Systematic revision of the Savignia genus group (Araneae: Linyphiidae: Erigoninae) with notes on their cephalic lobe evolution

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  Systematic revision of the Savignia genus group (Araneae: Linyphiidae: Erigoninae) with notes on their cephalic lobe evolution Abstract The Savignia genus group includes nine morphologically complex yet similar genera where species were assigned based mainly on the cephalic lobes. Among these genera, males of Diplocephalus Bertkau, 1883, Savignia Blackwall, 1833 and Araeoncus Simon, 1884 show some of the most extraordinary cephalic lobes among dwarf spiders (Linyphiidae, Erigoninae). In this study we undertake the first phylogenetic analysis of the Savignia genus group. We use 269 morphological characters (175 newly defined) and 70 taxa (59 ingroup taxa) to reconstruct the relationships and evolutionary trends of cephalic lobes in this lineage. Our findings show that cephalic lobes with varying shapes and sizes appear in several Savignia genus group lineages, highlighting that it is not a good diagnostic character. The high support in several clades allows the redefinition of t...

Exploring the evolutionary path of male genitalia in the genus Heterophrynus (Arachnida: Amblypygi) from the Colombian Andes: a new endemic species revealed

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Exploring the evolutionary path of male genitalia in the genus Heterophrynus (Arachnida: Amblypygi) from the Colombian Andes: a new endemic species revealed

Abstract
The genus Heterophrynus of the family Phrynidae, endemic to South America, presents a cryptic diversity previously reported in genetic population studies, especially in the group of species similar to H. batesii, which is distributed from the Brazilian Amazonia to the North of Colombia. Describing new species inside this group could be difficult due to the lack of diagnostic characters, however, the male genitalia presents a little studied group of characters that could be useful. We evaluate the variation in the male genital morphology of the group using SEM pictures, showing the differences in some structures between species from the Amazon and the Andean region, and for the first time, we present a time-calibrated phylogeny of the Colombian species based on COI. We describe a new species Heterophrynus nasa, based on the male and female genitalia morphology, which is also supported by analyses of genetic species delimitations. Variations on the Lobus Dorsalis, Laterialis, and the Processus Internus, show patterns in the Amazonian species that differ from the Andean and Caribbean species. According to the genetic analysis, the raising of the Andean Oriental Cordillera could have produced species differentiation dating from 27 to 7 mya, since the Oligocene to the Miocene. 
Daniel Chirivi Joya, Sebastián Vazquez-Palacios, Sebastián Cuadrado-Ríos, Exploring the evolutionary path of male genitalia in the genus Heterophrynus (Arachnida: Amblypygi) from the Colombian Andes: a new endemic species revealed, Acta Arachnologica, 2025, Volume 74, Issue 2, Pages 71-84, Released on J-STAGE December 11, 2025, Online ISSN 1880-7852, Print ISSN 0001-5202, https://doi.org/10.2476/asjaa.74.71, https://www.jstage.jst.go.jp/article/asjaa/74/2/74_71/_article/-char/en