[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

[Invertebrate • 2021] Scutopus variabilis • Better Alone Than in Bad Company: New Species of Caudofoveate Limifossorid (Mollusca, Aplacophora) Unravels Patterns of Distribution Hidden in the Deep Atlantic

Scutopus variabilis 

Passos, Corrêa & Miranda, 2021

 DOI: 10.3389/fmars.2021.669478

Aplacophorans are common inhabitants of the deep-sea, where many places remain unexplored regarding their biodiversity. Filling a gap in knowledge about these animals from the South Atlantic, Scutopus variabilis sp. nov. (Caudofoveata, Limifossoridae) is described; further, species distribution modelling (SDM) was performed to elucidate the distribution patterns of Atlantic species of Scutopus. The type materials of S. megaradulatus Salvini-Plawen (1972) and S. chilensis Salvini-Plawen (1972), were examined and a search was performed for specimens of Scutopus held in museum collections. Scutopus variabilis sp. nov. has a slender and highly variable body form and a very distinct suture line is present midventrally. Two dominant types of trunk sclerites were observed by Scanning Electron Microscopy (SEM): one elongated with lateral margins slightly concave in medial portion, and another longer, with narrower base; its radula bears up to eight rows of heavily sclerotized teeth bearing 12–16 small denticles. The species occurs in a wide bathymetric range (40–1300 m), being more abundant at the edge between the continental shelf and upper slope. Outside the areas from where these samples were obtained, suitable areas for S. variabilis sp. nov. were found in the Southern Caribbean Sea (from where S. megaradulatus is recorded) and in the Brazilian Northern coast; the Gulf of Mexico and the Brazilian Northeastern coasts were found as unsuitable. Species of Scutopus appear to exhibit different patterns of geographical distribution: the European S. ventrolineatus Salvini-Plawen (1968) and S. robustus Salvini-Plawen (1970) are known as widely distributed, while non-European representants, the American S. megaradulatus, S. chilensis and S. variabilis sp. nov., and the Japanese S. schanderi Saito and Salvini-Plawen (2014) and S. hamatamii Saito and Salvini-Plawen (2014) have more restricted distributions. However, clear and definite patterns of distribution of some of these species are probably blurred by sampling bias, for the European area is better studied. In the Atlantic, the SDM showed that species of Scutopus occur in a way that overlapping is minimized. Great sampling efforts combined with detailed descriptions based on SEM have revealed an interesting, abundant and up to now undescribed Brazilian deep-sea malacofauna.

Keywords: taxonomy, biogeography, species distribution modeling, Caudofoveata, Limifossoridae

Family Limifossoridae Salvini-Plawen, 1969

Genus Scutopus Salvini-Plawen, 1968

Type species: Scutopus ventrolineatus Salvini-Plawen, 1968 

by original designation.

Remarks: Salvini-Plawen (1968) characterized S. ventrolineatus by its long, undivided, cylindrical body which coils up spirally when it is disturbed, its radula composed by multiple rows of paired teeth, each tooth bearing median denticles, an undivided or homogeneous, post-oral shield, and the presence of a long midgut sac or digestive gland, and by its sclerites that ventrally are positioned in a divergent way forming a clear external ventral sutural line. Later, Salvini-Plawen (1975) and Ivanov (1981) highlighted that the characters of the oral shield and the radula are typical of Scutopus species. The new species described herein has these main characteristics, as shown below.

Figure 1. Scutopus variabilis sp. nov. Photomicrographs under stereomicroscope of specimens of different sizes showing their variable body form and color (all in same scale). The body regions are shown in (A) (holotype) and (H), (B) and (D) had their soft parts dissolved for the extraction of their radulas [which are shown in Figures 4A,E, respectively and of their sclerites from the different body regions. The peribuccal region is protruded in (C) and (I). The midventral suture line is visible in (E) and (H); the main collar in (B), (F), (I), (K), (M), and (O); and the secondary collar in (H). The asterisks in (D), (E), (G), (J–N), (P), and (Q) show the anterior end.

fgr - foregut region; mc - main collar; mgr - midgut region; msr - midgut sac region; pbr - peribuccal region; ppr - prepallial region; pr - pallial region; sc - secondary collar; sl - midventral suture line. 

Voucher numbers: (A) – ZUEC APL 277, (B) – ZUEC APL 285, (C) – ZUEC APL 287, (D) – ZUEC APL 284, (E) – ZUEC APL 279, (F) – ZUEC APL 282, (G) – ZUEC APL 306, (H) – ZUEC APL 298, (I) – ZUEC APL 286, (J) – MZSP 154099, (K) – ZUEC APL 286, (L) – ZUEC APL 326, (M) – MNRJ 23638, (N) – ZUEC APL 331, (O) – ZUEC APL 291, (P) – ZUEC APL 311, (Q) – ZUEC APL 283.

Scutopus variabilis sp. nov. Passos, Corrêa and Miranda

Diagnosis. Body long, slender, up to 14 mm in length, often contorted, almost uniform in diameter; in most specimens divided in three parts: an anterior part separated by a main collar from a median part, and a slightly tapered posterior part. Oral shield post-oral, ventral to the mouth. Midventral suture line present. Two main types of sclerites: one elongated, with lateral margins slightly concave in medial portion, with base wider and about a half of the blade length, and another shorter, triangular, base and blade with continuous straight lateral margins; in both, blade ornamented with a central keel and weak adjacent longitudinal grooves. Radula distichous, with up to eight transversal rows of heavily sclerotized teeth (except for the two most proximal pairs); each tooth inwardly curved, with 12–16 small median bent denticles present in all the extension of the concave, inner margin.

