Research Article |
Corresponding author: Julio Parapar ( jparapar@udc.es ) Academic editor: Christopher Glasby
© 2020 Julio Parapar, María Capa, Arne Nygren, Juan Moreira.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Parapar J, Capa M, Nygren A, Moreira J (2020) To name but a few: descriptions of five new species of Terebellides (Annelida, Trichobranchidae) from the North East Atlantic. ZooKeys 992: 1-58. https://doi.org/10.3897/zookeys.992.55977
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The number of described species of the genus Terebellides Sars, 1835 (Annelida, Trichobranchidae) has greatly increased in the last years, particularly in the North East Atlantic. In this context, this paper deals with several putative species recently delineated by molecular means within a well delimited clade of Terebellides. Species are characterised here by a combination of morphological characters, and a complementary nucleotide diagnostic approach. Three species were identified as the nominal species T. stroemii Sars, 1835, T. bigeniculatus Parapar, Moreira & Helgason, 2011 and T. europaea
DNA barcoding, DNA species delineation, identification key, integrative taxonomy, new species, North East Atlantic, polychaetes, SEM, systematics
The species richness in the genus Terebellides Sars, 1835 (Annelida, Trichobranchidae) in the North East Atlantic (NEA hereafter) seemed to be well known after several taxonomic studies (
Terebellides is the most species-rich genus of trichobranchids, with 82 nominal species (
Phylogenetic analyses consistently showed that the NEA Terebellides are divided into four major clades, named Groups A–D in
This paper is based on the study of 132 specimens identified as belonging to Group A as defined in
The sampling area covered in this paper is mostly the Norwegian and Swedish continental shelf but also includes some samples from the Irish and Celtic seas, North Sea, Barents Sea, Greenland Sea, South Icelandic coast and the Arctic Ocean (Suppl. material
Light microscope images were obtained by means of an Olympus SZX12 stereomicroscope equipped with an Olympus C-5050 digital camera. Line drawings were made with an Olympus BX40 stereomicroscope equipped with camera lucida. Specimens for Scanning Electron Microscopy (SEM) were prepared by critical point drying, covered with gold and examined and photographed under a JEOL JSM-6400 electron microscope at the Servizos de Apoio á Investigación (SAI, Universidade da Coruña, Spain).
Methyl green (MG) staining patterns and thoracic uncini morphology were characterised based on the classification proposed by
The species dealt within the present study are quite homogenous morphologically. Therefore, common traits shared by all members of Group A are described first in order to avoid repetition of the same characters in each species description.
For each species, the list of the museum registration numbers and collection details (geographic area, locality, coordinates, depth, collecting date and habitat) is provided in Suppl. material
The present systematic account follows the phylogenetic hypothesis presented by
Phylogenetic tree after Maximum Likelihood analyses on a concatenated dataset of cox1, 16S rDNA, ITS2, and 28S rDNA (as in
The COI universal barcoding gene proved to be very informative for species delimitation purposes alone, but insufficient to resolve deeper relationships in the Terebellides radiation (
Phylogenetic tree after Maximum Likelihood analyses on a dataset of cox1 (including all sequences in
Abbreviations used in text, tables and figures:
abl anterior branchial lobe (lobe #5);
babv branchial afferent blood vessel;
bbv branchial blood vessel;
bdl branchial dorsal lobes;
bdlfl branchial dorsal lobes fusion line;
bdltp branchial dorsal lobe terminal papilla;
blp branchial lamellar papillae;
bst branchial stem;
bt buccal tentacles;
bvl branchial ventral lobes;
bvltp branchial ventral lobe terminal papilla;
cap capitium;
cbh contractile branchial heart;
cr ciliary row;
ct ciliary tuft;
ctrX capitium teeth row X;
dg digestive gland;
dpn dorsal projection of notopodium;
fi fore intestine;
fs fore stomach;
gc geniculate chaetae;
gr glandular region;
hs hind stomach;
loli lower lip;
MG Methyl Green;
nop notopodial protuberance;
np nephridial papilla;
oes oesophagus;
ooc oocytes;
ros rostrum;
SEM Scanning Electron Microscope;
SG segment;
STM stereomicroscope;
TC thoracic chaetiger;
tdp thoracic dorsal papilla;
tll thoracic lateral lappets;
tm tentacular membrane;
TU thoracic unciniger.
The revision of the specimens of Terebellides Group A as found in
Species included in Group A have been grouped as follows: A) subgroup A1 (species 10, 11, 12, 13, 18, 19; as in
Comparison of discriminatin g taxonomic characters of the species studied in this work. Cells with text in italic show discriminatory characters of each subgroup. Species 18, 19, and 23 were not studied and 12 and 21 only examined with SEM.
