Research Article |
Corresponding author: Deborah Wall-Palmer ( dmwallpalmer@gmail.com ) Academic editor: Eike Neubert
© 2019 Deborah Wall-Palmer, Mona Hegmann, Erica Goetze, Katja T. C. A. Peijnenburg.
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:
Wall-Palmer D, Hegmann M, Goetze E, Peijnenburg KTCA (2019) Resolving species boundaries in the Atlanta brunnea species group (Gastropoda, Pterotracheoidea). ZooKeys 899: 59-84. https://doi.org/10.3897/zookeys.899.38892
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Atlantid heteropods are a family of holoplanktonic marine gastropods that occur primarily in tropical and subtropical latitudes. Atlantids bear a delicate aragonitic shell (<14 mm) and live in the upper ocean, where ocean acidification and ocean warming have a pronounced effect. Therefore, atlantids are likely to be sensitive to these ocean changes. However, we lack sufficiently detailed information on atlantid taxonomy and biogeography, which is needed to gain a deeper understanding of the consequences of a changing ocean. To date, atlantid taxonomy has mainly relied on morphometrics and shell ornamentation, but recent molecular work has highlighted hidden diversity. This study uses an integrated approach in a global analysis of biogeography, variation in shell morphology and molecular phylogenies based on three genes (CO1, 28S and 18S) to resolve the species boundaries within the Atlanta brunnea group. Results identify a new species, Atlanta vanderspoeli, from the Equatorial and South Pacific Ocean, and suggest that individuals of A. brunnea living in the Atlantic Ocean are an incipient species. Our results provide an important advance in atlantid taxonomy and will enable identification of these species in future studies of living and fossil plankton.
Atlantidae, biogeography, phylogenetic analysis, shell morphology, South Pacific Ocean
The heteropods (Pterotracheoidea) are a superfamily of marine gastropods (Order Littorinimorpha) consisting of three families: Pterotracheidae, Carinariidae and Atlantidae (
To date, the taxonomy of atlantid heteropods has mainly relied on morphometrics and shell ornamentation, even though it is hard to tell some species apart only by use of morphological characteristics (
Based on morphological characters (shell, eye type, radula, operculum), atlantid heteropods are divided into groups of closely related species (
A total of 22 A. brunnea, 14 A. vanderspoeli (based on the descriptions of
Collection information for specimens examined in this study, with inclusion into each type of analysis as indicated at right. Specimens used for the combined gene phylogeny are indicated with +.
Species | BOLD/GenBank accession number | Museum accession number | Ocean | Cruise | Station | Biogeography Latitude/Longitude | Morphological analysis | Molecular analysis | ||
