Comparative morphology of the musculature of the sting apparatus in Ampulex compressa (Hymenoptera, Ampulicidae) and Sceliphron destillatorium (Hymenoptera, Sphecidae)

Abstract

The sting apparatus of aculeate Hymenoptera is derived from the ovipositor and is their most prominent apomorphy. In contrast to the frequently analysed sclerites of the sting apparatus, the associated musculature has largely been neglected. In this study, we use micro-computed tomography to present a detailed description of the musculature of the sting apparatus of Ampulex compressa (Ampulicidae) and Sceliphron destillatorium (Sphecidae). We found that 12 of 15 muscles corresponding to the sting apparatus are homologous between both species examined and 13 muscles in comparison with Hymenoptera described in the literature. All muscles identified as critical for the act of stinging were found in both species. Moreover, we found the ventral tergum 8-tergum 9 muscle and the tergum 8-tergum 8 muscles in A. compressa and the second valvifer-second valvifer muscle in S. destillatorium. For the first time, we describe the ventral tergum 8-tergum 9 muscle and the second valvifer-second valvifer muscle that interconnects both body sides, in Hymenoptera.

Ovipositor of the braconid wasp Habrobracon hebetor: structural and functional aspects

“…The shape of the 1 st valvifer varies between the various hymenopteran superfamilies (Oeser 1961). Ichneumonoid species such as the braconid H. hebetor in the present study possess a 1 st valvifer with a rounded compact shape (Snodgrass 1933;Eggs et al 2018), in contrast to the elongated and bow-shaped 1 st valvifers of members of the superfamily Chalcidoidea (Copland and King 1972a, 1972b, 1972c, 1973, the triangularly shaped 1 st valvifers of Apis mellifera (Linnaeus, 1758) and other aculeate species (Snodgrass 1933;Oeser 1961;Matushkina 2011;Matushkina and Stetsun 2016;Stetsun and Matushkina 2020;Graf et al 2021), and the highly diverse 1 st valvifers of basal hymenopterans (e.g. the robust-appearing 1 st valvifers of Tentredinidae (Snodgrass 1933;Vilhelmsen 2000) or the triangular 1 st valvifers in some Xyelidae (Vilhelmsen 2000).…”

“…Studies that describe all the inherent cuticular elements and muscles of the ovipositor and (in part) also consider functional aspects include several basal 'symphytan' families (Smith 1970(Smith , 1972Vilhelmsen 2000;Vilhelmsen et al 2001), some aculeate species (i.e. Apis melifera Linnaeus, 1758 (Apidae) (Snodgrass 1933), species belonging to Chrysidoidea (Barbosa et al 2021), Sceliphron destillatoruim (Illiger, 1807) (Sphecidae), Ampulex compressa (Fabricius, 1781) (Ampulicidae) (Graf et al 2021), Vespa crabro Linnaeus, 1758 (Vespidae) (Stetsun and Matushkina 2020), and species belonging to the Crabronidae (Matushkina 2011;Matushkina and Stetsun 2016;Stetsun et al 2019) and Pompilidae (Kumpanenko and Gladun 2018)), and a few parasitoid species belonging to the Cynipoidea (Frühauf 1924;Fergusson 1988), Platygastroidea (Field and Austin 1994), Chalcidoidea (Hanna 1934;King 1962;King and Copland 1969;Copland and King 1972a, 1972b, 1972c, 1973Copland 1976), and Ceraphronoidea (Ernst et al 2013). The musculoskeletal ovipositor system and the actuation mechanisms of ichneumonoid wasps have been described recently in the ichneumonid Venturia canescens (Gravenhorst, 1829) (Eggs et al 2018) and the braconid Diachasmimorpha longicaudata (Ashmead, 1905) (van Meer et al 2020, respectively.…”

The ant abdomen: The skeletomuscular and soft tissue anatomy of Amblyopone australis workers (Hymenoptera: Formicidae)

“…The fact that an improvement of around 1-2 µm/pixel resolution enabled reconstruction of a muscle which could otherwise not be unambiguously ruled present or absent implies that an even higher resolution scan of just the sting apparatus could reveal if a second muscle is present in Amblyopone. However, many parameters of the scan, and organismal traits, differed between our study and Graf et al (2021), so we aware of the limitations of this analogy. An additional complicating factor in our case is that the scanned Amblyopone specimen has some of the sting elements torqued to the side, making it more difficult to differentiate folded membrane from flexible sclerite and distorted muscle fibers of the abdominal apex.…”

“…Note 6 , Spiracular dilator of ATVIII. Note 7 , Only observed by Graf et al (2021) in Ampulex . Note 8 , The precise homology of 9domm is uncertain.…”

“…in Formica. Note 10, The homology of the tergogonocoxital muscles among taxa is somewhat ambiguous due to the presence of an additional Bauplan descriptive system, only explicitly noting which taxa were observed when a muscle is absent; this column is a collation of all present muscles described, see reference for patterns of absence Graf et al (2021)…”