European Journal of Taxonomy

Tatarocyclops dayanae — a new hyporheic genus and species of Cyclopidae (Copepoda, Cyclopoida) from the European part of Russia

Aleksandr A. Novikov — 2026-08-21

A new genus and species of Cyclopidae (Copepoda, Cyclopoida) from the hyporheic zone of small rivers in Tatarstan (Russia) is described. The diagnosis of Tatarocyclops dayanae gen. et sp. nov. includes: female antennule 11-segmented; first to fourth swimming legs with two-segmented exopods and endopods; endopod of the fourth leg with two apical spines; and fifth leg two-segmented, not fused to the somite. The new genus shares a two-segmented fifth leg with Reidcyclops Karanovic, 2000, but differs from it and from other genera of the Mixocyclops Kiefer, 1944 group by the following combination: mandibular palp with one seta; maxilliped armature formula 2.2.1.2; first swimming leg basis with inner spine; spine formula of the second exopodal segments of the first to fourth swimming legs 2.3.3.3; third swimming leg without sexual dimorphism; fourth swimming leg endopod with two apical spines; and distal segment of the fifth leg with two setae. Among Cyclopidae with 9–11-segmented antennules, Tatarocyclops gen. nov. is distinctly separated by its unique combination of characters, especially the two-segmented fifth leg. The discovery of a stygobiotic cyclopid genus in the Middle Volga region aligns with recent findings of endemic amphipods in the same area and highlights a previously unexplored diversity of groundwater fauna, which is important for understanding the biogeography of Palearctic freshwater crustaceans.

Review of the bee subgenus Lasioglossum (Hemihalictus) in western North America (Hymenoptera: Halictidae)

Thilina Hettiarachchi — 2026-08-20

Sweat bees in the cosmopolitan genus Lasioglossum are some of the most diverse and commonly collected bees in terrestrial ecosystems. The bee subgenus Lasioglossum (Hemihalictus) has never been reviewed in western North America. A taxonomic study was conducted to assess the status and validity of species in this region. Twenty-two species of L. (Hemihalictus) are treated, five of which are described as new: L. angusticulum sp. nov., L. engleri sp. nov., L. opata sp. nov., L. pathiranae sp. nov., and L. tomentosum sp. nov. Linear discriminant analysis and partitioning around medioids were used to test species limits in the L. arizonense species complex. Lasioglossum vanduzeei (Sandhouse & Cockerell, 1924) stat. rev. is resurrected from synonymy with L. arizonense (Crawford, 1907). Two Palaearctic species are documented in North America: L. villosulum (Kirby, 1802) and L. buccale (Pérez, 1903). The male of L. subobscurum (Cockerell, 1895) is described for the first time. Additionally, several taxonomic synonymies are proposed: L. aspilurus (Cockerell, 1925) is recognized as a senior subjective synonym of L. humboldtense (Michener, 1936); within the L. nitidiusculum species group, L. diatretum (Vachal, 1904) is recognized as a senior subjective synonym of L. supranitens (Cockerell, 1919); L. ruficorne (Crawford, 1907) is considered a senior subjective synonym of L. vaporellum (Cockerell, 1910) and L. pulveris (Cockerell, 1930); and L. synthyridis (Cockerell, 1906) is considered a senior subjective synonym of L. inconditum (Cockerell, 1916). Updated keys to species are provided for the L. (Hemihalictus) bees of North America north of Mexico.

Integrative review of cis-Andean monadal coralsnakes of the genus Micrurus (Elapidae: Serpentes) reveals considerable overestimation of species diversity

Jorge H. Valencia — 2026-08-11

Coralsnakes of the genus Micrurus Wagler, 1824 contain approximately 89 species distributed from the United States to Argentina. The genus Micrurus comprises numerous species and presents important taxonomic challenges, particularly in lineages where morphological similarity among species complicates species delimitation. Many species have been described based on subtle morphological differences and/or inadequate molecular analyses. In this study, we focused on cis-Andean monadal coralsnakes using an integrative taxonomic approach that combines a multilocus dataset of mitochondrial (mtDNA) and nuclear (nDNA) gene fragments with morphological data, ecological niche models (ENMs), and extent of occurrence (EOO) analyses to assess species boundaries and infer phylogenetic relationships. Maximum Likelihood and Bayesian phylogenies revealed discrepancies between morphology-based taxonomy and molecular data. Among our findings, we support the junior synonymization of M. petersi Roze, 1967, M. peruvianus Schmidt, 1936, M. steindachneri (Werner, 1901), and M. tikuna Feitosa, Da Silva Jr., Pires, Zaher & Prudente, 2015, with M. ornatissimus (Jan, 1858), and of M. albicinctus Amaral, 1926, M. annellatus annellatus (Peters, 1871), M. a. balzani (Boulenger, 1898), and M. bolivianus Roze, 1967, with M. corallinus (Merrem, 1820). In contrast, our results confirm the distinctiveness of M. langsdorffi (Wagler, 1824) and M. medemi Roze, 1967 as separate evolutionary lineages, warranting their recognition as valid species. Multivariate analyses of morphometric traits showed limited differentiation among the three focal species in both sexes. Discriminant analysis of localities in environmental niche space showed an overall classification accuracy of 92.2%. The distributions of M. langsdorffi and M. ornatissimus broadly overlap, indicating sympatry, whereas both species are allopatric with respect to M. corallinus. Both occur between the Amazon and Negro rivers, whereas M. corallinus is distributed south of the Amazon River, with an isolated population in the Brazilian Atlantic Forest. These disjunctions are consistent with Wallace’s Riverine Barrier Hypothesis, suggesting river systems as major isolating factors. Micrurus medemi occurs along the eastern Andean foothills of Colombia. These results indicate that past morphology-based and/or organellar DNA-based taxonomic studies have overestimated species diversity. Our study highlights the importance of integrative taxonomy for accurately delimiting species and improving our understanding of the evolutionary history of monadal coralsnakes.

