Abstract
Simple SummaryPhytophagous members of the family Cynipidae induce a spectacular diversity of plant galls that are often complex in structure. Knowledge of the biology, life cycle, and life history of known cynipid species is largely fragmentary; gall wasps can exhibit an alternation of generations known as heterogony in which an all-female alternates with a bisexual generation. The unisexual generation produces eggs parthenogenetically, and these are usually inserted into a specific plant part. At the site of oviposition, galls are induced, within which a bisexual generation develops and later emerges. Emergent males and females mate, and females in turn induce galls from which the unisexual generation emerges. Females of the two generations may be morphologically dissimilar and may induce galls that differ greatly morphologically. Differences in the morphology of both wasps and galls between generations of the same species, coupled with incomplete knowledge of life cycles, have led to considerable taxonomic confusion. Alternating generations of numerous species have been described as separate species or even genera. Here, we demonstrate experimentally that two cynipid species, Cynips conifica (presently Andricus conificus) and Andricus cydoniae, which are morphologically different and produce very different galls on different host oaks, represent alternate generations of a single species.We demonstrated the life cycle closure of Cynips conifica Hartig, 1843 (presently Andricus conificus), previously supposed on the basis of molecular data, and the identity of the sexual generation, through laboratory experiments. As a consequence, Andricus cydoniae Giraud, 1859 became a junior synonym of A. conificus (Hartig, 1843). We provide illustrations and a diagnosis for adults and galls, observations on biology, and information on distribution. Moreover, as sexual galls of A. conificus cannot be distinguished from those of Andricus multiplicatus, a detailed comparison between sexual galls and adults of these two species is reported.
Highlights
1300 gall-forming wasp species have been described within the family Cynipidae [1,2,3], and among these 174 species are reported at present for the Italian fauna [4]
Cook et al [19] showed that Andricus conificus (Hartig, 1843), for which at present only the asexual generation is known, has the same DNA sequence for the cytb fragment found in wasps of the sexual generation of Andricus cydoniae Giraud, 1859 and supposed that these two gall-inducing cynipids could represent the alternate generations of a single species
We report results of laboratory assays and morphological identification, allowing to demonstrate that the sexual generation of A. cydoniae belongs to the previously described species A. conificus
Summary
1300 gall-forming wasp species have been described within the family Cynipidae [1,2,3], and among these 174 species are reported at present for the Italian fauna [4]. In almost all remaining species for which only the sexual or asexual form is known, it is likely that alternate generation occurs but is yet to be described This happens because in heterogonic gall wasps, the gall structure, phenology, and adult morphology differ between the asexual and sexual generations, even within the same species. Cook et al [19] showed that Andricus conificus (Hartig, 1843), for which at present only the asexual generation is known, has the same DNA sequence for the cytb fragment found in wasps of the sexual generation of Andricus cydoniae Giraud, 1859 and supposed that these two gall-inducing cynipids could represent the alternate generations of a single species. We report results of laboratory assays and morphological identification, allowing to demonstrate that the sexual generation of A. cydoniae belongs to the previously described species A. conificus. We provide information on the species distribution, illustrations, and diagnosis for adults and galls, highlighting the morphological differences between the asexual and sexual generation individuals and galls of this species and closest Western Palaearctic congeners
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