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

Umimayanthus mirnangga sp. nov.

Montenegro, Kise & Reimer urn:lsid:zoobank.org:act:50E0D7DC-D383-45EE-B921-1140F1E29347

Etymology. The specific epithet “mirnangga ” is derived from the phoneme used to refer to a young single woman in the Wunambal language. This in reference to the fact that the colonies of U. mirnangga sp. nov. are exclusively composed of solitary polyps. “mɨrnangga binya” n., B-class young woman. Syn: munangga. See Bengmoro et al. (1971) and Boona (2022).

Material examined. Type locality: Maret Is. [loc. 19], Western Australia, - 14.35445 °S, 124.9488 °E. Holotype: WAM Z88824 About WAM (− 14.35445 °S, 124.9488 °E, loc. 19, Maret Is., Western Australia, 61 m depth, December 16, 2015 by O.A. Gomez & J.A. Ritchie). Paratype: WAM Z88823 About WAM (− 14.424417 °S, 125.040933 °E, loc. 17, Maret Is., Western Australia, 55 m depth, December 9, 2015 by O.A. Gomez & J.A. Ritchie) GoogleMaps .

Other material. Other examined specimens belong to the Western Australian Museum; WAM Z88817 About WAM (− 15.446442 °S,

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124.083022 °E, loc. 15, Camden Sound , Western Australia, 61 m depth, March 20, 2015 by J. Fromont & L. Kirkendale ).

Diagnosis. U. mirnangga sp. nov. can be distinguished from other species in the genus Umimayanthus by having colonies exclusively formed of solitary polyps, and by having symbiotic associations with sponges in genus Endectyon Topsent, 1920 and Ectyoplasia Topsent, 1931 ; current known hosts are Endectyon (Endectyon) fruticosum (Dendy, 1887) and Ectyoplasia vannus Hooper, 1991 . Additionally, U. mirnangga sp. nov. can be differentiated from all other species in genus Umimayanthus by three unique nucleotide substitutions across the ITS-rDNA region as follows: “C” in positions 88 bp and 418 bp, and “G” at position 438 bp ( fig. 8).

Description. Size. Preserved polyps were on average 2.41 mm ± 0.23 mm (σ2 = 0.05, max 2.722 mm, n = 9 polyps) in diameter, and 2.18 mm ± 0.23 mm (σ2 = 0.05, max 2.506 mm, n = 9 polyps) in height. All measurements were performed of ethanol- preserved specimens: zoantharian voucher numbers WAM Z88824, WAM Z88823, and WAM Z88817.

Morphology. The type specimens are associated with Ectyoplasia vannus . The

CONTRIBUTIONS TO ZOOLOGY 93 (2024) 466–522

CONTRIBUTIONS TO ZOOLOGY 93 (2024) 466–522

species has solitary polyps spread all over the surface of the sponges. The inter-polyp distance is variable, with a minimum distance of 2.35 mm between polyps, and an average of 4.27 mm ± 0.91 mm (σ2 = 0.83, max. 6.751 mm, n = 44 polyps) between them. Capitulary ridges were visible, 14–16 in number. Polyps preserved in ethanol are yellowish in colour. No cnidae or internal morphological data are available for this species due to the poor condition of the preserved specimens.

Distribution. All specimens analysed were collected along the west coast of Australia. Camden Sound [loc. 15] and Maret Is. [loc. 17, 19] ( fig. 1). Specimens were found at depths of 55– 61 m.

Associated host. Umimayanthus mirnangga sp. nov. was found associated with two different sponge species, Ectyoplasia vannus and Endectyon (Endectyon) fruticosum , both in the family Raspailiidae .

Remarks. Umimayanthus mirnangga sp. nov., U. wunanggu sp. nov., and U. jebarra sp. nov. are sibling species based on our phylogenetic analyses. Key diagnostic molecular and morphological characters, including the general external morphology of the colonies and the height of the polyps, as well as the different host species, clearly separate these three species from each other.

Out of all the species in Umimayanthus the closest resemblances can be found between the sibling species U. wunanggu sp. nov., and U. jebarra sp. nov., which have similar polyp diameters as U. mirnangga sp. nov. Nonetheless, the heights of polyps in U. mirnangga sp. nov. are 2.41 mm ± 0.23 mm, twice as large as U. wunanggu sp. nov. (0.92 mm ± 0.36 mm), and smaller than U. jebarra sp. nov. (3.09 mm ± 0.63 mm). Furthermore, the morphological differences between U. mirnangga sp. nov. and U. wunanggu sp. nov. are present even though both species were found to establish associations with the same sponge species, Endectyon (Endectyon) fruticosum . Out of the three sibling species, U. mirnangga sp. nov. is the only species composed exclusively of solitary polyps.

The type locality of Ectyoplasia vannus , the host sponge of Umimayanthus mirnangga sp. nov., is Port Essington in the Northern Territory, Australia, and this sponge species has otherwise only been reported from other areas in the Northern Territory and tropical Western Australia.