The genus Pectenoniscus Andersson, 1960 currently presents two described species, one epigean, Pectenoniscus angulatus Andersson, 1960, from Nova Teutônia municipality, Santa Catarina state (Southern Brazil) and the hypogean Pectenoniscus liliae Campo-Filho, Bichuette and Taiti, 2019, found in two caves in the Serra do Ramalho karst area (Carinhanha municipality), Bahia state (northeastern Brazil). Recent surveys in karstic areas of Minas Gerais and Bahia revealed six new cave species from this genus, which are herein described. Two species occur in Minas Gerais state in the transition between the biomes Cerrado (Brazilian savannah) and Caatinga (mesophytic and xeromorphic forests): Pectenoniscus montalvaniensis n. sp. from Abrigo da Ema cave (Montalvânia municipality) and Pectenoniscus juveniliensis n. sp. from Gruta do Tabuleirinho cave ( Juvenilia municipality). The other four species were found in Bahia state, in Caatinga biome: Pectenoniscus iuiuensis n. sp. from Baixa da Fortuna cave (Iuiu municipality); Pectenoniscus carinhanhensis n. sp. from three caves in Serra do Ramalho (Carinhanha municipality); Pectenoniscus santanensis n. sp. from Gruta do Padre cave (Santana municipality); and Pectenoniscus morrensis n. sp. from Gruta dos Brejões cave (Morro do Chapéu municipality). Aside from the taxonomic descriptions, we provide ecological notes for each described species, as well as an identification key for Pectenoniscus.

In the present work, five new species of Xangoniscus are described, increasing to eight the number of the known troglobitic species for the genus. Xangoniscus species can be distinguished from each other by the shape of pleonites epimera, the number and size of aesthetascs in the distal article of antennula, the modifications on pereopods, the shape of male pleopods and the proportion between uropod rami. Species from this genus are known for the states of Minas Gerais and Bahia with Xangoniscus aganju representing the northernmost occurrence, and X. lundi n. sp. and X. dagua n. sp. the southernmost occurrences. Of the six caves where specimens were collected, four are not registered in the national speleological database, what points to all the potential to yet be discovered regarding number of cavities and the associated biodiversity in Brazil. Some of the here mentioned type localities are not located inside protected areas, therefore exposing the species to risks related to the adjacent land use and consequent influence on water table level and input of food resources. The contribution of this work with descriptions of new troglobitic species provides support to consider them as plausible candidates to be assessed in the next list of threatened species as well as to elaborate conservation actions for the species, the caves where they inhabit and the surrounding landscape.

A new genus of Styloniscidae, Chaimowicziagen. nov., is described with two new species: Chaimowiczia tatussp. nov. from Gruta do Padre cave (Santana, Bahia) and Chaimowiczia uaisp. nov. from Lapa d’água do Zezé cave (Itacarambi, Minas Gerais). The new genus and species were allocated into the subfamily Iuiuniscinae, hitherto monotypic, by the pronounced rectangular-shaped lateral pereonites epimera, dorsal surface smooth, body outline continuous without a gap between pereon and pleon, and pleonites 3 to 5 developed forming tips. The two species of Chaimowiczia gen. nov. differ in the shape of cephalon antennal lobes, pereonite 1 epimera, pleonite 5 posterior margin and uropod exopod and endopod proportion.

Xangoniscus (Styloniscidae, Synocheta, Isopoda) includes only two species, both occurring in Brazil. Here a new amphibious troglobitic species of this genus found at Olhos D’Água Cave, Northern Minas Gerais, Brazil, is described. Xangoniscus itacarambiensis sp. nov. differs from the congeneric species mainly due to the following characters: head well-detached from the first pereonite, second and third articles of antennula subequal in length, presence of six short aesthetascs in the antennula and reduced triangular lobe in the distal part of pleopod 2 endopod.

Th e reproductive aspects of populations are important determinants of their ability to maintain themselves throughout time. In the case of amphipods from the genus Hyalella Smith, 1874, the reproductive period is easily determined by the presence of ovigerous females and pre-copula pairs in the population. Th is study evaluated the fecundity, pairing patterns and reproduction period of Hyalella carstica Bastos-Pereira and Bueno, 2012 in a karst environment in the West of Minas Gerais, Brazil. Monthly, from April, 2010 to April, 2011, amphipods were sampled using a hand net with 15 cm diameter and 250 µm mesh size. In the laboratory, animals were sexed and measured, and the ovigerous state of females was evaluated. Couples in pre-copula and ovigerous females were found throughout the year, with the exception of the dry months (September−November). During drought, the stream's superfi cial water dried out, and only a few refuges for the population remained. Although couples were found in all months with a water fl ow, a higher number of unpaired males and females was found after the dry season. In all months, ovigerous females were more abundant than non-ovigerous, and the relationship between head length and the number of eggs in the marsupium was positive. Most eggs were in the fi rst developmental stage, although all other stages were found before the dry season. Considering the frequency of pre-copula pairs, as well as ovigerous females, the reproduction in this H. carstica population seems to be continuous throughout the year, without a distinct peak.

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The absence of eyes in Hyalella (Hyalellidae, Amphipoda) is typical of obligate groundwater-dwelling species. However, a new intriguing blind amphipod of this genus was found in epigean streams from the Iron Quadrangle (state of Minas Gerais, Brazil). Hyalella troglofugia sp nov. presents antenna 1 shorter than antenna 2, gnathopod 1 propodus inner face with four setae, gnathopod 2 propodus posterior margin longer than palm, dactylus slightly longer than palm, pereopod 5 shorter than others and uropod 3 shorter than telson. The absence of eyes and presence of reduced U3 and pereopods of H. troglofugia sp nov. may suggest that such species also inhabits interstitial subterranean spaces. Moreover, the presence of the new species on streams associated to distinct hydrological zones indicates that this species may be present in different types of subterranean habitats of the region. We hypothesize that at least part of the population of this species may have left the subterranean environment looking for food and when out of this habitat it preferentially inhabits high water flow stretches of the stream in function of predation avoidance.

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