---|---|---|---|---|---|---|---|---|---|---|
CO1 | 28S | 18S | ||||||||
Atlanta brunnea | AGD001-17 | RMNH.MOL.341299 | Atlantic | AMT24 | 05 | 34.75, -26.62 | ✓ | ✓ | ✓ | |
ATCP003-19 | RMNH.MOL.341308 | Atlantic | AMT27 | 09 | 35.30, -26.28 | ✓ | ✓ | ✓ | ||
ATCP008-19 | RMNH.MOL.341314 | Atlantic | AMT27 | 11 | 32.87, -26.91 | ✓ | ✓ | ✓ | ✓ | |
ATCP009-19 | RMNH.MOL.341315 | Atlantic | AMT27 | 11 | 32.87, -26.91 | ✓ | ✓+ | ✓+ | ✓+ | |
ATCP010-19 | RMNH.MOL.341316 | Atlantic | AMT27 | 11 | 32.87, -26.91 | ✓+ | ✓+ | ✓+ | ||
ATCP004-19 | RMNH.MOL.341309 | Atlantic | AMT27 | 37 | -6.87, -25.04 | ✓ | ||||
ATCP006-19 | RMNH.MOL.341311 | Atlantic | AMT27 | 41 | -12.63, -25.05 | ✓ | ✓ | |||
ATCP007-19 | RMNH.MOL.341312 | Atlantic | AMT27 | 47 | -24.01, -25.05 | ✓+ | ✓+ | ✓+ | ||
ATCP011-19 | RMNH.MOL.341317 | Atlantic | AMT27 | 47 | -24.01, -25.05 | ✓+ | ✓+ | ✓+ | ||
AGD008-17 | RMNH.MOL.341304 | Indian | SN105 | 04 | 8.02, 67.08 | ✓+ | ✓+ | ✓+ | ||
AGD009-17 | RMNH.MOL.341305 | Indian | SN105 | 04 | 8.02, 67.08 | ✓ | ||||
AGD010-17 | RMNH.MOL.341300 | Indian | SN105 | 08 | 4.38, 67.00 | ✓ | ||||
AGD011-17 | RMNH.MOL.341301 | Indian | SN105 | 08 | 4.38, 67.00 | ✓+ | ✓+ | ✓+ | ||
AGD012-17 | RMNH.MOL.341302 | Indian | SN105 | 08 | 4.38, 67.00 | ✓ | ||||
AGD013-17 | RMNH.MOL.341303 | Indian | SN105 | 08 | 4.38, 67.00 | ✓ | ||||
– | – | Indian | SN105 | 08 | 4.38, 67.00 | ✓ | ||||
AGD002-17 | RMNH.MOL.341313 | Pacific | KH1110 | 05 | -23.00, 180.01 | ✓ | ✓ | |||
ATCP001-19 | RMNH.MOL.341306 | Pacific | KOK1703 | 07 | 23.62, -157.61 | ✓ | ✓ | |||
ATCP002-19 | RMNH.MOL.341307 | Pacific | KOK1703 | 07 | 23.62, -157.61 | ✓ | ✓ | |||
ATCP005-19 | RMNH.MOL.341310 | Pacific | SO255 | 100 | -28.52, 179.59 | ✓ | ✓ | |||
– | NHMD-232129 | Pacific | DANA | 3556 VIII | 2.87, -87.63 | ✓ | ||||
– | NHMD-232129 | Pacific | DANA | 3556 VIII | 2.87, -87.63 | ✓ | ||||
Atlanta vanderspoeli | AGD003-17 | RMNH.MOL.341320 | Pacific | KH1110 | 15 | -23.00, -119.27 | ✓ | |||
AGD004-17 | RMNH.MOL.341321 | Pacific | KH1110 | 15 | -23.00, -119.27 | ✓ | ✓ | ✓ | ||
AGD005-17 | RMNH.MOL.341322 | Pacific | KH1110 | 15 | -23.00, -119.27 | ✓ | ✓ | ✓ | ||
AGD006-17 | RMNH.MOL.341323 | Pacific | KH1110 | 21 | -23.00, -100.00 | ✓ | ✓ | |||
ATCP013-19 | RMNH.MOL.341324 | Pacific | KH1110 | 21 | -23.00, -100.00 | ✓ | ✓ | |||
AGD007-17 | RMNH.MOL.341325 | Pacific | KH1110 | 21 | -23.00, -100.00 | ✓ | ✓ | ✓ | ||
ATCP012-19 | RMNH.MOL.341319 | Pacific | SO255 | 057 | -29.95, -178.73 | ✓ | ✓ | |||
ATCP014-19 | RMNH.MOL.341326 | Pacific | SO255 | 057 | -29.95, -178.73 | ✓ | ||||
– | – | Pacific | SO255 | 073 | -28.13, 179.02 | ✓ | ||||
ATCP015-19 | RMNH.MOL.341327 | Pacific | SO255 | 073 | -28.13, 179.02 | ✓ | ✓+ | ✓+ | ✓+ | |
ATCP016-19 | RMNH.MOL.341328 | Pacific | SO255 | 080 | -29.10, -179.72 | ✓ | ✓+ | ✓+ | ✓+ | |