Subgroups | A1 | A2 | A3 | A4 | ||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Species sensu |
10 | 11 | 12 | 13 | 18 | 19 | 6 | 7 | 8 | 9 | 20 + 28 | 21 | 23 | |
SPECIES | T. bakkeni sp. nov. | T. stroemii Sars, 1835 | Terebellides sp. 1 | T. kongsrudi sp. nov. | T. europaea Lavesque et al., 2019 | T. ronningae sp. nov. | T. norvegica sp. nov. | T. scotica sp. nov. | T. bigeniculatus Parapar et al., 2011 | Terebellides sp. 2 | ||||
(as reported/described here) | ||||||||||||||
Branchiae | type (1) | 1 | 1 | 1 | 1 | – | – | 1 | 1 | 1 | 1 | 1 (2) | 1 (2) | – |
papillae on lamellae edge | no | no | no | no | – | – | yes | yes | yes | yes | no | no | – | |
Thorax | ciliated papilla dorsal to notopodium | yes | yes | yes | yes | – | – | no | no (?) | no | no | yes | yes | – |
chaetiger(s) with geniculate chaetae | TC6 | TC6 | TC6 | TC6 | – | – | TC6 | TC6 | TC6 | TC6 | TC5 + TC6 | TC5 + TC6 | – | |
uncini type (3) | 3 | 3 | 3 | 3 | – | – | 3 | 1 | 3 | 3 | 3 | 3 | – | |
Abdomen | uncini type (4) | 1A | 2 | 2 | 1A | – | – | 2 | 2 | 2 | 2 | 1B | 1B | – |
Bathymetry – Above (A) / Below (B) 200 m depth (5) | A / B | A / B | A | A / B | B | B | A | A | B | A | B | A / B | B | |
Distribution – North (N) /South (S) of 60°N (5) | N | N | S | N / S | N | N | S (6) | N / S | N / S | S (7) | N | N | N |
Terebellides stroemii Sars, 1835, redescribed by
The morphological features shared by all studied species in Group A are itemized below. Some of these are also shared by Groups B, C and D as defined in
Complete individuals ranging from 10.0–50.0 mm in length. Body tapering posteriorly with segments increasingly shorter and crowded towards pygidium (Fig.
Branchiae
. Branchiae arising as single structure from SGIII, with a single stalked mid-dorsal stem (Figs
Thorax
. Eighteen pairs of notopodia (SGIII-SGXX) (Fig.
Abdomen and pygidium
. Approximately half as long as thorax and progressively thinner (Fig.
Colour pattern. Colour in preserved specimens pale brown (Fig.
STM photographs of several Terebellides species. A Terebellides bakkeni sp. nov. (species 10; holotype, ZMBN116395) B Terebellides stroemii Sars, 1835 (species 11; non-type specimen, ZMBN116397) C Terebellides kongsrudi sp. nov. (species 13; holotype, GNM14632) D Terebellides bigeniculatus Parapar, Moreira & Helgason, 2011 (species 20 + 28; non-type specimen, ZMBN116514) E Terebellides europaea Lavesque, Hutchings, Daffe, Nygren & Londoño-Mesa, 2019 (species 6; non-type specimen, GNM14628) F Terebellides ronningae sp. nov. (species 7; holotype, ZMBN116357) G Terebellides norvegica sp. nov. (species 8; holotype, ZMBN416378) H Terebellides scotica sp. nov. (species 9; holotype, ZMBN116385). Abbreviations: bdl – branchial dorsal lobe; bvl – branchial ventral lobe; TC – thoracic chaetiger.
Among the aforementioned characters, branchial features might serve to distinguish most of Group A species (except for A3 species) from those in Groups B–D. Those include branchial size, lobes size (i.e., whether dorsal and ventral are of similar size or differ), presence of terminal papilla/filament on posterior lobes, and presence of ciliary structures (rows, tufts or buttons) on lamellae. Other taxa described or reported worldwide bear similar branchiae including T. stroemii sensu
Line drawings of several Terebellides species. A Terebellides bakkeni sp. nov. (species 10; holotype, ZMBN116395), anterior end, right lateral view B Terebellides stroemii Sars, 1835 (species 11; non-type specimen, ZMBN116397), anterior end, right lateral view C Terebellides kongsrudi sp. nov. (species 13; holotype, GNM14632), anterior end, left lateral view D Terebellides bigeniculatus Parapar, Moreira & Helgason, 2011 (species 20 + 28; non-type specimen, ZMBN116514), anterior end, left lateral view. Abbreviations: bdl – branchial dorsal lobe; bvl – branchial ventral lobes; dpn – dorsal projection of notopodium ; TC – thoracic chaetiger.
The other species groups as found in
Terebellides bakkeni sp. nov. (species 10; paratypes,
Regarding Group A, six morphological characters have been considered to delineate subgroups and species (Table
Furthermore, species will be also characterised according to geographic and bathymetric distribution according to available data.
