A new species of Pseudione Kossmann, 1881 is described from two parasitized specimens of the clawed lobster Nephropsis aculeata Smith, 1881, collected from Brazilian waters in the southwestern Atlantic. It is the second species of the genus from Brazil and is the fourth species parasitizing nephropid lobsters in the world.

Two new species of Parastacus Huxley, 1879 are described from the Atlantic Forest in southern Brazil: Parastacus buckupi sp. nov. from a highland stream in the hydrographic basin Maquiné river, Maquiné, state of Rio Grande do Sul; and Parastacus pilicarpus sp. nov. from a first order stream in the hydrographic basin Araranguá River, Morro Grande, state of Santa Catarina. Parastacus buckupi sp. nov. is distinguishable from all other Parastacus species via its large and globose chelipeds, by the presence of tufts of long and simple setae in the cutting edge of cheliped fingers, which are more abundant proximally and by possessing a telson with an acute distal margin. Parastacus pilicarpus sp. nov. is diagnosed mainly by the distal portion of the carpus which possess tufts of long, simple setae, and by having an epistome whose anteromedian lobe is heptagonal and as long as it is wide. Finally, P. pilicarpus antennal scales lateral margin terminates in a very strong terminal spine and mandibles incisive lobe has nine teeth, with the first tooth from the anterior margin

This study describes and illustrates the morphology of the second juvenile stage of the blue-fingered burrowing crayfish Parastacus caeruleodactylus. One female carrying 20 juveniles was collected in January 2019 from a swamp forest in the municipality of Dom Pedro de Alcântara, state of Rio Grande do Sul, southern Brazil. Juveniles were dissected and the appendages were mounted in slides. The general morphology and the pattern of attachment of the second juvenile stage of P. caeruleodactylus correspond to that reported for other parastacids. The main differences among the co-generic species are related to the number of articles in the flagella of the antennae, the number of spines in the antennal scale, the number of setae in the articles of the appendages, the number of teeth in the mandible molar and incisor processes, the absence of segmentation in the exopod flagellum of the maxillipeds and the number of teeth in the crista dentata of the ischium of maxilliped 3.

In this contribution we describe a new species of burrowing crayfi sh of the genus Parastacus Huxley, 1879 from a swamp forest in southern Brazil and determine its conservation status. Th e distinction of the new species is based on morphology and the mitochondrial DNA marker 16S rRNA. Th e extinction risk was assessed according to the sub-criterion B1 of IUCN that estimates the Extent of Occurrence (EOO). Parastacus tuerkayi sp. nov. is morphologically distinguishable from all species of Parastacus by having three lines of verrucous tubercles on the dorsomesial margin of the cheliped propodus and a suborbital angle exceeding 90°. Th e EOO comprises 647,674 km², and the species is classifi ed as "endangered". Phylogenetic relationships indicate the distinct position of this new species in relation to the already described species. key words 16S, mtDNA sequence, burrowing crayfi sh, Neotropical region, taxonomy . Ribeiro et al.2

Cymothoa ianuarii Schioedte & Meinert, 1884 is rediscovered almost 136 years after its original description and redescribed from specimens collected in the state of São Paulo. This species is mainly characterized by adult females with cephalon with conspicuous eyes and not deeply immersed in pereonite 1, pereonites 5-6 much wider than 4, pleotelson twice as wide as long and pleopods 1-5 decreasing in size; Cymothoa excisa Perty, 1833 and C. oestrum (Linnaeus, 1758) are recorded from the state of Bahia. Illustrations and an updated distribution map for these species in Brazil are provided.

Neognathophausia ingens (Dohrn, 1870) is a bathypelagic crustacean distributed worldwide. In the western Atlantic it has been recorded off the La Plata region, Argentina, and off the coast of Brazil, from the state of Bahia to Rio de Janeiro. We provide new records of N. ingens from the state of Rio Grande do Sul, Brazil, about 1188 km south of its previous distribution limit off Brazil, filling the gap between the central West Atlantic and Argentina. Five specimens were analyzed and drawings for all body regions and appendages are presented. Mandible, thoracopods 2, 4, 5, 6 and 8 and pleopods are illustrated and described for the first time. An updated synonym list and a distribution map for this species in Brazil are provided.

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In this contribution, we describe two new species of burrowing crayfish species complex Parastacus brasiliensis from forestry areas in the central region of the state of Rio Grande do Sul, southern Brazil. We used an integrative taxonomy approach with morphology and the mitochondrial DNA 16S rRNA gene and also evaluated their conservation status according to the IUCN Red List Criteria. Parastacus guapo sp. nov. was collected near the municipality of Pantano Grande and it differs from all other congeneric species in having an epistome anterolateral section with a large conical projection ending in a big sharp spine on both sides. It also differs from P. brasiliensis sensu stricto in the shape of the rostral surface, sub-orbital angle, postorbital carina straight, sub-orbital angle > 90°, postorbital carinae prominent in anterior and middle portions, carpal spine present, the internal surface of chelipeds palm with sparse tubercules, areola narrow and pleon short. Parastacus gomesae sp. nov. was collected in the municipality of São Jerônimo, it differs from all analysed species for rostral spine absent, epistome anteromedian lobe heptagonal and mandible incisive process with seven teeth (the second tooth from the anterior margin is the largest). It is also distinguished of P. brasiliensis sensu stricto in the sub-orbital angle > 90°, postorbital carinae prominent in anterior and middle portions, 3–4 rows of verrucose tubercles irregularly distributed on the palm dorsal surface of chelipeds, areola narrow and pleon short. Phylogenetic relationships confirmed the distinct position of these new species to the already described species. The extent of occurrence (EOO) / area of occurrence (AOO) of P. guapo sp. nov and P. gomesae sp. nov. were estimated at 937 km² / 1,87 km², and 2.107 km² / 23,9 km² respectively. The main threats identified were continued decline in the quality of habitats, resulting from deforestation and forestry areas. However, as we know only one point of occurrence for each new species, we suggest that both be categorized as Data Deficient.