ATCP017-19 | RMNH.MOL.341329 | Pacific | SO255 | 080 | -29.10, -179.72 | ✓ | ✓ | |||
– | NHMD-232153 | Pacific | DANA | 3613 V | -22.72, 166.10 | ✓ | ||||
– | NHMD-232154 | Pacific | DANA | 3620 IV | -24.78, 170.31 | ✓ | ||||
Atlanta helicinoidea | ATCP052-19 | RMNH.MOL.341459 | Pacific | KOK1703 | 06 | 23.52, -156.78 | ✓+ | ✓+ | ✓+ | |
ATCP049-19 | RMNH.MOL.341456 | Pacific | KOK1703 | 08 | 23.62, -157.61 | ✓+ | ✓+ | ✓+ | ||
ATCP047-19 | RMNH.MOL.341454 | Pacific | KOK1703 | 08 | 23.62, -157.61 | ✓+ | ✓+ | ✓+ | ||
Atlanta turriculata | AGD372-17 | RMNH.MOL.341775 | Indian | SN105 | 01 | 11.89, 66.97 | ✓ | |||
AGD367-17 | RMNH.MOL.341779 | Indian | SN105 | 01 | 11.89, 66.97 | ✓ | ✓ | ✓ | ||
AGD368-17 | RMNH.MOL.341780 | Indian | SN105 | 01 | 11.89, 66.97 | ✓ | ||||
AGD369-17 | RMNH.MOL.341781 | Indian | SN105 | 01 | 11.89, 66.97 | ✓ | ||||
AGD370-17 | RMNH.MOL.341782 | Indian | SN105 | 01 | 11.89, 66.97 | ✓ | ||||
AGD371-17 | RMNH.MOL.341783 | Indian | SN105 | 01 | 11.89, 66.97 | ✓ | ||||
AGD376-17 | RMNH.MOL.341774 | Indian | SN105 | 04 | 8.02, 67.08 | ✓ | ||||
Atlanta turriculata | AGD375-17 | RMNH.MOL.341776 | Indian | SN105 | 04 | 8.02, 67.08 | ✓ | |||
AGD373-17 | RMNH.MOL.341784 | Indian | SN105 | 04 | 8.02, 67.08 | ✓+ | ✓+ | ✓+ | ||
AGD374-17 | RMNH.MOL.341785 | Indian | SN105 | 04 | 8.02, 67.08 | ✓ | ||||
AGD380-17 | RMNH.MOL.341769 | Indian | SN105 | 08 | 4.38, 67.00 | ✓ | ||||
AGD378-17 | RMNH.MOL.341777 | Indian | SN105 | 08 | 4.38, 67.00 | ✓ | ||||
AGD379-17 | RMNH.MOL.341778 | Indian | SN105 | 08 | 4.38, 67.00 | ✓ | ||||
AGD377-17 | RMNH.MOL.341786 | Indian | SN105 | 08 | 4.38, 67.00 | ✓ | ||||
ATCP123-19 | RMNH.MOL.341814 | Indian | SN105 | 08 | 4.38, 67.00 | ✓ | ✓ | ✓ | ✓ | |
AGD381-17 | RMNH.MOL.341770 | Indian | SN105 | 19 | -2.95, 66.99 | ✓+ | ✓+ | ✓+ | ||
AGD382-17 | RMNH.MOL.341771 | Indian | SN105 | 19 | -2.95, 66.99 | ✓ | ✓ | ✓ | ||
AGD383-17 | RMNH.MOL.341772 | Indian | SN105 | 19 | -2.95, 66.99 | ✓ | ||||
AGD384-17 | RMNH.MOL.341773 | Indian | SN105 | 19 | -2.95, 66.99 | ✓ | ||||
AGD363-17 | RMNH.MOL.341797 | Pacific | KH1110 | 05 | -23.00, 180.01 | ✓ | ✓ | ✓ | ||
AGD361-17 | RMNH.MOL.341801 | Pacific | KH1110 | 05 | -23.00, 180.01 | ✓ | ||||
AGD362-17 | RMNH.MOL.341802 | Pacific | KH1110 | 05 | -23.00, 180.01 | ✓ | ✓ | ✓ | ||
AGD365-17 | RMNH.MOL.341798 | Pacific | KH1110 | 08 | -22.79, -158.10 | ✓ | ||||
AGD364-17 | RMNH.MOL.341799 | Pacific | KH1110 | 08 | -22.79, -158.10 | ✓ | ||||
AGD366-17 | RMNH.MOL.341800 | Pacific | KH1110 | 08 | -22.79, -158.10 | ✓ | ||||
ATCP103-19 | RMNH.MOL.341788 | Pacific | KOK1703 | 01 | 22.91, -157.72 | ✓ | ✓ | ✓ | ||
ATCP112-19 | RMNH.MOL.341803 | Pacific | KOK1703 | 01 | 22.91, -157.72 | ✓ | ✓ | ✓ | ||
ATCP102-19 | RMNH.MOL.341787 | Pacific | KOK1703 | 03 | 22.65, -157.69 | ✓ | ✓ | |||
ATCP116-19 | RMNH.MOL.341807 | Pacific | KOK1703 | 03 | 22.65, -157.69 | ✓ | ✓ | ✓ | ||