Analyses of molecular data found low or no support for monophyly of this clade (Figs
None (Table
Terebellides stroemii Sars, 1835 (species 11; non-type specimen,
Species 10
Type material. Holotype: ZMBN116395. Paratypes (10 specimens): Barents Sea (ZMBN116388, ZMBN116389), Norwegian coast and shelf (ZMBN116390, ZMBN116391, ZMBN116392, ZMBN116393, ZMBN116394, ZMBN116396, NTNU–VM61376, NTNU–VM61377).
Holotype. Complete specimen, 32.0 mm long and 2.0 mm width (Figs
Complete individuals ranging from 23.0–32.0 mm in length (Fig.
Members of T. bakkeni sp. nov. share the following unique nucleotides at these given positions of our alignement: 162 (G), 168 (C), 345 (G; shared only with one specimen from species 17).
Nordland, Sortlaandssunder (Lofoten Islands); 119 m deep (Suppl. material
Barents Sea, Greenland Sea, northern Norwegian coasts from the Lofoten Islands to Trondheim; at depths of102–378 m (
This species is named after Dr. Torkild Bakken, from the NTNU–University Museum, Trondheim (Norway), housing institution of some of the specimens used in the present study, for his dedication to the study of Norwegian polychaetes and his friendship.
Terebellides bakkeni sp. nov. is a small-sized species, maximum-sized specimens reaching 20.0 mm in length (n = 3). This species is characterised by the presence of ciliated papilla dorsal to thoracic notopodia, lack of papillae on the margins of branchial lamellae and presenting abdominal uncini of type 1. Most of these features are also shared by the closest relative, T. stroemii (species 11 herein), but they differ in the morphology of the abdominal uncini, being of type 2 in T. stroemii and type 1 in T. bakkeni sp. nov. (Table
Of the 462 sequences, including all NEA species, and 659 positions in the COI alignment, the 12 sequences assigned to T. bakkeni sp. nov. hold two unique nucleotides positions, and an additional one only shared by a single specimen from another clade (see Suppl. material
Terebellides stroemii
Sars, 1835: 48–50, pl. 13, fig. 31a–e.
Species 11 –
Helle, Manger, Bergenfjord (Norway) (
5 specimens (Suppl. material
Neotype (NHMOC5896) and seven “neoparatypes” (NHMOC5899, NHMOC5902, NHMOC5904, NHMOC5905, NHMOC5907, NHMOC5956, NHMOC5968) of T. stroemii (Suppl. material
Complete individuals ranging from 6.0–20.0 mm in length (Fig.
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
Terebellides stroemii was traditionally considered as a cosmopolitan species, but its known distribution seems in fact restricted to the Norwegian coastline (
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. (
Terebellides stroemii is a large species, reaching up to 52 mm in length (
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.
Geographic and bathymetric distribution of our specimens also agree with that of T. stroemii (see
Finally, the Icelandic specimens reported as T. stroemii by
Species 13 –
Type material. Holotype: GNM14632. Paratypes (20 specs): Barents Sea (ZMBN116409, ZMBN116411, ZMBN116414); Norwegian coast and shelf (ZMBN116412, ZMBN116413, ZMBN116415, ZMBN116416, ZMBN116417, ZMBN116418, NTNU-VM66568, NTNU-VM66570, NTNU-VM66571, NTNU-VM66572, NTNU-VM68195, NTNU-VM72560, NTNU-VM72561, NTNU-VM72562, NTNU-VM72563); Skagerrak (GNM15136, GNM14632, GNM14638).
Holotype. Complete specimen, 50.0 mm long and 5.0 mm width (Figs
Complete individuals 12.0–50.0 mm in length (Fig.
Terebellides kongsrudi sp. nov. (species 13; paratypes,
All sequences of T. kongsrudi sp. nov. share the unique apomorphic nucleotides in positions 300 (G) and 624 (G) of our alignement.
Terebellides kongsrudi sp. nov. (species 13; paratype,
Skagerrak; 429–445 m deep (Fig.
Barents Sea, Greenland Sea, along the Norwegian coast and shelf, reaching the Skagerrak to the South; 108–534 m deep (
This species is named after Dr. Jon Anders Kongsrud, Department of Natural History, Zoological Museum Bergen–ZMB (Norway), housing institution of some of the specimens used in the present study, for his dedication to the study of Norwegian polychaetes and his friendship.
This is a large species reaching up to 50.0 mm long, and is characterised by the presence of ciliated papilla dorsal to thoracic notopodia, lack of papillae on the margins of branchial lamellae, thoracic uncini of type 3 and abdominal uncini of type 1. These features are also shared by species 12 (sensu
Finally, in the 26 sequences belonging to this species (see Suppl. material
Species 12 –
4 specimens. Skagerrak.
