Cryptic-diversity
Guides
Acanthophrynus
tailless whipscorpion, whip spider
Acanthophrynus is a monotypic genus of tailless whipscorpions in the family Phrynidae, represented by the single described species Acanthophrynus coronatus. These arachnids inhabit deciduous tropical forests along the Pacific coast of Mexico and are among the largest known amblypygids. The sole species is capable of stridulation, producing an audible hiss by rubbing its chelicerae together when threatened. Genetic studies suggest that populations currently assigned to this single species may contain cryptic diversity equivalent to interspecific divergence in other genera.
Arenivaga apacha
Apache sand cockroach, desert cockroach, sand cockroach
Arenivaga apacha, commonly known as the Apache sand cockroach, is a species of desert cockroach in the family Corydiidae. The genus Arenivaga was revised in 2014, revealing extensive cryptic diversity with 39 new species described. Like other Arenivaga species, A. apacha exhibits dramatic sexual dimorphism, with males possessing fully developed wings and females being wingless. This species inhabits arid regions of southwestern North America, including Arizona and California.
Bisetocreagris
pseudoscorpion
Bisetocreagris is a genus of pseudoscorpions (family Neobisiidae) endemic to China, with many species adapted to cave environments. Members are characterized by small body size and relatively conservative morphology, making species-level identification challenging. The genus is concentrated in southeastern China, particularly in Guizhou Province, where stable cave microenvironments support narrow-range endemics. It serves as a model system for studying climate sensitivity in cave-dwelling arachnids, and research indicates its suitable habitat is highly threatened by projected climate change.
Branchinecta
fairy shrimp
Branchinecta is a genus of fairy shrimp (Anostraca) comprising approximately 50 species distributed across all continents except Australia. The genus includes the largest anostracan, Branchinecta gigas, reaching up to 10 cm in length, and the highest-altitude crustacean, B. brushi, recorded at 5,930 m elevation. Species occupy diverse temporary freshwater habitats from Arctic and Antarctic regions to high-elevation Andean pools. Two species, B. gaini and B. granulosa, have been synonymized based on molecular evidence showing insufficient genetic differentiation.
Brillia
Brillia is a genus of non-biting midges in the subfamily Orthocladiinae of the family Chironomidae. The genus exhibits remarkable cryptic diversity, with DNA barcoding studies revealing 30 Barcode Index Numbers and 158 unique haplotypes across 13 described species. East Asian and North American populations show complete genetic distinctness, suggesting long-term isolation. The larvae inhabit freshwater depositional zones and serve as sensitive bioindicators for ecosystem monitoring.
Caleremaeus
Caleremaeus is a genus of minute oribatid mites in the family Caleremaeidae. Its members are small enough that species boundaries can be difficult to see from external form alone: integrative work on the familiar European example Caleremaeus monilipes revealed five genetically distinct lineages associated with ecological and slight morphological differences. The genus includes documented Palaearctic and North American species, and its representatives have been found in substrates ranging from soil and litter to mosses, lichens, decaying wood, and algae. Fine structures such as prodorsal costulae, the notogastral shape, leg segments, and claws are important in specialist identification.
Caryocolum
Curved-horn moths
Caryocolum is a genus of small moths in the family Gelechiidae, commonly known as Curved-horn moths. The genus contains over 80 species distributed across the Palearctic and Nearctic realms, with the highest diversity in mountainous regions of Europe. Species are specialized feeders on plants in the carnation family (Caryophyllaceae), particularly genera such as Cerastium and Stellaria. The genus has been subject to intensive taxonomic revision due to high levels of cryptic diversity, with numerous species described in recent decades using integrative approaches combining DNA barcoding and morphology.
Cephennium
Cephennium is a genus of minute rove beetles in the family Staphylinidae, subfamily Scydmaeninae, first described by Müller and Kunze in 1822. The genus is predominantly western European in distribution but has been recorded across Europe, Northern America, the Middle East, and as far east as Kyrgyzstan. Recent taxonomic work has revealed substantial undescribed diversity, particularly in Turkey where 25 named species are now recognized. The genus has been introduced to North America via port cities, with C. gallicum documented from Halifax, Nova Scotia.
