Andricus conificus ( Hartig, 1843 )

Andricus conificus ( Hartig, 1843)

Figs 4–6 View FIGURES 1–9 , 42–43 View FIGURE 42 View FIGURE 43

Generation matching through DNA sequencing. Sottile et al. (2022) used rearing experiments to link asexual A. conificus with its alternate sexual generation that was originally described under the name A. cydoniae . New cytb and ITS data generated for this study confirm this pairing, with sexual and asexual individuals from this species grouping in the phylogenetic trees ( Figs 42–43 View FIGURE 42 View FIGURE 43 ). Asexual individuals had been identified based on their distinctive gall morphology while sexual individuals were confirmed as the correct species using the morphological characters outlined in Sottile et al. 2022 and below.

Cytb sequences between asexual and sexual generation individuals differed on average by 0.49% (range 0– 1.16%), comparable to divergence observed among individuals within a single generation of this species (0–1.39%). Two ITS2 sequences were observed among the seven A. conificus individuals that differed by 0.62%, with identical sequences present in two asexual and four sexual individals ( Fig. 43 View FIGURE 43 ). Preliminary molecular data had already suggested this pairing (one cytb sequence from each of the generations; see Cook et al. 2002), but the more extensive multi-locus data presented here confirm this pairing.

Similar multilocular integral leaf galls on section Cerris oaks in Europe

Generally, most gall-makers can be identified to species level on the basis of gall characteristics and the host plant species; however, some exceptions have recently been reported (e.g. Sottile et al. 2022; 2023; Abe et al. 2021). These exceptions are particularly apparent for some sexual generations of Cynipini , where overlap between within-species and among-species variation in gall morphology can be influenced by factors such as developmental stage, host plant vigour, infestation density, and parasitisation. The sexual generation galls of Andricus pseudomultiplicatus sp. nov. ( Figs 7–9 View FIGURES 1–9 ; 10–13 View FIGURES 10–15 ), A. truncicolus (= Andricus multiplicatus ; Fig. 3 View FIGURES 1–9 ) and A. conificus (= A. cydoniae ; Fig. 6 View FIGURES 1–9 ) present such a complex of effectively indistinguishable galls. By the end of gall development, all three species cause hypertrophic plant tissue degeneration on Quercus section Cerris oaks which appears as a muddled agglomerate of deformed leaves. All three species are also effectively indistinguishable from the sexual galls of A. crispator when these occur gregariously.

The galls of these species sometimes show distinctive morphological patterns at particular developmental stages, aiding identification; for example, developing galls of sexual A. truncicolus can present with a red pubescence as illustrated in Fig. 17 View FIGURES 16–24 of Sottile et al. (2023) and mentioned in Giraud’s (1859) original description of this species. However, these characteristics converge into forms resembling galls of other species as they mature, making subsequent accurate identification challenging or even impossible. The gall induction phenology of sympatric populations of these species might be useful for distinguishing them (for example, Giraud 1859 mentioned an earlier phenology for sexual A. conificus galls relative to sexual A. truncicolus ), but the rapid development of these species’ galls during spring makes this potentially quite unreliable. However, species identification using adults can be easily achieved based on the morphological differences outlined in the following key.