Abstract The present paper describes a new species of freshwater crayfish of the genus Parastacus Huxley, 1879 from the municipality of Amaral Ferrador in the state of Rio Grande do Sul, southern Brazil, evaluates its conservation status according to the IUCN Red List Criteria (sub-criterion B1), and updates the identification key for the genus. Parastacus longidactylus sp. n. differs from all analyzed species by the large eyes, the prominent and wide rostral carinae, surpassing the rostral basis and extending to the proximal third of the postorbital carinae, postorbital carinae and rostral carinae prominent and with similar lengths, chelipeds carpus dorsomedial surface not divided longitudinally by groove and long dactylus, surpassing the fixed finger. The possible extent of occurrence was estimated to be 6,968 km² and the species was recorded in only one location in the Camaquã River basin. The main threats to the region are the replacement of native vegetation by crops and livestock, water pollution and soil erosion. However, because there is only one known location where Parastacus longidactylus sp. n. occurs we suggest classifying the species as Data Deficient.

Abstract The natural history and conservation status of the West Indian endemic freshwater crabs of the genus Epilobocera are poorly known. Several species have restricted distributions and apparently specific ecological requirements, which make them particularly vulnerable to anthropogenic threats. Epilobocera capolongoi is known to occur exclusively in mountain streams and rivers above 300 m elevation in the Guamuhaya Massif, central Cuba. In addition to the publication with the original description, there is only one paper exclusively on this species, which reported it as being preyed upon by a heron and recorded it from some additional localities in the vicinity of Topes de Collantes, provinces of Cienfuegos and Sancti Spíritus. Epilobocera capolongoi is herein reported from Pico San Juan Ecological Reserve and Lomas de Banao Ecological Reserve, which expands its geographic range to about 60 km and its elevation to 1,000 m. The species was found living sympatric with the congeneric Epilobocera cubensis poliorcetes in Lomas de Banao Ecological Reserve, but apparently there exists some habitat segregation between them. Some phenotypic characters important to distinguish both species are described, some basic data on their natural history are provided, and an assessment of the conservation status of E. capolongoi following current IUCN criteria is made.

Abstract Alpheus christofferseni Anker, Hurt and Knowlton, 2007 was described based on four specimens from Atol das Rocas, northeastern Brazil, and one specimen from Bocas del Toro, the Caribbean coast of Panama. Here, we report the collection of two specimens from Pernambuco, Brazil (~ 8°41’S), thus increasing the knowledge on species distribution along the Brazilian coast by approximately five latitudinal degrees south of its type locality (Atol das Rocas, Rio Grande do Norte, ~ 3°51'S). We also report a substantial increase in the known bathymetric distribution from shallow intertidal to approximately 51 m. Notes on morphological variation are provided based on the new material, and the first sequence of the 16S ribosomal subunit gene for the Brazilian coast is provided and compared with congeners.

Abstract A new podocerid amphipod, Leipsuropus seisuiae sp. nov., from 338-340 m depth in the Kumano Sea, Japan, Northwestern Pacific, is described. This is the deepest record of any Leipsuropus species. Leipsuropus seisuiae sp. nov. is distinguished from four other congeneric species in having: i) pereonites 2-5 each with five narrow spiniform projections on tergal plate, ii) one dorsal tubercle on the telson, and iii) one small, proximal, denticulate projection on gnathopod-2 palmar margin. A key to males of the species of Leipsuropus is provided.

Abstract A body entirely covered with long and sharp-pointed spines makes Acanthoniscus spiniger Gosse, 1851, one of the rarest and most ornamented terrestrial isopods in the world. The original description of this species was based on a single specimen collected by the British naturalist Philip Henry Gosse in Jamaica in 1845 and deposited in the British Museum (currently The Natural History Museum, London). A second specimen, presumably of this species, was collected by the American entomologist Henry Guernsey Hubbard in 1877 and deposited in the United States National Museum, Smithsonian Institution, which served as the basis for a further description by Richardson (1909). After Gosse and Hubbard specimens, no additional material appears to have reached any museum collection. Due to the scarce available information on this genus, it has been indistinctly placed in at least four different families through history, without a consensus on its definitive placement to date. Herein, we describe a new species of Acanthoniscus Gosse, 1851, based on a population discovered in the Blue Mountains, Jamaica, above 1,200 m elevation and more than 150 km eastward of A. spiniger’s type locality. We also emend the authorship and diagnoses of the genus Acanthoniscus and its type species. Finally, we discuss the possible relationships of Acanthoniscus at the family level, concluding that, despite some putative autapomorphies, it belongs to Armadillidae, as its present-day status.

