Atlantoscia, Ferrara & Taiti, 1981

Zimmermann, Bianca L., Campos-Filho, Ivanklin S., Deprá, Maríndia & Araujo, Paula B., 2015, Taxonomy and molecular phylogeny of the Neotropical genus Atlantoscia (Oniscidea, Philosciidae): DNA barcoding and description of two new species, Zoological Journal of the Linnean Society (Zool. J. Linn. Soc.) 174 (4), pp. 702-717 : 711

GENUS ATLANTOSCIA

The final alignment consisted of 33 sequences (11 from A. petronioi , ten from A. floridana , five from A. inflata , three from A. meloi , two from A. ituberasensis , one from A. sulcata , and one from A. rubromarginata ) of 640 bp of the COI gene. These sequences contained 235 variable sites (36.7%), of which 223 (34.8%) were parsimony informative. The sequences were not saturated, based on an Iss that was significantly lower than the critical Iss (Iss = 0.255, Iss. c = 0.735, P <0.001). The phylogenetic methods (NJ and BI) produced trees with highly congruent topologies. Their main difference was in clade support, which was higher in the BI analysis; for example, the support of the Atlantoscia genus was 1.0 in the BI tree and 67% in the NJ tree. Hence, only the Bayesian analysis is presented ( Fig. 5 ). The NJ tree is shown in Figure S1 . In the figures, posterior probabilities and bootstrap supports are marked at selected nodes and major clades of Atlantoscia are highlighted.

All nominal species of the genus Atlantoscia had high support values (bootstrap of 99% and posterior probability of 1.0), including those described in the present study. According to the Bayesian tree, A. ituberasensis and A. rubromarginata form a more basal clade within the genus. Atlantoscia sulcata and A. inflata form distinct clades, whereas a larger clade is formed by the species A. petronioi , A. meloi , and A. floridana .

Sequence divergence (K2P) within species of Atlantoscia ranged from 0 to 4.4%. Atlantoscia inflata showed the highest intraspecific divergence, with a mean of about 2% ( Table 2). Sequence divergence amongst congeneric species ranged from 14.8% ( A. rubromarginata and A. ituberasensis ) to 29.3% ( A. meloi and A. ituberasensis ) ( Table 3). The average congeneric distance was 20.8%. Amongst the Atlantoscia species , A. ituberasensis and A. rubromarginata had the highest average genetic divergences, 25.9 and 23%, respectively. The divergence between A. meloi and A. inflata , the two new species described in this study, was 22%.

The results obtained by applying the ABGD algorithm to the COI data set of the seven analysed Atlantoscia species are presented in Figure 6 . Distance values showed a gap between the intraspecific and interspecific distances ( Fig. 6A ). The data set was partitioned into seven groups based on the assumption of a maximum intraspecific divergence ≤ 1.3% ( Fig. 6B ). These results corroborated those of the phylogenetic analysis and confirmed the taxonomic validity of the currently recognized species of Atlantoscia .

Figures

Figure 1. Atlantoscia inflata sp. nov., male holotype MZUSP 32622. A, habitus, dorsal view; male paratype MZUSP 32623; B, scale-seta; C, cephalothorax, frontal view; D, cephalothorax, dorsal view; E, noduli laterales coordinates d/c; F, noduli laterales coordinates b/c; G, pleotelson; H, antennula; I, antenna; J, left mandible; K, right mandible; L, maxillula, outer endite; M, maxilla; N, maxilliped.

Figure 5. Consensus tree obtained from a 640-bp alignment of cytochrome c oxidase subunit I gene sequences of the Atlantoscia species by using Bayesian inference. Numbers at nodes represent posterior probabilities values (1 000 000 generations). Clades highlighted by grey shading in the tree correspond to nominal species of Atlantoscia. Letters (a–k) represent the different individuals of terrestrial isopods analysed.

Figure 6. Histogram of pairwise distances divergence for Atlantoscia species (A) and automatic partition of the cytochrome c oxidase subunit I data set of seven Atlantoscia species (B) as generated by automatic barcode gap discovery. The lower distance values (<0.05) represent intraspecific divergences, whereas higher distance values (> 0.12) represent interspecific divergences. Dist., distance.