Aeolidia libitinaria, Valdés & Lundsten & Wilson, 2018

Valdés, Ángel, Lundsten, Lonny & Wilson, Nerida G., 2018, Five new deep-sea species of nudibranchs (Gastropoda: Heterobranchia: Cladobranchia) from the Northeast Pacific, Zootaxa 4526 (4), pp. 401-433 : 424-425

publication ID	https://doi.org/ 10.11646/zootaxa.4526.4.1
publication LSID	lsid:zoobank.org:pub:3CFFF3AC-C447-4FCE-B6F8-D2B7BAE8B678
DOI	https://doi.org/10.5281/zenodo.5971420
persistent identifier	https://treatment.plazi.org/id/F7BA0675-FA22-485F-AE01-3E9DBFF97BA1
taxon LSID	lsid:zoobank.org:act:F7BA0675-FA22-485F-AE01-3E9DBFF97BA1
treatment provided by	Plazi
scientific name	Aeolidia libitinaria
status	sp. nov.

Treatment

Aeolidia libitinaria View in CoL sp. nov.

( Figs. 2H View FIGURE 2 , 15 View FIGURE 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 View Materials ( COI), MH 756132 View Materials (16S), MH 756143 View Materials (H3).

Description. Body elongate, wide, with numerous elongate, dorso-lateral cerata ( Fig. 2H View FIGURE 2 ). Cerata arranged in densely packed rows, running from behind oral tentacles to posterior end of body ( Fig. 2H View FIGURE 2 ). Cerata increase in size in each row, lateral cerata typically shorter, dorsal cerata longer ( Fig. 2H View FIGURE 2 , 15G View FIGURE 15 ). Oral tentacles tentacular, narrow, elongate ( Figs. 2H View FIGURE 2 , 15G View FIGURE 15 ). Foot corners absent ( Figs. 15G View FIGURE 15 ). Rhinophores elongate ( Figs. 2F View FIGURE 2 ), with low irregular swellings ( Fig. 15H View FIGURE 15 ). Body color brown-ochre, covered with densely arranged yellowish spots ( Fig. 2H View FIGURE 2 ). Rhinophores and oral tentacles same color as body but two distal thirds yellowish-white. Cerata also with same color as body ( Fig. 2H View FIGURE 2 ), 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 View FIGURE 18 ). 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 View FIGURE 19 ), with 43–52 elongate acutely pointed denticles, lacking central cusp. Teeth progressively smaller towards the posterior end of radula. Jaws elongate ( Fig. 19A View FIGURE 19 ), no denticles on masticatory border.

Reproductive system with very elongate, convoluted ampulla forming numerous loops ( Fig. 18B View FIGURE 18 ), 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 View FIGURE 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 View FIGURE 14 ). No seminal receptacle was observed in Aeolidia libitinaria sp. nov. but this could be an artifact of the dissection.