NSF ARTS Litter Bugs
Tiny and stunningly diverse Dipsocoromorpha (Hemiptera: Heteroptera), or litter bugs, are the least known Heteroptera (Insecta). Among the 7 infraorders of true bugs, only Dipsocoromorpha have not been subjected to phylogenetic analysis and even their monophyly has been disputed. This worldwide group with highest diversity in the tropics of the Old and New Worlds comprises only ~320 described species in 5 families. Species inhabit cryptic microhabitats including leaf litter, mosses, and the interstitial zone of streams. Even within the largest and best documented family, the Schizopteridae (~238 spp.), we estimate that >500 spp. remain to be described, mostly from the Afrotropical, Neotropical, and Indo-Pacific regions. Schizopteridae are small (1-2mm), sturdy, show complexity of male genitalia that is unparalleled among Heteroptera, and are often strikingly sexually dimorphic with coleopteroid females featuring true elytra. Few experts have focused on Dipsocoromorpha, and none have trained students. Litter bugs are collected by various techniques, including leaf litter extraction and yellow pan traps, and are seemingly rare in collections (e.g., 1 unsorted drawer at The Natural History Museum, London). We have been using existing resources, i.e., residues of trap samples housed in natural history collections, and little additional field work, to build a large (~15,000 specimens) and well curated collection of Dipsocoromorpha. Together with Pavel Štys, the only active, but retired, world authority on Dipsocoromorpha, and other collaborators, the Christiane Weirauch (PI) and 9 students have been assembling material of Dipsocoromorpha with emphasis on Schizopteridae and conducting taxonomic, phylogenetic and evolutionary research on litter bugs.
We have been assembling material from 5 of the largest depositories of relevant trap samples with near worldwide scope (Field Museum; Florida State Collection of Arthropods; Natural History Museum, Geneva; Iziko Museums, Capetown; National Museum of Natural History), collaborations with other NSF-funded projects (ASWEA, LLAMA, TIGER, Phorid RevSys), fieldwork in West Africa, the least studied biogeographic region for Schizopteridae, and fieldwork (by collaborators) in Brazil and Colombia. Integrative taxonomic revisions of genera and species of Schizopteridae, with emphasis on the poorly studied Schizopterinae, will use established protocols for specimen processing and databasing and semi-automated species descriptions and will reveal the true diversity of Schizopteridae while facilitating matching of highly sexually dimorphic sexes. Based on available material and proven phylogenetic approaches (morphology, molecular data), we will test the monophyly of Dipsocoromorpha and establish a supra-generic classification. Together with comparative morphological studies, these phylogenies will allow testing of hypotheses on the stepwise evolution of elytra and on the complex evolution of genital asymmetries in litter bugs.