Osedax tiburon, 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 : 462

Osedax tiburon n. sp.

Figure 4A, B, C

‘nude-palp-A’ ( Jones et al. 2008; Rouse et al. 2011; Rouse et al. 2009; Rouse et al. 2015; Vrijenhoek et al. 2009)

Material examined. Holotype: SIO-BIC A7817 female (GenBank COI sequence FJ347622 ), fixed in formalin preserved in ethanol, collected from 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. Paratypes: All females, fixed in formalin preserved in ethanol, SIO-BIC A1642 (GenBank COI sequence EU223359 ), SIO-BIC A7820 (GenBank COI sequence EU223356 , EU223357 ), same locality as holotype, ROV Tiburon dive number 1119, Aug. 16, 2007; SIO-BIC A7818, A7819 (GenBank COI sequences FJ347623 , FJ347624 , respectively) same locality and date as holotype.

Diagnosis and description. Holotype female ( Fig. 4B ); preserved trunk 0.75 mm long, 0.2 mm wide; crown of four palps, 3 mm long. Tube gelatinous 6 mm long ( Fig. 4A ). Oviduct not discerned. In life, palps reddish with blood ( Fig. 4A ). Four palps without obvious pinnules ( Fig. 4B, C ). Trunk with no obvious demarcation into upper and lower trunk ( Fig. 4B, C ). Ovisac mostly missing in holotype, some traces of roots present ( Fig. 4A ). In paratype ovisac and root complex extends laterally on either side of trunk and posteriorly ( Fig. 4C ). Males not seen.

Distribution. Known from Monterey Bay, California from 1820 meters depth ( Table 2).

Etymology. This species is named (noun in apposition) for the ROV Tiburon, which was used to collect the first Osedax specimens.

Remarks. Osedax tiburon n. sp. is part of Osedax Clade II and is closest relative (though with low support) to Osedax nordenskjoeldi from which it shows a divergence of 15%, though it shows a smaller pairwise distance (14%) to O. ryderi n. sp. ( Table 4). The seven available COI sequences for Osedax tiburon n. sp. ( Table 3) show less than 1% sequence divergence. It has been found in whale bones and experimentally deployed cow bones. There is little to distinguish Osedax tiburon n. sp. from other 'nude palp' species in Clade II, which share a similar morphology. The species status of Osedax tiburon n. sp. is supported largely on its COI divergence from other Osedax .

Figures

FIGURE 4. Osedax tiburon n. sp., previously Osedax ‘nude-palp-A’; Osedax ventana n. sp., previously Osedax ‘nude-palp- B’; Osedax docricketts n. sp., previously Osedax ’nude-palp-C’. A. Lateral view of Osedax tiburon n. sp. in situ in cow bone before dissection.Elongate apinnulate (‘nude’) palps are within a gelatinous tube. B. Osedax tiburon n. sp. preserved holotype (SIO-BIC A7817), removed from cow bone, showing elongate palps clustered together, obscuring oviduct. Trunk is relatively short and ovisac and roots were largely removed for DNA sequencing.C. Osedax tiburon n. sp. preserved paratype (SIO-BIC A7818) removed from cow bone, also showing elongate palps clustered together, obscuring oviduct. D. Holotype (SIO-BIC A1643) of Osedax ventana n.sp. beforeremoval from cow bone deployed at 2898 meters depth inMonterey Canyon.Elongate apinnulate (‘nude’) palps are within gelatinous tube and are all that were retained for this species. E. Holotype (SIO-BIC A1644) of Osedax docricketts n. sp. incomplete after dissection, and before preservation.