Annotated checklist and keys for cumaceans (Crustacea: Peracarida) from the Tropical Eastern Pacific, with six new species from the Southern Mexican Pacific.

In the Tropical Eastern Pacific (TEP) 23 species of cumaceans are known, however none of these species has been previously registered in the southern Pacific coast of Mexico. The examination of 378 specimens resulted in six new species, belonging to two families and five genera, Coricuma zurai sp. nov., Cyclaspis boquillensis sp. nov., Cyclaspis hyalinus sp. nov., Cumella (Cumewingia) carmeinae sp. nov., Elassocumella krakeri sp. nov. and Nannastacus corallinus sp. nov. The genus Coricuma Watling & Breedy, 1988, increases its geographical range from Costa Rica to Mexico, and a second species is described. Recorded for the first time in the Eastern Pacific are the genera Elassocumella Watling, 1991 and Nannastacus Bate, 1865. An annotated checklist and illustrated key to all species of cumaceans recognised from the Tropical Eastern Pacific are included.

Taxonomic insights into Panopeuslacustris Desbonne (Crustacea, Decapoda, Brachyura) based on morphological and molecular data.

The genus Panopeus belongs to the family Panopeidae and comprises a group of brachyuran crabs native to the American continent (except for P.africanus). However, taxonomic problems related to the presence of cryptic species have made it difficult to recognize the species and advance the biological knowledge of this group. Herein, a detailed description based on morphological and molecular data is provided for the species P.lacustris for the first time. Additionally, new morphological characters are proposed for the discrimination of the species. It is strongly suggested to increase the knowledge of the gene pool of the group, explore new morphological characters, and update the species descriptions to advance the group's knowledge. This proposal will serve as a reference for future studies aimed at clarifying the taxonomic, conservation and ecological status of the species of Panopeus.

Chondrochelia Gutu, 2016 (Crustacea, Peracarida, Tanaidacea, Leptocheliidae) from North America: new species, redescription and distribution using morphological and molecular data.

Until now, four species of the genus Chondrochelia Gutu, 2016 have been recorded from America. Using morphological and molecular data, we were able to recognize and describe two new species, Chondrochelia caribensis sp. nov. from the Mexican Caribbean and Chondrochelia winfieldi sp. nov. from the Gulf of Mexico. We found significant genetic divergence values between species based on the nucleotide sequences of cytochrome oxidase subunit I to support the morphological data. Also, the range of distribution of two species: Chondrochelia mexicana (Jarquín-González, García-Madrigal & Carrera-Parra, 2015) and Chondrochelia ortizi (Jarquín-González, 2016), were expanded within their described geographic regions. In contrast, the supposed distribution of the Brazilian C. dubia in the Mexican Caribbean and the Gulf of Mexico was rejected. Additionally, Chondrochelia algicola (Harger, 1878) was redescribed based upon type material. Minute details and ornamentation of some structures of three species were examined using SEM.

Redescription of Hargeria rapax (Harger, 1879) and description of H. chetumalensis a new species from the Mexican Caribbean (Crustacea, Peracarida, Tanaidacea, Leptocheliidae) based upon morphological and molecular evidence.

Until now, Hargeria was considered a monospecific leptocheliid genus, with the species Hargeria rapax considered a taxon with a wide distribution, from the Northwestern Atlantic to the Mexican Caribbean. Herein, after a detailed revision of type and topotype materials and specimens collected from the Mexican Caribbean, a new species H. chetumalensis sp. nov. is described, and the redescription of H. rapax is provided. Also, we found a significant genetic divergence between the two species based on the nucleotide sequences of cytochrome oxidase subunit I, which support the morphological data. The morphological features used to recognize both species are also adequate to link males, females, and juvenile stages, although these species have a high intraspecific polymorphism.

First species of Leptochelia Dana, 1849 (Crustacea: Tanaidacea) from the Eastern Pacific, with an annotated checklist and identification keys for the genus.

Forty three species of leptocheliids are known worldwide. In the American region only eight species have been described from the Western Atlantic, while for the Eastern Pacific none have been described, suggesting that the diversity of this family has been severely underestimated in this region. Here we describe the first species of Leptochelia from the Eastern Pacific, Leptochelia mexicana n. sp., which is characterized by the males having a spiniform seta on the second segment of uropodal endopod, a novel feature for the genus. In addition, the first annotated checklist and a taxonomic key with illustrations for Leptochelia species are included. The list includes the type locality, type depository, distribution, habitat and, in some cases, remarks.

A new species of Peltidium Philippi, 1839 (Crustacea, Copepoda, Harpacticoida) from the Pacific coast of Mexico.

During the analysis of phytal meiobenthic samples collected from a rocky-sandy beach in the state of Nayarit, in the Mexican Pacific, several specimens of harpacticoid copepods were obtained and taxonomically examined. These specimens were found to represent an undescribed species of the peltidiid genus Peltidium Philippi, 1839. The new species, Peltidium nayarit sp. n. is described herein. It resembles Peltidium nichollsi Geddes and Peltidium lerneri Geddes from Bahamas but also the widespread Peltidium speciosum Thompson & Scott and Peltidium purpureum Philippi. The new species from the Mexican Pacific differs from its known congeners by its possession of a unique combination of characters, including a modified pectinate seta on the antennary exopod, three terminal setae on the second endopodal segment of leg 1, third exopodal segment of leg 1 with three elements, inner terminal claw twice as long as outer claw, female fifth leg with 5 exopodal setae, exopodal setae I-III stout, spinulose and seta IV being as long as seta V. This is the second species of the family known to be distributed in the Eastern Tropical Pacific and in Mexico. Pending additional data, the distribution of this species appears to be restricted to this area of the Mexican Pacific.