Osedax knutei, Rouse & Goffredi & Johnson & Vrijenhoek, 2018

Rouse, Greg W., Goffredi, Shana K., Johnson, Shannon B. & Vrijenhoek, Robert C., 2018, An inordinate fondness for Osedax (Siboglinidae: Annelida): Fourteen new species of bone worms from California, Zootaxa 4377 (4), pp. 451-489 : 465-468

Osedax knutei n. sp.

Figure 6

‘nude-palp-E’ ( Rouse et al. 2011; Rouse et al. 2015; Vrijenhoek et al. 2009; Worsaae et al. 2016)

Material examined. Holotype: SIO-BIC A 7812 , Female (GenBank COI sequence FJ347635 ), fixed in formalin preserved in ethanol, collected from whale fall ( Balaenoptera musculus ) deployed at 1018 meters depth in Monterey Submarine Canyon , California (36°46.308’N; 122° 4.981’W), ROV Tiburon dive number 1049, Oct. 25, 2006; Allotype, dwarf male from tube of holotype SIO-BIC A7813. Paratypes: All females, fixed in formalin preserved in ethanol; SIO-BIC A1646 (GenBank COI sequence FJ347634 ), SIO-BIC A7814, (GenBank COI sequence FJ347632 ), same locality and date as holotype; SIO-BIC A7815, (GenBank COI sequence JF509952 ), collected from fish bones deployed at 1018 meters depth in Monterey Submarine Canyon, California (36°46.308’N; 122° 4.981’W), ROV Doc Ricketts dive number 209, Oct. 29, 2010; SIO-BIC A7816, (GenBank COI sequences MG262306 ), collected from turkey ( Meleagris gallopavo ) bone deployed at 1018 meters depth in Monterey Submarine Canyon, California (36°46.308’N; 122° 4.981’W), ROV Doc Ricketts dive number 233, June 2, 2011.

Diagnosis and description. Holotype female preserved partially dissected from whale bone ( Fig. 6A ); trunk contracted 1.6 mm long, 0.3 mm wide; crown of apinnulate palps contracted, 2.3 mm long. Tube not kept for holotype, but forms a tight sheath in other specimens, from which palps emerge. Oviduct not visible in holotype ( Fig. 6A ), but is slightly shorter (1.5 mm) than contracted palps in paratype SIO-BIC A7816, and much shorter than extended palps in live specimen spawning eggs ( Fig. 6D ). In life, palps reddish with two blood vessels each ( Fig. 6E ). Trunk with no obvious pigmentation or demarcation into upper and lower trunk ( Figs 6A, D ). Ovisac represented as lobes on either side of trunk in holotype, extending laterally, or as long lobes in other specimens. Roots of holotype longer that the remaining body, extending in several directions ( Fig. 6A ). In other specimens, roots also extend in various directions ( Fig. 6D ). Males dwarfs, 450 µm long by 100 µm wide, with anterior prototroch and sperm, two posterior expanded segments bearing hooked chaetae ( Figs 6B, C ).

Distribution. Known from Monterey Bay, California from 1018 to 2898 meters depth ( Table 2). It has been found in whale, cow, turkey and teleost bones.

Etymology. This species is named (noun in the genitive case) for Knute Brekke, Chief ROV pilot for MBARI, who expertly collected many bones and Osedax over the years.

Remarks. Osedax knutei n. sp. is part of Osedax Clade II and closest relative to Osedax westernflyer n. sp, ( Fig. 1 ) with a minimum uncorrected distance for COI of 16% ( Table 4). Twelve COI sequences for Osedax knutei n. sp. ( Table 3) generally showed less that 1.2% sequence divergence from each other. An exceptional sequence ( JF509952 ) from paratype SIO-BIC A7815 dissected from fishbone ( Rouse et al. 2011), diverged by 3.2% to 4.5% from the other Osedax knutei n. sp. specimens (see example distance in Table 4). The tentative assignment of paratype SIO-BIC A7815 to Osedax knutei n. sp. requires further investigation. Two new COI sequences for Osedax knutei n. sp. were also deposited on GenBank for which no voucher specimens were retained; MG262305 was recovered from a fishbone deployed at 2898 meters and MG262307 was from a turkey deployed at 1018 meters

Figures

FIGURE 1. Osedax phylogenetic analyses. Osedax multi-gene phylogeny with Monilifera as outgroup.Maximum likelihood tree topology based on a partitioned dataset of five gene segments (MAFFT-aligned) for data shown in Table 2. The Bayesian analyses gave the same topology. Bootstrap support % (BS) is at each node, followed by posterior probability (PP) from the MrBayes analyses. * indicates values were ± 95% (BS) and 0.95 (PP). Missing values indicate BS <50% and PP <0.7. Six major Osedax clades are distinguished, following Vrijenhoek et al. (2009), Rouse et al. (2015) and Taboada et al. (2015). The various forms of palps (or absence thereof in the case of O. jabba n. sp.) are indicated for the major clades but these are not intended to indicate apomorphic states.

FIGURE 6. Osedax knutei n. sp., previously Osedax ‘nude-palp-E’. A. Preserved female holotype (SIO-BIC A7812) with bone dissected away, but leaving bodyin place.Roots have ramified laterally parallel to bone surface.Trunk is short and palps, though contracted, are much longer.B. Dwarf male allotype (SIO-BICA7813) found intube of holotype.Prominentprototroch and sperm mass anteriorly. Posterior segmented region is slightly swollen with hooked chaetae clearly visible. C. Posterior region of allotype (SIO-BIC A7813), showing paired hooks on one side of segments 2 and 3. D. Live image of paratype (SIO- BIC A7816) partially dissected from bone. Palps are contracted, but still longer than the trunk. Ovisac is visible with root and blood vessel extending further into the bone. E. Live female Osedax knutei n. sp. in turkey bone and spawning oocytes into water. Trunk and lower palp region retracted into bone. Palps and oviduct extend out of the tube and compressed oocytes are visible in oviduct and freshly deposited in water.Specimen was destroyed for sequencing = GB MG262305.