Biodiversity and palaeoecology of the Maastrichtian marine molluscs from the Paris Basin (France)

Didier Merle — 2026-08-07

Since the first half of the 19^th century, the limestones of Vertus Mont Aimé (Marne) and Bois d’Esmans (Seine-et-Marne) have been confused with the Danian pisolitic limestone and their malacological content has been the subject of partial lists. For the first time, the complete description of the malacofauna of these limestones is provided. Its study is based on recent samples (fieldtrips in 2014 and 2017) and a new examination of material collected by the previous authors. As a result, 57 taxa were recognised, including 31 formally identified species; nine species are in open nomenclature and the other taxa identified at the higher ranks. Among these, 14 species of gastropods, including a new genus and 5 species of bivalves, are newly described: ?Calliostoma monswavinarensis sp. nov., Sparnollonia bicarinata gen. et sp. nov., ?Tectus acmantensis sp. nov., ?Tectus fraterculus sp. nov., ?Tectus senarmonti sp. nov., ?Clypeostoma vertusensis sp. nov., Calliomphalus (Planolateralus) montenati sp. nov., Rhinoclavis parvisulcatus sp. nov., ?Vicinocerithium heberti sp. nov., Granulolabium cretaceum sp. nov., Haustator bergierensis sp. nov., Sveltella binkhorsti sp. nov., Fusinus bouchardae sp. nov., ?Pseudopisania cretacea sp. nov., Nucula bauti sp. nov., Arca (s. str.) submontensis sp. nov., Plicatula pacaudi sp. nov., Bathytormus sparnacensis sp. nov. and Chama loubryi sp. nov. This fauna was previously unknown from the Paris Basin or even from Northwestern Europe. With the exception of endemic taxa which are dominant, it shares significantly more species with the Maastrichtian of Limburg (28% of the assemblage) than with the Danian of the Paris Basin (9% of the assemblage). This allows it to be attributed to the Maastrichtian age, in accordance with other palaeontological data on ostracods, chondrichthyans, large benthic Foraminifera and mosasaurs discovered recently. The assemblages at Vertus and Mont Aimé indicate palaeoenvironments deposited under shallow waters (with some brackish elements), probably close to the coastline. Therefore, this study highlights the distinctive character of the faunal content of the limestones of Vertus Mont Aimé and Bois d’Esmans, which constitute a unique Maastrichtian formation in the Paris Basin and which can be called the Vertus-Mont Aimé-Esmans Formation.

Two new species and new country records of Eustigmaeus (Trombidiformes: Prostigmata: Stigmaeidae) in Japan

Satsuki Ikeda — 2026-08-06

The genus Eustigmaeus Berlese, 1910 contains over 140 known species distributed worldwide, including parasites of sandflies and moss-feeders. Here, we examine the taxonomic status of five previously unidentified species of Eustigmaeus from Japan. Two species with broad geographic ranges in Shikoku and Honshu islands are described as E. specialis sp. nov. and E. saxicola sp. nov. Eustigmaeus grandis Khaustov, 2019 is recorded for the first time in Japan and exhibits considerable morphological variation. The remaining two species are tentatively identified as E. cf. etruscus (Berlese, 1910) and E. cf. clavatus (Canestrini & Fanzago, 1876).

Four new species of the genus Psechrus Thorell, 1878 (Araneae: Psechridae) from Yunnan Province, China

Run Chen — 2026-07-24

Four new species of the genus Psechrus Thorell, 1878 are described from Yunnan Province, China: Psechrus luopingensis sp. nov. (♂♀), P. mingshengi sp. nov. (♂♀), P. cornutus sp. nov. (♂♀) and P. cordatus sp. nov. (♂♀). Detailed morphological descriptions, photographs of living specimens, and a distribution map of the new species are provided.

