78. DOI: 10.11646/zootaxa.4570.1.1

[Cnidaria • 2017] Additions to The Hydroids (Cnidaria, Hydrozoa) of the Bay of Fundy, northeastern North America, with A Checklist of Species Reported from the Region

FIGURE 1. Tubularia acadiae, hydranth with male gonophores, Minas Basin, Nova Scotia.

Photograph by J.S. Bleakney.  DOI: 10.11646/zootaxa.4256.1.1

Abstract

Two new species of hydroids, Eudendrium bleakneyi and Halecium praeparvum, are described from the Bay of Fundy. Fourteen others, Tubularia acadiae Petersen, 1990, Coryne pusilla Gaertner, 1774, Sarsia lovenii (M. Sars, 1846), Zanclea implexa (Alder, 1856), Corydendrium dispar Kramp, 1935, Rhizogeton fusiformis L. Agassiz, 1862, Bougainvillia muscus (Allman, 1863), Rhizorhagium roseum M. Sars, in G.O. Sars, 1874, Hydractinia symbiolongicarpus Buss & Yund, 1989, Eudendrium vaginatum Allman, 1863, Tiaropsis multicirrata (M. Sars, 1835), Obelia bidentata S.F. Clark, 1875, Halecium marsupiale Bergh, 1887, and Sertularella gigantea Hincks, 1874, are reported, with collection data, for the first time from the bay. All but Coryne pusilla, Rhizorhagium roseum, Eudendrium vaginatum, and Sertularella gigantea are also new to Atlantic Canada, while Zanclea implexa, Corydendrium dispar, and Halecium marsupiale are reported for the first time in the western North Atlantic. Two of those species, Hydractinia symbiolongicarpus and Obelia bidentata, are disjunct in distribution, with core populations occurring in warmer waters to the south of Cape Cod, Massachusetts. Both were discovered in Minas Basin, a hydrographically distinct embayment where surface water temperatures are much warmer during summer than in the perpetually cold lower Bay of Fundy. Rhizorhagium roseum and the subfamily Rhizorhagiinae are transferred from family Bougainvilliidae Lütken, 1850 to Pandeidae Haeckel, 1879. An annotated checklist of hydroids from the Fundy region, based on previously published reports and on new records of species, is added as an appendix. Included in the checklist are 43 species of anthoathecates and 75 species of leptothecates, referable to 30 families and 56 genera. Families with the most species were Sertulariidae (23), Haleciidae (13), Eudendriidae (11), and Obeliidae (10). Biogeographically, the aggregate hydroid fauna of the bay conforms with that occurring in other parts of the Western Atlantic Boreal Region. Halecium permodicum is proposed as a replacement name for Halecium minor Fraser, 1935, an invalid junior homonym of H. minor Pictet, 1893.

Keywords: Anthoathecata, Hydroidolina, Leptothecata, marine invertebrates, Medusozoa, Minas Basin, Passamaquoddy Bay, taxonomy, zoological nomenclature

FIGURE 1. Tubularia acadiae, hydranth with male gonophores, Minas Basin, Nova Scotia.

Photograph by J.S. Bleakney.

DOI: 10.11646/zootaxa.4256.1.1 

Dale R. Calder. 2017. Additions to the Hydroids (Cnidaria, Hydrozoa) of the Bay of Fundy, northeastern North America, with A Checklist of Species Reported from the Region. Zootaxa. 4256(1); 1-86. DOI: 10.11646/zootaxa.4256.1.1

[Cnidaria • 2016] Erenna insidiator & E. sirena • A Description of Two New Species of the Genus Erenna (Siphonophora: Physonectae: Erennidae), with Notes on Recently Collected Specimens of Other Erenna species

 Erenna laciniata Pugh, 2001  

DOI: 10.11646/zootaxa.4189.3.1 

Abstract

Two new Erenna species, Erenna insidiator sp. nov. and Erenna sirena sp. nov., are described from specimens collected in the vicinity of Monterey Bay, California, and also, for E. sirena at the southern end of the Gulf of California, Mexico. Further information on the three extant Erenna species is given, based on specimens collected in the same areas. These have enabled, for instance, the identification of three types of tentilla on the tentacles of E. cornuta Pugh, 2001, rather than the two noted on the single previously known specimen. The genus is remarkable for the presence of bioluminescent lures on the tentilla of all five species. In E. sirena sp. nov. the tentilla are also covered by a red-fluorescent layer, which was briefly described by Haddock et al. (2005), and further details are given herein. Another extraordinary feature of the colonies E. sirena sp. nov. is that the main part of the tentacle, with its tentilla, can be extended away from the siphosomal stem on a long peduncle. This phenomenon also appears to occur in E. laciniata Pugh, 2001, and has not been observed before for other physonect species.

Keywords: Coelenterata, Siphonophora, Physonectae, Erennidae, Erenna, taxonomy, Morphology, Lures

P.R. Pugh  and S.H.D. Haddock. 2016. A Description of Two New Species of the Genus Erenna (Siphonophora: Physonectae: Erennidae), with Notes on Recently Collected Specimens of Other Erenna species. Zootaxa. 4189(3); 401–446.  DOI: 10.11646/zootaxa.4189.3.1