taxonID	type	format	identifier	references	title	description	created	creator	contributor	publisher	audience	source	license	rightsHolder	datasetID
B5622CDC27E35D46B833F94F454DA642.taxon	http://purl.org/dc/dcmitype/StillImage	image/png	https://binary.pensoft.net/fig/1683966	https://doi.org/10.3897/zookeys.1282.191792.figure2	Figure 2. Phalacrostemma ritto sp. nov. A. Habitat of the sea urchin of the family Cidaridae; B. Tubes attached to sea urchin spines; C. Close-up view of the tube; D, E. Live animal (holotype); F. Dorso-lateral view of preserved specimen (holotype); G. Ventral view of head and operculum; H. Dorsal view of head and operculum; I. Anterior view of operculum; J. Middle to posterior abdomen, arrows indicate lobes of notopodia. Abbreviations: bf: buccal flap; ca: cauda; ip: inner palea; mo: median organ: nc: neuropodial cirri; nh: nuchal hook; op: outer palea; p: palp. Scale bars: 0.5 mm.	Figure 2. Phalacrostemma ritto sp. nov. A. Habitat of the sea urchin of the family Cidaridae; B. Tubes attached to sea urchin spines; C. Close-up view of the tube; D, E. Live animal (holotype); F. Dorso-lateral view of preserved specimen (holotype); G. Ventral view of head and operculum; H. Dorsal view of head and operculum; I. Anterior view of operculum; J. Middle to posterior abdomen, arrows indicate lobes of notopodia. Abbreviations: bf: buccal flap; ca: cauda; ip: inner palea; mo: median organ: nc: neuropodial cirri; nh: nuchal hook; op: outer palea; p: palp. Scale bars: 0.5 mm.	2026-06-17	Nishi, Eijiroh;Kobayashi, Genki;Jimi, Naoto;Fujiwara, Yoshihiro;Kupriyanova, Elena K.		Zenodo	biologists	Nishi, Eijiroh;Kobayashi, Genki;Jimi, Naoto;Fujiwara, Yoshihiro;Kupriyanova, Elena K.			
B5622CDC27E35D46B833F94F454DA642.taxon	http://purl.org/dc/dcmitype/StillImage	image/png	https://binary.pensoft.net/fig/1683967	https://doi.org/10.3897/zookeys.1282.191792.figure3	Figure 3. Phalacrostemma ritto sp. nov. A, B, G. Paratype; C – F. Holotype. A. Lateral view from head to parathoracic region, half of operculum omitted; B. Antero-ventral view of operculum, paleae omitted; C. Ventral view of head and operculum, paleae omitted; D. Ventral view of abdomen (right side), showing notopodia and neuropodia, left side omitted; E. Close-up view of second and third abdominal parapodia; F. Close-up view of 7 th and 8 th parapodia; 9 th parapodium also shown. pt 1–4 in A indicate first to 4 th parathoracic chaetiger, a 1 – a 3 in A, a 2 and a 3 in E, a 7 and a 8 in F indicate abdominal chaetiger number. Abbreviations: bf: buccal flap; br: branchia; ip: inner paleae; mo: median organ; nc: neuropodial cirri; nep: neuropodium; nh: nuchal hook; ntp: notopodium; op: opercular palea; p: palp; pa: opercular papillae; pt: parathoracx. Scale bars: 1 mm (A – F); 0.1 mm (G).	Figure 3. Phalacrostemma ritto sp. nov. A, B, G. Paratype; C – F. Holotype. A. Lateral view from head to parathoracic region, half of operculum omitted; B. Antero-ventral view of operculum, paleae omitted; C. Ventral view of head and operculum, paleae omitted; D. Ventral view of abdomen (right side), showing notopodia and neuropodia, left side omitted; E. Close-up view of second and third abdominal parapodia; F. Close-up view of 7 th and 8 th parapodia; 9 th parapodium also shown. pt 1–4 in A indicate first to 4 th parathoracic chaetiger, a 1 – a 3 in A, a 2 and a 3 in E, a 7 and a 8 in F indicate abdominal chaetiger number. Abbreviations: bf: buccal flap; br: branchia; ip: inner paleae; mo: median organ; nc: neuropodial cirri; nep: neuropodium; nh: nuchal hook; ntp: notopodium; op: opercular palea; p: palp; pa: opercular papillae; pt: parathoracx. Scale bars: 1 mm (A – F); 0.1 mm (G).	2026-06-17	Nishi, Eijiroh;Kobayashi, Genki;Jimi, Naoto;Fujiwara, Yoshihiro;Kupriyanova, Elena K.		Zenodo	biologists	Nishi, Eijiroh;Kobayashi, Genki;Jimi, Naoto;Fujiwara, Yoshihiro;Kupriyanova, Elena K.			
