Male-dimorphism
Guides
Batrisodes
gargoyle beetle, ant-loving beetle
Batrisodes is a genus of myrmecophilous rove beetles in the family Staphylinidae, subfamily Pselaphinae. The genus contains at least 80 described species distributed across North America, Europe, and Asia. Males of many species exhibit highly modified facial structures with horns, spines, shelves, or cavities, earning the group the informal name 'gargoyle beetles.' Species are primarily associated with ants, though specific ecological relationships remain poorly documented for most taxa.
Centris pallida
Pallid Desert-Digger, digger bee, desert bee, pallid bee
Centris pallida is a solitary desert bee native to the Sonoran Desert region of North America. Males exhibit two distinct morphs associated with alternative reproductive tactics: large patrollers that use olfactory cues to locate buried virgin females near the ground, and small hoverers that use visual cues to find females above vegetation. The species has evolved remarkable thermal adaptations to survive extreme desert temperatures, including high thoracic conductance and dorsal solar reflectance in large-morph males. Long-term studies document a persistent decline in male body size since the 1970s, with potential consequences for the stability of alternative reproductive tactics.
Empis geneatis
dance fly
Empis geneatis is a species of dance fly in the family Empididae, first described by Melander in 1902. It belongs to the subgenus Enolempis within the genus Empis. Males of this species exhibit distinctive leg modifications: an opposing pair of large teeth on each side of the "knee" joint on the hind leg, a character absent in females. The species is part of a diverse group of predatory flies known for their elaborate courtship behaviors.
Eucera cordleyi
Cordley's Long-horned Bee
Eucera cordleyi is a species of long-horned bee in the family Apidae, first described by Viereck in 1905. Like other members of the genus Eucera, males are characterized by exceptionally long antennae. The species occurs in North America and is part of the Eucerini tribe, which includes important pollinators of agricultural crops such as cucurbits. Specific ecological details for this species remain poorly documented.
Gnatocerus guatemalensis
Gnatocerus guatemalensis is a species of darkling beetle in the family Tenebrionidae. The genus Gnatocerus is known for species with enlarged mandibles in males, which function as weapons in male-male combat for mating opportunities. This species is native to Mexico and belongs to a genus closely related to the well-studied flour beetle Tribolium.
Jassa marmorata
Marbled Scud
A tube-building amphipod native to the northeast Atlantic Ocean, now introduced to northeast Asia. Distinguished by greyish coloration with reddish-brown markings and a maximum length of 10 mm. Notable for exhibiting two distinct male morphs with alternative mating strategies: larger 'major' males that fight for access to females, and smaller 'minor' males that sneak copulations. Constructs protective tubes from detritus and algae fragments bound with mucus secretions.
Kennethiella trisetosa
A mite species in the family Winterschmidtiidae, Kennethiella trisetosa exhibits male dimorphism and maintains a symbiotic relationship with the potter wasp Ancistrocerus antilope. The species inhabits the nests of its host wasp. Research has focused on its life history and the developmental and behavioral consequences of its two distinct male morphs.
Lispe tentaculata
A muscid fly with Holarctic distribution, widespread across the Palearctic from the Iberian Peninsula to Kamchatka. Males exhibit distinctive modified fore tarsi with brush-like setulae and a finger-like yellow process on tarsomere 1. The species inhabits riparian environments including river banks, pond margins, and forest streams. Taxonomic identification relies on male genitalic structures and specific leg chaetotaxy patterns.
Maevia
Dimorphic Jumping Spider (M. inclemens)
Maevia is a genus of jumping spiders (Salticidae) historically encompassing species from both the New World and Asia. The genus has undergone significant taxonomic revision, with most Asian species transferred to other genera. The best-studied species, M. inclemens, exhibits remarkable male dimorphism with two distinct morphs differing in appearance and courtship behavior.
Maevia albozonata
Maevia albozonata is a species of jumping spider in the family Salticidae, described by van Hasselt in 1882. The genus Maevia is notable for containing species with pronounced male dimorphism, though specific details for M. albozonata remain poorly documented. It belongs to a group of spiders characterized by excellent vision and active hunting behavior.
Maevia expansa
Maevia expansa is a species of jumping spider in the family Salticidae, described by Barnes in 1955. It belongs to a genus notable for pronounced male dimorphism, though specific details for M. expansa remain poorly documented. The species occurs in the United States, with records from North America. Information regarding its biology, behavior, and distinguishing characteristics is sparse compared to the well-studied congener Maevia inclemens.
Maevia inclemens
Dimorphic Jumping Spider
Maevia inclemens is a small jumping spider native to eastern North America, notable for its extreme male dimorphism. Adult males occur in two genetically determined morphs of equal frequency: a 'tufted' morph with an all-black body, white legs, and three cephalothoracic tufts, and a 'gray' morph with black-and-white striping and orange pedipalps. Each morph performs a distinct courtship display, and both achieve equal mating success. The species frequents vegetation, fences, and building exteriors.
Praestigia
Praestigia is a genus of sheet-weaving spiders (family Linyphiidae) described by Alfred Frank Millidge in 1954. The genus is distinguished by a unique male cephalic projection bearing a detachable cap composed of interconnected fibers bound with a waxy substance. Eight species are recognized, distributed across boreal and arctic regions of the Northern Hemisphere. The etymology combines Latin 'prae' (before/in front) and Greek 'stigios' (awl), referencing this distinctive projection.
Sancassania
Sancassania is a genus of mites in the family Acaridae containing more than 80 species. Many species are associated with fungi, particularly mushrooms, with some lineages having specialized to exploit this ephemeral resource. Other species are phoretic on beetles or occur in soil and decomposing organic matter. The genus includes economically significant species associated with agricultural crops and biocontrol systems.
Vespula atropilosa
Prairie Yellowjacket
Vespula atropilosa, the prairie yellowjacket, is a social wasp native to western North America. It forms annual underground colonies in prairie and grassland habitats, typically nesting in abandoned rodent burrows. Unlike scavenging yellowjackets, it is strictly predatory, hunting live insects to feed its larvae. The species exhibits male color polymorphism with xanthic (yellow) and melanic (black) abdominal variants.
Walckenaeria
dwarf spiders
Walckenaeria is a genus of dwarf spiders in the family Linyphiidae, first described by John Blackwall in 1833. The genus contains approximately 195-198 species as of 2020, distributed across multiple continents. Males in this genus exhibit distinctive eye morphology, with some species having eyes elevated on mounds, turrets, or stalks that can exceed the height of the carapace. Walckenaeria is a senior synonym of several previously described genera including Paragonatium, Wideria, and Cornicularia.
Winterschmidtiidae
Winterschmidtiidae is a family of over 140 mite species in the order Astigmata, distributed worldwide. The family comprises four subfamilies with distinct ecological specializations: Ensliniellinae associated with Hymenoptera (especially wasps and bees), Winterschmidtiinae with wood-boring beetles, Saproglyphinae with decaying materials and fungi, and Oulenziinae with leaves, vertebrate nests, and stored foods. Many species exhibit complex life cycles synchronized with insect hosts, including phoretic deutonymphs for dispersal and seasonal polymorphisms for environmental resistance.
Zygoballus rufipes
Hammer-jawed Jumping Spider
Zygoballus rufipes is a small jumping spider distributed from Canada through the United States to Central America. Adult females measure 4.3–6 mm in body length, while males are smaller at 3–4 mm. Males exhibit body-size dimorphism with two distinct size classes, a trait linked to alternative life-history strategies. The species was first described from Guatemala in 1885 and later synonymized with Z. bettini in 1980.