The Afrotropical species of the genus Pristaulacus Kieffer, 1900 are revised and illustrated for the first time. Four species are recognized: P. africanus (Brues, 1924), P. pilatoi sp. n. and P. thoracicus (Westwood, 1841), from the Republic of South Africa, and P. smithi sp. n. from Zimbabwe and Mozambique. P. thoracicus (Westwood), comb. n., is transferred from Aulacus Jurine. The previously unknown male of P. africanus (Brues) is described for the first time and additional data on the distribution of this species are given. A key to the species of Afrotropical Pristaulacus is provided.

BackgroundOne key question in evolutionary biology deals with the mode and rate at which reproductive isolation accumulates during allopatric speciation. Little is known about secondary contacts of recently diverged anuran species. Here we conduct a multi-locus field study to investigate a contact zone between two lineages of green toads with an estimated divergence time of 2.7 My, and report results from preliminary experimental crosses.ResultsThe Sicilian endemic Bufo siculus and the Italian mainland-origin B. balearicus form a narrow hybrid zone east of Mt. Etna. Despite bidirectional mtDNA introgression over a ca. 40 km North-South cline, no F1 hybrids could be found, and nuclear genomes display almost no admixture. Populations from each side of the contact zone showed depressed genetic diversity and very strong differentiation (FST = 0.52). Preliminary experimental crosses point to a slightly reduced fitness in F1 hybrids, a strong hybrid breakdown in backcrossed offspring (F1 x parental, with very few reaching metamorphosis) and a complete and early mortality in F2 (F1 x F1).ConclusionGenetic patterns at the contact zone are molded by drift and selection. Local effective sizes are reduced by the geography and history of the contact zone, B. balearicus populations being at the front wave of a recent expansion (late Pleistocene). Selection against hybrids likely results from intrinsic genomic causes (disruption of coadapted sets of genes in backcrosses and F2-hybrids), possibly reinforced by local adaptation (the ranges of the two taxa roughly coincide with the borders of semiarid and arid climates). The absence of F1 in the field might be due to premating isolation mechanisms. Our results, show that these lineages have evolved almost complete reproductive isolation after some 2.7 My of divergence, contrasting sharply with evidence from laboratory experiments that some anuran species may still produce viable F1 offspring after > 20 My of divergence.

The results of the first phylogenetic investigation of members of the Aulacidae of the world are presented. The main objective was to test the monophyly of the currently recognised genera. In total, 79 morphological characters were scored for a substantial sample of the extant aulacid fauna, including 72 species, as well as 12 outgroup taxa belonging to Evaniidae, Gasteruptiidae, Megalyridae, Trigonalidae, Braconidae and Stephanidae. All zoogeographic regions were represented. The dataset was analysed under different conditions (ordered, unordered, equal and implied weighting). The results under different weighting conditions are not fully congruent and many relationships remain unresolved. However, the analyses demonstrate that the current generic classification of the Aulacidae is not a natural one. There is support for a very large, monophyletic clade which includes all Pristaulacus Kieffer spp. + Panaulix Benoit spp. This suggests a wider generic concept for Pristaulacus, which is redefined and rediagnosed here. As a consequence, Panaulix becomes a junior synonym of Pristaulacus (syn. nov.), and the two described species of Panaulix are transferred to Pristaulacus: Pristaulacus rex (Benoit, 1984), comb. nov., and Pristaulacus irenae (Madl, 1990), comb. nov. The genus Aulacus Jurine was consistently paraphyletic and is not valid as currently defined. Furthermore, we failed to retrieve a consistent topology among the different clades of Aulacus. A satisfactory reclassification of Aulacus, however, requires a much more comprehensive taxon sample and/or additional character data.

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The endemic southeastern Asiatic Pristaulacus comptipennis species group is revised and illustrated. Twenty species are recognized: P. asiaticus Turrisi & Smith, sp. nov. (China), P. boninensis Konishi (Japan), P. comptipennis Enderlein (Japan, China, Taiwan, Laos), P. corellianus Turrisi & Smith, sp. nov. (Laos), P. dilleri Turrisi & Smith, sp. nov. (Laos), P. emarginaticeps Turner (Vietnam), P. excisus Turner (Vietnam), P. gusenleitneri Turrisi & Smith, sp. nov. (Thailand), P. insularis Konishi (Japan, South Korea), P. jenningsi Turrisi & Smith, sp. nov. (Laos), P. konishii Turrisi & Smith, sp. nov. (Thailand), P. lagrecai Turrisi & Smith, sp. nov. (Vietnam), P. nobilei Turrisi & Smith, sp. nov. (China), P. porcatus Sun & Sheng (China), P. sharkeyi Turrisi & Smith, sp. nov. (Thailand), P. thailandensis Turrisi & Smith, sp. nov. (Thailand), P. vietnamensis Turrisi & Smith, sp. nov. (Vietnam, Thailand), P. vilhelmseni Turrisi & Smith, sp. nov. (Laos), P. vivaldianus Turrisi & Smith, sp. nov. (Laos), P. watanabei Turrisi & Smith, sp. nov. (Thailand). Phylogenetic analyses are based on a previous set of 79 morphological characters. Of this data set, 28 informative including five newly added characters were analysed using TNT under different schemes (equal and implied weighting). All analyses support two large clades, the first with five species, and a more derived and diverse one containing 15 species. Other minor clades are identified and discussed. A key for identification of the species is provided.