ATCP118-19 | RMNH.MOL.341809 | Pacific | KOK1703 | 03 | 22.65, -157.69 | ✓ | ✓ | ✓ | ||
ATCP120-19 | RMNH.MOL.341811 | Pacific | KOK1703 | 03 | 22.65, -157.69 | ✓ | ✓+ | ✓+ | ✓+ | |
ATCP122-19 | RMNH.MOL.341813 | Pacific | KOK1703 | 03 | 22.65, -157.69 | ✓ | ✓ | |||
ATCP124-19 | RMNH.MOL.341815 | Pacific | KOK1703 | 03 | 22.65, -157.69 | ✓ | ✓ | ✓ | ||
ATCP104-19 | RMNH.MOL.341789 | Pacific | KOK1703 | 05 | 22.65, -157.69 | ✓ | ✓ | |||
ATCP125-19 | RMNH.MOL.341816 | Pacific | KOK1703 | 05 | 22.65, -157.69 | ✓ | ✓ | ✓ | ✓ | |
ATCP127-19 | RMNH.MOL.341818 | Pacific | KOK1703 | 05 | 22.65, -157.69 | ✓ | ✓ | ✓ | ✓ | |
ATCP129-19 | RMNH.MOL.341820 | Pacific | KOK1703 | 05 | 22.65, -157.69 | ✓ | ✓ | ✓ | ||
ATCP113-19 | RMNH.MOL.341804 | Pacific | KOK1703 | 06 | 23.52, -156.78 | ✓ | ✓ | |||
ATCP117-19 | RMNH.MOL.341808 | Pacific | KOK1703 | 06 | 23.52, -156.78 | ✓ | ✓ | ✓ | ✓ | |
ATCP119-19 | RMNH.MOL.341810 | Pacific | KOK1703 | 07 | 23.62, -157.61 | ✓ | ✓ | ✓ | ✓ | |
ATCP115-19 | RMNH.MOL.341806 | Pacific | KOK1703 | 08 | 23.62, -157.61 | ✓ | ✓ | ✓ | ||
ATCP121-19 | RMNH.MOL.341812 | Pacific | KOK1703 | 08 | 23.62, -157.61 | ✓ | ✓+ | ✓+ | ✓+ | |
ATCP105-19 | RMNH.MOL.341790 | Pacific | SO255 | 057 | -29.95, -178.73 | ✓ | ✓ | ✓ | ||
ATCP106-19 | RMNH.MOL.341791 | Pacific | SO255 | 073 | -28.13, 179.02 | ✓+ | ✓+ | ✓+ | ||
ATCP114-19 | RMNH.MOL.341805 | Pacific | SO255 | 073 | -28.13, 179.02 | ✓ | ✓ | |||
– | – | Pacific | SO255 | 073 | -28.13, 179.02 | ✓ | ||||
ATCP126-19 | RMNH.MOL.341817 | Pacific | SO255 | 073 | -28.13, 179.02 | ✓ | ✓+ | ✓+ | ✓+ | |
ATCP128-19 | RMNH.MOL.341819 | Pacific | SO255 | 073 | -28.13, 179.02 | ✓ | ✓ | ✓ | ✓ | |
ATCP107-19 | RMNH.MOL.341792 | Pacific | SO255 | 080 | -29.10, -179.72 | ✓ | ✓ | ✓ | ||
ATCP108-19 | RMNH.MOL.341793 | Pacific | SO255 | 080 | -29.10, -179.72 | ✓ | ✓ | ✓ | ||
ATCP109-19 | RMNH.MOL.341794 | Pacific | SO255 | 080 | -29.10, -179.72 | ✓ | ✓ | |||
ATCP110-19 | RMNH.MOL.341795 | Pacific | SO255 | 080 | -29.10, -179.72 | ✓ | ✓ | ✓ | ||
ATCP111-19 | RMNH.MOL.341796 | Pacific | SO255 | 100 | -28.52, 179.59 | ✓ | ||||
– | NHMD-232140 | Pacific | DANA | 3563 IV | -7.76, -131.37 | ✓ | ||||
– | NHMD-232145 | Pacific | DANA | 3586 VII | -9.72, -170.67 | ✓ |
Specimens were identified based on the species keys of
Due to the small size of atlantid shells it is difficult to orientate them in a reproducible way for reliable morphometric measurements. Therefore, micro-computed tomography (micro-CT) was used to generate 3D-models for a subset of specimens in order to create 2D-slices through the larval shell for reproducible morphological measurements. A total of five A. brunnea, seven A. vanderspoeli, and 19 A. turriculata were imaged using a SkyScan 1172 high resolution micro-CT scanner. In total 958 images were collected per specimen using the following parameters: no filter, medium resolution camera, an image pixel size of 1.31–2.23 µm, a source voltage of 57 kV, a source current of 177 µA and an exposure time 600–800 ms. The rotation pitch was 0.2°, with averaging frames of 4, and random movement of 10. The software Avizo 9.0 was used to generate a 3D-surface of each shell, and to make 2D-slices perpendicularly through the earliest part of the suture of the protoconch (Figure
