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Tick abnormalities have been unusual in nature, and they can be divided into local and general. In the present study, external morphological anomalies were described in 31 individual adult ticks of 15 different species of Ixodidae, which were collected on wild hosts (20 ticks), domestic hosts (7 ticks), and in the environment (4 ticks) in 11 states of Brazil from 1998 to 2022. Among the 31 tick specimens, 14 (45%) were categorized as local anomalies, and 17 (55%) as general anomalies. The ticks were taxonomically identified into 14 species of Amblyomma, and one species of Rhipicephalus. Local anomalies included malformations of scutum/alloscutum, ectromely, leg atrophy, and a third ectopic spiracular plate. General anomalies included opisthosoma duplication, no expansion of dorsal alloscutum in engorged females, and gynandromorphism; the latter is described for 13 tick specimens. Morphological anomalies in Amblyomma aureolatum, Amblyomma brasiliense, Amblyomma humerale and Amblyomma longirostre are reported for the first time. Although the results herein expand the list of anomalous tick species in the Neotropics, future studies should be conducted to clarify the origin of these anomalies.

We present a field-collected Hyalomma anatolicum gynandromorph in Xinjiang, China. Compared to the normal H. anatolicum, the gynandromorphic tick was a typical bipartite protogynander: half of the tick body displayed normal female traits, whereas the other side showed normal male traits. The engorged gynandromorphic tick laid hundreds of eggs, and the eggs looked normal. [ABSTRACT FROM AUTHOR]

Abstract Gynandromorphs are individuals that display both male and female features throughout the body and are rarely found in nature. We document and describe two new gynandromorphs of the large carpenter bee Xylocopa (Neoxylocopa) augusti reared from a trap-nest in La Plata, Buenos Aires, Argentina. In addition, based on a literature review, we assessed the frequency of the different types of gynandromorphs, and the body part affected, among large carpenter bees. Both gynandromorphs were assigned to the mixed category, the most common category reported in the literature (22 of 25 specimens). The remaining three specimens exhibit a bilateral pattern in all tagmata. The presence of both sexes’ secondary sexual characteristics occurred more frequently on the mesosoma than on the head or metasoma. Trap nests used in bee hotels promote the conservation and study of wild bees and might facilitate the discovery of rare cases of gynandromorphs that would remain unknown otherwise under normal nesting conditions in the wild.

The present study reports anomalies in Hyalomma dromedarii and Hyalomma rufipes adults collected from dromedary camels (Camelus dromedarius) in Aswan, Egypt, between January and June 2022. A total of 52 adult ticks displayed one or several local and/or general anomalies. A wide variety of local anomalies was observed including atrophy of one or multiple legs, ectromely, absence of accessory adanal and subanal plates, fusion of adanal and accessory plates, and presence of sclerotized formation in the ventral plate, as well as abnormalities of the spiracle, anal groove, festoon, parma, and posteromedian groove. General anomalies comprised of asymmetries and gynandromorphism. Local anomalies were documented among H. dromedarii and H. rufipes, whereas general anomalies were documented only from H. dromedarii. The present work represents the first report of deuterogynander intrigue gynandromorphism in H. dromedarii, as well as the first report of morphological abnormalities in H. dromedarii and H. rufipes from Egypt. [ABSTRACT FROM AUTHOR]

A gynander specimen belonging to the genus Dryinus Latreille, 1804 (Hymenoptera: Dryinidae) is described from Ecuador (Zamora Province). It has a female aspect, but with male genitalia, no chelae and no Antennal Dorsal Organs (ADOs). This is the first record of a gynander specimen of Dryininae. [ABSTRACT FROM AUTHOR]

New teratological cases including one gynandromorph and chromatic aberrations of Mutillidae are described based on the examination of 27 specimens belonging to Myrmilla (Pseudomutilla) capitata (Lucas, 1848), Myrmilla (Myrmilla) erythrocephala (Latreille, 1792), Myrmilla (Pseudomutilla) glabrata (Fabricius, 1775), Mutilla europaea Linnaeus, 1758, Mutilla quinquemaculata Cyrillo, 1787, Ronisia barbara barbara (Linnaeus, 1758), Ronisia brutia brutia (Petagna, 1787), Tropidotilla litoralis (Petagna, 1787), Nemka viduata viduata (Pallas, 1773), Physetopoda cf. pusilla (Klug, 1835), Smicromyrme giarabubensis Invrea, 1932, Smicromyrme partitus partitus (Klug, 1835), Smicromyrme perisii (Sichel & Radoszkoswski, 1870), Smicromyrme ruficollis ruficollis (Fabricius, 1793), and Smicromyrme ruficollis ceresae Invrea, 1952. A brief account of data from scientific literature, as well a discussion on the ascertained cases are provided. [ABSTRACT FROM AUTHOR]

