The Phylogenetic Relationships of the Fanniidae within the Muscoid Grade (Diptera: Calyptrata) Based on the Musculature of the Male Terminalia

Abstract

The abdominal and pregenital segments and the genitalia were studied in males of Fannia subpellucens (Zetterstedt, 1845), Fannia canicularis (Linnaeus, 1761) and Fannia incisurata (Zetterstedt, 1838). In comparison with the remaining members of the muscoid grade, in addition to the symmetry of the pregenital segments, significant reductions of the sclerites and musculature of the male terminalia have been observed in Fanniidae. The muscular structure of pregenital segments confirms that the fused pregenital ring is syntergosternite VI + VII + VIII. Symmetry and fusion, as well as the lower number of the sclerites and muscles of the pregenital segments and male genitalia of the Fanniidae, can be considered apomorphic character states. The presence of the lateral bacilliform sclerite, as well as the presence and position of the epandrial muscles M 26, three pairs of muscles M 19 and paired muscles M 18, can be considered as a plesiomorphic character state of the Fanniidae. The structure of the sclerites and muscles of the male abdominal segments and terminalia place the Fanniidae at the base of the muscoid grade and Oestroidea, as has been confirmed by recent molecular studies.

Musculature of the male abdominal segments and terminalia of Zaphne barbiventris (Zetterstedt, 1845) and Delia fabricii (Holmgren, 1872) (Diptera: Anthomyiidae)

“…Hennig followed the numbering of Calliphora muscles according to Salzer (1968): muscles M 35 extend from the ligament (transverse ligament between the ends of the hypandrial arms) to the phallapodeme, muscles M 36 extend from the basiphallus and the epiphallus with a membranous connection to the phallapodeme, muscles M 37 extend from the hypandrial arms to the phallapodeme. However, the latter muscles are absent in Hennig's description of muscles of Delia platura, as well as they are absent in the figures of muscles, and these muscles have not been found by the authors of this paper in Zaphne barbiventris and Delia fabricii, but M 37 (=M 2 1 ) were previously found by the authors in Muscidae and Fanniidae (Ovtshinnikova et al, 2018;, 2022. In addition, muscles M 35 extending from the ligament in Zaphne barbiventris and Delia fabricii are so close to muscles M 36 that they look like one broad muscle.…”

“…These are the muscles connecting tergite VI with syntergosternite VII + VIII, syntergosternite VII + VIII with the epandrium (tergite IX); sternite VI with sternite VII, sternite VII with syntergosternite VII + VIII, syntergosternite VII + VIII with the hypandrium (sternite IX). The authors of this paper previously considered a larger set of muscles of pregenital sclerites as a basal state for the Calyptratae (Ovtshinnikova & Sorokina, 2021; Sorokina & Ovtshinnikova, 2020, 2022).…”

“…The muscles of the male terminalia of other studied Muscidae have undergone various degrees of reduction (Ovtshinnikova & Sorokina, 2020; Sorokina & Ovtshinnikova, 2020). In comparison with the Anthomyiidae, Muscidae and Scathophagidae, there is a symmetry and a significant reduction of the sclerites and muscles of the pregenital segments of the male genitalia of the Fanniidae (Sorokina & Ovtshinnikova, 2022). However, the set of muscles of the Fanniidae extending from the pregenital sclerites to the epandrium and the hypandrium are generally similar to those of the Anthomyiidae, Scathophagidae and basal Muscidae (Azeliinae).…”

“…Both the sclerites and the muscles of pregenital segments VI–VIII and part of IX are asymmetrical, and the structure of sclerites and muscles of the pregenital and genital segments differs significantly in different families of Cyclorrhapha. Earlier, the musculature of male terminalia in muscoid flies was studied in detail on members of the families Muscidae (Ovtshinnikova, 1989; Ovtshinnikova et al, 2018, 2019; Ovtshinnikova & Sorokina, 2020; Sorokina & Ovtshinnikova, 2020), the Fanniidae (Sorokina & Ovtshinnikova, 2022) and only partially on the Anthomyiidae ( Delia platura Meigen, Fucellia tergina Zetterstedt) (Hennig, 1976) and the Scathophagidae (Ovtshinnikova, 1994). In previous studies by the authors, the apomorphic transformations of the muscles of the pregenital segments of males important in the phylogenetic branching of the Calyptratae have been identified.…”

“…In previous studies by the authors, the apomorphic transformations of the muscles of the pregenital segments of males important in the phylogenetic branching of the Calyptratae have been identified. It was shown that characters of sclerites and muscles of the pregenital segments of this group were more important in constructing suprafamily phylogeny than the transformations of the genital sclerites and muscles (Ovtshinnikova et al, 2018, 2019; Ovtshinnikova & Sorokina, 2020, 2021; Sorokina & Ovtshinnikova, 2020, 2022). However, the pregenital muscles have not been thoroughly studied in the Anthomyiidae and the Scathophagidae.…”