Examples of shell parameters measured from 2D slices of micro-CT scans. Measurements include A apical angle B larval shell height C maximum larval shell width, and D maximum adult shell diameter. The position of the slice through the 3D model to create a 2D image is shown in E relative to the suture.
Scanning Electron Microscopy (SEM) images were also made on a subset of specimens to investigate the surface shell morphology and ornamentation for each clade. Two specimens of A. vanderspoeli and three specimens of A. turriculata were scanned using a JEOL JSM-7600F Field Emission SEM. For A. brunnea, images of two specimens from
DNA extraction was carried out on whole specimens using the NucleoMag 96 Tissue kit on a Thermo Scientific KingFisher Flex magnetic particle processor with a final elution volume of 75 µl. A ~920 bp fragment of the nuclear 18S rRNA gene was amplified using primers 18S-KP-F (
Sequences (forward and reverse strands) were assembled, aligned and verified in Geneious R8 and multiple sequence alignment was performed using MEGA-X (
The phylogenetic, morphological and biogeographical analyses produced a congruent result, distinguishing three species within the A. brunnea species group. This includes the two previously known species, A. brunnea and A. turriculata. In addition, the previously described A. brunnea form B, (
Phylogenetic analyses of CO1 (Figure
A Distribution maps showing the collection locations for each clade identified in B. The collection location of specimens of A. turriculata forma B identified by
Maximum likelihood phylogeny of the A. brunnea species group based on analysis of the combined genes CO1, 28S and 18S with a total alignment of 2447 bp. All four clades within the A. brunnea species group are monophyletic with strong bootstrap support. Bootstrap support (%) for nodes is displayed and branch lengths are proportional to the amount of inferred change, as indicated by the scale bar (mean number of nucleotide substitutions per site).
Genetic distances for CO1 support the position of A. vanderspoeli as a valid new species. Atlanta brunnea and A. vanderspoeli are separated by a CO1 genetic distance of 13–16% (Table
Mean values (in bold) and ranges for genetic distances among members of the A. brunnea species group, based on a 658 bp fragment of the mitochondrial cytochrome c oxidase subunit 1 gene calculated using a Kimura 2-parameter substitution model with uniform rates.
