Cytogenetics
Guides
Aclerda
flat grass scales
Aclerda is a genus of scale insects (family Aclerdidae) commonly known as flat grass scales. Species in this genus are legless as adults, with strongly reduced 1-segmented antennae and a unique anal apparatus. They inhabit leaf sheaths of grasses in hot, dry regions. The genus includes both sexually and parthenogenetically reproducing species, with unusual cytogenetic systems including heterochromatinization of one haploid chromosome set in males of some species.
Agallia constricta
Constricted Leafhopper
Agallia constricta is a leafhopper species in the family Cicadellidae, commonly known as the Constricted Leafhopper. The species has been documented across much of the eastern and central United States. It possesses distinctive cytogenetic characteristics, including holokinetic chromosomes with diffuse kinetochores distributed along the chromosome length rather than localized at a centromere, as demonstrated in cell line AC-20 studies. This chromosomal architecture results in unique mitotic behavior where chromatin moves as unified plates during anaphase.
Boreonectes
Boreonectes is a genus of small predaceous diving beetles established by Angus in 2010, comprising approximately 16 described species. The genus was separated from Deronectes based on morphological and cytogenetic evidence. Species occur across North America, the Neotropics, and the Palearctic, with West European species showing distinct chromosomal differentiation despite minimal genetic divergence. These beetles occupy cold-water habitats including mountain lakes and barren pools, with some species extending to Arctic Scandinavia.
Brachystola magna
Plains Lubber Grasshopper, Western Lubber Grasshopper, Homesteader
Brachystola magna is one of the largest grasshoppers in North America, a flightless species inhabiting the Great Plains from the Canadian border to central Mexico. Adults reach 4–6 cm in length, with females substantially larger and heavier than males. The species exhibits a two-year life cycle, with eggs overwintering twice before hatching. Though primarily herbivorous, adults display notable omnivory including scavenging and predation on other insects. The species has historical scientific significance as the subject of Walter Sutton's pioneering work on reduction division and chromosome theory.
Chironomus atrella
Chironomus atrella is a non-biting midge species in the family Chironomidae, studied primarily through cytogenetic analysis of its polytene chromosomes. Research has clarified taxonomic confusion surrounding this name, which had been applied to at least two distinct species. Populations across North America show moderate to high chromosomal polymorphism, with heterozygosity ranging from 0.36 to 0.92 in different habitats. The species has been documented in both shallow freshwater environments and tidal coves.
Circotettix
Circotettix is a genus of band-winged grasshoppers in the family Acrididae, containing approximately 9-10 described species. The genus is notable for its cytogenetic characteristics, with several species studied for chromosomal variations that correlate with geographic distribution. Species within this genus are distributed across western North America, with records from Arizona, California, Colorado, Idaho, and Kansas. Some species, such as C. rabula, have been subjects of thermal behavior studies examining altitudinal variation.
Dendrotettix
Dendrotettix is a genus of spur-throated grasshoppers in the family Acrididae, containing at least three described species distributed in the southeastern United States. Species include the scrub pine grasshopper (D. australis), post oak grasshopper (D. quercus), and Carolina oak grasshopper (D. zimmermanni). Cytogenetic studies have identified chromosome numbers of 2n=23 (male) and 2n=24 (female) with an XO sex determination system, distinguishing this genus from related taxa such as Boonacris and Appalachia.
Enchenopa latipes
wide-footed treehopper
Enchenopa latipes, commonly known as the wide-footed treehopper, is a species of treehopper in the family Membracidae. It is characterized by an enlarged, inflated pronotum typical of the family, which often resembles plant thorns or buds. The species has been documented in field observations on goldenrod stems in the Ozarks and adjacent regions. Males possess a unique XX-X0 sex determination system with a univalent X chromosome that exhibits distinctive segregation behavior during meiosis, segregating intact toward one spindle pole in late anaphase I after autosomes have initiated movement.
