Zeaione everta Boyko & Williams, 2025

(SOSA), Senckenberg Ocean Species Alliance, Andrade, Luiz F., Boyko, Christopher B., Brandt, Angelika, Buge, Barbara, Dávila Jiménez, Yasmín, Henseler, Mats, Hernández Alcántara, Pablo, Jóźwiak, Piotr, Knauber, Henry, Marcondes Machado, Fabrizio, Martínez-Muñoz, Carlos A., Momtazi, Farzaneh, Nakadera, Yumi, Qiu, Jian-Wen, Riehl, Torben, Rouse, Greg W., Sigwart, Julia D., Sirenko, Boris, Souza-Filho, Jesser F., Steger, Jan, Stępień, Anna, Tilic, Ekin, Trautwein, Bianca, Vončina, Katarzyna, Williams, Jason D. & Zhang, Junlong, 2025, Ocean Species Discoveries 13 – 27 — Taxonomic contributions to the diversity of Polychaeta, Mollusca and Crustacea, Biodiversity Data Journal 13, pp. e 160349-e 160349 : e160349-

Zeaione everta Boyko & Williams sp. nov.

Materials

Type status: Holotype. Occurrence: catalogNumber: NMV J 62877 ; occurrenceRemarks: infesting left branchial chamber of female Eucalliaxiopsis aequimana (Baker, 1907) (9.6 mm carapace length; MV J 59759 ); recordedBy: Museum Research Group of Victoria; individualCount: 1; sex: female; lifeStage: adult; reproductiveCondition: mature; preparations: 70 % EtOH; occurrenceID: F3E9A10D-072C-57F1-A9DA-57A45CDC716B; Taxon: scientificName: Zeaione everta Boyko & Williams ; kingdom: Animalia; phylum: Arthropoda; class: Malacostraca; order: Isopoda ; family: Bopyridae ; genus: Zeaione ; specificEpithet: everta ; taxonRank: species; scientificNameAuthorship: Boyko & Williams; nomenclaturalCode: ICZN; Location: higherGeography: Pacific Ocean; continent: Australia; country: Australia; stateProvince: Victoria; locality: San Remo, transect 4, northwest from rock outcrop 1.1 km ; verbatimDepth: intertidal; verbatimCoordinates: 38°32'S, 145°23'E; verbatimLatitude: 38°32'S; verbatimLongitude: 145°23'E; Identification: identifiedBy: G. C. B. Poore (host); C. B. Boyko, J. D. Williams (parasite); Event: samplingProtocol: hand collected; eventDate: 13-03 - 1993; habitat: intertidal sediment; Record Level: institutionID: http://grscicoll.org/institution/museum-victoria; institutionCode: NMV; basisOfRecord: PreservedSpecimen

Type status: Paratype. Occurrence: catalogNumber: NMV J 76267 ; occurrenceRemarks: infesting left branchial chamber of female Eucalliaxiopsis aequimana (Baker, 1907) (9.6 mm carapace length; MV J 59759 ); recordedBy: Museum Research Group of Victoria; individualCount: 1; sex: male; lifeStage: adult; reproductiveCondition: mature; preparations: 70 % EtOH; occurrenceID: 1C2648FB-0E92-51B1-ABC2-4C83D475554C; Taxon: scientificName: Zeaione everta Boyko & Williams ; kingdom: Animalia; phylum: Arthropoda; class: Malacostraca; order: Isopoda ; family: Bopyridae ; genus: Zeaione ; specificEpithet: everta ; taxonRank: species; scientificNameAuthorship: Boyko & Williams; nomenclaturalCode: ICZN; Location: higherGeography: Pacific Ocean; continent: Australia; country: Australia; stateProvince: Victoria; locality: San Remo, transect 4, northwest from rock outcrop 1.1 km ; verbatimDepth: intertidal; Identification: identifiedBy: G. C. B. Poore (host); C. B. Boyko, J. D. Williams (parasite); Event: samplingProtocol: hand collected; eventDate: 13-03 - 1993; habitat: intertidal sediment; Record Level: institutionID: http://grscicoll.org/institution/museum-victoria; institutionCode: NMV; basisOfRecord: PreservedSpecimen

Description

Female holotype (Fig. 28 ) body length 8.7 mm, maximal width 5.1 mm, head length 1.2 mm, head width 1.9 mm, pleon length 2.3 mm. Body elongate (Fig. 28 A), approximately straight, head deflected very slightly to right (sinistrally rotated <5 °).

