Pampacladius, a new genus of Orthocladiinae (Diptera: Chironomidae) and comments on the Gondwana biogeography

Abstract

Pampacladius gaucho Donato, Zanotto, Arpellino et Siri gen. nov., sp. nov. is described and illustrated based on all life stages from the Pampean province in Central Argentina. This genus can be separated from all other male adult Orthocladiinae by absence of virga; anal point placed slightly forward on tergite IX with apical part short and reduced to a hump with posterior elongation; more than two scalpellate median acrostichals; bare wings; straight Cu1; presence of a squamal fringe; and well developed pulvilli. Molecular analyses support the status of Pampacladius as a new genus within Orthocladiinae. The analyses place the new form closely related to Echinocladius Cranston, Paulfreemania Cranston and Krosch, genus ‘Australia’ (called by Cranston after Brundin’s notebook name for two very distinctive pupae), Tonnoirocladius Cranston, and Naonella Boothroyd. Event-based biogeographical analysis found this clade as part of a major clade whose ancestral distribution was on continents that were part of Gondwana. This ‘late Gondwanan’ clade was dated in 76.4 Mya (95% HPD: 90.4–61.5 Mya) and in such scenario several events took place linking Pampacladius gaucho with other species belonging to Austral areas, mainly Australia and New Zealand.