New subgenus and three new species of soldier beetles from the Eocene of Baltic amber

Janusz Kupryjanowicz and Fabrizio Fanti

Plain Language Abstract

The family Cantharidae (soldier beetles) are soft bodied family of insects evolved from Cretaceous Period and very frequent in Eocene Baltic forests, with many species described and also with genera or lineages actually extinct which can shed light on various biogeographical aspects. The new article describe three new species: a Cantharis and two Malthodes from the amber deposits of Kaliningrad region, Russia. Cantharis is widespread in Nearctic and Palearctic region, and is frequent in flowers where catches its preys even if can sometimes supplement the diet with pollen and nectar, while Malthodes, present with about extant 650 species described in Palearctic and North America, is essentially predator, in fact, it is not rare to see it while feeding on aphids in trees and bushes, a food that was very frequent also in the Eocene Epoch. Malthodes is a small-sized (range is 2-4 mm) and very variable genus, which tends to have short elytra that leave several abdominal segments uncovered, such as Malthodes (Malthodes) nublar herein described, but at least in the Eocene some species had elytra very elongated as in M. (Libertimalthodes) elytratus sp. nov. This latter new species is also interesting for its last abdominal segments little modified and in particular for the huge aedeagus, a character unknown until now for this genus, that allowed us to ascribe it to a new subgenus. The presence in the genus Malthodes of long elytra, could suggest that it is a primitive character and only afterwards with the evolution they are shortened becoming the norm.

GLOSSARY

tg9: penultimate tergite.
tg10: last tergite.
st9: last sternite.
tergite: a sclerotized plate forming the tergum of a segment.
sternite: a sclerotized plate forming the sternum of a segment.
aedeagus: is a reproductive organ of male arthropods.

Resumen en Español

Nuevo subgénero y tres nuevas especies de escarabajos cantáridos del Eoceno en ámbar del Báltico

Se describen, a partir del ámbar eoceno del Báltico, un subgénero fósil y tres especies fósiles de escarabajos cantáridos: Libertimalthodes subg. nov., Cantharis (Cantharis) dougi sp. nov., Malthodes (Libertimalthodes) elytratus sp. nov. y Malthodes (Malthodes) nublar sp. nov. El depósito parece ser comparativamente rico en inclusiones de Cantharidae. El nuevo subgénero difiere del subgénero nominotípico en que posee élitros alargados que cubren los últimos uritos abdominales, un gran edeago y que el último esternito abdominal es ancho y poco modificado. Además, la nueva especie tiene un edeago que está casi completamente extruido, lo cual es una característica rara que se encuentra en los fósiles de escarabajos cantáridos. Malthodes nublar sp. nov. se caracteriza por los élitros cortos y tiene una forma diferente de la terminalia, mientras que Cantharis dougi sp. nov. tiene una forma pronotal diferente a la de las especies fósiles conocidas. Malthodes aphidiphagus Fanti et Michalski, 2018, se transfiere del subgénero nominotípico Malthodes al nuevo subgénero Libertimalthodes.

Palabras clave: escarabajos cantáridos; resina; paleoinclusiones; Eoceno; fósiles; nuevos taxones

Traducción: Enrique Peñalver (Sociedad Española de Paleontología)

Résumé en Français

In progress

Translator: Antoine Souron

Deutsche Zusammenfassung

Eine neue Subgattung und drei neue Arten von Weichkäfern aus dem eozänen Baltischen Bernstein

Eine fossile Subgattung und drei fossile Arten von Weichkäfern, Libertimalthodes subg. nov., Cantharis (Cantharis) dougi sp. nov., Malthodes (Libertimalthodes) elytratus sp. nov. und Malthodes (Malthodes) nublar sp. nov., werden aus dem eozänen Baltischen Bernstein beschrieben. Die Ablagerungen scheinen vergleichsweise reich an Inklusionen von Cantharidae zu sein. Die neue Subgattung unterscheidet sich von der nominotypischen Subgattung durch das Vorhandensein von Elytren, die länglich sind und die letzten abdominaen Uriten bedecken, durch einen großen Aedeagus und dadurch, dass der letzte abdominale Sternit breit und wenig modifiziert ist. Zudem ist der Aedaegus bei der neuen Art komplett extrudiert, was bei fossilen Weichkäfern selten zu finden ist. Malthodes nublar sp. nov. ist charakterisiert durch kurze Elytren und eine unterschiedliche Form der Terminalia, während Cantharis dougi sp. nov. eine andere pronatale Form aufweist als bei bekannten fossilen Arten. Malthodes aphidiphagus Fanti und Michalski, 2018, wird aus der nominotypischen Subgattung Malthodes in die neue Subgattung Libertimalthodes übertragen.

Schlüsselwörter: Weichkäfer; Harz; Paläoinklusionen; Eozän; Fossilien; neue Taxa

Translator: Eva Gebauer

Arabic

Translator: Ashraf M.T. Elewa

Polski

In progress

Translator:  Krzysztof Stefaniak