Terebellides scotica, Parapar & Capa & Nygren & Moreira, 2020

Parapar, Julio, Capa, Maria, Nygren, Arne & Moreira, Juan, 2020, To name but a few: descriptions of five new species of Terebellides (Annelida, Trichobranchidae) from the North East Atlantic, ZooKeys 992, pp. 1-58 : 1

Terebellides scotica sp. nov. Figs 1 , 2 , 3H , 9 , 17F , 18D , 19D , 24 , 25 ; Table 1; Suppl. material 1: Table S1; Suppl. material 2: Table S2

Species 9 - Nygren et al. 2018: 18-22, figs 5, 6, 10, Suppl. material 1: Table S1.

Material examined.

Type material. Holotype: ZMBN116385. Paratypes (3 specs), North Sea (ZMBN 116382, ZMBN 116386, ZMBN 116387).

Holotype. Complete specimen, 45.0 mm long and 4.5 mm width (Fig. 3H , 19D ).

Additional material.

SMA_BR_23 (GenBank number: MN207187) and SMA_BR_33 (GenBank number: MN207188) of Terebellides sp. in Lavesque et al. (2019) (Suppl. material 1: Table S1).

GenBank accession numbers of material examined (COI).

Holotype: MG025157. Paratype: MG025158.

Diagnostic features of type material.

Complete individuals ranging from 6.0-45.0 mm in length and 1.0-4.0 mm in width (Figs 9 , 17F ). Branchial dorsal lobes lamellae provided with low anterior papillary projections (Fig. 24B ). Ventral branchial lobes hidden (Fig. 24A ) or not (Figs 3H , 19D ) by dorsal ones. Lateral lappets and dorsal projection low marked being only discernible on TC1-3 (Fig. 24A ). Geniculate chaetae acutely bent and provided with hardly distinguishable capitium (Fig. 25A, B ). Ciliated papilla dorsal to thoracic notopodia not observed. Thoracic uncini in one or two rows (Fig. 25C ) with rostrum/capitium length ratio of approximately 2: 1, and capitium with a first row of 2-4 medium-sized teeth, followed by several progressively smaller teeth (Fig. 25D, E ). Abdomen with 18-33 uncinigers provided with type 2 uncini (Fig. 25F ).

Nucleotide diagnostic features.

There are no unique apomorphic nucleotides in the fragments of COI analysed for T. scotica sp. nov., when considering all Terebellides species present in the NEA (Suppl. material 2: Table S2). However, when comparing homologous nucleotide positions with members of only Group A (192 sequences in the COI alignment), the following autapomorphies arise: 279 (G), 444 (C), 517 (A), 630 (C).

Type locality.

East Orkney Island; 85 m deep (Fig. 18D ).

Distribution and bathymetry.

North Sea; 48-111 m deep ( Nygren et al. 2018) (Fig. 18D ; Suppl. material 1: Table S1). Two specimens ( Terebellides sp. in Lavesque et al. 2019) were identified as T. scotica sp. nov. according to molecular sequences; Bay of Brest (France), in rhodolith beds, 5 m deep.

Etymology.

This new species is named after Scotland, since its type locality is in the Scottish Orkneys Islands.

Remarks.

Among A2 species, T. scotica sp. nov., T. europaea and T. norvegica sp. nov. have thoracic uncini of type 3 and show ventral branchial lobes that may be hidden in between dorsal lobes in some specimens. As stated previously, these species can only be distinguished according to DNA sequences.

The specimen studied under SEM shows a small knob near the notopodial lobe of TC1 (nop, Fig. 24C ); its biological role is unknown and it may correspond to an artefact.

Two different sequences (see Suppl. material 2: Table S2; 0.2% distance) have been attributed to this species ( Nygren et al. 2018). As stated above, the closest NEA congener is T. norvegica sp. nov., at 10.5% genetic distance.

Figures

Figure 1. Phylogenetic tree after Maximum Likelihood analyses on a concatenated dataset of cox 1, 16 S rDNA, ITS 2, and 28 S rDNA (as in Nygren et al. 2018). Bootstrap support values above nodes. Coloured squares indicate the major clades referred herein as Groups A-D. Within Group A, the focus of present study, subgroups A 1 - A 4 and species 6 - 13, 18 - 21, 23, 28 are labelled.

Figure 2. Phylogenetic tree after Maximum Likelihood analyses on a dataset of cox 1 (including all sequences in Nygren et al. 2018 and in Lavesque et al. 2019). Bootstrap support values above nodes. Species other than members of Group A are collapsed. Species with names refer to those dealt with in present study.

Figure 3. STM photographs of several Terebellides species. A Terebellides bakkeni sp. nov. (species 10; holotype, ZMBN 116395) B Terebellides stroemii Sars, 1835 (species 11; non-type specimen, ZMBN 116397) C Terebellides kongsrudi sp. nov. (species 13; holotype, GNM 14632) D Terebellides bigeniculatus Parapar, Moreira & Helgason, 2011 (species 20 + 28; non-type specimen, ZMBN 116514) E Terebellides europaea Lavesque, Hutchings, Daffe, Nygren & Londono-Mesa, 2019 (species 6; non-type specimen, GNM 14628) F Terebellides ronningae sp. nov. (species 7; holotype, ZMBN 116357) G Terebellides norvegica sp. nov. (species 8; holotype, ZMBN 416378) H Terebellides scotica sp. nov. (species 9; holotype, ZMBN 116385). Abbreviations: bdl - branchial dorsal lobe; bvl - branchial ventral lobe; TC - thoracic chaetiger.

Figure 9. Bathymetric distribution of Terebellides species studied in this work. Subgroups (A 1 - 3) within group A sensu Nygren et al. (2018) are indicated.

Figure 17. Relationship between number of abdominal chaetigers and body length (complete specimens) for Terebellides species described in this work.

Figure 18. Geographic distribution of A T. europaea Lavesque et al., 2019, B T. ronningae sp. nov., C T. norvegica sp. nov., D T. scotica sp. nov. Yellow frame showing Hordaland (Fig. 10).

Figure 19. Line drawings of several Terebellides species. A Terebellides europaea Lavesque, Hutchings, Daffe, Nygren & Londono-Mesa, 2019 (species 6; non-type specimen, GNM 14628), anterior end, left lateral view B Terebellides ronningae sp. nov. (species 7; holotype, ZMBN 116357), anterior end, left lateral view C Terebellides norvegica sp. nov. (species 8; holotype, ZMBN 416378), anterior end, right lateral view D Terebellides scotica sp. nov. (species 9; holotype, ZMBN 116385), anterior end, left lateral view. Abbreviations: bdl - branchial dorsal lobe; bvl - branchial ventral lobe; TC - thoracic chaetiger.

Figure 24. Terebellides scotica sp. nov. (species 9; paratype, ZMBN 1163887), SEM micrographs. A anterior end, left lateral view B anterior dorsal branchial lamellae and papillae C TC 1 and TC 2, lateral view (framed in A). Abbreviations: bdl - branchial dorsal lobe; blp - branchial lamellae papillae; dpn - dorsal projection of notopodium; loli - lower lip; nop - notopodial protuberance; TC - thoracic chaetiger.

Figure 25. Terebellides scotica sp. nov. (species 9; paratype, ZMBN 1163887), SEM micrographs. A TC 6 (TU 1), geniculate chaetae B detail of geniculate chaeta (arrow pointing to capitium) C double row of thoracic uncini D, E thoracic uncini, capitium F abdominal uncini. Abbreviations: cap - capitium; ctr 1 - first row of capitium teeth; ros - rostrum.