Morphological observations on a gynandromorph of Maniola jurtina (Linnaeus, 1758) (Lepidoptera, Nymphalidae, Satyrinae)

Gynandromorphism is a teratological condition consisting in the simultaneous presence of both male and female phenotypic characteristics, with a clear demarcation between one and the other, in the same individual of an animal species with separate sexes. To whatever degree, it is always a rather uncommon phenomenon; in the class of insects it is fairly widespread. The major or minor frequency at which this anomaly has been reported for different taxa of insects also derives from the presence (or lack thereof), in the different species, of more or less marked sexual dimorphism. For the Lepidoptera, in which in a relatively large number of taxa (mainly in Papilionoidea) a sometimes very pronounced sexual dichromatism is present and evident above all in the colouring of the two pairs of wings, over time many gynandromorph specimens have been reported (e.g. in Lycaenidae, Nymphalidae, Pieridae, Papilionidae, etc.). The case presented here concerns a specimen of the Meadow Brown butterfly, Maniola jurtina (Linnaeus, 1758) (Nymphalidae Satyrinae). The salient morpho-chromatic characteristics are illustrated, including the conformation of the final abdominal segments and the ectodermal genital structures, examined after clarification. Reports of gynandromorphs of Lepidoptera species presenting sexual dichromatism are often limited to the illustration of the habitus of the whole insect, without examination of genital morphology. M. jurtina has a wide distribution in the Palearctic region: it is common throughout almost all Europe and in the Mediterranean basin, from sea level up to about 2000 m, and it is found in Anatolia, Iran, Iraq, Kazakhstan, the Urals and western Siberia. It is a univoltine species, which flies between late May and September, with a more or less long period of flight, characterized by proterandry; in the southernmost part of its range it has a prolonged aestivation. It frequents flowery meadows and pastures, grassy glades with bushes, forest edges, gardens and parks. The host plants of the larvae are spontaneous Poaceae. The specimen of the present report has right wings with the typical female colouring, therefore with a striking orange area on the upper surface of the forewing, which stands out against the general brown colour of the fore- and hindwing, while on the upper surface of the left wings the brown colour dominates uniformly. Similarly, on both sides the lower surface has the less striking chromatic differences that distinguish, respectively, the two sexes. The shape and size of the four wings (right forewing 22 mm long, left forewing 21 mm) are rather similar on both sides. Overall, the relatively small specimen size is closer to the average male size of this species than to the slightly larger female. The antennae on the two sides are similar. The final abdominal segments in the still intact specimen, dry preserved, do not show dissymmetries or other anomalies of any kind; an initial examination of the preparation of the tip of the abdomen highlights female structures both on the right side and on the left side. The specimen was field-collected at Buguggiate (northern Italy: Lombardy: province of Varese) on 20.07.1990.