Gynandromorphism is one of the most striking sexual anomalies known in the animal kingdom. In a strict descriptive sense, a gynandromorph displays a mosaic condition in which distinctly male and female structures occur in clearly separated parts of the body. This differs from intersexuality, in which individuals lack such discrete boundaries and instead show intermediate sexual traits throughout their anatomy. The distinction also reflects presumed underlying mechanisms. Gynandromorphs are usually interpreted as genetic chimeras composed of both male and female cell lineages, while intersexes are genetically uniform individuals whose unusual phenotypes arise from developmental disruptions driven by genetic or environmental factors. In practice, the two terms are often used inconsistently, which is why the authors of the new study favor a purely morphology-based classification that avoids speculative assumptions about developmental causes.

Sexual anomalies of this kind are not unique to crickets. Reports of gynandromorphism and intersexuality span at least fifteen insect orders, including beetles, flies, mayflies, true bugs, bees and wasps, butterflies and moths, mantises, dragonflies, stick insects, stoneflies, fleas, caddisflies, and zorapterans. Within Orthoptera, the order that includes crickets, grasshoppers, and katydids, such anomalies have been recorded in grasshopper families such as Acrididae, as well as in true crickets, camel crickets, pygmy grasshoppers, katydids, eumastacid grasshoppers, and trigonidiid crickets. Until now, however, no gynandromorph had ever been documented among the Phalangopsidae, the large family of spider-like crickets to which the new specimen belongs.

The remarkable individual was collected on 20 April 2025 during an active search inside Dos Dois Cave, located at coordinates 5°34’06.5″S, 37°40’50.4″W. The specimen, preserved in 70 percent ethanol and deposited in the Collection of Subterranean Invertebrates of Lavras at the Federal University of Lavras in Minas Gerais, was found alongside seven males and two females of the same species collected during the same sampling event. This concomitant collection proved crucial, because it allowed the researchers to compare the anomalous individual directly with normal males and females from the very same population. The cave record itself also represents a new geographical occurrence for the species, extending its known distribution within the cave systems of western Rio Grande do Norte.

The sexual dimorphism of Endecous potiguar made the anomaly immediately apparent. Adult males of the species possess a pair of superposed tegmina, the modified forewings that cover roughly half of the abdomen, along with a laterally symmetrical phallic complex characterized by a markedly elongated endophallic sclerite. Adult females, in contrast, are entirely wingless and bear an elongated, spear-shaped ovipositor composed of four valves, two dorsal and two ventral. The gynandromorph displays a conspicuous split: its right side shows predominantly male characteristics, including a well-developed tegmen, while its left side lacks a tegmen altogether, as observed in females of the genus, and instead bears an ovipositor.

But neither sexual apparatus is complete or functional. The male side carries an underdeveloped and malformed phallic complex, and the female side carries an ovipositor that is malformed and reduced, measuring only about two-thirds the length of a typical ovipositor, which in normal females ranges from 9.14 to 9.72 millimeters. The gynandromorph’s ovipositor consists of two left valves, an upper and a lower one, and just a single right valve that is shorter than the left and barely exceeds the paraprocts when viewed from the side. Even more revealing, closer examination of the terminal abdominal region uncovered ovipositor valves on both sides of the body, indicating that the male and female tissues are arranged in a more complex, patchy pattern than the apparent left-right split suggests.

To characterize the specimen in detail, the team employed a range of microscopy techniques. The right tegmina of the gynandromorph and of six normal males were removed to assess venation and the number of stridulatory teeth under a Zeiss Axio Lab.A1 microscope, and three adult males were dissected so that their phallic complexes could be cleared of muscle tissue using a pancreatin enzymatic solution over 24 hours. Notably, the researchers chose not to dissect the gynandromorph itself, preserving the natural arrangement of its internal organs for future comparative anatomical analyses. Measurements of body length, compound eyes, pronotum, tegmen, hind femora, hind legs, and ovipositor were taken for the anomalous specimen and compared with the conspecific males and females, and the gynandromorph was photographed using an Axiocam 506 camera mounted on a Zeiss Axio Zoom V16 stereomicroscope.

The acoustic apparatus of the gynandromorph yielded particularly interesting results. In male crickets, the stridulatory file on the tegmen, called the pars stridens, is used to produce the familiar chirping song. The gynandromorph’s right tegmen bears 53 stridulatory teeth, a value falling within the range observed in normal males from Dos Dois Cave, which averaged 59 teeth with a standard deviation of 6.39 and a range of 50 to 70. The venation pattern of the tegmen, with a mirror of three bifurcated, interconnected, arched crossveins and a harp with three weakly defined irregular crossveins, falls within the intraspecific variation seen in specimens from the same cave and in populations from other caves of the Apodi speleological group. Interestingly, the tooth counts recorded in males from Dos Dois Cave are lower than previously reported for the species, hinting at population-level variation worth further study.

How does such an individual arise? At first glance, the distribution of sexual traits suggests a bilateral gynandromorph, with the right side male and the left side female, the most common pattern reported in gynandromorphic Orthoptera. Previous researchers have discussed two cytogenetic theories that could explain bilateral gynandromorphism in the order: one involves the loss of an X chromosome in an XX zygote during the first cleavage division, producing one male and one female cell lineage; the other involves the fertilization of a binucleate egg by two spermatozoa, one carrying an X chromosome and the other lacking it. However, the presence of ovipositor valves on both sides of the Brazilian specimen points to a mosaic or patchy arrangement of male and female tissues rather than a clean bilateral split, and the development of such mosaic patterns remains far less well understood. Untangling these mechanisms will require genetic, ontogenetic, and anatomical investigations into sex determination and cellular differentiation in Orthoptera, particularly in phalangopsid crickets.

The discovery also says something about where and why such rarities come to light. Endecous potiguar is abundant in Dos Dois Cave and in other caves throughout the region, its broad distribution across the subterranean environments of western Rio Grande do Norte likely reflecting dispersal through interconnected underground voids or episodic surface movements during the rainy season, when the harsh semiarid landscape above ground temporarily softens. Adults show conspicuous sexual dimorphism, making it easy to distinguish males from females and therefore easy to spot anomalous individuals. Both factors raise the probability of encountering rare phenotypes, so the researchers caution that this single record cannot be used to estimate the true frequency of gynandromorphism in natural populations. Still, the rarity of the condition is underscored by two decades of sampling in the region’s caves: across all that effort, only one gynandromorph has ever been found. Preserved intact, with its internal architecture untouched, this half-male, half-female cricket now awaits the next generation of studies into how the boundaries of sex are drawn, and occasionally broken, in the natural world.

Subject of Research: First record of gynandromorphism in a phalangopsid cave cricket

Article Title: Breaking sex boundaries: The first record of a gynandromorph in a phalangopsid cricket ( Orthoptera , Grylloidea , Phalangopsidae )

Article References: Mendes-Carvalho, P. H., & Ferreira, R. L. (2026). Breaking sex boundaries: The first record of a gynandromorph in a phalangopsid cricket (Orthoptera, Grylloidea, Phalangopsidae). Journal of Orthoptera Research, 35(2), 293-298. https://doi.org/10.3897/jor.35.193650

Image Credits: AI Generated

DOI: 10.3897/jor.35.193650

Keywords: gynandromorphism, crickets, Orthoptera, Phalangopsidae, Endecous potiguar, sexual dimorphism, cave biology, Brazil, entomology, sex determination, intersexuality, morphology