Osedax traceyae Berman & Hiley & Read & Rouse 2024, n. sp.

Osedax traceyae n. sp.

Fig. 7A, C, 8B

Material examined. Holotype: NIWA 159435 female (GenBank COI sequence ON211990, 16S = ON212680, 18S = ON210988, 28S = ON220740, H3 = ON254808), collected from a whale skull (most likely a southern minke whale Balaenoptera bonaerensis) at 390 m depth on the Pukaki Rise SE of New Zealand (49.121° S; 172.136° E) scientific trawl TAN1614 Station 9, from R/V Tangaroa, December 1, 2016. Fixed and preserved in 95% ethanol. Paratypes: NIWA 159437, SIO-BIC A13927, NIWA 159439, NIWA 159440 (GenBank COI ON211991, ON211992, ON211987, ON211988), collection data for paratypes is the same as for the holotype.

Diagnosis and description. Live animals red, in transparent tubes on whale skull (Fig. 7A). Holotype consists of desiccated palps in ethanol (Fig. 7C). Apinnulate palps are brown, approximately 4 mm in length and 1 mm wide (Fig. 7C). Palps contained inside translucent membrane (Fig. 7C). Palp tips curled up inside membrane (Fig. 7C). No dwarf males observed. Paratypes are in a similar state as the holotype, though some have trunk and apparent root tissue. The rDNC diagnosis for Osedax traceyae n. sp. was recovered as: ‘A’ at site 280, ‘C’ at site 546, and ‘G’ at site 582 of mitochondrial COI.

Distribution. Osedax traceyae n. sp. was recovered from a whale fall on the Pukaki Rise off SE New Zealand at 390– 393 m.

Etymology. Osedax traceyae n. sp. is named in appreciation of Dianne (Di) M. Tracey of the National Institute of Water and Atmospheric Research (NIWA), Wellington, New Zealand. An outstanding deep-sea fisheries and coral researcher, her shipboard initiatives secured the whale skull and worms for our study.

Remarks. Osedax traceyae belongs to Clade II, a nude palp (apinnulate) clade (Fig. 2). The species had a 0.5% maximum intraspecific pairwise distance among the eleven sequences analyzed. The haplotype network for this species revealed two haplotypes, one of which was shared by ten of the eleven sequences (Fig. 8B). All 11 COI sequences showed the rDNC diagnostic bases for the species. Specimens of O. traceyae n. sp. were not observed alive, however images of the whale skull at the time it was collected show red palps in transparent tubes scattered over the surface (Fig. 7A), suggesting that living O. traceyae n. sp. may have red palps. Osedax traceyae n. sp. was recovered as the sister group to two Antarctic species, Osedax antarcticus Glover et al., 2013 and O. crouchi, belonging to Clade II, but the support value for this grouping was very low, as was support for most nodes in that clade (Fig. 2). The minimum interspecific COI distance between O. traceyae and each of these two Antarctic species was at least 15.4% (Table 3).