DOI: 10.3897/asp.82.e108906

Authors: Bao-Jun Xie, Ping-Ping Chen, Jakob Damgaard, Jie-Yi Xie, Qiang Xie, Yan-Hui Wang

Abstract: The genus Micronecta Kirkaldy, 1897 is the most species-rich genus in the family Micronectidae, containing more than 160 species. Micronecta is currently divided into 11 subgenera, five of which are monotypic. Moreover, the subgenus Micronecta is an empirical mixture group. The definitions of some subgenera were based on only a few aberrant morphological features, which are specializations with few phylogenetic significances. The relationship between these subgenera remains unclear. In this study, we newly sequenced mitochondrial genomes (mitogenomes) and nuclear rDNAs (nrDNAs) for 13 Micronecta species, representing seven subgenera, and those for ten other water bugs. Our phylogenetic analyses showed that the subgenus Lundbladella represents the sister group to all other studied subgenera of Micronecta. The subgenus Unguinecta was the sister group to the clade that contains Dichaetonecta and Sigmonecta. More importantly, the subgenus Micronecta represents a paraphyletic group, which further forms a monophyletic group together with the subgenera Basileonecta and Ctenonecta. This is for the first time that the phylogeny of the genus Micronecta was investigated based on molecular data and the paraphyly of the subgenus Micronecta was revealed. Such evidence suggested the necessity of the revision of the taxonomic system of the genus in the future, and may also serve as a reference for the delimitation of subgeneric characters.

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DOI: 10.3897/asp.81.e87378

Authors: José R. I. Ribeiro, Augusto Ferrari

Abstract: The Belostoma plebejum group comprises nine species, and the most evident characteristic shared by all species of the group is a phallus that is strongly curved ventrally. The difficulty in studying its species is much aggravated by the scarcity of identified material in Brazilian collections, and this has negatively impacted phylogenetic studies within the group. We tested the monophyly of the B. plebejum group using discrete and continuous characters under different weighting schemes and inferences. We described B. lanemeloi sp. nov. and B. nieseri sp. nov. and they served as the basis to study the phylogenetic relationships. A strict-consensus tree recovered under maximum parsimony and with implicit weighting scheme is as follows: (B. parvum, ((B. lanemeloi sp. nov., (B. nessimiani, B. nieseri sp. nov.)), (B. micantulum var1, (B. micantulum var2, (B. estevezae, ((B. plebejum, (B. minusculum var1, B. minusculum var2)), ((B. nicaeum var1, B. nicaeum var2), ((B. lariversi var1, B. lariversi var2), (B. pygmeum var1, B. pygmeum var2))))))))). The monophyly of the B. plebejum group is corroborated by four non-homoplastic synapomorphies, and the aforementioned condition of the phallus is one of them. We tested the phylogenetic integrity of some species of the B. plebejum group, and only the exemplars of B. micantulum did not constitute monophyletic clades. Comparing the topologies obtained by different approaches clearly showed the presence of different scenarios in terms of heterogeneity of evolutionary rates among characters, but this could also be influenced by the disproportionate number of discrete characters compared with continuous characters.

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