Abstract The status of the obscure Pagurus bouvieri (Faxon, 1895), a replacement name proposed for the preoccupied Eupagurus smithii A. Milne-Edwards and Bouvier, 1893, was evaluated. Based on types and numerous unreported museum materials, P. bouvieri is found to be synonymous with Pagurus politus (Smith, 1882) a commonly encountered but infrequently discussed northwestern Atlantic species. The taxonomy and geographic distribution of P. politus is updated with a complete synonymy, redescription, and illustrations. The taxonomy of the northeastern Pacific species Pagurus smithi (Benedict, 1892) is also updated, including a redescription with illustrations.

Abstract The mysid Rhopalophthalmus hastatus Hanamura, Murano and Man, 2011 was collected from the shallow zone of the Thale Sap Songkhla, Songkhla Lagoon, southern Thailand on 18 November 2018. Specimens are described and illustrated using material collected by hand with a Riley push net. Rhopalophthalmus hastatus is characterized by the presence of one large spine, one mesial, two small spines on the antennal sympod, antennal scale slightly overreaching the end of the antennular peduncle, carpopropodus of the fourth to seventh thoracic endopods composed of six articles, two red chromatophores on the telson and lateral margin of the apical spine forming sharp spine-like process. This species was found in the shallow zone of the Songkhla Lagoon with brackish water and muddy substratum.

Abstract The genus Trichoniscoides Sars, 1899 is composed mostly of cave-dwelling species. In the Iberian Peninsula, 32 species, and three additional species of uncertain status (partially described but not named), are currently known to occur. We were able to study one of these unnamed species, clarify its status, and name it. Most of the Iberian species of this genus are troglobiotic (22) and the ten remaining are epigean or troglophilic. The description of the new species from the surface can help in understanding the variability observed in the troglobitic species. The new, formally described, species has morphological characteristics that fit in several currently proposed groups for the genus, therefore, it is not possible to attribute Trichoniscoides gallaecus n. sp. to any of them.

Abstract Five anomuran and one brachyuran species collected from continental shelf and slope off southern Brazil have their geographic ranges considerably extended southward: Neolithodes agassizii (Smith), Paguristes spectabilis McLaughlin and Provenzano, Pagurus heblingi Nucci and Melo, Phimochirus occlusus (Henderson), Mixtopagurus paradoxus A. Milne-Edwards, and the brachyuran Euchirograpsus antillensis Türkay. Pagurus heblingi was previously known only from its type locality (off Cabo Frio, Rio de Janeiro) and from off Espírito Santo. Paguristes spectabilis was known only from the holotype (off Trinidad, Caribbean Sea) and two additional females from off Rio de Janeiro. One female was found of the brachyuran Robertsella meridionalis Tavares and Gouvêa, a species previously known only from two males. Additionally, the occurrence of the hermit crabs Dardanus venosus (H. Milne Edwards) and Oncopagurus gracilis (Henderson), and the brachyuran Hexapanopeus paulensis Rathbun are confirmed for Santa Catarina. The record of the brachyuran Neopilumnoplax americana (Rathbun) from Santa Catarina (27°S) probably actually refers to Neopilumnoplax lipkeholthuisi Tavares and Melo, a species described from Rio Grande do Sul (33°S) and Mar del Plata (37°S).

Abstract A new epigean asellid isopod, Caecidotea contrerasbalderasi sp. nov. is described from Nayarit, northwestern Mexico. This new species has morphological characters belonging to two different types of environments, both depigmentation and anophthalmia, indicators of organisms adapted to live in constant darkness as cavernicolous species. Despite showing characteristics of hypogean species, the new taxon does not show elongation of appendages, such as pereiopods, antennae or uropods. Its pleopod IV exopod lacks false sutures. This is a new pattern type “C”, and differs from that observed in types A and B. The description of this new species brings a new total of 101 species and three subspecies, for the genus Caecidotea in North America all morphologically poorly differentiated and with a restricted distribution.

