Abstract
A new braconid wasp from the Upper Cretaceous (Cenomanian) amber of the Hukawng Valley in Kachin State, Myanmar is described and figured from a unique female. Seneciobracon novalatus Engel & Huang, gen. et sp. n., is placed in a distinct subfamily, Seneciobraconinae Engel & Huang, subfam. n., owing to the presence of a unique combination of primitive protorhyssaline-like traits, with an otherwise more derived wing venation. The fossil is discussed in the context of other Cretaceous Braconidae.
Highlights
Seneciobracon novalatus has a distinctive combination of traits not found among rhyssalines such as the absence of the stub of 2a in the forewing, complete absence of m-cu in the hind wing, presence of a well-defined 2Rs+M (1m-cu typically confluent with 2Rs in Rhyssalini), presence of a distinct costal cell at the apex of the otherwise fused C+Sc+R, incomplete occipital carina, and absence of a dorsope on metasomal tergum I
Both Seneciobraconinae and Rhyssalinae, cyclostome, differ from the extinct Protorhyssalinae in the absence of hind wing 2Cu, a putatively derived feature as 2Cu is present in Eoichneumoninae, Protorhyssalinae, Trachypetinae, Apozyginae, and Ichneumonidae. Both lack the five-sided second submarginal cell more typical of the protorhyssalines (e.g., Basibuyuk et al 1999; Perrichot et al 2009; Ortega-Blanco et al 2011; Engel 2016; Engel and Wang 2016; Engel et al 2017), a condition that results from the meeting of 1m-cu with the second submarginal cell
Seneciobracon novalatus has a venation that is more similar to modern Braconidae than to any of the other mid-Cretaceous or older braconids, and cannot be included within Protorhyssalinae or the more basal stem of Braconidae
Summary
Braconids are a frequently encountered lineage in the modern hymenopteran fauna (Grimaldi and Engel 2005; Quicke 2015), and are represented in Cenozoic ambers by diverse subfamilies (e.g., Brues 1933, 1939; van Achterberg 1982, 2001; Tobias 1987; Zuparko and Poinar 1997; Engel and Bennett 2008; Butcher et al 2014), their. It is surprising that so few braconids have been recovered from Cretaceous deposits, and several interesting new taxa have been described recently, they remain relatively rare with hitherto only 11 formally named species (vide Discussion, infra). Those that have been documented are interestingly phylogenetically basal to crown-group Braconidae (e.g., Perrichot et al 2009), and so have the greatest potential for illuminating our understanding of the phases of braconid diversification. The subfamily is similar to modern Rhyssalini, sharing varied plesiomorphies with this group, but can be distinguished in features of the notal and metasomal structure as well as wing venation and putatively apomorphic effacement of the occipital carina
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