CO1 | A. brunnea Atlantic | A. brunnea Indian & Pacific | A. vanderspoeli Pacific | A. turriculata Indian & Pacific | A. helicinoidea Pacific |
A. brunnea Atlantic | 0 | ||||
0 | |||||
A. brunnea Indian & Pacific | 6 | 1 | |||
6–7 | 0–1 | ||||
A. vanderspoeli Pacific | 16 | 14 | 0 | ||
15 –16 | 13–15 | 0–1 | |||
A. turriculata Indian & Pacific | 2 | 19 | 19 | 0 | |
19–20 | 18–20 | 18–20 | 0–1 | ||
A. helicinoidea Pacific | 24 | 23 | 24 | 21 | 0 |
24–25 | 22–24 | 23–24 | 21–22 | 0 |
Within A. brunnea, the molecular data identify a further separation into two well supported geographic clades, one containing the Indian and Pacific Ocean population and one containing the Atlantic Ocean population (Figure
Principal Component Analysis (PCA) identifies the apical angle of the protoconch and the number of whorls in the larval shell as the most informative morphological characters to distinguish between A. brunnea, A. vanderspoeli, and A. turriculata (Figure
Principal Component Analysis (PCA) performed on apical angle, height: width ratio and the number of whorls in the larval shell. Species identity confirmed for most specimens (N = 25) using DNA barcoding (CO1). Two specimens of each species (total N = 6) derive from the DANA collection, and could not be DNA barcoded (formalin-fixed). Morphometric data are reported in Suppl. material
Ornamentation is limited in its use as an identifying feature for this species group, and the fine micro-ornamentation is only really visible with the use of SEM. All three species have a prominent ridge, or carina that runs slightly above mid-whorl height of the larval shell. The larval shell of A. brunnea is easily identified by the heavy zig-zag, and in places, net-like reticulate spiral lines covering the surface (Figure
Scanning Electron Microscopy (SEM) and stacked light microscopy images of representative specimens of A. brunnea: A, B DANA_3929VIII C SN105_08, A. vanderspoeli: D–E DANA_3558VII (Holotype, NHMD-232132) F KH1110_15 and A. turriculata: G, H DANA_3929VIII I SN105_19. Apical angle is the most useful morphological feature for distinguishing between the species (B–C, E–F, H–I). The shell of A. brunnea is always brown (C); however, the colour of A. vanderspoeli and A. turriculata shell and soft tissues (F, I) can vary and these are not reliable features for identification.
Data gathered in this study expand the known distribution of the A. brunnea group (
Atlanta turriculata was described by d’
Additional diversity within the A. brunnea species group has long been recognised, but, until now, this has not been thoroughly investigated.
Results of the phylogenetic analysis also highlight a probable incipient species. The morphospecies A. brunnea was found to have two genetically different populations, one in the Indian and Pacific Oceans, and one in the Atlantic Ocean. The genetic distance between the two populations is relatively small, but suggests that the populations of A. brunnea in the Atlantic Ocean must be isolated and becoming a new species. This result agrees with
Subclass Caenogastropoda Cox, 1960
Order Littorinimorpha Golikov & Starobogatov, 1975
Superfamily Pterotracheoidea Rafinesque, 1814
Family Atlantidae Rang, 1829
Genus Atlanta Lesueur, 1817
Atlanta turriculata
forma B –
Atlanta turriculata
forma B –
Atlanta brunnea
–
Atlanta brunnea
form B –
DANA expedition (1928–1930) station 3558VII, South Pacific 0.30S, 99.12W. Specimen collected on the 18h September 1928 at 19:00 from 200–300 m water depth.
Holotype. Figure
Paratypes. NHMD-232153. DANA_3613V, South Pacific 22.72S, 166.10E. Specimen collected on 28 April 1928 at 03:15 from 100–200 m water depth. Housed at the Natural History Museum of Denmark, Copenhagen. RMNH.MOL.342212. Type material of A. turriculata forma B (Figure
Atlanta species with a larval shell of 3 ¼ to 4 whorls. The larval shell is much higher than wide, conical with an apical angle of 35–46°. The larval shell has a prominent carina slightly above mid-whorl height. The whorls of the larval shell are further covered in a micro-ornamentation of interrupted spiral lines and small projections roughly arranged in spiral lines (approximately five lines in total) above this carina, and zig-zagged ornamentation below it (Figs
The shell is small and fresh specimens vary in colour from brown to pink-purple. The adult shell is on average 1000 μm in diameter without the keel (Suppl. material
The shape of the larval shell, shell size, colouration, operculum and eye type demonstrate that A. vanderspoeli belongs within the A. brunnea species group. This is supported by the molecular analysis presented within this study and by
All specimens were found in the equatorial and south Pacific Ocean from 0.80N to 29.95S, and from 127.28E to 100.00W (Figure
Named after Professor emeritus Siebrecht van der Spoel, who first noticed A. vanderspoeli, but described it only as A. turriculata forma B due to a lack of specimens (
The great Austral Ocean between 30 and 34S.
