Fig 1.
Live specimens of A) Terebellides williamsae (specimen 2181_2), in lateral view, with oocytes in the coelomic cavity and B) species 7 (specimen 2448_7), in lateral view. Abbreviations: ab (abdomen), bl (branchial lamellae), br (branchiae), bs (branchial stalk), bt (buccal tentacles), gc (geniculate chaetae), ll (lateral lappets), tr (thorax).
Fig 2.
Line drawings made from different Terebellides species showing main macroscopic body characters with taxonomic relevance.
A. Ventro-lateral view of T. gracilis or T. williamsae from Iceland showing most relevant taxonomic characters (e.g. position of anterior 1–5 thoracic chaetigers with whitish ventral colouration). B. Ventral view of branchiae in T. shetlandica from the Shetland Islands showing branchial stalk, size and shape of dorsal and ventral lobes, branchial lamellae, and branchial filaments. C. Left lateral view of anterior thoracic region of T. cf stroemii from Iceland showing lateral lappets in TC3 and TC4, position of geniculate chaetae in TC6 and enlarged glandular area in TC3. D. Detail of thoracic chaetigers TC5 to TC7 of T. atlantis from Iceland showing position of geniculate chaetae in TC6 and normal thoracic uncini in TC7. E. Detail of three geniculate chaetae. A, C, D, E redrawn from [11], B redrawn from [18]. Abbreviations: bf (branchial filament), bl (branchial lamellae), br (branchiae), bs (branchial stalk), dbl (dorsal branchial lobe), ga (glandular area), gc (geniculate chaetae), ll (lateral lappets), TC (thoracic chaetiger), tn (thoracic notopodium), tr (thorax), tu (thoracic uncini), vbl (ventral branchial lobe).
Fig 3.
Collecting sites, biogeographic regions, and type localities for Terebellides irinae (ir), T. atlantis (at), T. bigeniculatus (bi), T. shetlandica (sh), T. williamsae (wi), T. stroemii (st), and T. gracilis (gr) indicated with an arrow.
Type localities for T. irinae and T. atlantis are located outside the map's area. Biogeographic regions given by colours of samples (collecting sites) (see text for definitions): Kattegat (magenta); Skagerrak (dark green); North Sea (light green); Irish Sea, Celtic Sea (orange); Norwegian coast and shelf (red); Norwegian Sea (brown); Barents Sea (dark blue); Arctic Ocean (rose red); Greenland Sea (yellow); South of Iceland (light blue).
Fig 4.
Depth distribution for collecting sites, including number of sites and specimens for each biogeographic region.
Scale is logarithmic.
Table 1.
Locality and collecting data, including sample size, and species sampled.
Table 2.
Overview of sequence coverage for each genetic marker (COI, ITS2, 16S rDNA, 28S rDNA) and respective clade, as well as the combination of COI and ITS2 (used in the STACEY analysis), and the combination including specimens with at least three out of the four genetic markers (CONCAT).
Table 3.
Summary of haplotype and distance analyses for COI, with specification of excluded sequences, alignment length, number of haplotypes, and uncorrected intra- and interspecific distances.
Species number to which the species is compared with, for the minimum and maximum interspecific distances, in parentheses.
Table 4.
Summary of haplotype and distance analyses for ITS2, with specification of excluded sequences, alignment length, number of haplotypes, and uncorrected intra- and interspecific distances.
Species number to which the species is compared with, for the minimum and maximum interspecific distances, in parentheses.
Fig 5.
Results from the phylogenetic analyses, summarized on the ML estimate of the combined data set with xinsi-aligned ITS2-sequences including 91 terminals.
Specimens are named according to the extraction-number and the appended clade-number. The phylogenetic tree is arbitrarily divided into four colour-coded groups, A–D. These colours are used as background colour in the distribution and haplotype network figures (Figs 6–8). Specimens with at least three of the genetic markers were included in the phylogenetic analyses, outgroups are not shown. Pie diagrams indicate support values for the node, left pie shows results from ML analyses, and right pie diagram results from Bayesian analyses. Upper two slices of a pie illustrate results from the combined data sets' two different alignments, with xinsi-aligned ITS2-sequences to the left, and salsa-aligned ITS2-sequences to the right. The three remaining slices illustrate results from the combined mitochondrial data (lower left slice), and the combined nuclear data sets' two different alignments, where lower median slice has xinsi-aligned ITS2-sequences, and lower right slice has salsa-aligned ITS2-sequences. Yellow, blue and red colour indicate low, moderate and strong support, which equals ML support in the intervals 50–74, 75–89, and 90–100, or BI posterior probabilities in the intervals 0.50–0.84, 0.85–0.94 and 0.95–1.0 respectively. White means support <50/0.50 for the node. Columns show clustering of terminals according to different methodologies performed on more inclusive data sets where all specimens with COI or ITS2 data, or specimens with both COI and ITS2 data, were included. The first columns under the headings COI, ITSx and ITSs represent the results from TCS, and the second columns represent the results from GMYC. The columns under the heading STACEY show the two different outcomes from this analysis. White means that the network or species recovered is identical to the initial haplotype network found in COI including all COI-sequences, light grey means that less inclusive networks or putative species were recovered, and dark grey means that a more inclusive network or putative species was recovered. Double-headed arrows to the right of the columns show our final judgement of species delimitation. The two small letters to the right indicate our designation of described species, st = T. stroemii, bi = T. bigeniculatus, at = T. atlantis, sh = T. shetlandica, ir = T. irinae, wi = T. williamsae, and gr = T. gracilis.
Fig 6.
Distribution maps, depth distribution in meters, and haplotype networks for group A, species 10, 11, 18, 19, 23, 21, 12, 13, and 20/28. All species except for species 20/28 that we refer to T. bigeniculatus (bi) are undescribed. Sites are colour coded as in Fig 3. Type locality for T. bigeniculatus indicated with yellow arrow.
Fig 7.
Distribution maps, depth distribution in meters, and haplotype networks for group A, species 6, 7, 8, and 9, and for group B, species 1, 17, 14, 4, 26, and 27. All species except for species 6 that we refer to as T. stroemii (st), and clade 1 that we refer to as T. shetlandica (sh) are undescribed. Sites are colour coded as in Fig 3. Type localities for T. stroemii, and T. shetlandica indicated with yellow arrows.
Fig 8.
Distribution maps, depth distribution in meters, and haplotype networks for group B, species 5 and 16, group C, species 22, 24, and 25, and group D, species 2, 3, and 15. Species 5, 22, 25, and 15 are undescribed, while we refer species 16 to T. atlantis (at), species 24 to T. irinae (ir), species 2 to T. williamsae (wi), and species 3 to T. gracilis (gr). Sites are colour coded as in Fig 3. Type localities for T. atlantis, T. irinae, T. williamsae, and T. gracilis indicated with yellow arrows.
Fig 9.
Accumulation curve showing the relationship between sampling size (number of specimens) and number of species found among the different biogeographic regions.
Fig 10.
Diagram showing the distribution of different Terebellides species in the ten biogeographic regions.
Fig 11.
Overview of the diversity found in the ten biogeographic regions.
Pie diagrams show the relative proportions of the different species found where all species have their own colour, sampling size (N) indicated next to the pie diagrams.
Fig 12.
Pie diagrams from Fig 11 for the six best sampled biogeographic regions with bathymetric results in meters.
Species number next to its slice in the pie diagrams, species number in red when the species is a described species, where species 1 = T. shetlandica, species 2 = T. williamsae, species 3 = T. gracilis, species 6 = T. stroemii, species 16 = T. atlantis, and species 20/28 = T. bigeniculatus.