Heteropeza pygmaea
A minute gall midge (family Cecidomyiidae) described from Europe in 1846. The species has been studied extensively for its unusual cytogenetics and developmental biology, particularly its paedogenetic reproduction and dramatic chromosome elimination during early embryogenesis. Germ-line cells contain approximately 58 chromosomes, but somatic nuclei retain only 10 chromosomes through programmed elimination of E-chromosomes during cleavage.
Loxa viridis
Loxa viridis is a stink bug species in the family Pentatomidae, characterized by holocentric chromosomes with a diploid number of 2n = 14 (12A + XY). The species exhibits inverted meiosis for sex chromosomes and has been studied cytogenetically from specimens collected in Brazil. Its distribution spans the Caribbean, Middle America, North America, South America, and the Galápagos Islands.
Marinarozelotes barbatus
A ground-dwelling spider species in the family Gnaphosidae, first described by L. Koch in 1866. The first cytogenetic analysis of this species was conducted on specimens from Turkey, revealing a diploid chromosome number of 2n♂=22 with an X1X20 sex chromosome system. All chromosomes are telocentric, with X1 being the largest and X2 the smallest chromosome in the karyotype. Sex chromosomes exhibit positive heteropycnosis during prophase I of meiosis. The species has a broad native distribution across the Mediterranean to Caucasus region and has been introduced to the USA.
Paratylotropidia brunneri
Brunner's grasshopper
Paratylotropidia brunneri is a species of spur-throated grasshopper in the family Acrididae, first described by Scudder in 1897. The species has been the subject of cytogenetic study due to its unusual chromosome structure, with 19 chromosomes in diploid male cells including four V-shaped multiples. It is found in North America, primarily in the north-central United States.
Physocyclus
cellar spiders
Physocyclus is a genus of cellar spiders (family Pholcidae) established by Eugène Louis Simon in 1893. The genus comprises 38 recognized species distributed across multiple continents, with the highest diversity in Mexico. Two distinct species groups are recognized: the globosus group (11 species) and the dugesi group (21 species), distinguished by morphological and biogeographic patterns. The type species, P. globosus, has been widely introduced globally through human activity.
Podismini
spur-throated grasshoppers
Podismini is a tribe of spur-throated grasshoppers within the subfamily Melanoplinae of the family Acrididae. It is distinguished from other Melanoplinae tribes by a cosmopolitan northern hemisphere distribution, with substantial representation outside the Americas. The tribe comprises approximately 12 genera and at least 20 described species, organized into four subtribes (Miramellina, Podismina, Tonkinacridina) and one genus group (Bradynotae). Members are characterized by winglessness or reduced wings in many species, particularly in montane and temperate lineages.
Rhionaeschna
blue-eyed darners, Neotropical Darners
Rhionaeschna is a genus of dragonflies in the family Aeshnidae, commonly known as blue-eyed darners or Neotropical darners. The genus contains approximately 42 species distributed across the Americas from southern Canada to southern Argentina, with the greatest diversity in the Neotropics. Notable exceptions to this range include a complete absence from the Amazon basin. The genus exhibits remarkable cytogenetic diversity, with multiple sex chromosome systems documented across species.
Rhyparochromini
dirt-colored seed bugs
Rhyparochromini is a tribe of dirt-colored seed bugs within the family Rhyparochromidae, representing the most diverse tribe in its family with over 40 genera and 360 described species. Members are characterized cytogenetically by the presence of a pair of microchromosomes (m-chromosomes) and an XY/XX sex chromosome system. The tribe exhibits highest diversity in the Afrotropical, Palearctic, and Oriental biogeographic regions.
Spartocera batatas
Giant Sweet Potato Bug, Giant Sweetpotato Bug
Spartocera batatas is a large leaf-footed bug in the family Coreidae, commonly known as the giant sweet potato bug. The species has been subject to detailed cytogenetic study, revealing a complex karyotype with multiple sex chromosomes. It occurs across the Caribbean, Central America, and South America.