This species will be described elsewhere by D. Gaeva and I. Jirkov (pers. comm.). In order to confirm characters here used to link species within each subgroup, two specimens were examined under the SEM that share with subgroup A1 the following features: branchiae type 1 sensu
Terebellides sp. 1 (species 12;
Molecular analyses of mitochondrial and nuclear markers recovered a strongly supported subgroup A2 (Fig.
None (Table
Several species described by
Terebellides gentili does not fit morphologically within any clade defined here because of having numerous marginal branchial lamellae that reach the posterior end of dorsal lobes, the dorsal lobes are longer and reach TC5(TC6) instead of TC3(TC4), and TC3 has a distinct whitish glandular region with a well-defined central white line. On the contrary, T. lilasae was found within subgroup A2 according to molecular-based analyses (Fig.
Terebellides europaea
Species 6 – T. stroemii (non Sars, 1835).
31 specimens: Norwegian coast and shelf (GNM14625, GNM14628, GNM15107, GNM15114, GNM15115, GNM15116, GNM15120, GNM15121, GNM15122, GNM15123, GNM15124, GNM15125, GNM15126, GNM15127, GNM15128, ZMBN116334, ZMBN116335, ZMBN116343, ZMBN116344, ZMBN116346, ZMBN116347); Irish Sea (ZMBN116336, ZMBN116337, ZMBN116338, ZMBN116339, ZMBN116340, ZMBN116341, ZMBN116342).
MG025072, MG025073, MG025074, MG025075, MG025076, MG025077, MG025078, MG025079, MG025080, MG025081, MG025082, MG025083, MG025084, MG025085, MG025086, MG025087, MG025088, MG025089, MG025090, MG025091, MG025092, MG025093, MG025094, MG025095, MG025096, MG025097, MG025098, MG025099, MG025100, MG025101, MG025102, MG025103, MG025104. Paratypes (not examined): MN207179, MN207181. Additional sequences (material not examined): MN207180, MN207182.
Complete individuals ranging from 17.0–46.0 mm in length and 2.0–5.0 mm in width (Fig.
STM photographs of live specimens of several Terebellides species in lateral view. A Terebellides europaea Lavesque, Hutchings, Daffe, Nygren & Londoño-Mesa, 2019 (
All sequences belonging to T. europaea share the unique apomorphic nucleotide in position 240 (C) of the alignement.
Terebellides europaea Lavesque, Hutchings, Daffe, Nygren & Londoño-Mesa, 2019 (species 6; non-type specimens, GNM15116 and GNM15118), SEM micrographs. A anterior end, right lateral view B buccal tentacles and branchiae, left lateral view C branchial lamellae, detail. Abbreviations: bdl – branchial dorsal lobe; bdltp – branchial dorsal lobe terminal papilla; blp – branchial lamellae papillae; bst – branchial stem; bt – buccal tentacles; bvltp – branchial terminal lobe terminal papilla; cr – ciliary row; dpn – dorsal projection of notopodium; gc – geniculate chaetae; gr – glandular region; loli – lower lip; SG – segment; TC – thoracic chaetiger; tll – thoracic lateral lobes.
Bay of Brest (Brittany, France) (
SEM images, Terebellides europaea Lavesque, Hutchings, Daffe, Nygren & Londoño-Mesa, 2019 (species 6; non-type specimen, GNM15116). A TC1 to TC4, lateral view B TC6 (TU1), geniculate chaetae C thoracic double row of uncini D thoracic uncinus, capitium, upper view E abdominal uncini F epibiont ciliate (position pointed by arrowhead) attached near TC5 nephridial papilla. Abbreviations: cap – capitium; dpn – dorsal projection of notopodium; ros – rostrum; TC – thoracic chaetiger.
Bay of Biscay (
This species is characterised by the combination of the following features: presence of papillary projections over the edge of the anterior border of dorsal branchial lamellae, lack of ciliated papilla dorsal to thoracic notopodia, thoracic uncini of type 3 and abdominal uncini of type 2. The original description states that body length is less than 17 mm, but maximal length of specimens examined here was up to 46.0 mm. Examination of live and preserved specimens has revealed that the size ratio between the ventral and dorsal branchial lobes is similar in all specimens; however, their arrangement differs among specimens, i.e., the ventral lobes are visible in some while in others are hidden behind the dorsal lobes.
Terebellides europaea was misidentified as T. stroemii by
In the 37 sequences analysed attributed to this species (see Suppl. material
Species 7 –
Type material. Holotype: ZMBN116357. Paratypes (8 specs): Norwegian coast (
Holotype. Complete specimen, 19.0 mm long and 2.0 mm width (Figs
Complete individuals ranging from 12.0–35.0 mm in length and 1.5–3.0 mm in width (Fig.