Charmon
Charmon is a genus of parasitoid wasps in the family Braconidae, subfamily Charmontinae, established by Haliday in 1833. The genus comprises 10 recognized species with a predominantly Holarctic distribution, though recent records extend its range to Southeast Asia. Charmon thailandensis, described from Doi Phu Kha National Park in Thailand, represents the first documented occurrence of the genus in Southeast Asia. DNA barcode data suggest that morphologically similar species may not be closely related, indicating potential cryptic diversity within the genus.
Darlingtonea kentuckensis
A troglobitic cave beetle endemic to eastern Kentucky karst systems. Adults measure 7.3–7.7 mm. The species exhibits surprisingly broad thermal tolerance (threshold ~20–24°C, mortality at 30°C within 24 hours), suggesting remnant physiological characteristics from epigean ancestors. However, it shows extreme specialization for constant high-humidity environments, with survival declining dramatically below 100% relative humidity and mortality within 3 days at 50–80% RH. Population densities can exceed 100 individuals per sand bank in suitable cave habitats.
Diplectrona
diplectronan caddisflies
Diplectrona is a genus of net-spinning caddisflies in the family Hydropsychidae, containing over 100 described species distributed across multiple continents. The genus exhibits considerable morphological diversity in both larvae and adults, with larvae inhabiting various lotic freshwater habitats. Recent studies have revealed cryptic diversity within currently recognized species, particularly in North America, suggesting the genus requires taxonomic revision. Species occur in Asia, Europe, North America, and other regions, with new country records continuing to be documented.
Eukoeneniidae
microwhip scorpions
Eukoeneniidae comprises genera such as Eukoenenia, Allokoenenia, and Koeneniodes, many of which inhabit subterranean environments including limestone caves and wet soil interstices. Species within the family exhibit varying degrees of troglomorphic adaptation, including appendage elongation and modification of lateral prosomal organs. Certain narrowly endemic cave-dwelling species are vulnerable to anthropogenic disturbances, and targeted surveys have shown they can be more regularly encountered in appropriate habitats than previously assumed.
Euphilotes pallescens
Pallid Blue, Pale Blue, Pallid Dotted Blue
Euphilotes pallescens is a small lycaenid butterfly endemic to the Great Basin region of western North America. Populations exhibit significant genetic and morphological differentiation among isolated mountain ranges, reflecting long-term isolation in sky-island habitats. The species has a complex evolutionary history involving periods of divergence and potential reticulation. Its restricted distribution and habitat specificity make it a valuable model for studying phylogeography in arid mountain systems.
Exosphaeroma
Spherical Isopods, marine pillbugs
Exosphaeroma is a genus of marine isopods in the family Sphaeromatidae, found in shallow ocean waters worldwide. The genus exhibits highest diversity in the Southern Hemisphere and is notably one of few sphaeromatid genera occurring in the southern reaches of the Southern Ocean. Recent taxonomic work has described new species from the northeastern Pacific, including one discovered in urban Los Angeles and another from 142-year-old Alaskan collections.
Haustoriidae
Haustoriidae is a family of amphipod crustaceans characterized by stout, robust bodies adapted for burrowing in sandy sediments. They are dominant members of intertidal and shallow subtidal sandy beach communities along the Atlantic coast of North America, with some species extending into the Gulf of Mexico and Pacific coast. The family radiated during the Eocene, with the Pacific-endemic genus Eohaustorius representing the most basal lineage, diverging approximately 31 million years ago. Haustoriidae are distinguished from other amphipod families by their specialized morphology for sand-burrowing and their limited dispersal capabilities, which have resulted in strong population structure and cryptic diversity across their range.
Hemiscorpiidae
Hemiscorpiidae is a family of scorpions whose included genus Hemiscorpius is documented across Africa and Asia, with a recognized diversity hotspot in southern Iran. The family has undergone taxonomic revision, having previously been called Ischnuridae and Liochelidae. Species delimitation within Hemiscorpius is complicated by morphological similarity and cryptic diversity, necessitating integrated molecular, morphometric, and ecological data. Many regional populations are endemic and restricted to specific habitats, making them vulnerable to environmental change.
Isotomurus
Isotomurus is a genus of elongate-bodied springtails established by Börner in 1903. The genus contains at least 40 described species and is classified in the family Isotomidae. Members are distributed across diverse habitats including desert, tropical, and polar regions. As with other springtails, they possess a furcula for jumping.
