Osedax bozoi, Berman & Hiley & Read & Rouse, 2024

Berman, Gabriella H., Hiley, Avery S., Read, Geoffrey B. & Rouse, Greg W., 2024, New Species of Osedax (Siboglinidae: Annelida) from New Zealand and the Gulf of Mexico, Zootaxa 5443 (3), pp. 337-352 : 342-343

Osedax bozoi n. sp.

Fig. 3A , 4A–D , 6A

Material examined. Holotype: SIO-BIC A13918, female (GenBank COI sequence ON357631), collected from experimentally deployed cow bones deployed at 1,996 m depth in the Gulf of Mexico, offshore of New Orleans, Louisiana (28.103° N; 88.451° W); ROV Global Explorer dive number 17, April 15, 2019; fixed and preserved in 95% ethanol . Paratypes: SIO-BIC A10278 (destroyed, GenBank numbers in Table 2 ), A13920 (GenBank COI sequence ON357630), A13922 (GenBank COI sequences ON357686), females, collection data for paratypes is the same as for the holotype.

Diagnosis and description. Preserved holotype and other specimens white with greenish patches on root/ ovisac ( Fig. 4A–D ). Four apinnulate palps, distally coiled, ~ 1.5 mm long, ~ 0.2 mm wide, mainly contained inside transparent tube ( Fig. 4A–D ). Trunk ~ 0.5 mm long, 0.2–0.4 mm wide ( Fig. 4A, B, D ). Clear demarcation between palps and trunk; small ‘collar’ visible ventrally at truck/palp junction ( Fig. 4B ). Oviduct visible dorsally along trunk and extends into crown of palps, complete length unknown ( Fig. 4A ). Roots incomplete in holotype ( Fig. 4B–D ), though root extensions may be present on either side of the trunk ( Fig. 4B, D ). Paratype SIO-BIC A13922 with lobed ovisac, lateral root lobes, root extensions present on either side of the trunk ( Fig. 4D ). No dwarf males observed. The rDNC diagnosis for Osedax bozoi n. sp. was recovered as: ‘C’ at site 465, ‘G’ at site 468, and ‘T’ at site 561 of mitochondrial COI.

Distribution. Osedax bozoi n. sp. was recovered from cow bones ( Fig. 3A ) deployed at 1,996 m in the Mississippi River Delta region of the Gulf of Mexico south of New Orleans, Louisiana ( Fig. 1 ).

Etymology. Osedax bozoi n. sp. is named for the first author’s late cat, Bozo.

Remarks. Osedax bozoi n. sp. belongs to Clade II ( Fig. 2 ), an apinnulate ‘nude palp’ clade. Only associated with deployed cow bones ( Fig. 3A ). Paratype SIO-BIC A10278 was sequenced for 16S, 18S, 28S, and H3 as well as COI ( Table 2 ), but the specimen was destroyed for DNA extraction. SIO-BIC A13918, which had a close COI sequence and was largely intact, has been designated as the holotype ( Fig. 4A, B ). Specimens SIO-BIC A10276 (ON357629) and SIO-BIC A10277 (ON357628) were also destroyed for sequencing COI. Osedax bozoi n. sp. had a 1.3% maximum pairwise distance among the six available sequences, which all showed the rDNC diagnostic bases. The haplotype network for Osedax bozoi n. sp. had four unique haplotypes ( Fig. 6A ). One was shared by three of the six sequences, including the holotype. There were three nucleotide substitutions between the most divergent haplotypes, based on a trimmed datafile of 344 bases. Osedax bozoi n. sp. was recovered as the sister group to a clade within Clade II that comprised O. docricketts , O. westernflyer and O. knutei ( Fig. 2 ), though this was poorly supported. These three taxa are all from the Pacific Ocean. In terms of phylogenetic relatedness, the nearest species was Osedax docricketts , an apinnulate species known from Monterey Bay (California, USA) and Sagami Bay ( Japan) on cow and whale bones ( Rouse et al. 2018). Osedax bozoi n. sp. and O. docricketts share some morphological characteristics: both lack pigmentation on the trunk and palps and pinnules, both have a tube containing the palps. However, where O. bozoi n. sp. has a distinct demarcation between the palps and the trunk, O. docricketts does not, and the ovisac and oviduct are distinctive on O. bozoi . Osedax docricketts is suspected to be a cryptic species complex ( Berman et al. 2023; Rouse et al. 2018) and the minimum interspecific distance between the two species was 13.7% based on sequence EU267676, an individual of Osedax docricketts from Monterey Bay ( Table 3 ).

Figures

FIGURE 1. Map of geographic distributions of the four new Osedax species described here. The map was generated using the R package marmap (Pante & Simon-Bouhet 2013).

FIGURE 2. Maximum likelihood Osedax phylogenetic tree generated with data from five genetic markers as listed in Table 2. Bootstrap support values are on each node; those below 50% not shown. Presence or absence of pinnules is noted for each clade.

FIGURE 3. A. Cow bones from which Osedax bozoi n. sp. were found being recovered by ROV after 51 days at ~2,000 m in the Gulf of Mexico. B. Spine and skull of Alligator mississippiensis deployed at ~2,000 m in the Gulf of Mexico. Osedax are visible on the vertebrae and jaw. Osedax craigmcclaini n. sp. was found on these bones. C. Alligator mississippiensis skull with Osedax visible on the jaw. Images courtesy of Craig McClain.

FIGURE 4. A. Osedax bozoi n. sp., dorsal view of female holotype (SIO-BIC 13918) still partially in bone. B. Osedax bozoi n. sp., ventral view of holotype (SIO-BIC 13918) removed from bone. C. Paratype female Osedax bozoi n. sp. (SIO-BIC 13920) removed from bone showing palps, ovisac, and roots. D. Paratype female Osedax bozoi n. sp. (SIO-BIC 13922) showing palps, trunk, ovisac, and root system.

FIGURE 6. Haplotype networks using COI. Circles are haplotypes, green circles and crosshatches are single nucleotide substitutions. * indicates the haplotype of the holotype. A. Network for six specimens of Osedax bozoi n. sp. GenBank accession numbers: ON357627, ON357628, ON357629, ON357630, ON357631 (Holotype), ON357686. B. Network for two specimens of Osedax craigmcclaini n. sp. GenBank accession numbers: MN258704, ON211944 (Holotype).