Ophryotrocha ravarae, Georgieva & Wiklund & Ramos & Neal & Glasby & Gunton, 2023

Georgieva, Magdalena N., Wiklund, Helena, Ramos, Dino A., Neal, Lenka, Glasby, Christopher J. & Gunton, Laetitia M., 2023, The Annelid Community of a Natural Deep-sea Whale Fall off Eastern Australia, Records of the Australian Museum (Rec. Aust. Mus.) 75 (3), pp. 167-213 : 177

Ophryotrocha ravarae sp. nov.

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Fig. 10

Holotype: AMW.53701 (length 1.6 mm for 19 chaetigerous segments), IN2017_V03_100; 9 June 2017; off Byron Bay , NSW, Australia, beam trawl, start: 28.05°S 154.08°E, 999 m, end: 28.10°S 154.08°E, 1013 m . Paratypes: NMV F296822–296824 , and NHMUKANEA 2022.772–774, same locality as holotype . DNA vouchers: AMW.53698–53700, samelocalityas holotype .

Description. Body length upto 1.6 mm for type material. Body compressed dorsoventrally, width tapering towards pygidium. Rounded head, anterior half flattened with high transverse ridge at level of antennae and palps. Long antennae, simple palps equally long but thinner ( Fig. 10A, 10D ). Mandibles andmaxillae weakly sclerotized, mandibles rod-likewith dentate inner ridge, maxillae K-typewith blunt forceps tips and seven free denticles ( Fig. 10B ).

Parapodia uniramous with long dorsal cirri inserted mid-dorsal on parapodia, without ventral cirri ( Fig. 10C ). Supra-acicular chaetae simple ( Fig. 10F ), sub-acicular chaetae compound falcigers with short blades ( Fig. 10E ), sub-acicular lobe with one compound chaeta. Pygidium with terminal anus, pygidial cirri not observed ( Fig. 10E ).

Distribution. IN2017_V03, Station 100. Pilot whale carcass, off Byron Bay, New South Wales, Australia in 999–1013 m.

Etymology. Thisspecies is namedinhonour of Dr Ascensão Ravara, University of Aveiro, Portugal, for her extensive knowledge of and love for Ophryotrocha .

Remarks. In the phylogenetic tree ( Fig. 8 ), this species falls in a clade with Ophryotrocha nauarchus Wiklund et al., 2012 describedfrom awhale-fall habitat and an undescribed species from a seep, both off the California coast in the eastern Pacific Ocean. However, the support for this clade is low. The head shape of the new species is similar to O. nauarchus , but the new species has longer palps and differs in the shape of the parapodia with the dorsal cirri being placedfurther distally on the parapodium, and the compound chaetae having short blades. The head shape of the new species issimilar to Ophryotrochascutellus Wiklund, Glover, & Dahlgren, 2009 , but the shape of the parapodia isdifferent between the species, with O. scutellus having long ventral cirri on parapodia.

Figures

Figure 8. Phylogeny of the Ophryotrocha genus based on Bayesian analysis of the 16S gene. Numbersadjacent to nodes indicateposterior probabilities, and taxa for which sequences have been contributed by the present study are indicated in bold. GenBank accession numbers are given after taxa names for the GenBank sequences.

Figure 10. Ophryotrocha ravarae sp. nov. (A) Photo of holotype, dorsal and ventral side, holotype 1.6 mm long; (B) weakly sclerotized jaws, scale bar is 25 μm; (C) parapodium, scale bar is 100 μm; (D) overview of anterior end, scale bar is 250 μm; (E) supra-acicular simple chaeta, scale bar is 50 μm; (F) sub-acicular compound falcigerous chaeta, scale bar is 50 μm.