Spinther bohnorum Tilic & Rouse 2025, sp. nov.

Spinther bohnorum Tilic & Rouse sp. nov. Spinther n. sp.: Andrade et al. (2015): fig. 1 E, tables 1, 2. Spinther sp.: Tilic et al. (2022): fig. S 2. Materials Type status: Holotype. Occurrence: catalogNumber: A 2846; recordedBy: K. White; individualCount: 1; sex: female; lifeStage: adult; occurrenceStatus: present; preparations: fixative: formalin 8 %; preservative: ethanol 50 %; disposition: in collection; previousIdentifications: Spinther sp.; occurrenceID: CE88DCFA-8FEF-5D1B-9FF9-3D51F42F3DCC; Taxon: scientificName: Spinther bohnorum Tilic & Rouse; kingdom: Animalia; phylum: Annelida; class: Polychaeta; family: Spintheridae; genus: Spinther; specificEpithet: bohnorum; taxonRank: species; scientificNameAuthorship: Tilic & Rouse; nomenclaturalCode: ICZN; Location: higherGeography: Pacific Ocean; continent: Oceania; waterBody: South Pacific Ocean; islandGroup: Society Islands; island: Mo'orea; country: French Polynesia; countryCode: FP; locality: between Opunohu Bay and Cook's Bay; verbatimDepth: 10-15 m; minimumDepthInMeters: 10; maximumDepthInMeters: 15; verbatimCoordinates: 17.4768°S, 149.8316°W; verbatimLatitude: 17.4768°S; verbatimLongitude: 149.8316°W; decimalLatitude: - 17.4768; decimalLongitude: - 149.8316; Identification: identifiedBy: Greg Rouse; Event: eventDate: 14-11 - 2010; year: 2010; month: 11; day: 14; verbatimEventDate: 11 / 14 / 2010; Record Level: institutionID: http://biocol.org/urn:lsid:biocol.org:col:14844; collectionID: http://grbio.org/cool/t8vy-919z; institutionCode: SIO; collectionCode: BIC; basisOfRecord: PreservedSpecimen Type status: Paratype. Occurrence: catalogNumber: SMF 32994; recordedBy: K. White; individualCount: 1; lifeStage: juvenile?; occurrenceStatus: present; preparations: fixative: formalin 8 %; preservative: ethanol 50 %; disposition: in collection; otherCatalogNumbers: SIO: BIC: A 18597; previousIdentifications: Spinther sp.; occurrenceID: ADD7BF30-2295-5EAA-A693-60F159B03765; Taxon: scientificName: Spinther bohnorum Tilic & Rouse; kingdom: Animalia; phylum: Annelida; class: Polychaeta; family: Spintheridae; genus: Spinther; specificEpithet: bohnorum; taxonRank: species; scientificNameAuthorship: Tilic & Rouse; nomenclaturalCode: ICZN; Location: higherGeography: Pacific Ocean; continent: Oceania; waterBody: South Pacific Ocean; islandGroup: Society Islands; island: Mo'orea; country: French Polynesia; countryCode: FP; locality: between Opunohu Bay and Cook's Bay; verbatimDepth: 10-15 m; minimumDepthInMeters: 10; maximumDepthInMeters: 15; verbatimCoordinates: 17.4768°S, 149.8316°W; verbatimLatitude: 17.4768°S; verbatimLongitude: 149.8316°W; decimalLatitude: - 17.4768; decimalLongitude: - 149.8316; Identification: identifiedBy: Greg Rouse; Event: eventDate: 14-11 - 2010; year: 2010; month: 11; day: 14; verbatimEventDate: 11 / 14 / 2010; Record Level: institutionID: http://biocol.org/urn:lsid:biocol.org:col:34838; institutionCode: SMF; basisOfRecord: PreservedSpecimen Type status: Other material. Occurrence: catalogNumber: —; recordedBy: K. White; individualCount: 1; lifeStage: adult; occurrenceStatus: present; preparations: fixative: RNAlater; disposition: used up; previousIdentifications: Spinther sp.; associatedSequences: https://www.ncbi.nlm.nih.gov/sra/SRR2005641, https://www.ncbi.nlm.nih.gov/nuccore/PV053298; occurrenceID: E1001A2A-E6ED-5124-8821-EA1AA88EEEA4; Taxon: scientificName: Spinther bohnorum Tilic & Rouse; kingdom: Animalia; phylum: Annelida; class: Polychaeta; family: Spintheridae; genus: Spinther; specificEpithet: bohnorum; taxonRank: species; scientificNameAuthorship: Tilic & Rouse; nomenclaturalCode: ICZN; Location: higherGeography: Pacific Ocean; continent: Oceania; waterBody: South Pacific Ocean; islandGroup: Society Islands; island: Mo'orea; country: French Polynesia; countryCode: FP; locality: between Opunohu Bay and Cook's Bay; verbatimDepth: 10-15 m; minimumDepthInMeters: 10; maximumDepthInMeters: 15; verbatimCoordinates: 17.4768°S, 149.8316°W; verbatimLatitude: 17.4768°S; verbatimLongitude: 149.8316°W; decimalLatitude: - 17.4768; decimalLongitude: - 149.8316; Identification: identifiedBy: Greg Rouse; Event: eventDate: 14-11 - 2010; year: 2010; month: 11; day: 14; verbatimEventDate: 11 / 14 / 2010; Record Level: institutionID: http://biocol.org/urn:lsid:biocol.org:col:14844; collectionID: http://grbio.org/cool/t8vy-919z; institutionCode: SIO; collectionCode: BIC; basisOfRecord: PreservedSpecimen Type status: Other material. Occurrence: catalogNumber: 1430143; recordedBy: K. White; S. El-Tourky,; individualCount: 1; occurrenceStatus: present; preparations: fixative: Ethanol; disposition: used up; previousIdentifications: Spinther sp.; associatedSequences: https://www.ncbi.nlm.nih.gov/nuccore/PV054334; occurrenceID: 1B25BF80-5028-5638-8626-CBCF147EB326; Taxon: scientificName: Spinther bohnorum Tilic & Rouse; kingdom: Animalia; phylum: Annelida; class: Polychaeta; family: Spintheridae; genus: Spinther; specificEpithet: