Fig. 17 in A general theory of genital homologies for the Hexapoda (Pancrustacea) derived from skeletomuscular correspondences, with emphasis on the Endopterygota

Fig. 17. Key skeletomuscular morphological apomorphies of genitalia here inferred, mapped on the phylogenetic chronogram of the Hexapoda pruned to the specific terminals compared in the present study (tree modified from Misof et al., 2014). Bayesian analysis may provide estimates of rate and timing of inferred transformations.1. Hexapoda: male gonopore(s) situated on a lateromedially-undifferentiated gonopod (the penis). 2. Protura: male gonopores situated on distal (second) endopodal segment. 3. Collembola, Diplura: penes independently reduced to papillae. 4. Ectognatha: male and female genitalia derived from appendages (primary and secondary gonopods) of two successive segments. 5. Ectognatha: male phallic complex reduced to single, simple structure (the penis), modified from gonopores of abdominal segment X. 6. Dicondylia: dorsoventral penial extrinsic muscle lost. 7. Gonapophyses (endopods of coxopods IX) probably lost once in the Odonatoptera (along stem to Odonata) and once or twice in the Chiastomyaria. 8. Odonata: plesiomorphic condition of gamete transfer via spermatophore retained, although the latter is deposited in the autapomorphic secondary genitalia. 9. Ephemeroptera, Neoptera: sperm directly deposited in the female via intromission of the penis.10. Ephemeroptera: gonopods derive multiannulate styli.11. Ephemeroptera: penis laterally articulated with tergum IX, bearing derived tergopenial musculature. 12. Neoptera: sternopenial muscle duplicated, resulting in novel penial promotor. 13. Polyneoptera: secondary gonopods (coxopods IX) not incorporated into penial ("phallic") complex, being rather (usually) undifferentiated from sternum IX.14. Two independent lines of increasing complexity and disparity observed in the penial complex of Polyneoptera, once for the Zoraptera, the other for the Orthopterida (i.e., core Polyneoptera). 15. Two independent lines of penial complex simplification observed in Polyneoptera, once for the Plecoptera, the other for the Dictyoptera (namely, reduction observed in Isoptera).16. Grylloblattodea: coxopods IX secondarily differentiated from sternum IX.17. Eumetabola: gonostyli strengthened for clasping, bearing differentiated abductor and adductor muscles.18. Condylognatha: dorsal extrinsic penial muscle gained. 19. Hemiptera: gonopods undifferentiated from fused tergum and sternum IX, forming pygophore; pygophore also bearing origins of the penial extrinsic muscles. 20. Endopterygota: penis completely integrated with gonopods developmentally and gonopods, as in Hemiptera, bear the origins of the penial extrinsic muscles. 21. Endopterygota: penial musculature is duplicated dorsoventrally, resulting in greater functional potential of copulatory apparatus (penial-gonopodal complex). 22. Endopterygota: lateropenite ("parandrite" or "paramere" sensu Verhoeff) uniquely derived from penial sclerite (skeletomusculature of Psocodea in need of renewed study).23. Hymenoptera: origin of cupula (¼ "basal ring"), which controls overall motion of gonopods. 24. Hymenoptera: parossiculus derived from ventromedial gonocoxa, forming volsellar complex with lateropenite ("digitus"). 25. Sialida (sensu Bodreaux,1979 modified from Handlirsch,1908): gonocoxae migrated dorsally, fusing with tergum IX over the penis. 26. Sialida: external gonopore dissociated from the penial sclerites (probably in correlation with female loss of ovipositor). 27. Coleopterida: lateropenite lost. 28. Strepsiptera: genitalia reduced, with only a penis (or coxopenis) expressed. 29. Coleoptera: ancestral gonocoxa divided into two parts: the first or anterior gonocoxites ("phallobase") bearing the insertions of the extrinsic gonopodal musculature, the second or posterior gonocoxites incorporated to completely integrated with the penis (forming "coxopenis"); gonostyli variably associated with phallobase. 30. Euantliophora: genitalic complexity increases to extreme degree, extant taxa inheriting an autapomorphic aedeagal apodem (present in Siphonaptera and Nannochoristidae). 31. Siphonaptera: gonopodites, bearing styli, fused with tergo-proctiger complex. 32. Siphonaptera: sternum IX with lateral elongate arms. 33. Siphonaptera: sperm-pumping complex significantly modified. 34. Mecoptera: sperm-pumping complex with mittelplatte (note uncertainty of homology for boreid penial sclerites).35. Boreidae: sperm-pumping complex reduced, most slerites lost. 36. Boreidae: spermatophore regained. 37. Pistillifera: pistilltrö ager derived in sperm-pumping complex. 38. Diptera: partial to complete integration of sternum IX with gonopods; increasing genitalic complexity observed. 39. Amphiesmenoptera with relatively unmodified genitalia, although Lepidoptera with lateromedially fused lateropenites ("median plate") and enlarged and unmusculated gonostylus.