Terebellides stroemii Sars, 1835

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

publication ID	https://dx.doi.org/10.3897/zookeys.992.55977
publication LSID	lsid:zoobank.org:pub:0F038B5B-120E-4583-8E85-4092C9798566
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scientific name	Terebellides stroemii Sars, 1835
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Terebellides stroemii Sars, 1835 Figs 1 View Figure 1 , 2 View Figure 2 , 3B View Figure 3 , 4B View Figure 4 , 7 View Figure 7 , 8B View Figure 8 , 9 View Figure 9 , 10 View Figure 10 , 17A View Figure 17 , 28D View Figure 28 ; Suppl. material 1: Table S1; Suppl. material 2: Table S2

Terebellides stroemii Sars, 1835: 48-50, pl. 13, fig. 31a-e. Parapar and Hutchings 2014: 10, fig. 5-10. Non Parapar et al. 2011: 14-17, figs 11, 12, 13G.

Species 11 - Nygren et al. 2018: 18-22, figs 6, 10. Non Clade 6 in Nygren et al. (2018) (see Remarks).

Type locality.

Helle, Manger, Bergenfjord (Norway) ( Parapar and Hutchings 2014).

Material examined.

5 specimens (Suppl. material 1: Table S1), Norwegian coast and shelf: ZMBN 116397, ZMBN 116398, ZMBN 116399, ZMBN 116400, ZMBN 116401.

A dditional material.

Neotype (NHMOC5896) and seven " neoparatypes " (NHMOC5899, NHMOC5902, NHMOC5904, NHMOC5905, NHMOC5907, NHMOC5956, NHMOC5968) of T. stroemii (Suppl. material 1: Table S1).

GenBank accession numbers of material examined (COI).

MG025171, MG025172, MG025173, MG025174, MG025175.

Diagnostic features of studied material.

Complete individuals ranging from 6.0-20.0 mm in length (Fig. 17A View Figure 17 ). Branchial dorsal lobes lamellae without papillary projections. Ventral branchial lobes hidden behind dorsal lobes (Figs 3B View Figure 3 , 4B View Figure 4 ). Lateral lappets present on TC1-TC4; dorsal projection well marked from TC3-TC4 (Fig. 7A View Figure 7 ). Geniculate chaetae in TC6, acutely bent (Fig. 7C View Figure 7 ) with low marked capitium. Ciliated papilla dorsal to thoracic notopodia (Fig. 7B View Figure 7 ). Thoracic uncini in one row with rostrum/capitium length ratio approximately 2: 1 and capitium with a first row of three or four medium-sized teeth, followed by several smaller teeth (Fig. 7E, F View Figure 7 ). Abdomen with 23-32 chaetigers (Fig. 17A View Figure 17 ) with type 2 uncini (Figs 7G View Figure 7 , 28D View Figure 28 ).

Nucleotide diagnostic features.

There are no unique apomorphic nucleotides in the fragments of COI analysed for T. stroemii , 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 (183 sequences in the COI alignment), the following autapomorphies arise: 174 (C), 183 (C), 453 (A), 612 (C).

Distribution and bathymetry.

Terebellides stroemii was traditionally considered as a cosmopolitan species, but its known distribution seems in fact restricted to the Norwegian coastline ( Parapar et al. 2011; Parapar and Hutchings 2014; Lavesque et al. 2019). Specimens examined by Nygren et al. (2018) and in the present paper, obtained after comprehensive sampling in the NEA, were found only in W Norway, between 115 and 388 m deep (Figs 8B View Figure 8 , 10 View Figure 10 ; Suppl. material 1: Table S1).

Remarks.

In the five sequences belonging to this species, there were four haplotypes showing 0-1.1% of intraspecific divergence, and a minimum of 11.5% uncorrected genetic distance with members of the closest relative, T. bakkeni sp. nov. ( Nygren et al. 2018).

Terebellides stroemii is a large species, reaching up to 52 mm in length ( Parapar and Hutchings 2014) and is characterised by the presence of ciliated papilla dorsal to thoracic notopodia, lack of papillae on margins of branchial lamellae, thoracic uncini of type 3 and abdominal uncini of type 2. All these features are shared with T. kongsrudi sp. nov.; T. bakkeni sp. nov. is also very close morphologically to T. stroemii but they differ in the morphology of the abdominal uncini as explained above.

Nygren et al. (2018) misidentified species 6 as T. stroemii , but this was later corrected by Lavesque et al. (2019) who pointed out that the molecular sequences of these specimens fit with those of T. europaea .

Specimens examined here bear thoracic uncini that are most similar to other members of Group A; SEM examination showed, however, that some uncini have a rostrum distal tip that is distinctly bent downwards (deformity?) (Fig. 7E View Figure 7 , arrow) as already described for the type specimens by Parapar and Hutchings (2014: 8, fig. 7F, G), and attributed to preservation for too long in EtOH. However, we have found similar bent rostrum among specimens of T. kongsrudi sp. nov. (Fig. 12D View Figure 12 , arrow), T. ronningae sp. nov. (species 7) (Fig. 21C View Figure 21 , arrows) and T. bigeniculatus (species 20 + 28) (Fig. 26E View Figure 26 , frame) suggesting this may not be related to preservation. The abdominal uncini are quite similar to those described in Parapar and Hutchings (2014: 9, fig. 8C-E) also showing a small gap among the anteriormost teeth of rostrum ( Parapar and Hutchings 2014: 8-9, fig. 8F; Fig. 7G View Figure 7 ); these features are not shared by other species of subgroup A1, i.e., T. bakkeni sp. nov. and T. kongsrudi sp. nov. In all, species 11 agrees well with the redescription of T. stroemii .

Geographic and bathymetric distribution of our specimens also agree with that of T. stroemii (see Parapar and Hutchings 2014), with Manger (Norway) (i.e., type locality of T. stroemii ; Fig. 10 View Figure 10 ) being its southernmost distribution limit. The other three taxa, i.e., species 5, T. europaea and T. bigeniculatus , were also found near Manger, but all can be clearly distinguished morphologically from each other (see above and below for T. europaea and T. bigeniculatus ) and species 5 belongs to Group B and seems closer morphologically to T. atlantis . On the other hand, type specimens of T. stroemii come from depths of 55-110 m ( Parapar and Hutchings 2014) as well as specimens belonging to T. europaea , T. ronningae sp. nov., T. scotica sp. nov. (species 9) and species 12 (<200 m), and therefore they seem to constitute a shallow-water assemblage of species from an ecological point of view.

Finally, the Icelandic specimens reported as T. stroemii by Parapar et al. (2011) might not correspond to this species. In fact, it is likely that they represent at least two different species, namely T. bakkeni sp. nov. and T. kongsrudi sp. nov., both reported here to the North and East of Iceland. Therefore, the aforementioned specimens deserve further revision.