Etymology. The name variabilis refers to the variable form and color exhibited by the specimens of this species.

 

 

Flávio Dias Passos, Paulo Vinicius Ferraz Corrêa and Marcel Sabino Miranda. 2021. Better Alone Than in Bad Company: New Species of Caudofoveate Limifossorid (Mollusca, Aplacophora) Unravels Patterns of Distribution Hidden in the Deep Atlantic. Front. Mar. Sci. 8:669478. DOI: 10.3389/fmars.2021.669478

[Invertebrate • 2021] Tedania (Tedaniopsis) rappi • Increasing Knowledge of Biodiversity on the Orphan Seamount: A New Species of Tedania (Tedaniopsis) Dendy, 1924 (Demospongiae, Poecilosclerida)

Tedania (Tedaniopsis) rappi 

Ríos, Cristobo & Kenchington

in Ríos, Cristobo, Baker, ... et Kenchington, 2021. 

DOI: 10.3389/fmars.2021.612857 

 twitter.com/ralip88

A new Tedania species (Porifera) was collect using remotely operated vehicles during the Canadian mission HUD2010-029 and the British RRS Discovery Cruise DY081, on the Orphan Seamount near the Orphan Knoll, northwest Atlantic, between 2999.88 and 3450.4 m depth. Orphan Knoll is an isolated, drowned continental fragment 550 km northeast Newfoundland in the Labrador Sea. This region is biologically rich and complex and in 2007, the regional fisheries management organization operating in the area regulated that no vessel shall engage in bottom-contact fishing activities until reviewed in 2020 with a review slated at the end of this year. Members of the genus Tedania are uncommon in the temperate northern hemisphere with only six species known previously: Tedania (Tedania) anhelans; Tedania (Tedania) pilarriosae; Tedania (Tedania) suctoria; Tedania (Tedania) urgorrii; Tedania (Tedaniopsis) gurjanovae; and Tedania (Tedaniopsis) phacellina. The particular features of the new sponge we describe are the very peculiar external morphology which is tree-like with dichotomous branching—a morphology not previously described in this subgenus; and the combination of spicules found: long styles, the typical tornotes of the subgenus and two sizes of onychaetes. Additional information is provided on other species of Tedaniopsis described from the Atlantic Ocean. Based on the characteristics reported, we propose a new species, Tedania (Tedaniopsis) rappi sp. nov. in honor of Prof. Hans Tore Rapp (1972–2020), University of Bergen, Norway, a renowned sponge taxonomist and coordinator of the Horizon 2020 SponGES project. The holotype of T. (T.) phacellina Topsent, 1912 from the Azores, the only other northern Atlantic species in the subgenus Tedaniopsis, was reviewed for comparison.

Keywords: sponges, VMEs, taxonomy, new species, Tedania (Tedaniopsis) rappi

Figure 2. Tedania (Tedaniopsis) rappi sp. nov.
(A,B) Environment of holotype. (C) In situ collection of holotype.

Phylum PORIFERA Grant, 1836

Class DEMOSPONGIAE Sollas, 1885

SubClass HETEROSCLEROMORPHA Cárdenaset al., 2012

Order POECILOSCLERIDA Topsent, 1928

Family TEDANIIDAE Ridley and Dendy, 1886

Genus Tedania Gray, 1867

Definition: Tedaniidae with differentiated ectosomal and choanosomal megascleres Van Soest (2002).

Subgenus Tedaniopsis Dendy, 1924

Diagnosis: Tedania with relatively long thick, smooth styles, occasionally modified to anisostrongyles or anisoxeas, as structural megascleres. Ectosomal megascleres are mucronate or tylostrongylote tornotes occasionally with one or more vestigial spines (Desqueyroux-Faúndez and Van Soest, 1996).

Tedania (Tedaniopsis) rappi Ríos, Cristobo and Kenchington sp. nov.

Type material: Holotype: TBD Orphan Seamount (NW Atlantic), 50.1119; −45.3199. Depth 2999.88 m, Coll. CCGS Hudson, 19.07.2010, 1 specimen. Rock substrate. In 70% Ethanol Canadian Museum of Nature number CMNI 2020-0004. Paratype: Atlantic Reference Centre (ARC) Museum (ARC 81604) Orphan Seamount (NW Atlantic), 50.0484; -45.3757, 3,450 m depth, Coll. RRS Discovery, 08.07.2017, 1 specimen. Rock substrate. In 100% Ethanol.

Holotype of Tedania (Tedaniopsis) phacellina Topsent, 1912, was revised. Museé Oceanographique Monaco; Collection of S.A.S. Le Prince de Monaco Station 2183, 28th August 1905, 1,998 m in depth. A small fragment (Schizotype) was analyzed by SEM.

Derivatio nominis: In honor of Prof. Hans Tore Rapp (1972–2020), University of Bergen, Norway, a renowned sponge taxonomist and dear colleague, who described 50 new species of sponges for science. Prof. Rapp was also coordinator and leader of the EU Horizon 2020 SponGES project which focused much needed attention on deep-sea sponges and their habitats.

 

Pilar Ríos, Javier Cristobo, Emily Baker, Lindsay Beazley, Timothy Culwick and Ellen Kenchington. 2021. Increasing Knowledge of Biodiversity on the Orphan Seamount: A New Species of Tedania (Tedaniopsis) Dendy, 1924. Front. Mar. Sci. 8:612857. DOI: 10.3389/fmars.2021.612857

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