We report and describe new Chirocephalus diaphanus Prévost, 1803 gynandromorphs from Tunisia and review the literature of anostracan gynandromorphy and other, possibly associated, somatic aberrations, with comments on their evolutionary significance. Our material has three specimens that are specifically deformed on the left side of the head. [ABSTRACT FROM AUTHOR]

ABSTRACT Gynandromorphism or intersexuality is a rare condition where the individual has male and female features. In this report we described two imagoes of Farrodes xingu Domínguez et al. (1996) from Brazil presenting intersex traits. We considered the arranged sexual characters as antero-posterior and bilateral. One individual has a male head, abdomen full of eggs and the subgenital plate with a malformed outset of penes (antero-posterior), while the other individual has half of the head with a male-like turbinate eye and the other half with a regular female-like one, and with malformed male genitalia (bilateral).

During a review of the Tick Collection of the Gorgas Memorial Institute of Panama, of 6,624 Ixodidae analyzed, 255 presented abnormalities. We detail morphological abnormalities and gynandomorphism in adults of 16 species: Amblyomma auricularium, A. calcaratum, A. dissimile, A. mixtum, A. naponense, A. cf. oblongoguttatum, A. ovale, A. sabanerae, A. tapirellum, A. varium, Dermacentor nitens, Haemaphysalis juxtakochi, Ixodes auritulus, I. tapirus, Rhipicephalus microplus, and R. sanguineus s.l. No abnormalities were found in A. coelebs, A. geayi, A. longirostre, Amblyomma nodosum, A. pacae, A. cf. parvum, A. pecarium, A. rotundatum, Dermacentor imitans, D. latus, D. panamensis, Haemaphysalis leporispalustris, I. affinis, I. bequearti, I. bocatorensis, I. boliviensis, and I. luciae. This represents the first findings of these phenomena in A. auricularium, A. calcaratum, A. naponense, A. ovale, A. sabanerae, A. tapirellum, A. varium, D. nitens, H. juxtakochi, I. auritulus, and I. tapirus. Local abnormalities were more frequent than general malformations. Amblyomma dissimile had the highest percentage of individuals with malformations, including specimens with two or more local abnormalities and gynandromorphism. It is possible that these malformations may go unnoticed or confused with loss appendages or mechanical damage. [ABSTRACT FROM AUTHOR]

A SUPPOSED bilateral gynandromorph Black Redstart Phoenicurus ochruros in northwestern Switzerland formed a pair with a phenotypically classical male, but apparently was not breeding. The bird was documented before and after moult, when all replaced feathers were again of the same sex type. It was also recorded singing, the song being typical for the species. This is the second recorded case of a bilateral gynandromorph Black Redstart, one of only a handful cases where wild bilateral gynandromorph birds have been observed throughout the breeding season, and the first unequivocal documentation of a presumed bilateral gynandromorph bird forming a stable pair with a typical male. [ABSTRACT FROM AUTHOR]

Tick abnormalities have been unusual in nature, and they can be divided into local and general. In the present study, external morphological anomalies were described in 31 individual adult ticks of 15 different species of Ixodidae, which were collected on wild hosts (20 ticks), domestic hosts (7 ticks), and in the environment (4 ticks) in 11 states of Brazil from 1998 to 2022. Among the 31 tick specimens, 14 (45%) were categorized as local anomalies, and 17 (55%) as general anomalies. The ticks were taxonomically identified into 14 species of Amblyomma, and one species of Rhipicephalus. Local anomalies included malformations of scutum/alloscutum, ectromely, leg atrophy, and a third ectopic spiracular plate. General anomalies included opisthosoma duplication, no expansion of dorsal alloscutum in engorged females, and gynandromorphism; the latter is described for 13 tick specimens. Morphological anomalies in Amblyomma aureolatum, Amblyomma brasiliense, Amblyomma humerale and Amblyomma longirostre are reported for the first time. Although the results herein expand the list of anomalous tick species in the Neotropics, future studies should be conducted to clarify the origin of these anomalies. [ABSTRACT FROM AUTHOR]