Karripurcellia
Karripurcellia is a genus of mite harvestmen in the family Pettalidae. It is endemic to tall, wet eucalypt forests in south-western Western Australia, within the Southwest Australian Floristic Region. The genus currently includes two accepted species, K. peckorum and K. sierwaldae, although genetic data indicate that additional cryptic diversity may be present. Its populations are geographically structured, with low apparent gene flow between many sampled localities.
Laevicaudata
clam shrimp
Laevicaudata is a suborder of small branchiopod crustaceans commonly known as clam shrimp, characterized by a laterally compressed bivalved carapace that encloses the entire body. The group contains approximately 36 described species in the single family Lynceidae, with the genus Lynceus as the primary representative. Laevicaudatans inhabit temporary freshwater habitats worldwide, with documented occurrences across six continents including remote insular locations. The group has been historically understudied compared to other large branchiopods, though recent taxonomic revisions have clarified species boundaries, particularly in Australia where six species are now recognized.
Leptonetidae
cave spiders
Leptonetidae is a family of small, primitive haplogyne spiders first described by Eugène Simon in 1890. The family comprises approximately 22 genera and 400 species, though taxonomic boundaries have been revised recently with elevation of Archoleptonetinae to family rank (Archoleptonetidae). Leptonetids are characterized by their small size (2-5 mm), reduced eye number, and adaptation to dark, moist microhabitats. They represent a relict fauna with origins dating to the Cretaceous period and exhibit complex biogeographic patterns across the Holarctic.
Microphotus
Microphotus is a genus of fireflies (family Lampyridae) in western North America. At least one undescribed species is known to exist, distinguished from described congeners by morphological and potentially genetic differences. The genus is poorly studied relative to more widespread firefly genera, and taxonomic revision is needed to clarify species boundaries.
Mycetaeidae
Mycetaeidae is a small family of beetles in the superfamily Coccinelloidea, established as distinct from Endomychidae based on morphological and molecular evidence. The family contains three genera: Agaricophilus (one species, Europe), Mycetaea (two species, North America, Europe, South Africa, and Canary Islands), and Afromycetaea (seven species, sub-Saharan Africa and Madagascar). The family is confirmed as monophyletic and sister to Cerasommatidiidae. Members of the genus Mycetaea are known to be mycophagous, feeding on molds.
Nemastoma
harvestman
Nemastoma is a genus of small harvestmen (Opiliones) in the family Nemastomatidae, first described by C.L. Koch in 1836. Species in this genus are litter-dwelling arachnids found primarily in Eurasia, with some introduced populations in North America. The genus includes species complexes with notable morphological diversity, such as the N. bidentatum complex, which exhibits extensive subspecific differentiation and parapatric distribution patterns in Slovenia. Several species have been documented as introduced to North America, including N. bimaculatum, which has established populations in Canada.
Neogoveidae
Neogoveid Harvestmen
Neogoveidae is a family of small, eyeless harvestmen (Cyphophthalmi) distributed across tropical regions of West Africa and the Neotropics. Members range from 1 to 4.5 mm in body length and exhibit distinctive morphological features including a heavily granulated dorsal scutum, laterally projecting ozophores, and variable adenostyle morphology. The family shows substantial undescribed diversity, with many species awaiting formal description.
Orthemis
An undescribed species in the dragonfly genus Orthemis, recognized as distinct from described congeners but not yet formally named. The genus Orthemis is part of the skimmer family Libellulidae, with most described species occurring in the Neotropical region. This taxon represents one of many insect species awaiting formal taxonomic description.
Parasitiformes
mites and ticks
Parasitiformes is a superorder of arachnids constituting one of two major mite lineages, alongside Acariformes. The group includes ticks (Ixodida), the highly diverse predatory and parasitic Mesostigmata, the small scavenging Holothyrida, and the large segmented Opilioacarida. Over 12,000 species have been described, with estimates of 100,000–200,000 total species. Recent phylogenomic analyses indicate Parasitiformes is more closely related to other chelicerates (spiders, scorpions, horseshoe crabs) than to Acariformes, challenging the traditional unification of all 'mites' as a single natural group.
