Revision of the Exechiaparva group (Diptera: Mycetophilidae).

Jostein Kjærandsen,Jon Peder Lindemann,Geir Søli

doi:10.3897/bdj.9.e67134

Abstract

BackgroundExechia is a diverse genus of small fungus gnats, widespread in the Holarctic Region, while the fauna is largely unknown elsewhere, such as in the Afrotropical and Oriental Region. Members of Exechia can be arranged into several species groups, based on homologies in the male and female terminalia. The Exechiaparva group is delimited, based on male terminalia possessing a pair of gonocoxal lobes on the apicoventral gonocoxal margin. Eight previously-described species can be placed in this group, of which six are from the Holarctic Region, while one is recorded each from the Oriental and the Afrotropical Regions.New informationThe Exechiaparva group was reviewed and found to include 33 species, of which 24 were described as new to science and six were re-described. Identification keys to 32 species for males and nine species for females are provided together with illustrations and photos of male and female terminalia. Species delimitations were based on morphological examination of 94 male and female specimens, as well as DNA barcodes obtained from 124 specimens. Molecular and morphological species delimitations were mostly congruent, except in two cases where two species were delimited within a single Barcode Index Number (BIN). We found that each species is only known from a single zoogeographical region and that several species complexes are largely congruent with zoogeographical divisions, indicating that intercontinental barriers may have a strong impact on the species diversity of the group.

Highlights

The genus Exechia Winnertz, 1863 is known from all zoogeographical regions, except the Neotropical Region and Antarctica (Bechev 1999)
Exechia is a diverse genus of small fungus gnats, widespread in the Holarctic Region, while the fauna is largely unknown elsewhere, such as in the Afrotropical and Oriental Region
The Exechia parva group is delimited, based on male terminalia possessing a pair of gonocoxal lobes on the apicoventral gonocoxal margin

Summary

Background

Exechia is a diverse genus of small fungus gnats, widespread in the Holarctic Region, while the fauna is largely unknown elsewhere, such as in the Afrotropical and Oriental Region. Members of Exechia can be arranged into several species groups, based on homologies in the male and female terminalia. The Exechia parva group is delimited, based on male terminalia possessing a pair of gonocoxal lobes on the apicoventral gonocoxal margin. Eight previously-described species can be placed in this group, of which six are from the Holarctic Region, while one is recorded each from the Oriental and the Afrotropical Regions. Molecular and morphological species delimitations were mostly congruent, except in two cases where two species were delimited within a single Barcode Index Number (BIN). We found that each species is only known from a single zoogeographical region and that several species complexes are largely congruent with zoogeographical divisions, indicating that intercontinental barriers may have a strong impact on the species diversity of the group

Introduction

Materials and methods

Apicoventral gonocoxal margin distinctly protruding on each side of

Findings

Discussion