Malformations of crustaceans have been observed in their natural habitats as well as in laboratory studies. Two patterns of morphological abnormalities have been recorded in species of the brine shrimp genus Artemia , including a gynandromorphic pattern and a specimen with three compound eyes. Here we report a hitherto unknown pattern of morphological deformation, viz., a tumour-like abnormality that occurred in the telson skeleton of a specimen of Artemia from China. [ABSTRACT FROM AUTHOR]

Here we provide descriptions of gynandromorphs of two species oil-collecting bees: Lophopedia nigrispinis and Epicharis iheringii, both with partial bilateral phenotypic asymmetry. The bees have a female phenotype predominantly on mesosoma and metasoma. The specimen of L. nigrispinis has distinct characteristics on legs, suggesting a mosaic pattern of gynandromorphism. The pollen and oil loads on legs suggest that the bee was foraging normally. The gynander specimen of E. iheringii has mostly a female phenotype, except for head, with right half female type and left half male type. The specimen of L. nigrispinis was collected foraging on flowers of Bidens sp. at Parque Nacional Iguazú, Argentina with loads of pollen on legs suggesting it was reproductive and was provisioning a nest. The specimen of Epicharis iheriingi has no evidence of any oil or pollen collection, despite its mostly female phenotype. [ABSTRACT FROM AUTHOR]

A gynandromorph adult of the lawn ground cricket Polionemobius mikado (Shiraki, 1913) (Orthoptera: Trigonidiidae) was collected from a natural population. It had complete male forewings and a female ovi- positor at the end of abdomen. A normal male that encountered the gynandromorph performed a courtship song and tried to transmit a spermatophore, whereas a normal female was indifferent to the gynandro- morph. The gynandromorph showed aggressive behavior toward the normal male but not against the nor- mal female. The gynandromorph raised its forewings immediately after the antenna touched the body of the normal male and female, but no sound was produced. Overall, the gynandromorph behaved as a male, but was courted by conspecific males. Thus, the sexual identity of the gynandromorph was masculine, but sexual attractiveness was feminine. [ABSTRACT FROM AUTHOR]

Two new records of gynandromorphs in Xylocopa Latreille, 1802 (Hymenoptera, Apidae). Gynandromorphs are deviant morphological individuals with genetically distinct male and female tissues. Records of sex anomalies seems to be important to better understand the mechanisms regulating phenotypic expression. Herein, two new cases of gynandromorphs in carpenter bee species of Xylocopa from Brazil are described and figured: a mixed gynandromorph of the X. (Neoxylocopa) brasilianorum (Linnaeus, 1767) from São Paulo and a bilateral gynandromorph of the X. (Neoxylocopa) ordinaria Smith, 1874 from Sergipe. [ABSTRACT FROM AUTHOR]

We are concerned with the numerical approximation of the basic reproduction number R 0 , which is the well-known epidemiological threshold value defined by the spectral radius of the next generation operator. For a class of age-structured epidemic models in infinite-dimensional spaces, R 0 has the abstract form and cannot be explicitly calculated in general. We discretize the linearized equation for the infective population into a system of ordinary differential equations in a finite n -dimensional space and obtain a corresponding threshold value R 0 , n , which can be explicitly calculated as the positive dominant eigenvalue of the next generation matrix. Under the compactness of the next generation operator, we show that R 0 , n → R 0 as n → + ∞ in terms of the spectral approximation theory. [ABSTRACT FROM AUTHOR]

A systematic study of Perdita subgenus Procockerellia Timberlake and the related subgenus Allomacrotera Timberlake results in the synonymy of the latter with the former, and two specific synonymies: Perdita (Hexaperdita) glamis Timberlake is a junior synonym of Perdita (Procockerellia) stephanomeriae Timberlake, while Perdita (Procockerellia) brachyglossa Timberlake is a junior synonym of Perdita (Cockerellia) imbellis Timberlake. Perdita (Procockerellia) moldenkei Timberlake is moved to subgenus Cockerellia Ashmead. A revised subgeneric diagnosis and key to the three included species are provided. Diagnoses of species are updated with novel characters; distributions and biological data are expanded. A gynandromorph of P. (Procockerellia) moabensis Timberlake, the first known in the genus Perdita, is reported. [ABSTRACT FROM AUTHOR]

