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).