All sequences of T. ronningae sp. nov. share the unique apomorphic nucleotides in positions 129 (G), 399 (G) and 435 (G).
Norwegian coast and shelf, Skagerrak; 25–188 m deep (
This species is named after Dr. Ann-Helén Rønning, Head Engineer of the Department of Technical and Scientific Conservation, Natural History Museum–NHMO (Oslo), for her help and friendship.
Terebellides ronningae sp. nov. is characterised by the lack of ciliated papilla dorsal to thoracic notopodia and the presence of papillary projections pointing over the edge of the dorsal anterior border of branchial lamellae, thoracic uncini of type 1 and abdominal of type 2 (Table
Specimens examined with SEM bear thoracic uncini with rostrum bendings (Fig.
Twelve sequences (see Suppl. material
Species 8 –
Type material. Holotype: ZMBN116378. Paratypes (36 specs): Barents Sea (ZMBN11636, ZMBN116365, ZMBN116366, ZMBN116367); Norwegian coast (GNM146323, NTNU-VM61388, NTNU-VM61389, NTNU-VM61390, NTNU-VM66569, NTNU-VM66573, NTNU-VM66574, NTNU-VM68197, NTNU-VM68198, ZMBN116362, ZMBN116363, ZMBN116368, ZMBN116369, ZMBN116370, ZMBN116371, ZMBN116372, ZMBN116373, ZMBN116374, ZMBN116375, ZMBN116376, ZMBN116377, ZMBN116379, ZMBN116380, ZMBN116381, ZMBN116382, ZMBN116383, ZMBN116384); Skagerrak (GNM14637, GNM15131, GNM15232, GNM15134, ZMBN116361).
Holotype. Complete specimen, 19.0 mm long and 1.5 mm wide (Figs
Line drawings of several Terebellides species. A Terebellides europaea Lavesque, Hutchings, Daffe, Nygren & Londoño-Mesa, 2019 (species 6; non-type specimen, GNM14628), anterior end, left lateral view B Terebellides ronningae sp. nov. (species 7; holotype, ZMBN116357), anterior end, left lateral view C Terebellides norvegica sp. nov. (species 8; holotype, ZMBN416378), anterior end, right lateral view D Terebellides scotica sp. nov. (species 9; holotype, ZMBN116385), anterior end, left lateral view. Abbreviations: bdl – branchial dorsal lobe; bvl – branchial ventral lobe; TC – thoracic chaetiger.
Holotype: MG025148. Paratypes: MG025119, MG025120, MG025122, MG025124, MG025126, MG025127, MG025128, MG025129, MG025131, MG025132, MG025134, MG025135, MG025136, MG025137, MG025138, MG025139, MG025140, MG025141, MG025142, MG025143, MG025144, MG025145, MG025146, MG025147, MG025149, MG025151, MG025152, MG025153, MG025154, MG025155, MG025156. Additional material: MG025117, MG025118, MG025121, MG025123, MG025125, MG025130, MG025133, MG025150.
Terebellides ronningae sp. nov. (species 7; paratypes,
Terebellides ronningae sp. nov. (species 7; paratypes,
Complete individuals ranging from 20.0–50.0 mm in length and 1.2–5.0 mm in width (Fig.
Terebellides norvegica sp. nov. (species 8; paratypes, GNM15130 and GNM15134), SEM micrographs. A anterior end, left lateral view B branchial lobes, ventral view C anterior dorsal branchial lamellae and papillae D TC4 to TC6, lateral view. Abbreviations: abl – anterior branchial lobe; bdl – branchial dorsal lobe; bdlfl – branchial dorsal lobes fusion line; bdltp – branchial dorsal lobe terminal papilla; blp – branchial lamellae papillae; bt – buccal tentacles; dpn – dorsal projection of notopodium; gc – geniculate chaetae; gr – glandular region; loli – lower lip; np – nephridial papilla; TC – thoracic chaetiger; tll – thoracic lateral lappets.
All sequences of T. norvegica sp. nov. share the unique apomorphic nucleotides in positions 48 (C) and 285 (G) of the alignement.
Terebellides norvegica sp. nov. (species 8; paratypes, GNM15130 and GNM15134), SEM micrographs. A TC6 (TU1), geniculate chaetae B detail of geniculate chaeta, arrow pointing to capitium (framed in A) C simple row of uncini D thoracic uncinus, capitium E abdominal uncini F ciliate epibionts. Abbreviations: ctr1 – first row of capitium teeth.
Rogaland (Norway); at depths of between 226 and 242 m (Fig.
Barents Sea, Norwegian coast, Skagerrak; 190–1,268 m deep (
The name of the new species refers to the country where members of this lineage were found, along the Norwegian coast from the Barents Sea to the Skagerrak Strait.