bohnorum; taxonRank: species; scientificNameAuthorship: Tilic & Rouse; nomenclaturalCode: ICZN; Location: higherGeography: Pacific Ocean; continent: Oceania; waterBody: South Pacific Ocean; islandGroup: Society Islands; island: Mo'orea; country: French Polynesia; countryCode: FP; locality: Society Islands, Moorea, In front of Hilton; verbatimDepth: 15-17 m; minimumDepthInMeters: 15; maximumDepthInMeters: 17; verbatimCoordinates: -17.4756, -149.842; verbatimLatitude: - 17.4756; verbatimLongitude: - 149.842; decimalLatitude: - 17.4756; decimalLongitude: - 149.842; Identification: identifiedBy: Christopher Meyer; Event: eventDate: 05-12 - 2009; year: 2009; month: 12; day: 5; verbatimEventDate: 5 Dec 2009; fieldNotes: BIZ- 230; Record Level: institutionID: http://biocol.org/urn:lsid:biocol.org:col:34871; institutionCode: USNM; basisOfRecord: DNAExtraction Description Holotype adult female with nine chaetigers, body 0.95 mm long, 0.63 mm wide at the widest point (excluding parapodia and chaetae). Paratype, possibly juvenile, with seven chaetigers (Fig. 3 E). Body dorsoventrally flattened, oval. Live animals bright orange / red speckled with small white spots dorsally (Fig. 3 A). Preserved specimens in alcohol white, with faint white spots visible on delicate fan-like notopodial lamellae (Fig. 3 C). Notopodial fans covering the dorsum, except for the anteroposterior mid-line. Eyespots not visible. Prostomium small, spherical lobe situated dorsally between notopodial fans of chaetiger 2 (Fig. 3 A). Mouth ventral, located posterior to chaetiger 1. Proboscis protruded, long (0.84 mm), with a mid-ventral groove and ventrally folded tip (Fig. 4 A). Notopodia dorsally radiating, with thin, delicate lamellae between notochaetae (Fig. 3 A, Fig. 4 A). Most notochaetae bifid, with only a few entire ones irregularly distributed amongst them (Fig. 4 G), all similar in thickness, distal parts of bifid notochaetae spread (Fig. 4 C). Neuropodia cylindrical with slightly enlarged tips, without parapodial extensions (Fig. 4 D). A single, compound neuropodial hook projects distally from each neuropodium. Neuropodial hooks strongly curved, with a prominent lateral tooth (Fig. 4 F); 3-4 distally pointed aciculae embedded in neuropodia (Fig. 4 D). Pygidium with two elliptical pygidial cirri (Fig. 4 A). Spherical oocytes (diameter ± 30 µm) visible through the body wall and attached to neuropodia (Fig. 3 D, Fig. 4 D, E). Type material Holotype (SIO BIC A 2846) and one paratype (SMF 32994). Both specimens were collected between Opunohu Bay and Cook’s Bay, Mo'orea, Society Islands, French Polynesia, at depths of 10–15 m on 14 November 2010. The holotype is a female adult; the paratype is likely a juvenile. Material examined Holotype (SIO BIC A 2846), paratype (SMF 32994) and two additional specimens: one specimen collected at the same type locality on 14 November 2010 (unregistered, adult); one specimen collected in front of the Hilton, Mo'orea, Society Islands, French Polynesia (17.4756°S, 149.842°W), at 15–17 m depth on 5 December 2009 (USNM 1430143; associated with DNA extraction). Type locality South Pacific Ocean, Society Islands, French Polynesia, between Opunohu Bay and Cook’s Bay, Mo'orea (17.4768°S, 149.8316°W), at depths of 10– 15 m. Diagnosis Small species (ca. 1 mm) with bright red-orange colouration and white speckles dorsally. Ventral surface generally smooth. Neuropodia lacking parapodial extensions, with neurochaetae as falcate compound hooks bearing a marked lateral tooth. Notochaetae comprising both entire and bifid forms, with bifid chaetae having spread distal ends. Etymology Spinther bohnorum sp. nov. is named after Brenda and Jeffrey Bohn and their family in appreciation of their steadfast support for marine invertebrate taxonomy and biodiversity research. Distribution Known only from Mo'orea, French Polynesia. Taxon discussion Spinther is a small and easily recognised group of polychaetes, comprising only 12 accepted species reported worldwide, though half have been named from the North Pacific (Table 2). While the taxonomic history of Spinther is not extensive, it has been notably convoluted. Similarly, its phylogenetic affinities and placement within the annelid tree of life have long been a subject of debate (Rouse et al. 2022). Despite advances in molecular approaches, the placement of Spinther within the annelid tree of life remains unresolved. Andrade et al. (2015) included the transcriptome of Spinther bohnorum sp. nov. in their phylogenomic study, but their results were inconclusive, likely due to long-branch effects (see also Tilic et al. (2022)). Spinther is a monotypic genus, classified as Aciculata incertae sedis with uncertain affinities (Rouse et al. 2022), rendering the family name Spintheridae redundant. Most Spinther species live on the surface of sponges, clinging to their hosts using their hooked neurochaetae. Their bright colouration often matches the sponge, providing camouflage. Whether Spinther is parasitic or a highly