Vitrumanthus vanderlandi Kise & Montenegro & Santos & Hoeksema & Ekins & Ise & Higashiji & Fernandez-Silva & Reimer 2022, SP. NOV.

VITRUMANTHUS VANDERLANDI SP. NOV.

(FIG. 7A–F)

Z o o b a n k r e g i s t r a t i o n: u r n: l s i d: z o o b a n k. org:act: CE659473-CB9F-462B-97F7-4B974FAE96B9.

Material examined: Holotype: RMNH.COEL.42623, CANCAP-VII Expedition Station CV 7.041, Cape Verde Islands, SãoTiago, Ilheus Rombos, east of Cima, 14°56 ′ 59 ″ N, 24°37 ′ 59 ″ W, Agassiz trawl, at a depth of 700–800 m, coll. RV HNIMS Tydeman, 24 Aug 1986, fixed in 99.5% ethanol. Paratype: RMNH.COEL.42624, CANCAP-VII Expedition Station CV 7.041, Cape Verde Islands, SãoTiago, Ilheus Rombos, east of Cima, 14°56 ′ 59 ″ N, 24°37 ′ 59 ″ W, Agassiz trawl, at a depth of 580 m depth, coll. RV HNIMS Tydeman, 24 Aug 1986. Other material examined: RMNH.COEL.42625, Equalant II Expedition to the Gulf of Guinea, as part of the ICITA Programme (International Cooperative Investigations of the Tropical Atlantic), Sta. 18/8, 38 km off Liberia, 4°25 ′ N, 8°29 ′ W, trawl at a depth range of 380–510 m, on RV Geronimo Cruise 2, 31 Oct 1963, fixed in 99.5% ethanol.

Etymology: This species is named in honour of Dr Jacob van der Land, expedition leader of the CANCAP-VII expedition off the coast of West Africa (Van der Land, 1987), during which the type specimens of this species were collected. The Japanese name is 'Hime-ruri-sunaginchaku'.

Description: External morphology. Thirty-two cylindrical polyps in preserved specimen. Base of polyps embedded in Aphrocallistes sponge. Solitary polyps arise irregularly from host hexactinellid sponge. Preserved polyps cream white in coloration. Surface of column smooth, and ectoderm continuous. Ectoderm of polyps partially encrusted with small size of sand and silica particles. Transparent capitulum contracted and rounded. Contracted preserved polyps 0.3–2.5 mm in height, 0.8–3.0 mm in diameter. Capitulary ridges indiscernible when contracted. Approximately 20 tentacles in number.

Internal morphology. Zooxanthellae absent. Cyclically transitional marginal musculature. Mesoglea thickness 0.2–1.1 mm. Mesoglea thicker than ectoderm and endoderm. Siphonoglyph distinct and V-shaped. Mesenterial filaments present.

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

Distribution and habitats: West Africa: Guinea and Cape Verde at depths of 580– 800 m.

Associated host: Aphrocallistes beatrix Gray, 1858, Aphrocallistes sp.

Remarks: Vitrumanthus vanderlandi is phylogenetically close to V. oligomyarius, but these two species can be distinguished by dimensions of polyps and the numbers of tentacles. Vitrumanthus vanderlandi and V. oligomyaria are also associated with different host hexactinellid sponges (Aphrocallistes species vs. Tretochone duplicata). Moreover, V. vanderlandi does not have any holotrich nematocysts in all tissues we examined, while other species of Vitrumanthus have holotrich nematocysts present in some tissues.

Although the in situ polyp colour of V. vanderlandi is unknown, Buhl-Mortensen et al. (2017) have reported yellowed zoantharians that were observed on A. beatrix collected from the Gulf of Guinea. Therefore, the coloration of polyps of this species may be yellow. Further investigations with newly collected specimens are needed to confirm the in situ morphology of V. vanderlandi.