Terebellides norvegica sp. nov. is characterised by the presence of marginal papillae in the anterior region of branchial dorsal lamellae, thoracic uncini of type 3 and abdominal uncini of type 2, and by lacking ciliated papilla dorsal to thoracic notopodia (Table
On the other hand, the internal anatomy of T. norvegica sp. nov. has been examined by transparency in one alive specimen (Fig.
Forty sequences (see Suppl. material
Species 9 –
Type material. Holotype: ZMBN116385. Paratypes (3 specs), North Sea (
Holotype
. Complete specimen, 45.0 mm long and 4.5 mm width (Fig.
Complete individuals ranging from 6.0–45.0 mm in length and 1.0–4.0 mm in width (Figs
Terebellides scotica sp. nov. (species 9; paratype,
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
Terebellides scotica sp. nov. (species 9; paratype,
East Orkney Island; 85 m deep (Fig.
North Sea; 48–111 m deep (
This new species is named after Scotland, since its type locality is in the Scottish Orkneys Islands.
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.
Two different sequences (see Suppl. material
Analyses of molecular data recovered a strongly supported subgroup A3 (Figs
Terebellides bigeniculatus Parapar, Moreira & Helgason, 2011: 6–10, figs 1b, 4–7.
Species 20 + 28
Off North West Iceland; 333 m deep (
6 specimens: Barents Sea (
T. bigeniculatus: Holotype (IIH 24923) and 5 paratypes (IINH 24925) (Suppl. material
Complete individuals ranging from 10.0–24.0 mm in length. Branchiae clearly fitting with type 1 only in some specimens, irregular in others; dorsal lobes lamellae not provided with papillary projections. Lateral lappets from TC1-TC5 and well-marked dorsal projection of notopodia in TC3 (Figs
Terebellides bigeniculatus Parapar, Moreira & Helgason, 2011 (species 20 + 28; non-type specimens,
Material examined herein corresponds to a few small and incomplete specimens. Therefore, the list of diagnostic characters given was developed with the aid of the type specimens re-examined and the original description.
All sequences of T. bigeniculatus share the unique apomorphic nucleotides in positions 67 (G) and 138 (G) of the alignement.
Around Iceland at both sides of the GIF Ridge; 179–968 m deep (
In some of the species delimitation analyses performed,
As stated above, the sequenced specimens are small and not well preserved, hindering the examination of relevant morphological features with taxonomic value (i.e., branchial type). However, this species is characterised by having geniculate chaetae on TC5 and TC6 instead of only on one chaetiger (
The original description states that nephridial papillae are located on TC3–TC4 or TC4–TC5 (Suppl. material
Members of species 21 (see below, as Terebellides sp. 2) also bear geniculate chaetae in two chaetigers; this feature had been considered as unique to T. bigeniculatus regarding other NEA species. However, species 21 is present in Arctic waters (cf.
Species 21
4 specimens: Barents Sea.
As explained for Terebellides sp. 1, two specimens were examined under SEM; these share with T. bigeniculatus the irregular shape of branchial lobes (Fig.
Terebellides sp. 2 (species 21;
On the other hand, species 18 and 19 of A1 (not described here because of the few specimens being available) and 23 (A4) have a geographic distribution similar to that of T. bigeniculatus but their position in the cladogram by
There are no unique diagnostic nucleotide positions that are shared by the two haplotypes (in 18 sequences) in COI. Eighteen sequences, in one single haplotype, have been attributed to this species (
The following key of European Terebellides species is based on
1 | Geniculate chaetae on TC5 and TC6 |
(subgroup A3) T. bigeniculatus Parapar, Moreira & Helgason, 2011 |
– | Geniculate chaetae on TC6 only | 2 |
2 | Branchial lamellae margins lacking papillae |
3 |
– | Branchial lamellae margins with papillae | 11 |
3 | Lower branchial lobes with long posterior projections as filaments | 4 |
– | Lower branchial lobes with short posterior projections | 5 |
4 | Glandular region on TC3 present; branchial lamellae pointed; notochaetae from TC1 longer than following ones; dorsal papillae absent | T. parapari Lavesque, Hutchings, Daffe, Nygren & Londoño-Mesa, 2019 |
– | Glandular region on TC3 absent; branchial lamellae rounded; all notochaetae equal-sized; dorsal papillae present | T. shetlandica Parapar, Moreira & O’Reilly, 2016 |