Pselaphinae
Ant-loving Beetles, Short-winged Mould Beetles
Pselaphinae is a species-rich subfamily of rove beetles (Staphylinidae) containing approximately 9,000 to 10,000 described species. They are among the most diverse and abundant beetles in tropical and temperate forest leaf litter worldwide. The group was historically treated as a separate family Pselaphidae but was reclassified into Staphylinidae by Newton and Thayer (1995) based on shared morphological characters with the Omaliine group. Many species exhibit myrmecophilous associations with ants, and some groups such as Clavigeritae are obligate inquilines with extreme morphological specializations.
Pseudouroctonus
Pseudouroctonus is a genus of vaejovid scorpions established by H. L. Stahnke in 1974. The genus contains approximately 20 species distributed across the drylands and mountains of western North America. Members of this genus are notable for their stenotopic habitat requirements and have been subject to recent taxonomic revision using molecular methods, which has revealed substantial cryptic diversity. The genus includes the P. minimus complex, a group whose diversification patterns have been used to study the relative impacts of pre-Quaternary tectonics versus Pleistocene climate change on speciation.
Rhopalosiphina
Rhopalosiphina is a subtribe of aphids (Aphididae: Aphidinae) established by Mordvilko in 1914. It includes the genus Schizaphis and related taxa. A 2018 study of endemic New Zealand populations revealed exceptionally high mitochondrial DNA diversity within this group, with up to five distinct lineages identified from host plants Aciphylla and Dracophyllum.
Salmincola
Salmincola is a genus of freshwater parasitic copepods in the family Lernaeopodidae. These ectoparasites are common on salmonid fishes throughout the Northern Hemisphere. The genus exhibits substantial geographic variation in infection rates across water bodies, and current taxonomic definitions based on decades-old morphological descriptions may obscure cryptic diversity. Species in this genus are considered pests by fisheries management agencies due to their impact on host fish populations.
Schizidium
Split Pill Woodlice
Schizidium is a genus of terrestrial isopods in the pill-woodlouse family Armadillidiidae. Its broad “sensu lato” treatment has been reported from Greece east to Iran, although researchers have questioned whether that grouping is monophyletic. GBIF currently lists 29 species under the genus, while a 2023 study discussed 26 in its own taxonomic concept. Work on Cyprus revealed geographically distinct and partly cryptic lineages, including one confined to subterranean habitats.
Sternidius alpha
Alpha Long-horned Beetle
A longhorn beetle species in the family Cerambycidae, first described by Say in 1827. Exhibits multiple color variants across its broad North American range, which led to the description of several subspecies later synonymized under the current name. Molecular analysis of the cytochrome oxidase I gene has revealed three distinct clades among color morphs, suggesting potential cryptic diversity. The species remains taxonomically unsettled pending further study of additional color morphs from different localities.
Tapinella undescribed
An undescribed species within the fungal genus Tapinella, a group of ectomycorrhizal or saprotrophic bolete relatives in the family Tapinellaceae. As a formally undescribed taxon, it lacks a published species epithet and has not been characterized in peer-reviewed literature. Species in this genus produce fleshy, often fan-shaped or bracket-like fruiting bodies with porous undersurfaces rather than gills. The existence of this undescribed entity suggests ongoing cryptic diversity within Tapinella that awaits taxonomic resolution.
Unknown-genus barcode-antennae-fl
Unknown-genus barcode-antennae-fl is a provisional genus designation used in DNA barcoding studies for a Florida insect specimen with distinctive antennae characteristics. The genus has not been formally described in taxonomic literature, representing a known unknown in regional biodiversity surveys. It is recognized solely through molecular sequence data linked to morphological observations of the antennae.
Vaejovidae
Devil Scorpions
Vaejovidae is a family of scorpions comprising approximately 25 genera and over 230 species, with the common name 'Devil Scorpions.' The family is endemic to North America, ranging from western Guatemala through Mexico and into the western United States, with one species extending into the Appalachian Mountains. Members of this family occupy diverse habitats including desert playas, chaparral, pine-spruce forests at high elevations, and alkali sinks. Several species have been described recently from California, including new species discovered through community science platforms.
Valenzuela
lizard barklice
Valenzuela is a large genus of barklice in the family Caeciliusidae, commonly known as lizard barklice. The genus contains at least 300 described species, making it one of the most diverse genera within Psocodea. Some species are known from Eocene fossils in Poland and Russia, indicating a long evolutionary history. Members of this genus are small, winged or wingless insects that inhabit bark and leaf litter environments.