Morphological abnormalities in ticks seem to be very rare phenomena. In this paper, we describe interesting anomalies in adult Dermacentor reticulatus collected as questing ticks by flagging as part of a tick-borne encephalitis program in Battaune, Federal State of Saxony, Germany, at the end of September 2016. The observed anomalies in the three D. reticulatus adults were: general anomalies (gynandromorphism) and local anomalies (malformation of capitulum and abnormalities of appendages). One D. reticulatus specimen displayed gynandromorphism, the presence of both male and female features within the same organism. One female showed abnormal morphology of right palp, while also missing the right porose area, and multiple atrophied extremities: i.e. of the right leg IV and of the left legs III and IV. The third specimen, a male, presented an atrophied extremity of the right leg III (meiomely). This is the first report of complete mosaic type gynandromorphism in a flagged D. reticulatus and the first report of morphological abnormalities in D. reticulatus in Germany. [ABSTRACT FROM AUTHOR]

Copyright of SHILAP Revista de Lepidopterologia is the property of Sociedad Hispano-Luso-Americana de Lepidopterologia and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The Municipal Zoo of Guarulhos, located in the state of São Paulo, receives and recovers wild animals from the Guarulhos municipality and from some neighboring municipalities. Between the years of 1997 and 2016 ticks were collected on wild animals (Cariama cristata, Buteo brachyurus, Alouatta guariba, Bradypus variegatus, Tamandua tetradactyla, Puma concolor, Cerdocyon thous, Nasua nasua, Mazama gouazoubira, Didelphis aurita, Sphiggurus villosus, Myocastor coypus, and Hydrochoerus hydrochaeris) attended by the Zoo. The following tick species have been identified: Amblyomma aureolatum (Pallas, 1772), Amblyomma calcaratum Neumann, 1899, Amblyomma dubitatum Neumann, 1899, Amblyomma longirostre (Koch, 1844), Amblyomma nodosum Neumann, 1899, Amblyomma parkeri Fonseca and Aragão, 1952, Amblyomma sculptum Berlese, 1888, Amblyomma varium Koch, 1844, Haemaphysalis juxtakochi Cooley, 1946, Ixodes loricatus Neumann, 1899, and Rhipicephalus sanguineus sensu lato (Latreille, 1806). Although all tick-host associations have previously been reported in Brazilian territory, the present study records for the first time a gynandromorph of A. dubitatum. [ABSTRACT FROM AUTHOR]

Catasticta fulva anaranjada n. ssp. is described from Peru. In addition, the females belonging to Catasticta fulva Joicey & Rosenberg, 1915, Catasticta philone ecuadora Brown, 1939 and Catasticta tamsa yanganza Eitschberger & Racheli, 1998 are figured for the first time, and bilateral and mosaic gynandromorphs of Catasticta teutamis epimene (Hewitson, 1870) are illustrated. Finally, the status of Catasticta zamorana Eitschberger & Racheli 1998 stat. rev. and the distribution of Catasticta frontina muehlei Eitschberger & Racheli 1998 are revised. [ABSTRACT FROM AUTHOR]

The articled discusses the gynandromorphism in Megachile Latreille, wherein Leica M125 stereomicroscope and photographs has been used to study the external morphodlogical structures. It mentions the body description of the gynandromorph and that it belong to 32 genera distributed among all bee families.

Of 18,667 ticks examined, 33 specimens from species identified as Haemaphysalis parva, Hyalomma marginatum, Hy. scupense, Rhipicephalus bursa and Rh. turanicus were found to have external morphological anomalies. Anomalous Ha. parva, Hy. scupence and Rh. turanicus were reported in this study for the first time. General anomalies manifested as asymmetry and deformations of the idiosoma, whereas local anomalies occurred in legs, exoskeleton, spiracular, adanal, subanal and accessory plates, mouthparts and capitulum. With this study describing a gynandromorphic Hy. marginatum, the number of gynandromorphic tick cases has been raised to two in Turkey. [ABSTRACT FROM AUTHOR]

Copyright of Revista Colombiana de Entomología is the property of Universidad del Valle and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