5 | Ventral white band present on TC4 after MG staining | 6 |
– | No distinct pattern on TC4 after MG staining | 7 |
6 | Large species (>30 mm in length); 5th branchial lobe present; notochaetae of TC1 similar to following ones; main fang of thoracic uncini straight | T. gracilis Malm, 1874 |
– | Small species (<20 mm in length); 5th branchial lobe absent; notochaetae of TC1 absent or shorter than following ones; main fang of thoracic uncini ‘eagle head’-shaped | T. ceneresi Lavesque, Hutchings, Daffe, Nygren & Londoño-Mesa, 2019 |
7 | First notopodia and notochaetae longer than following ones | T. mediterranea Parapar, Mikac & Fiege, 2013 |
– | First notopodia and notochaetae similar or shorter than following ones | 8 |
8 | Large-sized species (>50 mm); dorsal rounded projections on TC1–TC5 conspicuous | (subgroup A1) 9 |
– | Small-sized species (<20 mm); dorsal rounded projections on TC1–TC5 absent; main fang of thoracic uncini straight | 10 |
9 | Abdominal uncini type 1 |
T. kongsrudi sp. nov. and T. bakkeni sp. nov. |
– | Abdominal uncini type 2 |
T. stroemii Sars, 1835 |
10 | 5th branchial lobe absent | T. atlantis Williams, 1984 |
– | 5th lobe present | T. gralli Lavesque, Hutchings, Daffe, Nygren & Londoño-Mesa, 2019 |
11 | Glandular region on TC3 round or oval | 12 |
– | Glandular region on TC3 otherwise | 13 |
12 | Glandular region on TC3 stained white; branchial lamellae with rounded papillae; TC1–3 without conspicuous dorsal projection | T. lilasae Lavesque, Hutchings, Daffe, Nygren & Londoño-Mesa, 2019 |
– | Glandular region on TC3 stained blue; branchial lamellae with conical papillae; TC1–3 with conspicuous dorsal projection | T. bonifi Lavesque, Hutchings, Daffe, Nygren & Londoño-Mesa, 2019 |
13 | Most branchial lamellae with marginal papillae; upper lip elongated | T. resomari Lavesque, Hutchings, Daffe, Nygren & Londoño-Mesa, 2019 |
– | Only anterior branchial lamellae with marginal papillae; upper lip not elongated | (subgroup A2) 14 |
14 | Thoracic uncini type 1 |
T. ronningae sp. nov. |
– | Thoracic uncini type 3 |
15 |
15 | Deep-water species; mostly below 200 m deep | T. norvegica sp. nov. |
– | Shallow-water species; mostly above 100 m deep | 16 |
16 | Present from Southern Norway to NW Iberian Peninsula | T. europaea Lavesque, Hutchings, Daffe, Nygren & Londoño-Mesa, 2019 |
– | Present in the Shetland and Orkneys Islands and in Brittany | T. scotica sp. nov. |
The comprehensive study by
Within Group A, three subgroups (A1–A3) can be defined based on molecular data, being only A2 and A3 well supported and congruent among all molecular analyses and datasets (Figs
The characters considered to delineate morphologically the aforementioned subgroups (A1–A3) should be taken with care because there are limitations due to number of specimens available to be studied and their condition of preservation. However, considering the variety and origin of the material examined we were able to elucidate some general patterns on taxonomy and distribution of the studied species. Thus, all studied species seem quite homogeneous in terms of general body features and share many characters; however, presence/absence of some macroscopic/microscopic characters has allowed their organization in the subgroups proposed above. Nevertheless, some species could not be differentiated according to morphological characters but genetic data. On the other hand, geographic distributions of species do not show apparent gaps; some species have a wider distribution and were more frequent in samples such as T. norvegica sp. nov. and T. kongsrudi sp. nov.; this suggests that many previous reports of T. stroemii in NEA might correspond to the aforementioned species. Other species apparently show a more restricted distribution, i.e., T. bakkeni sp. nov. in northern Norway or have their limit of distribution in southern Norway, as T. europaea. Similarly, there are no gaps in the bathymetric distribution of species, but some seem to appear typically at shallow depths, reaching the continental shelf (0–200 m) such as T. europaea, T. ronningae sp. nov. and T. scotica sp. nov. On the contrary, T. bigeniculatus and T. norvegica sp. nov. are found at depths of below 200 m while T. stroemii, T. bakkeni sp. nov. and T. kongsrudi sp. nov. show a wider bathymetric distribution.
