BALTOSTIGINI JAŁOSZYŃSKI & BRUNKE, 2018

BALTOSTIGINI JAŁOSZYŃSKI & BRUNKE View in CoL TRIB. NOV.

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Type genus: Baltostigus Jałoszyński, 2016 , here designated.

Diagnosis

Baltostigini differ from all remaining tribes in a unique combination of synapomorphies: maxillary palpomere 3 subtriangular, gradually broadening distally; palpomere 4 axe-shaped, broader than long and broadening distally; both scape and pedicel enlarged and bearing ventral spines; head capsule elongate; vertex evenly convex, not impressed posteromedially and lacking median longitudinal groove; pronotum lacking posterior collar; elytra with rows of punctures at least in anterior half; wings developed; mesoventral intercoxal process carinate and parallel-sided; aedeagus symmetrical, with both parameres equally well-developed.

Remarks

† Baltostigini View in CoL , represented only by the Upper Eocene † Baltostigus View in CoL distributed in north-central Europe, is a group closely related to Mastigini View in CoL and was previously included in the latter tribe ( Jałoszyński, 2016b). Placement of † Baltostigus View in CoL in a separate tribe is supported by its plesiomorphic characters, not known in any Mastigini View in CoL (including all extant species and the Cenomanian † Clidicostigus View in CoL ): fully developed wings ( Fig. 8A, E) and associated elytral structures (i.e. prominent humeral calli), fully symmetrical aedeagus ( Fig. 9C–E), with both parameres well-developed and equally long, and abdominal sternite 8 in males not emarginate. † Baltostigini View in CoL is an extinct and early diverging group of the ancestral lineage that gave rise to Mastigini View in CoL . Leptomastacini View in CoL , Papusini View in CoL , most Clidicini View in CoL and Leptochromini View in CoL have the aedeagi symmetrical or nearly symmetrical (examples are shown in Fig. 9H–P), with two long parameres; the aedeagus in Leptomastacini View in CoL is twisted in repose ( Fig. 9H), similar to that of Mastigini View in CoL (illustrated by Jałoszyński et al., 2015), that of Clidicini View in CoL , Papusini View in CoL and Leptochromini View in CoL is positioned symmetrically inside the abdomen, with the basal orifice facing dorsad. The symmetrical aedeagus with two long parameres (although in some cases partially fused to the lateral walls of the median lobe) is typical of Scydmaenini View in CoL , the sister-group of Mastigitae , and can be regarded as the plesiomorphic condition for Mastigitae . † Baltostigini View in CoL are characterized by this plesiomorphic condition, the aedeagus of † Baltostigus View in CoL ( Fig. 9B–E) is not only symmetrical with two long parameres, but also symmetrically positioned in repose, with its basal orifice facing dorsad. All Mastigini View in CoL ( Fig. 9Q–U), including the Cenomanian † Clidicostigus View in CoL , have the aedeagus strongly and uniquely transformed, with one paramere much longer than the other; in most ‘advanced’ extant forms one paramere is entirely obliterated and the long one monstrously enlarged ( Fig. 9T, U). Based on genital characters and ancestral character state reconstructions, we postulate an early (Cenomanian or earlier) split between † Baltostigus View in CoL and the ‘asymmetrical’ ancestor of Mastigini View in CoL (see Discussion).

† Baltostigus View in CoL preserved another character state that is ancestral for the clade † Baltostigus View in CoL + Mastigini View in CoL , i.e. the deep elytral punctures arranged in longitudinal rows (best visible in the new species described below, and only partly developed in two previously described species; see Fig. 1F). Among Mastigini View in CoL , this character state can be found only in the ancient, extinct Cenomanian † Clidicostigus View in CoL ( Fig. 1E), whereas the genera that survived until the present day (i.e. Mastigus View in CoL , Palaeostigus View in CoL and Stenomastigus View in CoL ) have only weakly marked, fine and often indistinct vestigial elytral rows or striae.