Abstract The poorly known pilumnid, Vellumnus penicillatus (Gordon, 1930), is redescribed by examining the Hong Kong types. A new species, Vellumnus tki n. sp., is described from Macclesfield Bank, South China Sea, and it is distinguished from its closest congener, Vellumnus minabensis (Sakai, 1969) from Japan, by the setal pattern on the carapace and pereiopods, carapace proportions, structure of the front and anterolateral teeth, armature on the chelipeds and relatively shorter ambulatory legs.

Abstract The study investigated the population parameters of the shrimp Xiphopenaeus spp. (commonly known as seabob shrimp) in Anchieta, south coast of the state of Espírito Santo, Brazil, focusing on reducing the sampling effort. Shrimp were collected between February 2013 and February 2015. Individuals were measured, analyzed for sex and stage of reproductive development. In total, 1,564 individuals were analyzed in Anchieta, 534 males (74 juveniles and 460 adults) and 663 females (88 juveniles and 575 adults), and 367 individuals were not identified to sex or maturity. Significant differences were observed in shrimp abundance, with higher catches at the shallowest sampling point and associated with the type of substrate (silt+clay), while in the rainy season (September to March) and dry season (April to August) there were no significant differences. Despite this, greater abundances were found in the rainy season. The sex ratio was 0.80♂: 1♀. Carapace length ranged from 5.7 to 28.9 mm, with larger sizes recorded for females, as well as a larger size at first maturation than males, 12.86 and 11.60 mm respectively. All stages of development of the seabob shrimp were observed at the sampling points and periods, which represents a pattern of continuous reproduction and recruitment of the species in the area. Considering the sample size used, which is comparatively smaller than other studies, all estimates confirm current knowledge about the biology of the species and provide robust data on the seabob shrimp off the Anchieta coast, which are necessary for management and conservation.

Abstract Two new species of Hyalella S.I. Smith, 1874 are described from state of Jalisco, Mexico. Hyalella marysolae sp. nov. can be identified by the presence of small projections or carinae on pleonites 1−2, with the first antenna being composed of 12 articles and the second antenna being composed of 15 articles. The first maxilla bearing 2−3 distal pappose setae, and the propodus in male first gnathopod is hammer-shaped. Conversely, in H. morronei sp. nov., dorsal projections or carinae are absent on pleonites 1−2, with the first antenna being composed of 10 articles and the second antenna of 14 articles. The first maxilla always bears two distal pappose setae, and the propodus in male first gnathopod is hatchet-shaped. Both species are distinguishable from other Hyalella species found in Mexico by the second antenna. In these two species, the second antenna is approximately half as long as the total body length, and the peduncle comprises 14 −15 articles; whereas, in other Mexican species, it is shorter and composed of maximum 12 articles. Here, we add two species to the four previously described in Mexico as it is necessary to increase the knowledge of the alpha taxonomy of this group of crustaceans and compensate for the biodiversity of the genus being underestimated.

Abstract Revised diagnoses are given for the mysid genus Parapseudomma Nouvel and Lagardère, 1976, and its type species Parapseudomma calloplura (Holt and Tattersall, 1905) from the Northeast-Atlantic, Mediterranean and waters off Japan, depth range 94-1200 m. Parapseudomma stenurum n. sp. from the sea floor off Cape Verde Islands and the Angola Basin, depth range 3825-5460 m, is described as the second species of its genus. It differs from the type species mainly by an unsegmented antennal scale, the carpus of thoracic endopods 3-8 separated from the propodus by a transverse articulation, the digitus mobilis of the right mandible reduced to a slender spine, and by a more slender telson. Reduction of the right digitus is also found in Abyssomysis and Xenomysis, the latter with potential genetic affinity to Parapseudomma. The three genera also share reduced eyes as in many other deep-sea Erythropinae. Both species of Parapseudomma share recently detected, probably sensorial structures: a pit-like depression here named 'antennular bursa', dorsally on the basal segment of the antennula, and a median 'eye-cyst' inside the fused 'eye-bar', the cyst opening to the surface by a duct. The evidence in Parapseudomma raises expectations that these sensorial organs are potentially present in a great variety of Erythropinae taxa.

Abstract Evidence is provided to support the synonymy of two species of sand crabs (Anomura: Albuneidae). Zygopa lalanai Ortiz, 2015 is a synonym of Zygopa michaelis Holthuis, 1961 and Lepidopa boykoi Ortiz, Tello-Musi and Morales-Moreno, 2018 is a synonym of Lepidopa benedicti Schmitt, 1935. Each of the recently described species was based on a single specimen collected well within the range of their respective senior synonyms.