Osedax sigridae, 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 : 459

Osedax sigridae n. sp.

Figure 2

‘green palp’ ( Katz et al. 2010; Katz et al. 2011; Katz & Rouse 2013; Rouse et al. 2015; Vrijenhoek et al. 2009)

Material examined. Holotype: SIO-BIC A7809 female (GenBank COI sequence FJ347641 ), collected from an experimentally deployed whale carcass ( Eschrichtius robustus ) deployed at 1820 meters depth in Monterey Submarine Canyon, California (36°42.496’N; 122°6.316’W) ROV Tiburon dive number 1163, Dec. 20, 2007. Fixed in formalin preserved in ethanol. Paratypes: All females. Fixed in formalin preserved in ethanol; SIO-BIC A7811 same locality and date as holotype (GenBank COI sequence FJ347642 ); SIO-BIC A1650 (GenBank COI sequence FJ347639 ) and SIO-BIC A7810 (GenBank COI sequence FJ347640 ), collected on cow bones deployed at 1820 meters depth in Monterey Submarine Canyon, California (36°42.496’N; 122°6.316’W) ROV Tiburon dive number 1119, Aug. 16, 2007.

Diagnosis and description. Holotype female ( Fig. 2D ); trunk 1 mm long, 0.5 mm wide; crown of pinnulated palps contracted, 2 mm long. Tube gelatinous, up to 10 mm long, 5 mm across. Oviduct shorter than palps ( Fig. 2C ). In life, palps green-yellow ( Figs 2A, C, D ). Pinnules of all four palps oriented dorsally ( Fig. 2D ). No obvious pigmentation on trunk, or clear demarcation into upper and lower trunk. Ovisac spheroidal with roots as simple lobes ( Figs 2B, D ). Males not found.

Distribution. Known from Monterey Bay, California from 1820 meters depth ( Table 2). It has been found in whale and cow bones.

Etymology. This species is named (noun in the genitive case) for Sigrid Katz, whose Ph.D. project involved detailed study of the anatomy of this species ( Katz et al. 2010; Katz et al. 2011).

Remarks. Osedax sigridae n. sp. is part of Osedax clade I and closest relative to the undescribed Japanese taxon Osedax ‘Sagami-5’ ( Fig. 1 ). All four available COI sequences for Osedax sigridae n. sp. ( Table 3) show less than 1% uncorrected sequence divergence, while the minimum uncorrected distance to Osedax ‘Sagami-5’ is 11% ( Table 4). Careful searching for males in some of the tubes of the Osedax sigridae n. sp. females shown in Figure 2A failed, though Katz & Rouse (2013) did find sperm in the ovisac of females. The most distinguishing features of the Osedax sigridae n. sp. specimens collected to date are the distinctive green/yellow palps and the lobate roots ( Fig. 2 ).

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 2. Osedax sigridae n. sp., previously Osedax ‘green palp’. A. View of cut surface of a cow femur deployed at 1820 meters in Monterey Canyon. Uncut surface of the bone has been heavily colonized by Osedax sigridae n. sp. Note greenishyellow color of the palps. B. Osedax sigridae n. sp. specimens in A. penetrated throughouter surface of the cow bone and then expanded into the area beneath. This allowed for the whole outer layer of outer bone, and the Osedax, to be peeled away. Posterior ends (ovisacs) of multiple individuals are shown here. No major root structures extend from the ovisacs. C. Paratype of Osedax sigridae n. sp. (SIO-BIC A7810) with some bone surrounding the trunk. Oviduct is visible and pinnules of all four palps are oriented dorsally.D. Dorso-lateral view of holotype of Osedax sigridae n. sp. (SIO-BIC A7809) dissected from bone. Oviductis not visibleas it lies amongthe palps,which havepinnules oriented dorsally.Notegreenish hue of palps.Greentissue surrounding part of the ovisac.