Aeolidia libitinaria Valdés & Lundsten & Wilson 2018, sp. nov.
Creators: name: Valdés, Ángel
name: Lundsten, Lonny
name: Wilson, Nerida G.
Publisher: name: Zenodo
Year: 2018
Subjects: Biodiversity
Taxonomy
Animalia
Mollusca
Gastropoda
Nudibranchia
Aeolidiidae
Aeolidia
Aeolidia libitinaria

description: Aeolidia libitinaria sp. nov.
(Figs. 2H, 15 G–H, 18–19)
Type material. Holotype: Gray whale skeleton (implanted on 10 Apr 2005), Monterey Bay, California (36.772, - 122.083), 382 m depth, ROV Doc Ricketts (dive 96), 17 Nov 2009, 23 preserved length, dissected (SIO-BIC M12138), GenBank accession numbers: MH 756137 (COI), MH 756132 (16S), MH 756143 (H3).
Description. Body elongate, wide, with numerous elongate, dorso-lateral cerata (Fig. 2H). Cerata arranged in densely packed rows, running from behind oral tentacles to posterior end of body (Fig. 2H). Cerata increase in size in each row, lateral cerata typically shorter, dorsal cerata longer (Fig. 2H, 15G). Oral tentacles tentacular, narrow, elongate (Figs. 2H, 15G). Foot corners absent (Figs. 15G). Rhinophores elongate (Figs. 2F), with low irregular swellings (Fig. 15H). Body color brown-ochre, covered with densely arranged yellowish spots (Fig. 2H). Rhinophores and oral tentacles same color as body but two distal thirds yellowish-white. Cerata also with same color as body (Fig. 2H), with digestive gland branches partially visible, particularly in smaller cerata, giving them a reddish tinge; cnidosacs white.
Digestive system with very large, muscular buccal bulb (Fig. 18A). Esophagus inflated, large, occupying nearly half of visceral volume, connecting anteriorly into buccal bulb. Digestive gland with lateral branches entering cerata. Intestine emerging dorsally from left side of digestive gland, forming a loop towards right side of body where it runs further posteriorly until it opens into anus on dorso-right side of body (cleioproctic). Intestine with several tubercles near proximal end.
Radular formula 19 × 0.1.0 in holotype. Radular teeth broad, arch-shaped (Fig. 19B), with 43–52 elongate acutely pointed denticles, lacking central cusp. Teeth progressively smaller towards the posterior end of radula. Jaws elongate (Fig. 19A), no denticles on masticatory border.
Reproductive system with very elongate, convoluted ampulla forming numerous loops (Fig. 18B), opening into female gland complex next to prostate opening. Prostate tubular, very elongate, forming numerous loops, expanding into elongate, muscular deferent duct. Penis simple, elongate. No vagina or seminal receptacle were observed, probably an artifact of the dissection.
Biology. This species was collected at 382 m depth on an implanted Gray Whale carcass that was being surveyed as part of a time-series analysis of whale-fall ecology (Lundsten et al. 2010b) in Monterey Bay, CA. The carcass of this whale was in the mid-sulphophilic stage, however, the 382 m site was heavily sedimented and the carcass was exposed to a changing regime of bone movement, burial, and re-exposure. Other organisms seen at this site included dense populations of Osedax sp. (siboglinid polychaete), the anenomes Actiniaria unid., and Metridium farcimen, Chorilia longipes (crabs), the echinoderms Ophiuroidea spp., Rathbunaster californicus, and Strongylocentrotus fragilis and many species of fish including Anoplopomia fimbria, Lycodes cortezianus, Lycodes diapterus, Merluccius productus, and Sebastolobus sp.
Phylogenetic position. Aeolidia libitinaria sp. nov. is sister to A. loui and this relationship is well supported (Fig. 14).
Etymology. The species name is derived from the Latin word for undertaker, owing to the type specimen being found among the bones of a deceased cetacean.
Remarks. Aeolidia libitinaria sp. nov. is distinguishable from other species of Aeolidia by its external coloration, no other species has a brown-ochre, covered with densely arranged yellowish spots. The morphology of the reproductive system of Aeolidia libitinaria sp. nov., with a wide and elongate penial sheath, resembles that of A. papillosa as described by Kienberger et al. (2016), but it is different from all other species of the genus including A. loui, its sister taxon, which has a much shorter, triangular penial sheath. The radular teeth of A. papillosa, A. loui and Aeolidia libitinaria sp. nov. are different. In A. papillosa and A. loui the teeth are wide and delicate, whereas in Aeolidia libitinaria sp. nov. are more robust, generally narrower. Additionally, these three species are genetically distinct as shown in the phylogenetic analysis results (Fig. 14). No seminal receptacle was observed in Aeolidia libitinaria sp. nov. but this could be an artifact of the dissection.
description: Published as part of Valdés, Ángel, Lundsten, Lonny & Wilson, Nerida G., 2018, Five new deep-sea species of nudibranchs (Gastropoda: Heterobranchia: Cladobranchia) from the Northeast Pacific, pp. 401-433 in Zootaxa 4526 (4) on pages 424-425, DOI: 10.11646/zootaxa.4526.4.1, http://zenodo.org/record/2611755