Osedax lehmani, 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 : 479

Osedax lehmani n. sp.

Figures 14 , 15

‘yellow collar’, ( Braby et al. 2007; Huusgaard et al. 2012; Katz & Rouse 2013; Rouse et al. 2009; Rouse et al. 2015; Tresguerres et al. 2013; Vrijenhoek et al. 2009; Worsaae et al. 2016)

‘sp.3 SBJ-2006’ (GenBank COI sequences DQ996629 - DQ99638)

‘sp.4 SBJ-2006’ (GenBank COI sequences DQ996640 , DQ99643)

‘orange collar’ (GenBank COI sequence EU267672 )

Material examined. Holotype: SIO-BIC A7804, Female (GenBank COI sequence DQ996629 ), fixed in glutaraldehyde, preserved in ethanol, collected from a whale carcass ( Eschrichtius robustus ) deployed at 385 meters depth in Monterey Submarine Canyon, California (36°47.401’N; 122° 53.235’W), ROV Tiburon dive number 933, Jan. 6, 2006. Paratypes: Females, fixed in formalin or glutaraldehyde, preserved in ethanol, same locality and date as holotype, SIO-BIC A1640 (GenBank COI sequence DQ996630 ), same locality and date as holotype, SIO-BIC A7806 (GenBank COI sequence DQ996631 ); SIO-BIC A7807 and A7808 (GenBank COI sequence EU223332 and EU223337 , respectively), same locality as holotype, ROV Tiburon dive number 1070, Jan. 11, 2007; dwarf males (Allotypes) SIO-BIC A7805 (no GenBank COI sequence), several in tubes of various females, same locality and date as holotype.

Diagnosis and description. Holotype female, in life trunk 8 mm long, 0.6 mm wide; crown of palps contracted, curled, 1.5 mm long ( Fig. 14C ). Palps up to 10 mm long when extended in other specimens ( Figs 14A, D ). Pinnules of all palps oriented dorsally and the oviduct lying between the dorsalmost pair of palps ( Figs 14B, D, E , 15A ). Oviduct extends from trunk into crown for 1.75 mm ( Figs 14 B-D). In life, palps reddish with two major blood vessels in each ( Figs 14A, D ). Tube a gelatinous loose mass around trunk ( Fig. 14D ). Trunk with pale yellow ring around anterior margin; ring broken mid-dorsally by oviduct ( Figs 14B, D ). and mid-ventrally by an oval unpigmented patch ( Fig. 14C ). Clear demarcation of upper and lower trunk with oviduct emerging onto outer surface of upper trunk ( Fig. 14B ). Internally trunk shows extensive musculature and glands with prominent dorsal and ventral blood vessels ( Fig. 15B ). Ovisac in holotype extending laterally as two masses; simple lobes in other specimens ( Fig. 14C ). Roots of holotype extend from ovisac lobes ( Fig. 14C ); in other specimens, roots as simple lobes or extending laterally in two lobe or lobes ( Fig. 14B ). Males dwarfs, with spermatids and sperm, chaetalbearing segments not inflated; found in tube lumen of females ( Fig. 15 C-D).

Distribution. Known from Monterey Bay, California only from 349 meters depth ( Table 2). It has been found in whale and cow bones.

Etymology. This species is named (noun in the genitive case) in memory of Alan George Lehman, father of Ellen Lehman, in recognition of her long and continued support of the Scripps Oceanographic Collections.

Remarks. Osedax lehmani n. sp. is part of Osedax Clade IV and is closest relative to Osedax packardorum n. sp., ( Fig. 1 ), with a minimum uncorrected distance for COI of 8-9% ( Table 4). This is one of the smaller intraspecific distances among Osedax species, with others being between O. frankpressi and the O. '1336_61_2' specimen from the Atlantic at ~10%; and O. randyi n. sp. and O. ‘MB16 at ~ 6-7% ( Table 4). The majority of the 31 available COI sequences for Osedax lehmani n. sp. ( Table 3) show less than 1% divergence, though a few sequences e.g. DQ996640 are around 2% divergent from the majority and DQ996631 shows the greatest distance, at ~3% ( Table 4), so the possibility of there being a cryptic species complex for O. lehmani n. sp. needs further investigation. The most distinguishing feature of Osedax lehmani n. sp. is the yellow ring around the anterior part of the trunk. ( Fig. 14 A-D). This is the only Osedax species from Monterey Bay that was not found deeper than 389 meters depth.

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 14. Osedax lehmani n. sp., previously Osedax ‘yellow collar’. A. Several adult females on rib bone of a gray whale calf (Eschrichtius robustus) that was deployed at385 meters inMonterey Canyon.Ribwas recovered tostudy the Osedax in an aquariumsetting.Note distinctive yellow ringaround most of the anteriorend of trunk.The massivecirculatory system intrunk and palps is evident from red color of worms. B. Micrograph of live paratype 4 (SIO-BIC A7808), a female, in dorsal view dissected from gray whale deployed at 385 meters. The ‘root’ mass is asingle lobe extending away to the right of ovisac. Palps are retracted and partly curled, with pinnules all oriented dorsally.Note mid-dorsal gap in yellow pigment ring, through which oviduct runs and extends into crown.Note demarcation of the lower and upper trunk (arrow). Oviduct emerges onto surface of dorsal trunk at this point. Oviduct is full of oocytes and highly contracted nature of the trunk is evident in zigzag shape of the oviduct on trunk. C. Live holotype (SIO-BIC A7804), a female, in ventral view. Holotype is partially dissected from the gray whale deployed at 385 meters.Root mass(also containing ovarian tissue) has been dissected out ofbone on right sideand more extends into the bone, away from ovisac. Palps are retracted and curled. Note midventral gap in yellow pigment ring. D. Live adultfemale inlateral view on same ribbone as in A.There is a gap in yellowpigment ring whereoviduct traverses thetrunk to become part of the crown. E. Scanning electron micrograph of a female dissected from whale bone deployed at 385 meters. Pinnules of all palps are oriented dorsally.

FIGURE 15. Osedax lehmani n. sp., previously Osedax ‘yellow collar’, ‘sp. 3 SBJ-2006’. A. Transverse section (7 µm) of paratype 3 (SIO-BIC A7807), through crown showing pinnules of all palps oriented dorsally and oviduct lying between the dorsalmost pair of palps. B. Transverse section (7 µm) through trunk of paratype 3 (SIO-BIC A7807) showing extensive musculatureand glands.Prominent dorsal and ventral blood vesselsare alsovisible.C. Live males, allotypes (SIO-BICA7805) in tube of their female (her pinnules are visible). Males show small patches of pigment anteriorly and posteriorly. D. Differential interference micrograph of a male dissected from tube of paratype 2 (SIO-BIC A7806). Prototroch is visible anteriorly.Somehooksare visiblein expanded posterior region. Nomature sperm is visible, though thereare severalbundlesof spermatids.