Recent Southern Hemisphere Lamprimine Stag Beetle in Cretaceous Burmese Amber and Its Biogeographic Implications (Coleoptera: Lucanidae)

A new stag beetle fossil, <i>Prostreptocerus burmiticus</i> Yu & Cai gen. et sp. nov., is described based on a single male specimen. This is the first representative of the subfamily Lampriminae (Coleoptera: Scarabaeoidea: Lucanidae) from mid-Cretaceous Burmese amber. The new species is distinctive among Lucanidae due to its well-developed, right-angled mandible, frons featuring a pair of large protuberances, a coarse and sparsely punctate elytral disc, and large tubercles on the humeri. <i>Prostreptocerus</i> Yu & Cai is placed within Lampriminae based on several key characteristics. Morphologically, it is most similar to the extant <i>Streptocerus</i> Fairmaire, 1850. The current distribution of <i>Streptocerus</i> and Lampriminae is primarily restricted to the Southern Hemisphere, suggesting that this lineage is ancient and existed on Gondwanaland, which has significant geographical implications. This discovery extends the fossil record of Lampriminae and provides additional evidence for the existence of sexual dimorphism and potential combat behavior in Mesozoic lucanids. Additionally, <i>Electraesalopsis</i> Bai, Zhang & Qiu, 2017, previously placed as Lucanidae <i>incertae sedis</i>, shares many characteristics with <i>Prostreptocerus</i> Yu & Cai and is also assigned to Lampriminae based on a suite of traits.