Phylogeny, evolution, and classification of the ant genusLasius, the tribe Lasiini, and the subfamily Formicinae (Hymenoptera: Formicidae)
Authors: Boudinot B. E. , Borowiec M. L. , Prebus M. M. 
Published: July 2021

Within the Formicidae, the higher classification of nearly all subfamilies has been recently revised due to the findings of molecular phylogenetics. Here, we integrate morphology and molecular data to holistically address the evolution and classification of the ant genusLasius, its tribe Lasiini, and their subfamily Formicinae. We accomplish this through a critical re-examination of morphology of extant and fossil taxa, molecular phylogenetic analyses, total-evidence dating under fossilized birth-death process, phylogeography, and ancestral state estimation. We use these results to provide revised taxonomic definitions for the Lasiini and select genera, and we provide a key to the genera of the Lasiini with emphasis on theLasiusgenus group. We find that the crown Lasiini originated around the end of the Cretaceous on the Eurasian continent and is divisible into four morphologically distinct clades:Cladomyrma, theLasiusgenus group, thePrenolepisgenus group, and a previously undetected lineage we nameXXXgen. n.The crown of theLasiusgenus group is considerably younger than that of thePrenolepisgenus group, indicating that extinction has played a major role in the evolution of the former clade.Lasiusitself is divided into two well-supported monophyletic groups which are approximately equally speciose. We present evidence that temporary social parasitism and fungiculture arose inLasiustwo times independently. Additionally, we recover the paraphyly of threeLasiussubgenera and propose replacing all subgenera with an informal species group classification:Lasius=Acanthomyopssyn. rev., =Austrolasiussyn. n., =Cautolasiussyn. n., =Chthonolasiussyn. n., =Dendrolasiussyn. n.Total-evidence analysis reveals that the Baltic-region amber fossil species †Lasius pumilusand †Pseudolasius boreusare misplaced to genus; we therefore designate †XXXgen. n.for the former and †XXXgen. n.for the latter. Further, we transfer †XXXand †Glaphyromyrmexout of the tribe, considering the former to beincertae sedisin the subfamily, and the latter a member of the Formicini (tribal transfer). Two final taxonomic actions are deemed necessary: synonymy ofLasius escamoleReza, 1925 withLiometopum apiculatumMayr, 1870syn. n.(subfamilial transfer), and transfer ofParatrechina kohlitoAnoplolepis(tribal transfer, formingA. kohli(Forel, 1916)n. comb.).

Summary of taxonomic actions

Subgenera ofLasiussynonymized:Lasius= Acanthomyopssyn. rev. = Austrolasiussyn. n. = Cautolasiussyn. n.= Chthonolasiussyn. n.= Dendrolasiussyn. n.

Lasius myrmidontransferred toXXXgen. n.(Lasiini,XXXgenus group).

†Lasius pumilustransferred to †XXXgen. n.(Lasiini,XXXgenus group).

†Pseudolasius boreustransferred to †XXXgen. n.(incertae sedisin Formicinae) (tribal transfer).

†Glaphyromyrmextransferred to the Formicini from the Lasiini (tribal transfer).

Lasius escamoleReza, 1925 synonymized withLiometopum apiculatumMayr, 1870, syn. n. (subfamilial transfer).

Paratrechina kohli(Forel, 1916) transferred toAnoplolepis(Plagiolepidini) (genus and tribal transfer).