As a phenomenon, androgyny is an ability to display both male and female characteristics in human identity through dress, ornaments, speech, body language and actions. Traditionally, androgynous behaviour is seen as a breach of standards of sexual norms and values, and gender-specific behaviour, and consequently, condemned and discouraged, but throughout human history, androgynous practices have existed in many cultures and religious traditions, wherein transformation of gender is viewed as a source of spiritual awakening. It exists as a symbolic practice in sufi culture, and is particularly associated with the socially non-conformist male sufis who take on the persona of women. Cross-dressed pilgrims can be seen at some of the sufi shrines as well. In South Asia, its most glaring example is Shaykh Musa 'Sadā Suhāg' (d. 1449) of Gujarat, who always dressed up as a female and wore female ornaments. However, some of the male sufis only occasionally adopted a feminine persona. Such androgyne sufis try to transcend normative gender categories, and redefine the concept of masculinity. Historically, some of them enjoyed popular esteem. Their androgynous behaviour was a metaphorical practice, which symbolized the idea of God's bride. In other words, it was a practical manifestation of that very idea. [ABSTRACT FROM AUTHOR]

This note brings, for the first time, findings obtained through both morphological and genetic analyses of a gynander orchid bee ( Euglossa melanotricha). For the genetic analysis, microsatellite markers were used to genotype the gynander bee. The morphological analysis revealed that the individual studied had a sting, and most parts of the insect body showed female phenotype, except for the three left legs. As in other reports on gynanders of orchid bees, the specimen of E. melanotricha analyzed herein was included in the category of mixed (or mosaic). From the seven microsatellite loci amplified, five were heterozygous for both male and female tissues, indicating that the organism analyzed is compatible with a diploid organism and not with a hemizygous or haploid one. Both the morphological and genetic characteristics of the gynander of E. melanotricha analyzed reveal that this specimen shows predominantly female characteristics. In parallel, when considering the genetic uniformity of phenotypically different tissues (male and female) of this individual, the gynandromorph of E. melanotricha would be, in fact, an intersex bee. [ABSTRACT FROM AUTHOR]

Gynandromorphic ticks are extremely rare, and often attract parasitologists' attention. During our examination of tick specimens, an engorged gynandromorph of Hyalomma asiaticum was noticed. This is the first record of gynandromorphic ticks from China. In this study, several important morphological structures of normal and gynandromorphic H. asiaticum were analyzed. Comparing to the normal H. asiaticum, the gynandromorphic specimen was a typical bipartite protogynander. Its right side showed normal female characteristics, whereas the left side had normal male traits. Different from other gynandromorphic ticks containing 1 anus, this tick reported here had 2 complete anuses, and the anus of the male part had a single adanal plate. [ABSTRACT FROM AUTHOR]

In the present note, we describe in detail an aberrant anomalous specimen of the scorpion Mesomexovis punctatus (Karsch, 1879) (Vaejovidae). This strange individual is an adult and exhibits a combination of hermaphroditism, gynandromorphism, and pectinal duplication (i.e., presence of four pectines); the latter represents the first report ever made of such teratology. It was collected by the authors in northeastern Guerrero State, Mexico. [ABSTRACT FROM AUTHOR]

We describe behavioral observations of a bilateral gynandromorph Northern Cardinal ( Cardinalis cardinalis) in northwestern Illinois from December 2008 through March 2010. The bird exhibited the typical bright red color of a male cardinal on the left half of its body, and the dull brownish-gray appearance of a female cardinal on the right half. We observed the bird more than 40 days, mostly in the vicinity of bird feeders. It was never paired with another cardinal, was never heard vocalizing, and was not subjected to any unusual agonistic behaviors from other cardinals. These observations are among the most extensive of any bilateral gynandromorph bird in the wild. [ABSTRACT FROM AUTHOR]

The brown moth Thyrinteina arnobia (Stoll, 1872) (Lepidoptera: Geometridae) is an important pest in Brazilian eucalyptus plantations. A gynandromorph individual of T. arnobia was found in a population of this pest in a laboratory rearing and it is described.A mariposa marrom Thyrinteina arnobia (Stoll, 1872) (Lepidoptera: Geometridae) é uma praga importante em plantios de eucalipto no Brasil. Um indivíduo ginandromorfo de T. arnobia foi encontrado em uma população desta praga em criação de laboratório e descrito nesta nota.

The article focuses on the unusual sighting of four Orange-tip Anthocharis cardamines butterflies in Cambridgeshire, England, which otherwise are found in ones or twos. Topics discussed include physiology observation of the insect included mixed gynandromorph, courtship and mating behavior of insects of the Pieridae species, and chart on appearance of male and female butterflies.

