Umimayanthus lynherensis, Montenegro & Fromont & Richards & Kise & Gomez & Hoeksema & Reimer, 2024

Montenegro, Javier, Fromont, Jane, Richards, Zoe, Kise, Hiroki, Gomez, Oliver, Hoeksema, Bert W. & Reimer, James Davis, 2024, Museum collections as untapped sources of undescribed diversity of sponge-zoantharian associations with the description of six new species of Umimayanthus (Zoantharia: Parazoanthidae) from Western Australia and eastern Indonesia, Contributions to Zoology 93 (5), pp. 466-522 : 503-507

Umimayanthus lynherensis sp. nov.

Montenegro, Kise & Reimer urn:lsid:zoobank.org:act:5047277C-8846-4965-81E1-53A2D5268A56

Etymology. The specific epithet “ lynherensis ” is derived from the locality where the type specimen was collected, the Lynher Bank sea country north Kimberley, Western Australia, Australia.

Materialexamined.Typelocality:Lynher Bank [loc. 14], − 15.493683 °S, 121.636233 °E. Holotype: WAM Z88821 (− 15.493683 °S, 121.636233 °E, loc. 14, Lynher Bank , Western Australia, 95 m depth, October 25, 2016 by J. Fromont & J.A. Ritchie). No other material was available.

Diagnosis. U. lynherensis sp. nov. can be differentiated from all other species in the genus Umimayanthus by combining polyp size, colony morphology and identity of the host sponges. U. lynherensis sp. nov. have comparatively the smallest polyp diameter of all the species described in here, 1.58 mm ± 0.17 mm, colonies exclusively composed of solitary polyps, and associate with sponges in Sigmaxinella

CONTRIBUTIONS TO ZOOLOGY 93 (2024) 466–522

soelae Hooper, 1984 of the order Biemnida Morrow, 2013 .

Additionally, there are multiple unique nucleotide substitutions and insertions across ITS-rDNA and COI-mtDNA in the concatenated alignment, as follows: for ITS-rDNA an “A” in positions 47 bp and 135 bp, a “C” at 65 bp and 354 bp, a “G” at 403 bp, 411bp, 426 bp and 705 bp, a “T” at 756 bp, and one unique insertion of 8 nucleotides “GGTGGGGT” between 695–702 bp. As well, multiple unique substitutions were also found in the COI region: a “G” at positions 1442 bp and 1446 bp, a “C” at 1804 bp, and an “A” at 1835 bp ( fig. 18).

Description. Size. Preserved polyps were on average 1.58 mm ± 0.17 mm (σ2 = 0.03, max. 1.74 mm, n = 3 polyps) in diameter, and 0.34 mm ± 0.06 mm (σ2 = 0, max. 0.39 mm, n = 3 polyps) in height. All measurements were performed on the ethanol preserved zoantharian specimen voucher WAM Z88821.

Morphology. The holotype specimen is associated with Sigmaxinella soelae . Colonies formed of solitary polyps, barely extending out from the surface of the sponge. The polyps were distributed all over the surface of the sponge, and inter-polyp distances were relatively constant, 3.58 mm ± 0.44 mm (σ2 = 0.19, max. 4.56 mm, n = 14 polyps). Capitulary ridges were visible, 10–12 in number. Tentacles up to 24 in number. Polyps preserved in ethanol were white in color.

Cnidae. All dissected tissues had a unique composition of cnidae compared to other species examined in this study ( table 6). Spirocysts were only present in tentacles. Bastrichs and microbasic b-mastigophores were found across most tissues except for the column. Special microbasic b-mastigophores were found

CONTRIBUTIONS TO ZOOLOGY 93 (2024) 466–522

CONTRIBUTIONS TO ZOOLOGY 93 (2024) 466–522

only in the pharynx. Holotrichs (L) were found in the column and filaments. Microbasic p-mastigophores were only present in filaments ( fig. 19).

Internal morphology. The sphincter muscle was located in the endoderm. Mesenterial arrangement was macrocnemic. Mesenteries were approximately 20–24 in number. Single siphonoglyph.

Distribution. The single available specimen was collected from Lynher Bank, Australia [loc. 14] ( fig. 1). This specimen was found at a depth of 95 m.

Associated host. U. lynherensis sp. nov. is associated with Sigmaxinella soelae in the family Biemnidae Hentschel, 1923 . The type locality of Sigmaxinella soelae is off Port Hedland with originally distribution reported between Exmouth and Broome ( Hooper, 1984) in tropical Western Australia. Sigmaxinella soelae is now known to be more widespread in Western Australia and occurs between Lynher Bank, Kimberley (− 15.493611 °S, 121.63611 °E) in the north and Point Cloates, Ningaloo (− 22.603333 °S, 113.609444 °E) on the upper central west coast of Western Australia.

Remarks. Only a single specimen of U. lynherensis sp. nov. was available, and the inter-polyp distances and polyp diameters were very consistent across the colony.

The colonies of U.lynherensis sp. nov. are formed by solitary polyps spread homog- enously across the surface of the host sponge, different from the arrangement of polyps in chains, as in U. discolor sp. nov. The diameter of the polyps of U. lynherensis sp. nov. are similar to those observed for U. chanpuru , U. nakama , U. miyabi , and U. parasiticus . Out of these four species, U. lynherensis sp. nov. most closely resembles U. parasiticus , however U. parasiticus has only been reported from the Atlantic Ocean while U. lynherensis sp. nov. was collected from Western Australia in the Indian Ocean. Furthermore, U. parasiticus has only been reported in association with sponges in the orders Clionaida Morrow & Cárdenas, 2015 , Haplosclerida Topsent, 1928 , Scopalinida Morrow & Cárdenas, 2015 , and Tetractinellida Marshall, 1876

CONTRIBUTIONS TO ZOOLOGY 93 (2024) 466–522

( Montenegro et al., 2020; Swain & Wulff, 2007), while U. lynherensis sp. nov. is associated with Sigmaxinella soelae in the order Biemnida .