Hocius, Moles & Avila & Malaquias, 2018

HOCIUS View in CoL GEN. NOV.

urn:lsid:zoobank.org:act:729058FA-DBF1-4F80-AA3C-A64132BFBB64

Type species: Newnesia joani Moles, Wägele, Schrödl & Avila, 2017 .

Diagnosis: Shell internal, globose. Radula three-seriate, with sharp unicuspid rachidian tooth and lamellate laterals. Left anterolateral repugnatorial gland with distinct funnel and right posterolateral repugnatorial gland present. Distinct parietal ganglion present. See Moles et al. (2017a) for a complete description of the type species.

Examined material: Hocius joani comb. nov.: Drake Passage , north of King George Island, 61°27.6 ′ S, 58°4.1 ′ W GoogleMaps to 61°26.5 ′ S, 58°7.4 ′ W, 19 March 1998,

967–1227 m depth, 1 spc., ZSMMoll 20150456, H = 15.7 mm (holotype); 1 spc., dissected and sequenced, CRBA2024 , H = 21 mm (paratype 1); 1 spc., dissected and sequenced, ZSM Moll 20150456, H = 19 mm (paratype 2); 1 spc., dissected, ZSM Moll 20150456, H = 18 mm (paratype 3); 1 spc., sectioned, H = 10.7 mm (paratype 4); 1 spc., ZSM Moll 20150456, H = 10.4 mm (paratype 5); 1 spc., ZSM Moll 20150456, H = 8.5 mm (paratype 6) .

Etymology: The genus name is derived from the toponymy of the type locality, the Sea of Hoces, named after the Spanish navigator Francisco de Hoces, who in 1526 first navigated these waters (commonly known as the Drake Passage; Lausic, 1993).

Remarks: Hocius joani comb. nov. was first ascribed to the genus Newnesia based on morphological similarities with N. antarctica (e.g. trapezoidal cephalic shield, dorsolateral velar lobes, globose shell, rachidian tooth shape) and phylogenetic evidence ( Moles et al., 2017a). However, the broad taxon sampling used in this study together with several morphological synapomorphies recognized in H. joani comb. nov. (e.g. internal shell, three-seriated radula; see ‘Diagnosis’) warrants in our opinion the designation of a new genus to include this species (see Table 1).

MOLECULAR SPECIES DELIMITATION AND PHYLOGENETIC ANALYSES

No saturation was found for the first, second and third codon positions of the protein-coding genes COI and H3. Thus, the combined concatenation included COI (including the third codon position), 16S with relaxed settings, 28S with relaxed settings and H3 (including the third codon position). The four-genes concatenated BI and ML trees were nearly congruent and both recovered the monophyly of Newnesiidae with maximum support (PP = 1; BS = 100), including N. antarctica , N. abyssalis sp. nov. and H. joani comb. nov. ( Fig. 4).

Intraspecific genetic variability for the COI gene (uncorrected p -distance) ranged between 0 and 0.7%, whereas interspecific differences for sister species pairs ranged between 11.2 and 11.4% ( N. antarctica / H. joani comb. nov.), 10 and 10.5% ( N. antarctica / N. abyssalis sp. nov.) and 7.6 and 7.8% ( H. joani comb. nov. / N. abyssalis sp. nov.). The recursive ABGD analysis identified three groups given a series of prior values from 0.001 to 0.059 (Supporting Information, Fig. S9). These groups correspond to morpho-species that also returned maximum or nearly maximum PPs in the BI and bootstrap supports of 96–100% in the ML analysis ( Fig. 4). The mean K80 Kimura intraspecific distance was 0.59% for N. antarctica , 1% for N. abyssalis sp. nov. and 0.0% for H. joani comb. nov. The mean interspecific Kimura distances between N. antarctica and N. abyssalis sp. nov. was 12.1% and 13.5% for H. joani comb. nov., while the distance between N. abyssalis sp. nov. and H. joani comb. nov. was 10%.