Arthrosaura, Boulenger, 1885, Boulenger, 1885

RESULTS

The BI and ML analyses of the full dataset recovered a non-monophyletic Arthrosaura , with Ar. kockii sister to all other Ecpleopodinae with high support [BI: 1.00 PP; ML: 100% BP (bootstrap probability)] ( Fig. 1 View Figure 1 ) and Ar. testigensis + Ar. sp. from the Chimantá Massif nested in Yanomamia with high support (BI: 1.00 PP; ML: 100% BP) ( Fig. 2 View Figure 2 ). Yanomamia is recovered sister to Arthrosaura with low support (BI: 0.89 PP; ML: 57% BP). The Ecpleopodinae consensus trees are otherwise similar with most published molecular phylogenies, except for poorly supported nodes ( Fig. 1 View Figure 1 ). Other Arthrosaura samples (i.e. except Ar. kockii and Ar. testigensis ) are recovered monophyletic with high support (BI: 0.97 PP; ML: 97% BP) and our results highlight high diversity within the genus, which contains at least five currently unnamed main lineages (hereafter referred to as ‘species’) in the Amazonian lowlands ( Figs 3 View Figure 3 , 4 View Figure 4 ). However, several relationships among and within clades recovered in Arthrosaura s.s. were poorly supported, and the use of a reduced dataset, including only Arthrosaura + the outgroups, improved the resolution of the phylogenetic relationships within that clade ( Fig. 3 View Figure 3 ). Arthrosaura reticulata s.s. is seemingly restricted to western Amazonia in Ecuador and the western Amazonas state in Brazil ( Fig. 4 View Figure 4 ), while Arthrosaura versteegii is probably a north-eastern Guiana Shield endemic ( Fig. 4 View Figure 4 ). Arthrosaura montigena is a Pantepui endemic, which is here reported for the first time from Guyana at 1411 m elevation (Mount Wokomung; Fig. 4 View Figure 4 ); the two samples have a genetic divergence of 2.0% in 16S. Arthrosaura montigena is recovered sister to Ar. reticulata + Ar. sp. 1 with moderate support (BI: 0.97 PP; ML: 83% BP). Arthrosaura sp. 1 is recovered sister to Ar. reticulata with high support (BI: 1.00 PP; ML: 100% BP) ( Fig. 3 View Figure 3 ) and is found in the western lowlands of Pantepui (Upper Rio Negro and Orinoco) between 50 and 200 m elevation ( Fig. 4 View Figure 4 ). Arthrosaura sp. 2 is recovered sister to Ar. versteegii with high support (BI: 0.99 PP; ML: 93% BP) ( Fig. 3 View Figure 3 ) and occurs in the Mitaraka Massif in south-western French Guiana ( Fig. 4 View Figure 4 ). Genetic distance on the 16S fragment between these two samples is 4.2% (see Table 3 View Table 3 ) in the absence of any obvious barrier to gene flow. Arthrosaura sp. 3 is possibly endemic to the Sipaliwini region in Suriname and is recovered sister to the clade containing Ar. montigena , Ar. reticulata , Ar. versteegii, Ar. sp. 1, and Ar. sp. 2, albeit with low support (BI: 0.81 PP; ML: 81% BP); genetic divergence between Ar. sp. 3 and other species in clade A is 4.3–7.0% ( Fig. 3 View Figure 3 , Table 3 View Table 3 ). A second clade (clade B) containing Ar. sp. 4 (largely distributed in eastern Amazonia, east of the Rio Purus/Negro/Branco and the Essequibo River) and Ar. sp. 5 (apparently restricted to the north-eastern part of the Guiana Shield in eastern French Guiana and Amapá state, Brazil) is recovered sister to all other Arthrosaura with high support (BI: 1.00 PP; ML: 100% BP) ( Figs 3 View Figure 3 , 4 View Figure 4 ), with Ar. sp. 4 and Ar. sp. 5 recovered as sister-species with high support (BI: 1.00 PP; ML: 100% BP). Genetic divergences within Ar. sp. 4 (up to 3.8 %, Table 3 View Table 3 ) suggest that more than one species is represented in that clade (see below). Two clades are recovered within Ar. sp. 5, but with low genetic distance (max 1.6%), even though these populations are separated by the Oyapock River, a major watercourse in the north-eastern Guiana Shield. Genetic divergences within and among clades in the ‘barcoding’ 16S fragment are provided in Table 3 View Table 3 .