Churabana kuroshioae, Kise & Montenegro & Santos & Hoeksema & Ekins & Ise & Higashiji & Fernandez-Silva & Reimer, 2022

Kise, Hiroki, Montenegro, Javier, Santos, Maria E. A., Hoeksema, Bert W., Ekins, Merrick, Ise, Yuji, Higashiji, Takuo, Fernandez-Silva, Iria & Reimer, James D., 2022, Evolution and phylogeny of glass-sponge-associated zoantharians, with a description of two new genera and three new species, Zoological Journal of the Linnean Society 194, pp. 323-347 : 333-336

CHURABANA KUROSHIOAE SP. NOV.

( FIG. 4A–I )

Synonymy: Parazoanthidae sp. 1 — Reimer et al., 2019: 7, fig. 2A.

Zoobank registration: u r n: l s i d: z o o b a n k. org:act: FC503255-BDC2-45C5-9788-41F52BC40FA5.

Material examined: Holotype: RUMF-ZG-04447, near Iejima Island , Motobu, Okinawa, Japan, 26°54 ′ 53.6 ″ N, 127°37 ′ 50.9 ″ E, 600–650 m, baskets, coll. T. Higashiji on vessel Daini-kuroshio-maru, 2 March 2018, divided into two pieces, one portion fixed in 5–10% saltwater formalin and other in 99.5% ethanol.

Paratype: RUMF-ZG-04448, near Iejima Island , Motobu, Okinawa, Japan, 26°54’53.6 ″ N, 127°37 ′ 50.9 ″ E, 600–650 m, baskets, coll. T. Higashiji on vessel Dainikuroshio-maru, 2 March 2018, fixed in 99.5% ethanol. MISE-JMG51J (NSMT-Co 1754), Nanpo Trough, Kikaijima Island, Kagoshima, Japan, 28°20 ′ 21.64 ″ N, 129°57 ′ 14.56 ″ E, depth 520 m, ROV, coll. Javier Montenegro on RV Natsushima , 14 Oct 2011, fixed in 99.5% ethanol .

Etymology: The species is named after the Dainik u r o s h i o -m a r u, a s t h e t y p e s p e c i m e n s w e r e collected by this vessel. The Japanese name is 'Beni-chura-tama-sunaginchaku'.

Description: External morphology. Four truncated cone-shaped or cylindrical polyps in preserved specimen. The polyp bases embedded within the sponge Pararete Ijima, 1927 . Solitary polyps arise irregularly from Pararete specimens. The living polyps cream-pink or beige and tentacles cream or whitish transparent in coloration. Preserved polyps beige and partially red. Surface of column rough and ectoderm continuous. Ectoderm and mesoglea of polyps encrusted with numerous and various sizes of sand and silica particles. The living expanded oral disks c. 1.5– 2.0 mm in diameter, expanded polyps c. up to 10 mm in height, 4.0–5.0 mm in diameter. Preserved contracted preserved polyps 3.0–4.0 mm in height, 2.8–4.0 mm in diameter. Capitulary ridges discernible, 15–16 in number when contracted. 30–32 tentacles in number.

Internal morphology. Zooxanthellae absent. Cteniform endodermal marginal musculature. Encircling sinus present and basal canals of mesenteries absent. Mesenteries thin, 30–32 in macrocnemic arrangement. Mesoglea thickness 0.5–1.6 mm. Mesoglea thicker than ectoderm and endoderm. Siphonoglyph distinct and U-shaped. Mesenterial filaments present.

Cnidae. Basitrichs and microbasic b-mastigophores, microbasic p-mastigophores, holotrichs and spirocysts ( Fig. 5A ; Table 2 ).

Distribution and habitats: Ryukyu Archipelago, Japan: Near Iejima Island, Okinawa and Nanpo Trough, Kikaijima Island, Kagoshima, Japan at depths of 520– 650 m.

Associated host: Pararete sp. 1 and Pararete sp. 2 .

R e m a r k s: C h u r a b a n a k u r o s h i o a e r e s e m b l e s Vitrumanthus species , but they can be easily separated by differences in their marginal musculatures (see also Remarks under Vitrumanthus ).

Figures

Figure 4. Images of external and internal morphology of Churabana kuroshioae (A, paratype: NSMT Co-1754; B–I, holotype: RUMF-ZG-04447). A, living polyps on Pararete sp.1 in situ at Nanpo Trough, Kikaijima Island; B, living polyps on Pararete sp.2 in an aquarium at Okinawa Churaumi Aquarium, Motobu, Japan; C, close-up image of preserved polyp; D–F, longitudinal section of polyp; G, cross-section of polyp; H, close-up image of cyclically transitional marginal musculature; I, drawing of cteniform endodermal marginal musculature. Abbreviations: A, actinopharynx; Dd, dorsal directives; Cemm, cteniform endodermal marginal musculature; Ec, ectoderm; En, endoderm; M, mesoglea; S, siphonoglyph; O, oral disk; 5th, fifth mesentery from dorsal directives. Scales: 5 mm (A, B), 2 mm (C–H).

Figure 5. Cnidae in the tentacles, column, actinopharynx and mesenterial filaments of holotypes of new species in this study. A, cnidae of Churabana kuroshioae; B, cnidae of Vitrumanthus schrieri; C, cnidae of Vitrumanthus vanderlandi; D, cnidae of Vitrumanthus oligomyarius. Abbreviations: Hl, holotrichs large; Hm, holotrichs medium; Hs, holotrich small; O, basitrichs and microbasic b-mastigophores; Pm, microbasic p-mastigophores; S, spirocysts.