A bilateral gynandromorph specimen of the tarantula Pterinochilus murinus Pocock, 1897 is here described and illustrated. In addition, encounters with conspecific females were studied. The possible explanations for this case of gynandry are discussed. This constitutes the first formal report of gynandry in a mygalomorph spider. [ABSTRACT FROM AUTHOR]

Four specimens with gynandromorphism were found among 1500 adult ticks ofHyalomma marginatum marginatumKoch, 1844 from a laboratory colony maintained at 20 ± 1°C and relative humidity of 65 ± 5% and fed on tick-naive rabbits. Mosaic partial dorsal, asymmetric unilateral dorsal, and asymmetric unilateral ventral gynandromorphism were detected in the abnormal ticks. Such anomalies are very rarely noticed in ticks. [ABSTRACT FROM AUTHOR]

Sawflies are important pests of various plant species. Diprion pini (L.) and Neodiprion sertifer (Geoffroy) (Hymenoptera: Diprionidae) are two of the most important sawfly pests in Italy, and both species are parasitized by the hymenopteran parasitoid Dahlbominus fuscipennis (Zetterstedt). Bacterial endosymbionts are currently studied for their high potential in strategies of biocontrol in a number of insect species. In this study, we investigated the presence of symbiotic bacteria (Wolbachia and Cardinium) in the three species of hymenoptera mentioned earlier, both in wild and laboratory populations. Although all samples were negative for the presence of Cardinium, 100% prevalence for Wolbachia was detected, as all examined individuals resulted to be PCR positive. Furthermore, 16S rDNA and ftsZ gene sequencing indicated that all individuals from the three hymenopteran species are infected by a single Wolbachia strain. Additionally, we report the presence of gynandromorphic individuals in D. pini, both in wild and laboratory-reared populations. Heat treatments on D. pini colonies removed the Wolbachia symbionts, but they also prevented the development of adults. [ABSTRACT FROM AUTHOR]

A fundamental question in developmental biology is how a chimeric animal such as a bilateral gynandromorphic animal can have different phenotypes confined to different lateral body halves, and how mutation-induced phenotypes, such as genetic diseases, can be confined to one lateral body half in patients. Here, I propose that embryos of many, if not all, bilaterian animals are divided into left and right halves at a very early stage (which may vary among different types of animals), after which the descendants of the left-sided and right-sided cells will almost exclusively remain on their original sides, respectively, throughout the remaining development. This embryonic left-right separation mechanism allows (1) mutations and the mutation-induced phenotypes to be strictly confined to one lateral body half in animals and humans; (2) mothers with bilateral hereditary primary breast cancer to transmit their disease to their offspring at twofold of the rate compared to mothers with unilateral hereditary breast cancer; and (3) a mosaic embryo carrying genetic or epigenetic mutations to develop into either an individual with the mutation-induced phenotype confined unilaterally, or a pair of twins displaying complete, partial, or mirror-image discordance for the phenotype. Further, this left-right separation mechanism predicts that the two lateral halves of a patient carrying a unilateral genetic disease can each serve as a case and an internal control, respectively, for genetic and epigenetic comparative studies to identify the disease causations. © 2013 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

Environmental and social effects on offspring sex ratio bias in birds are among the most studied topics in evolutionary biology. Although it is established that offspring sex is determined at the stage of the first meiotic division, there is no direct evidence for the common belief that the bias happens via nonrandom sex chromosome segregation. In this paper, we suggest an alternative mechanism based on the failure of polar body emission, followed by fertilization of multiple haploid nuclei through polyspermy and subsequent competition of Z and W bearing cells within chimeric embryos. Although the occurrence of failure of polar body extrusion is obvious from the observations of chimeric birds, the idea that it could be the first step of offspring sex ratio bias has been entirely overlooked. We review the evidence in support of that idea, demonstrate that it is consistent with the observations of biased offspring sex ratio reported so far, and suggest a way to verify it. [ABSTRACT FROM PUBLISHER]

In the Crustacea, sex determination is generally considered to be cell non-autonomous, with a centralized sex differentiation signaling system. However, observed frequencies of axial (anterior-posterior) morphological gynandromorphs of Branchinecta lindahli Packard, 1883 suggest cell autonomous sex determination. Thoracic appendages of seven Branchinecta lindahli axial gynandromorphs with male second antennae and female genitalia were compared to normal male and female thoracic appendages to quantitatively determine if the putative gynandromorphs showed evidence of intersexuality. None of the gynandromorphs showed evidence of intersexuality, supporting the occurrence of cell autonomous sex determination in branchiopod crustaceans. [ABSTRACT FROM AUTHOR]