Holotype. We have been unable to locate any type material for A. turriculata (thought to have been deposited in
Neotype. RMNH.MOL.342213. SN105_08, Indian Ocean 4.38N, 67.00E. Specimen collected during the SN105 expedition of the ORV Sagar Nidhi, on the 10th December 2015 at 04:40 from 67 m water depth. Housed at the Naturalis Biodiversity Center, Leiden.
Two additional specimens have been deposited at the Natural History Museum, London. NHMUK20191155 and NHMUK20191156, from station KOK1703_06, Pacific Ocean 23.52N, 156.77W. Specimens collected during the KOK1703 expedition of the RV “Ka’Imikai-O-Kanaloa” on the 3rd September 2017 at 03:59 from 0–250 m water depth.
The holotype of Atlanta vanderspoeli is the property of the Natural History Museum of Denmark, Copenhagen. The neotype of Atlanta turriculata is the property of the Naturalis Biodiversity Center, Leiden. Both institutes maintain a research collection with proper facilities for preserving name-bearing types and these types are made accessible for study.
Using an integrated species concept, this study demonstrates that the A. brunnea group contains three valid species, A. brunnea, A. turriculata, and A. vanderspoeli sp. nov. A further incipient species that is restricted to the Atlantic Ocean should also be considered in future research, in particular during ecological or experimental studies. We hope that the integrated approach to species validation reported here will facilitate other workers in identifying A. vanderspoeli in their studies. Increased spatial coverage is now needed to fully understand the current distributions and environmental tolerances of this new species. Only with a larger and more complete dataset, including collection depths and concurrently collected environmental data, will it be possible to understand the responses of these atlantids to a changing ocean.
We are grateful to Atsushi Tsuda (University of Tokyo), Alice K. Burridge and Lisette Mekkes (Naturalis Biodiversity Center) for providing specimens and/or helping with specimen collection. We thank Arie W. Janssen and María Moreno-Alcántara for comments and suggestions on our manuscript, and particularly for help with the systematic section. We would also like to thank Yamell Kuen (University of Amsterdam) for sorting specimens from AMT27 material, Dirk van der Marel and Rob Langelaan for assistance with SEM and micro-CT and Tom Schiøtte and Martin Vinther Sørensen (Natural History Museum of Denmark, Copenhagen), Jeroen Goud and Bram van der Bijl (Naturalis Biodiversity Center, Leiden) and Andreia Salvador and Jon Todd (Natural History Museum, London) for facilitating access to collections in their care and for making specimens available to us. We would like to acknowledge the scientists and crew who took part in cruises AMT24, AMT27, DANA 1928–1930, KH1110, SN105, SO255, and KOK1703, and the Atlantic Meridional Transect (AMT) programme. The Atlantic Meridional Transect is funded by the UK Natural Environment Research Council through its National Capability Long-term Single Centre Science Programme, Climate Linked Atlantic Sector Science (grant number NE/R015953/1). This study contributes to the international IMBeR project and is contribution number 334 of the AMT programme. The SN105 expedition is part of IIOE-2 and was funded by the Indian National Centre for Ocean Information Services (INCOIS), Ministry of Earth Sciences, Govt. of India. The RV “Sonne”’ cruise SO255 was funded by the German Federal Ministry of Education and Research (BMBF; grant 03G0255A). This project has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No. 746186 (POSEIDoN, D.W-P.).
Figures S1–S3
Data type: multimedia
Explanation note: Figure S1. Maximum likelihood phylogeny of the A. brunnea group based on 28S. Figure S2. Maximum likelihood phylogeny of the A. brunnea group based on 18S. Figure S3. The original illustration of (A) Atlanta brunnea by
Table S1. Morphometric data for A. brunnea, A. vanderspoeli and A. turriculata
Data type: measurement
Atlanta vanderspoeli video clip
Data type: multimedia
Explanation note: Atlanta vanderspoeli specimen (male) collected during cruise SO255 station 80 at 29.10S, 179.72W.