Overview of the lady beetle tribe Diomini and description of a new phytophagous, silk-spinning genus from Costa Rica that induces food bodies on leaves of Piper (Piperaceae)

Authors: VANDENBERG, N. - RETIRED ARS EMPLOYEE; HANSON, PAUL - UNIVERSIDAD DE COSTA RICA

Submitted to: Zootaxa
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/11/2018
Publication Date: N/A
Citation: N/A

Interpretive Summary: Many lady beetle species are important predators of crop and garden pests, while still others are plant-feeders and may be pests themselves. A new genus of plant-feeding lady beetles was discovered in Costa Rica. This genus is closely related to some predatory lady beetles that have been employed to control mealybugs, aphids, and scale insects in agriculture. The unusual habits of the new plant-feeding genus are discussed, and the known species are described, illustrated, keyed, and diagnosed as an aid to identification. This work will be useful to agriculturalists, biological control practitioners, and ecologists in identifying and better understanding the lady beetle species they encounter and what role they might play in relation to humans and their crop production.

Technical Abstract: A new genus of lady beetle, Moiradiomus gen. nov. (Coleoptera: Coccinellidae: Diomini), and four new species are described from Costa Rica, representing the first known occurrence of dedicated phytophagous lady beetle species outside of the subfamily Epilachninae (sens. Sasaji). The new species are described and illustrated and their life histories discussed. Each species of Moiradiomus occurs on a separate species of Piper (Piperaceae), where the larva constructs a small silken tent between leaf veins and inside this shelter induces the production of food bodies, which are its exclusive source of food. The taxonomic history of Diomus Mulsant, 1850 and related species in the tribe Diomini Gordon, 1999 is reviewed. The tribe Diomini is rediagnosed and recircumscribed to include Diomus, Decadiomus Chapin, 1933, Heterodiomus Brèthes, 1925, Dichaina Weise, 1923, Andrzej Slipinski, 2007, and Moiradiomus. Magnodiomus Gordon, 1999 and Erratodiomus Gordon, 1999 are removed from Diomini and transferred to Hyperaspidini Costa, 1849, subtribe Selvadiina Gordon, 1985, stat. nov. Mimoscymnus Gordon and Planorbata Gordon, originally described in Coccidulini are also transfered to Hyperaspidini and placed in Mimoscymnina, subtrib. nov. (type genus Mimoscymnus). The main features distinguishing Diomini and Hyperaspidini are described and illustrated. The identification of the Australian Diomus species illustrated in Gordon's publication on North American lady beetles is corrected from D. pumilio Weise to D. tenebricosus (Boheman), however specimens recently collected in California do not match these genitalic illustrations and are identified as true D. pumilio. The following species of Diomus are transferred to Decadiomus as new combinations: D. balteatus (LeConte, 1878), D. floridanus (Mulsant, 1850), D. amabilis (LeConte, 1852), D. liebecki (Horn, 1895), D. myrmidon (Mulsant, 1850), D. humilis (Gordon, 1976), D. pseudotaedatus (Gordon, 1976), D. taedatus (Fall, 1901), D. bigemmeus (Horn, 1895), and D. austrinus (Gordon, 1976). Decadiomus seini Segarra, 2014 is placed as a junior synonym of D. austrinus.