Megastigmidae, Thomson, 1876

Burks, Roger, Mitroiu, Mircea-Dan, Fusu, Lucian, Heraty, John M., Jansta, Petr, Heydon, Steve, Papilloud, Natalie Dale-Skey, Peters, Ralph S., Tselikh, Ekaterina V., Woolley, James B., van Noort, Simon, Baur, Hannes, Cruaud, Astrid, Darling, Christopher, Haas, Michael, Hanson, Paul, Krogmann, Lars & Rasplus, Jean-Yves, 2022, From hell's heart I stab at thee! A determined approach towards a monophyletic Pteromalidae and reclassification of Chalcidoidea (Hymenoptera), Journal of Hymenoptera Research 94, pp. 13-88 : 13

Megastigmidae

Megastigmidae Thomson, 1876. Type genus: Megastigmus Dalman, 1820.

Chromeurytominae Bouček, 1988 new placement. Type genus: Chromeurytoma Cameron, 1912.

Keiraninae Bouček, 1988 new placement. Type genus: Keirana Bouček, 1988.

Diagnosis.

Antenna with 10 ( Chromeurytoma ) or 12 ( Megastigminae and Keiraninae ) flagellomeres, including a 4th clavomere. Eyes not or only slightly divergent ventrally. Clypeus bilobed or medially produced, without transverse subapical groove. Labrum flexible and mostly or entirely hidden behind clypeus, divided into several small lobes or subtriangular. Mandibles with 3 teeth. Occipital carina present, at least dorsally in Chromeurytoma (Fig. 114 ), usually high on the head. Pronotum usually elongate, but about as long as mesoscutum or shorter in Chromeurytominae . Notauli complete. Mesoscutellum with frenum defined by a distinct frenal groove, with or without axillular sulcus (Fig. 114 ). Postmarginal vein longer than stigmal vein (excepted in Patiyana Bouček) and frequently longer than marginal vein. Basal fold usually pigmented, in a few genera developed into a basal vein curved outwards ( Megastigminae and Keiraninae ) (Fig. 115 ) or rarely basal fold hyaline ( Chromeurytominae ). All legs with 5 tarsomeres, protibial spur stout and curved; basitarsal comb longitudinal. Gaster, while sometimes rigidly convex, not strongly sclerotized; metasomal apex usually with a separate epipygium in females (in Chromeurytominae and Megastigminae ) or with a syntergum that is crossed by a sulcus immediately anterior to the cerci ( Keiraninae ). Cerci elongate. Ovipositor sheaths long and upcurved in females (Fig. 116 ).

Discussion.

Megastigminae had long been recognized as a monophyletic subfamily of Torymidae and has recently been upgraded to family rank ( Janšta et al. 2018). Next-generation molecular analyses (Cruaud et al., submitted) have consistently suggested that two previous subfamilies of Pteromalidae ( Chromeurytominae and Keiraninae ) were closely related to Megastigmidae . Morphological examination of species of Chromeurytoma Cameron and Keirana Bouček has confirmed that these clades share several diagnostic features with Megastigmidae and belong to this family. Adding these two entities has increased the morphological disparity within Megastigmidae and has decreased the already low number of apomorphies that define the family. Consequently, Megastigmidae now comprises three subfamilies: Megastigminae including most megastigmid genera ( Böhmová et al. 2022), Chromeurytominae new placement (including Chromeurytoma , Asaphoideus Girault and Patiyana ) and Keiraninae new placement (with only Keirana ).

Figures

Figures 109 - 114. 109, 110 Gastracanthus acutus (Kamijo) (Pteromalidae, Trigonoderinae) 109 lower face frontal view 110 mesosoma dorsal view 111 Cales noacki Howard (Calesidae): mesosoma lateral view 112 Eusandalum flavipenne Ruschka: mesosoma dorsal view 113 Pentacladia elegans Westwood: Mt 8 and Mt 9 fused, but delimited by an oblique suture below cercus 114 Chromeurytoma sp. (Megastigmidae, Chromeurytominae): head and mesosoma dorsal view.

Figures 115 - 120. 115, 116 Keirana sp. (Megastigmidae, Keiraninae) 115 wing 116 metasoma lateral view 117, 118 Metapelma sp. (Metapelmatidae) 117 mesosoma lateral view 118 apex of mesotibia and mesotarsus 119, 120 Neanastatus sp. (Neanastatidae) 119 mesosoma lateral view 120 mesosoma ventral view.