Paederinae, a diverse subfamily of rove beetles (Staphylinidae), is poorly explored with an outdated subtribal and generic classification lacking proper phylogenetic perspective. Therefore, the discovery of two Baltic amber fossil specimens resembling the genera Micrillus and Scymbalium, which are particularly challenging in terms of systematics, called for a thorough analysis to infer their phylogenetic position and their ecological requirements. The fossils were examined with light microscopy supplemented by X-ray micro-computed tomography, and then scored into a Paederinae-specific matrix of 99 morphological characters, along with a broad sample of recent Paederinae and non-paederine outgroups. Morphological phylogenetic analyses were conducted, using Bayesian Inference and Maximum Parsimony. The obtained phylogeny confirmed that the genera Scymbalium and Micrillus form a lineage outside Lathrobiina; therefore, both genera are now classified as Lathrobiini incertae sedis pending a more inclusive phylogenetic work on Paederinae. The analysis firmly placed both fossils in that recent lineage, albeit rendering Micrillus paraphyletic with respect to Scymbalium. Without a more extensive analysis based on the revised world fauna, any systematic changes would be premature. Thus, the fossils are described as Micrillus electrus, sp. nov. and Scymbalium phaethoni, sp. nov. in accordance with the current diagnoses of both genera. Given that the recent species of Micrillus and Scymbalium are predominantly thermophilic and mainly confined to dry open landscapes in Africa, southern Eurasia and Australia, the finding of Baltic amber representatives implies the very diverse landscape and the equable (sub)tropical palaeoclimatic conditions of the Eocene amberiferous ‘forest’, the latter being the subject of continued debates.

From an ecological and evolutionary standpoint, troglobitic organisms are of special interest because they have evolved in, and are restricted to, the subterranean environment. Iandumoema Pinto-da-Rocha, 1997 stands out for being the only Brazilian harvestmen genus with more than one troglobitic species, with three species described from caves in Minas Gerais state. Traditionally, testing the monophyly of troglobitic groups is more challenging than testing groups that do not include troglobites. Many of their shared features might be the result of convergence or parallelism imposed by the cave environment, such as the absence of light, limited and infrequent availability of food resources and low population density, among others. In the case of Iandumoema, this becomes even more difficult because the genus is currently included in the species-rich and polyphyletic subfamily Pachylinae. This study tested the monophyly of this troglobitic genus and proposed the first phylogenetic hypothesis for Iandumoema based on cladistic analysis using morphological data. The analysis included all described species of Iandumoema and three new troglobitic species: I. cuca, sp. nov. (type locality: Itacarambi, Gruta da Água do João Ferreira); I. gollum, sp. nov. (type locality: Presidente Juscelino, Lapa D’Água); and I. stygia, sp. nov. (type locality: Montes Claros, Gruta do Cedro). The matrix comprises 79 characters and 28 terminal taxa: six species of Iandumoema; 14 of Pachylinae; six from other Gonyleptidae subfamilies; one species of Cosmetidae; and one of Metasarcidae. The cladistic analysis resulted in one parsimonious tree (339 steps, consistency index = 0.35, retention index = 0.56). Iandumoema is a monophyletic and well supported genus, nestled among Brazilian ‘Pachylinae’. Three new species are described and an identification key and ecological remarks for all six species of the genus Iandumoema is provided.

The superfamily Bogidielloidea is one of the most wide-ranging hypogean amphipod taxa currently known, comprising over 130 species in 43 genera occurring on every continent except Antarctica. This large distribution among such cryptic organisms is curious, especially when combined with weak morphological characters uniting the superfamily. A unique new genus and species of bogidielloid amphipod, Simplexia longicrus, gen. et sp. nov., described from Terrell County, Texas, sheds light on the evolutionary relationships within this grouping. Molecular phylogenetic analyses of the order Amphipoda using two nuclear genes and one mitochondrial gene reveal that this species and the sympatric Parabogidiella americana form a clade removed from other sequenced members of Bogidiellidae sensu stricto, and, as such, the two species are placed in the newly erected Parabogidiellidae, fam. nov. Additional phylogenetic analyses of the cosmopolitan Bogidiellidae are recommended to further resolve its systematics.

Aenigmetopia Malloch is the only endemic genus of miltogrammine flesh flies (Diptera : Sarcophagidae) in Australia and, until now it has been known from a single species, A. fergusoni Malloch. This study constitutes the first comprehensive taxonomic revision of Aenigmetopia. Four new species, Aenigmetopia amissa, sp. nov., A. corona, sp. nov., A. kryptos, sp. nov. and A. pagoni, sp. nov., are described through the integration of molecular and morphological data and characters for genus- and species-level diagnoses are given. Aenigmetopia is included in a molecular phylogenetic analysis for the first time and the genus emerges as the sister taxon to Metopia Meigen, in agreement with morphological evidence.

The ragged sea hare (Bursatella leachii) and the long-tailed sea hare (Stylocheilus striatus) are two widely distributed species of benthic heterobranch sea slugs. In this paper, integrative taxonomic analyses have been conducted to detect possible cryptic diversity. Our results revealed that both nominal species are actually species complexes, consisting of five genetically distinct taxa. Two of them belong to the genus Bursatella and three to the genus Stylocheilus. The name B. leachii is retained for a widely distributed species, present in the Atlantic, the Mediterranean, and parts of the Indo-Pacific region. The name B. ocelligera is resurrected for the other species, restricted to the Indo-Pacific and co-occurring with B. leachii in that area. With the present data, it is not possible to test whether B. leachii and B. ocelligera have evolved allopatrically in the Atlantic and Indo-Pacific or sympatrically in the latter. Bursatella leachii has been able to maintain gene flow between the Atlantic and the Indo-Pacific Oceans, possibly because of a combined effect of the Agulhas Leakage process and the ability to survive the colder waters of South Africa. On the contrary, the three species of Stylocheilus are allopatric; the name S. striatus is retained for an Indo-Pacific species, while the names S. polyomma and S. rickettsi are resurrected for species inhabiting the Western Atlantic and the Eastern Pacific respectively. Finally, the discovery of a museum specimen mistakenly identified as B. leachii, but bearing a shell in its adult form, led to the resurrection of the genus Phycophila, previously synonymised with Aplysia. Phycophila euchlora, the only species described to date, is distributed in the Central and Western Pacific Ocean.