Given the morphological homogeneity, DNA sequences have been shown to provide advantageous data and support when it comes to species delineation in Terebellides. The most informative markers in previous studies are COI and ITS (
The first five species were already discussed above. Regarding the remaining three species, only T. ceneresi was sequenced by
Terebellides parapari differs from Group A species in the shape and arrangement of branchial lobes that are free from each other, and by the presence of terminal filament in ventral lobes. These features and its short body length relate T. parapari to T. shetlandica and Group B sensu
This study has revealed that some of the traditionally morphological-based taxonomic characters are not appropriate for Terebellides species identification. The number of species in the genus is now large and their morphological homogeneity high. Regarding Group A, two macroscopic characters have, however, been useful: 1) presence of geniculate chaetae in one or two chaetigers (A1+A2 vs A3), 2) presence of papillary projections in the border of branchial lamellae (A2 vs A1+A3). On the contrary, we found that the development of lateral lappets and the presence of a dorsal projection on the anterior thoracic notopodia seem dependent on size/age and preservation, and therefore these characters should be taken with care for species identification. Similarly, the species in Group A seem quite homogeneous when considering branchial morphology, particularly within A1 and A2. Some of the morphological differences observed between Terebellides species rely in the exposure of the ventral lobes (hidden or not behind the dorsal lobes). However, we have also observed some degree of variability between specimens belonging to the same species and could be due to size or the contraction of specimens after fixation.
Morphology of thoracic and abdominal uncini seems useful for species identification; such features need to be examined under SEM and are being considered in descriptions of Terebellides in the last years. Recently,
Capitium of ca. 0.7 of total length of rostrum (RvC = 1/0.7); capitium simple, composed of a few wide denticles, being 3(5) in first row and 1(2) in a second row (Fig.
SEM micrographs of abdominal uncini types of Terebellides species. A T. kongsrudi sp. nov. (species 13;
Capitium of almost same length as rostrum (RvC = 1/0.9); capitium much complex than in Type 1, composed of a first row of 4(5) denticles and a variable number of teeth in two more rows with decreasing number and size posterior to them (Fig.
On the other hand, we observed differences in whether the capitium is defined or not in geniculate chaetae of TC5/TC6, as previously highlighted by
The MG staining pattern was mostly similar across the studied species and according to type 1 sensu
To sum up all results and according to the discussion of the aforementioned characters, the general characteristics for each subgroup of Group A sensu
Species are similar morphologically and differ from A2 in lacking papillae on branchial lamellae and in having ciliated papillae on thoracic notopodia. Regarding morphology and distribution, T. bakkeni sp. nov. and T. kongsrudi sp. nov. are closest to each other than to T. stroemii. Terebellides stroemii (as species 11 here) shows also a similar geographic and bathymetric distribution (Table
The subgroup is morphologically homogeneous. It differs from A1 in having lamellae papillae and by the lack of thoracic ciliated papillae (at least not observed with SEM). The most recognisable species is T. ronningae sp. nov. because of having thoracic uncini of type 1, a long rostrum and a capitium provided with long first row teeth; the other three species bear thoracic uncini of type 3 and differ of each other in the geographic (T. europaea, T. scotica sp. nov.) and bathymetric distribution (T. norvegica sp. nov.).
This subgroup is composed by T. bigeniculatus (species 20 + 28) and species 21 (not formally described here). Branchial shape is irregular and geniculate chaetae are present in two thoracic chaetigers (TC5 and TC6). Other features are shared with A1 such as lack of lamellae papillae; thoracic uncini type 3 or presence of thoracic ciliated papillae. The bathymetric distribution of species is similar to A1.
We would like to thank all people involved in
This study was partly supported by the FAUNA IBÉRICA research project Polychaeta VII, Palpata, Canalipalpata II (PGC2018–095851–B–C64) funded by the Agencia Estatal de Investigación, Ministerio de Ciencia e Innovación, and coordinated by JP. Funding was also provided from the Ramón y Cajal program (RYC-2016- 20799) funded by Spanish MINECO, Agencia Estatal de Investigación, Comunidad Autónoma de las Islas Baleares and the European Social Fund to MC. Financial support was also provided by the Norwegian Taxonomy Initiative (Cryptic polychaete species in Norwegian waters, knr 49-13, project no. 70184228 to AN; Polychaetes in the Norwegian Sea, project no. 70184227; Polychaetes in Skagerrak, project no.70184216; and the MAREANO program.
Authors deeply thank Pat Hutchings and one anonymous reviewer as well as Chris Glasby, Zookeys Subject Editor, for their constructive comments on the manuscript.
Table S1. Locality and collecting data, museum registration numbers and references to figures of Terebellides specimens
Data type: occurences
Explanation note: Locality and collecting data, museum registration numbers and references to figures of Terebellides specimens described in this work. Country names are transcribed from original museum vials.
Table S2. List of COI sequences considered in present study (Group A), museum vouchers and GenBank accession numbers
Data type: COI sequences, museum vouchers and GenBank accession numbers
Explanation note: List of COI sequences considered in present study (Group A), museum vouchers and GenBank accession numbers. Abbreviations of housing institutions: ZMBN = Department of Natural History, University Museum of Bergen; GNM = The Gothenburg Museum of Natural History; NTNU-VM = Norwegian University of Science and Technology, University Museum, Trondheim; SMF = Senckenberg Museum Frankfurt.