B5622CDC27E35D46B833F94F454DA642.taxon	http://purl.org/dc/dcmitype/StillImage	image/png	https://binary.pensoft.net/fig/1683968	https://doi.org/10.3897/zookeys.1282.191792.figure4	Figure 4. Phalacrostemma ritto sp. nov. A – G. Light photographs; H – Q. SEM micrographs. A. Nuchal hook, lim indicates limbation; B. Outer palea, whole view; C. Outer palea, basal part; D. Outer palea, middle part; E. Outer palea, tip; F. Outer palea, black tip; G. Inner palea; H. Outer palea, whole view; I. Outer palea, basal part; J. Outer palea, middle part; K. Outer palea, tip; L. Inner palea, middle part; M. Inner palea, distal tip. N. Parathoracic chaetiger showing lanceolate chaetae and fine capillary chaetae; O. Middle abdomen; showing bilobed notopodia (right) and neurochaetal tuft (left); arrows indicate lobes of notopodia. P. Abdominal uncini, lateral view; Q. Abdominal uncini, ventral view. Scale bars: 200 µm (A, B, H); 50 μm (C – G, O, J – M); 20 μm (I, N); 10 μm (P); 5 μm (Q).	Figure 4. Phalacrostemma ritto sp. nov. A – G. Light photographs; H – Q. SEM micrographs. A. Nuchal hook, lim indicates limbation; B. Outer palea, whole view; C. Outer palea, basal part; D. Outer palea, middle part; E. Outer palea, tip; F. Outer palea, black tip; G. Inner palea; H. Outer palea, whole view; I. Outer palea, basal part; J. Outer palea, middle part; K. Outer palea, tip; L. Inner palea, middle part; M. Inner palea, distal tip. N. Parathoracic chaetiger showing lanceolate chaetae and fine capillary chaetae; O. Middle abdomen; showing bilobed notopodia (right) and neurochaetal tuft (left); arrows indicate lobes of notopodia. P. Abdominal uncini, lateral view; Q. Abdominal uncini, ventral view. Scale bars: 200 µm (A, B, H); 50 μm (C – G, O, J – M); 20 μm (I, N); 10 μm (P); 5 μm (Q).	2026-06-17	Nishi, Eijiroh;Kobayashi, Genki;Jimi, Naoto;Fujiwara, Yoshihiro;Kupriyanova, Elena K.		Zenodo	biologists	Nishi, Eijiroh;Kobayashi, Genki;Jimi, Naoto;Fujiwara, Yoshihiro;Kupriyanova, Elena K.			
B5622CDC27E35D46B833F94F454DA642.taxon	http://purl.org/dc/dcmitype/StillImage	image/png	https://binary.pensoft.net/fig/1683965	https://doi.org/10.3897/zookeys.1282.191792.figure1	Figure 1. Map of the collection site in Japanese waters (left) and the Western Mariana Ridge, Ritto Seamount, Japan (right). The arrow on the left indicates the location of Ritto Seamount and the adjacent area. The base map on the right has been modified from the U. S. NOAA SRTM 15 _ PLUS dataset.	Figure 1. Map of the collection site in Japanese waters (left) and the Western Mariana Ridge, Ritto Seamount, Japan (right). The arrow on the left indicates the location of Ritto Seamount and the adjacent area. The base map on the right has been modified from the U. S. NOAA SRTM 15 _ PLUS dataset.	2026-06-17	Nishi, Eijiroh;Kobayashi, Genki;Jimi, Naoto;Fujiwara, Yoshihiro;Kupriyanova, Elena K.		Zenodo	biologists	Nishi, Eijiroh;Kobayashi, Genki;Jimi, Naoto;Fujiwara, Yoshihiro;Kupriyanova, Elena K.			