Head ovate (Fig. 28 A), wider than long, anterior margin straight, narrow frontal lamina extending slightly beyond lateral margins of head, head weakly bilobed. Eyes absent. Barbula with three smooth tapered lobes on each side, smallest lobe covered by other two, median region smooth (Fig. 28 C, D, F). Antennules (Fig. 28 B) of three articles each, extending beyond anterior margin of head; antennae (Fig. 28 B) of five articles each; terminal two articles of antennules and antennae with distal setae. Maxilliped (Fig. 28 D – F) anterior lobe broad, rounded, with low rounded articulated palp, palp and anterior margin with many setae; posterior lobe with small, rounded spur with few plumose setae (Fig. 28 E). First oostegite anterior lobe ovate, posterior lobe oblong, smaller than anterior lobe, with small setae along posterior margin, lobes almost fused, internal ridge smooth, only present on mesiad half of inner surface (Fig. 28 G, H).

Pereon (Fig. 28 A) of seven pereomeres, broadest across pereomeres 2 and 3, tapering anteriorly and posteriorly. Dorsolateral margins of pereomeres 6 and 7 with numerous, irregular, mostly semi-spherical protuberances (Fig. 28 I). Small coxal plates on sides of pereomeres 1–5; dorsolateral bosses on pereomeres 1–5. Oostegites smooth; oostegite 5 with fringe of setae on posterior margin (Fig. 28 J). Pereopods 1–7 (Fig. 28 G, K) subequal in size and of similar morphology, small curved dactylus, ovate propodus, triangular carpus, small triangular merus, elongate ischium and subquadrate basis, basis more elongate on posterior pereopods; carpus with stout setae on distal tip (Fig. 28 K).

Pleon (Fig. 28 A, J) of six pleomeres, dorsolateral margins of pleomeres 1–6 with numerous, irregular, mostly semi-spherical protuberances (Fig. 28 I). Pleomeres 1–5 with biramous, lamellar pleopods with scalloped posterior margins, decreasing in size posteriorly (Fig. 28 J); exopod ovate; endopod bilobed, outer lobe smaller, round, inner lobe elongate (Fig. 28 L). Five pairs of broad lateral plates, lamellar, with scalloped posterior margins. Pleotelson with biramous, elongate lamellar uropods (missing on left side), inner lobe smaller (Fig. 28 M).

Male paratype ( allotype) (Fig. 29 ) body length 2.8 mm, maximal width 1.0 mm, head length 0.5 mm, head width 0.6 mm, pleon length 0.7 mm. Body elongate. Small, irregular patches of dark pigmentation on anterior portion of pereomere 1.

Head distinct from segment 1, anterior margin of head narrow and rounded, head widest medially (Fig. 29 A), small eyespots mediolaterally. Antennules of three articles each, extending slightly beyond anterior margin of head; antennae of six robust articles each, extending well beyond lateral margins of head; antennae and antennules with few distal setae on each segment, except for basal one; terminal segments of each with tuft of numerous setae (Fig. 29 B). Maxilliped present, two-segmented, distal segment with four long simple setae (Fig. 29 B).

Pereon of seven pereomeres, broadest across pereomeres 3 and 4, slightly tapering anteriorly and posteriorly. Lateral margins of pereomeres 1 and 2 directed anteriorly, 3 and 4 directed laterally, 5–7 directed posteriorly. Pereopods (Fig. 29 B, C) subequal; all articles distinct, curved dactylus with minute setae, ovate propodus, triangular carpus, rounded short merus, elongate ischium and basis; carpus with stout setae at anterior tip; pereopod 7 (Fig. 29 C) similar in morphology to pereopod 1, except dactylus slightly shorter, propodus proportionally larger and basis more elongate.

Pleon (Fig. 29 A, D) of six pleomeres, markedly narrower than pereon, pleomeres rounded posteriorly, all pleomeres distinctly segmented, pleomeres 1–5 with very low rounded pleopods; no mid-ventral tubercles (Fig. 29 D). Pleotelson (Fig. 29 A, D) indented medially with robust anal cone, distolaterally produced into rounded lobes, with scales and setae; uropods absent.

Type material

Holotype ( NMV J 62877 ) and allotype ( NMV J 62877 a). The holotype is an adult female; the paratype ( allotype) is an adult male.

Material examined

Holotype ( NMV J 62877 ), ♀ adult, in intertidal sediment, infesting left branchial chamber of ♀ Eucalliaxiopsis aequimana .

Paratype ( allotype) ( NMV J 62877 a), ♂ adult, same data as holotype.

Type locality

Pacific Ocean, Australia, Victoria, San Remo, 38°32'S, 145°23'E, intertidal.

Diagnosis

As for genus.

Etymology

The species name is given after the historical name of the corn variety Zea mays var. everta Bailey, 1925 (now considered a synonym of Z. mays mays Linnaeus, 1753 ) and, in combination with the genus name, refers to the resemblance between the irregular protuberances on the dorsolateral margins of the female pleomeres and popped kernels of popcorn.

