Contributions to Zoology, 85 (4) – 2016Deborah Wall-Palmer; Alice K. Burridge; Katja T.C.A. Peijnenburg; Arie Janssen; Erica Goetze; Richard Kirby; Malcolm B. Hart; Christopher W. Smart: Evidence for the validity of Protatlanta sculpta (Gastropoda: Pterotracheoidea)
Results and discussion

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DNA barcoding

DNA barcoding of 18 specimens of Protatlanta from the Atlantic Ocean revealed two monophyletic clades of Protatlanta with maximum bootstrap support (Figs 4, 5). The first clade consists of non-ornamented specimens (N=10), representing the species P. souleyeti. The second clade is exclusively made up of ornamented specimens (N=8). The ornamentation on these specimens is comparable to P. sculpta, as described by Issel (1911) and we therefore consider this second clade to be a separate species, P. sculpta. The average K2P pairwise distance (Table 3) between P. sculpta and P. souleyeti is 0.19. Average K2P pairwise distances show that the family Atlantidae overall, is highly diversified based on the CO1 gene. Representatives of the other Atlantidae genera Atlanta and Oxygyrus showed an average pairwise distance of 0.20 and 0.24 from P. souleyeti and 0.20 and 0.24 from P. sculpta, respectively. This molecular analysis supports that P. sculpta is a valid species and that shell ornamentation is an effective way to identify P. sculpta from P. souleyeti.


Table 3. Average K2P pairwise genetic distance of Cytochrome Oxidase 1 sequences for P. souleyeti, P. sculpta and representatives of the genera Atlanta and Oxygyrus.


Fig. 4. Maximum-likelihood tree showing relationships based on Cytochrome Oxidase 1 DNA sequences of Protatlanta and other heteropod genera, including several Hypsogastropoda outgroups (see text for more details). Branch lengths are proportional to the amount of inferred change, indicated by the scale bar. Only bootstrap supports (1000 replicates) above 70% are displayed. GenBank accession codes are presented in Table 1. Sequences from Jennings et al. (2010) begin with FJ, other outgroup sequences are from GenBank.


Fig. 5. Protatlanta biogeography in the Atlantic Ocean (a) occurrences of P. sculpta (in black) showing stations included in DNA barcoding (in white) and (b) occurrences of P. souleyeti (in black) showing stations included in DNA barcoding (in white). Average sea surface temperature from Tyberghein et al. (2012).