Taxonomic revision of the Phanaeus chalcomelas species group and a description of the new Phanaeus achilles species group (Coleoptera: Scarabaeidae: Scarabaeinae: Phanaeini)

Bruna Ribeiro Bordin — 2026-07-23

The Phanaeus chalcomelas species group includes coprophagous and necrophagous South American scarab beetles (Coleoptera: Scarabaeidae) that are widely distributed in the Amazon Basin and along the eastern slopes of the Andes. The group is characterized by the distinctly punctuated elytral striae and the black rugosities on the pronotum. It is composed of five species: Phanaeus chalcomelas (Perty, 1830); P. cambeforti Arnaud, 1982; P. meleagris Blanchard, 1845; P. lecourti Arnaud, 2000 and P. achilles Boheman, 1858. The P .chalcomelas group was revised based on the external morphology and the morphology of the medial endophallite, which are illustrated for the first time. We provide a new diagnosis of the P. chalcomelas group, along with updated geographical distribution maps and diagnosis of previously described species. The P. chalcomelas species group now comprises seven species: two new species described herein, one revalidated, and four previously described: P. cambeforti, P. chalcomelas, P. lecourti, P. meleagris, P. minos Erichson, 1847 stat. rev., P. divisor sp. nov., and P. mariocupelloi sp. nov. Based on morphological evidence and previous molecular studies, we propose the new Phanaeus achilles species group to include: P. achilles, P. arnaudorum sp. nov., and the subfossil species P. violetae Zunino, 2013.

Two new species of Cyclocephala Dejean, 1821 (Coleoptera, Melolonthidae, Dynastinae) with remarkably long antennal lamellae

Paulo R.M. Duarte — 2026-07-22

Cyclocephala everardoi Grossi, Santos & Almeida, 2016 and Cyclocephala machadoi Grossi, Santos & Almeida, 2016 comprise a distinct species group within Cyclocephala Dejean, 1821. This group was previously characterized by species with subtrapezoidal or parabolic clypeus, large eyes, antennae with long lamellae and parameres with a spine-like process on each lateroventral region. Here, two new species of the group are described from Brazil: Cyclocephala catimbauensis sp. nov., from the Caatinga biome in Pernambuco state, and Cyclocephala nhumirim sp. nov., from the Pantanal biome in Mato Grosso do Sul state. The new species are illustrated along with their differential diagnoses. An identification key and a distribution map for species of the group are provided. Additionally, a brief discussion on the characters that define the “machadoi” group is also presented.

Remarkable micro-endemism and high congeneric richness: eight new cave-restricted species of Pseudochthonius Balzan, 1892 (Pseudoscorpiones, Chthoniidae) from the Brazilian semi-arid

Lucas Guimarães — 2026-07-21

Eight new species of pseudoscorpions belonging to the genus Pseudochthonius Balzan, 1892 are described from the semi-arid region of Brazil. Comprehensive morphological descriptions, diagnostic characters, detailed illustrations, and ecological remarks of the habitats are provided for Pseudochthonius celestialis sp. nov., P. caritas sp. nov., P. patientia sp. nov., P. temperantia sp. nov., P. diligentia sp. nov., P. castitas sp. nov., P. humilitas sp. nov., and P. benignitas sp. nov. In addition, we present a brief discussion of the potential factors underlying the remarkable congeneric species richness observed in this geographically restricted region, as well as the principal threats faced by these species. These findings underscore the importance of conserving caves in order to protect their highly specialized fauna, with particular emphasis on the genus Pseudochthonius, which is increasingly recognized as strongly associated with subterranean environments.

Ghosts of subterranean waters: two new troglobitic species of Spelaeometra D. Polhemus & Ferreira, 2018 (Heteroptera: Hydrometridae) from Brazil, with remarks on the enigmatic species Cephalometra pallida D. Polhemus & Ferreira, 2018

Ingrid R. Serafim — 2026-07-20

Spelaeometra D. Polhemus & Ferreira, 2018 is a rare genus within the family Hydrometridae, currently composed exclusively of cave-dwelling species. Herein, we describe two new troglobitic species of this enigmatic genus from southwestern Bahia, Brazil: Spelaeometra ybykoara sp. nov. from the municipality of Carinhanha, and Spelaeometra iuiu sp. nov. from the municipality of Iuiú. The new species are primarily distinguished by diagnostic differences in the morphology of the male genitalia and, despite extensive sampling in surrounding caves, are currently known only from their respective type localities. Moreover the taxonomic descriptions, we provide new information on ecology, habitat characteristics, and potential threats affecting both species. Additionally, we present new remarks on Spelaeometra gruta Polhemus & Ferreira, 2018, and on the elusive, rarely collected species Cephalometra pallida D. Polhemus & Ferreira, 2018, providing new information on their natural history.