Distribution

Only known from type locality.

Ecology

Host: Eucalliaxiopsis aequimana (Baker, 1907) ( Crustacea, Decapoda, Axiidea , Eucalliacidae Manning & Felder, 1991 ), an axiidean shrimp known from intertidal to subtidal sediments in New South Wales (as far north as 33°S), Tasmania, Victoria, South Australia, Western Australia (as far north as 25°S), Australia ( Poore 2021). The female host was cited by Poore (2021), but the presence of the parasite was not noted.

Additional associates: Many patches of long, thin thalli with septa were observed on some pereomeres (Fig. 28 I), pleomeres and appendages of the holotype. We interpret these as an unidentified species of Ichthyosporea (formerly Mesomycetozoea): Eccrinales that are known to be ecto- and endosymbionts associated with crustaceans and other hosts (e. g. Boyko et al. (2017), Williams et al. (2019), Shields (2022) and Shabardina et al. (2024)).

Taxon discussion

The present record of a bopyrid parasitising Eucalliaxiopsis aequimana is unique amongst the 45 valid species described in Eucalliacidae . This is perhaps not surprising, given that only 15 hosts in Axiidea identified to species have previously been reported harbouring bopyrids ( Markham 2001, An et al. 2009, Romero-Rodríguez and Álvarez 2025) out of the 927 valid species in Axiidea ( WoRMS 2024). Clearly, axiideans are a group that is greatly undersampled in terms of the diversity of bopyrids and almost certainly in terms of other parasites as well.

The new genus and species reported herein is a member of Pseudioninae but, while the male resembles those belonging to a number of genera and is relatively non-descript, the female with the popcorn-like protuberances on the posterior pereon and pleon and possessing bilobed pleopodal endopods is not similar to that of any other described pseudionine species. Females of the genus Ionella possess extensive digitation on the sides of the pereomeres and pleomeres ( Romero-Rodríguez and Álvarez 2025) similar to those of some females of species belonging to Keponinae and Ionidae associated with axiidean hosts, but these long, thin digitate extensions are also found on the lateral plates and other surfaces, unlike in the new genus where the protuberances are rounded. Other female characters and those of males are very different between these taxa and the new genus. Digitations or protuberances may be an adaptation (e. g. increased surface area for respiration) found in those bopyroids associated with axiidean and other tube-dwelling shrimp hosts.

Methods

Line drawings of the bopyrid isopods were made by using camera lucida drawing tubes attached to Olympus compound (OLYMPUS CX 31) and dissecting microscopes (OLYMPUS SZX 12). Adobe Illustrator and a WACOM Cintiq pen display were used to trace original sketches and produce final figures. All parasite specimen measurements were made from camera lucida drawing tube sketches and slide micrometers. Morphological terminology follows that of Boyko et al. (2017).

Repository: The type specimens of the new species were sourced from the Museums Victoria (formerly National Museum of Victoria, NMV) and are deposited there.

Figures

Figure 28. Zeaione everta Boyko & Williams, gen. et sp. nov., adult female holotype (NMV J 62877). A Habitus, dorsal view; B Right antennule, antenna and mouthparts, ventral view; C Barbula, dashed lines indicate third extension behind outer two extensions; D Left maxilliped with outer barbula lobe, external view. E Maxilliped spur, close-up showing setae. F Scales on outer barbula lobe; G Left oostegite 1, external view; H Left oostegite 1, internal view; I Dorsolateral view of pereomere 7 and pleomere 1 showing irregular protuberences and thalli of an unidentified species of Eccrinales (indicated by asterisk); J Pleon, ventral view; K Right pereopod 7; L Right pleopod 1; M Pleomere 6 showing biramous uropod on right side, scar of left uropod shown by asterisk. Abbreviations: A 1 = antennule, A 2 = antenna, Ex = exopod, En = endopod, Mo = mouthparts, per 7 = pereomere 7, pleo 1, 6 = pleomere 1, 6, Uro = uropod. Scale bars: 2 mm (A), 250 µm (B, D, G – I, K), 500 µm (C, L, M), 50 µm (E, F), 1 mm (J).

Figure 29. Zeaione everta Boyko & Williams, gen. et sp. nov., adult male paratype (allotype) (NMV J 62877 a). A Habitus, dorsal view; B Left antennule, antenna, mouthparts, maxillipeds (base shown by arrow) and pereopod 1, ventral view; C Left pereopod 7; D Pleon, ventral view. Abbreviations: A 1 = antennule, A 2 = antenna, Mo = mouthparts, P 7 = pereopod 7. Scale bars: 250 mm (A, D), 50 mm (B, C).