Chromosome numbers are not fixed in Agaonidae (Hymenoptera: Chalcidoidea)

Abstract

Agaonidae (the pollinators of fig trees, Ficus spp., Moraceae) are a distinctive family of chalcid wasps with uncertain affinities within the Chalcidoidea. Chromosome numbers have only been described previously for one species (Blastophaga psenes, 2n=12, the pollinator of F. carica, of subgenus Ficus). In this paper, we used a modified technique to analyze the karyology of three Ceratosolen species, Ceratosolen solmsi, C. graveli and C. emarginatus which are associated with figs of Ficus subgenus Sycomorus. Their karyotypes are 2n=10. All the chromosomes are metacentric (NF=20) with little difference in relative lengths, making them hard to distinguish. The variation in chromosome numbers that we have detected suggests that karyology can usefully complement molecular-based studies of the phylogeny of fig wasps.

Chromosomes of Eupristina verticillata Waterston, 1921 and an overview of known karyotypes of chalcid wasps of the family Agaonidae (Hymenoptera)

“…two species of the same genus Eupristina Saunders, 1882, E. altissima and Eupristina sp. with n = 5, as well as three members of the genus Ceratosolen Mayr, 1885 from the subfamily Kradibiinae, C. solmsi, C. gravelyi, and C. emarginatus with the same chromosome number (Table 2), contain only large metacentrics of similar size (Liu et al 2011, Chen et al 2018). Analogously to the situation observed in a few other chalcid families, e.g.…”

“…With its exceptionally high morphological and ecological diversity, this superfamily includes about 23 thousand known species (Huber 2017), but karyotypes of less than 200 members of this group are studied up to now (Gokhman 2013). For example, in the family Agaonidae, a highly specialized tropical/subtropical group of Chalcidoidea exclusively associated with fruits of the plant genus Ficus, chromosomes of only six species were previously studied (Gokhman et al 2010, Liu et al 2011, Chen et al 2018. We have recently examined chromosomes of another member of this family, Eupristina verticillata Waterston, 1921 collected in Italy about 30 years after its introduction (Lo Verde et al 1991, 2007.…”

Results and prospects of the chromosomal study of the main groups of economically important Chalcidoidea (Hymenoptera)

“…The karyotype of B. psenes had n = 6 and was structurally similar to that found in the families Torymidae and Ormyridae. A short time later the chromosome sets of several species of the genus Ceratosolen Mayr were studied, and all these species were found to have more advanced karyotypes with n = 5 (Liu et al, 2011). They are structurally similar to the karyotypes of Torymidae and seem to have been formed in the same way, i.e., by fusion of the small subtelocentric or acrocentric chromosome with one of the larger bi-armed chromosomes (see above).…”