Neoceroplatus betaryiensis nov. sp. (Diptera: Keroplatidae) is the first record of a bioluminescent fungus-gnat in South America

Rafaela L Falaschi,Ana G S Martins,Adão H R Domingos,Jeremy D Mirza,Etelvino J H Bechara,Sérgio L Pompéia,Grant A Johnson,Anderson G Oliveira,Danilo T Amaral,Cassius V Stevani,Vadim R Viviani,Imran B Viroomal,Isaias Santos

doi:10.1038/s41598-019-47753-w

Abstract

Blue shining fungus gnats (Diptera) had been long reported in the Waitomo caves of New Zealand (Arachnocampa luminosa Skuse), in stream banks of the American Appalachian Mountains (Orfelia fultoni Fisher) in 1939 and in true spore eating Eurasiatic Keroplatus Bosc species. This current report observes that similar blue light emitting gnat larvae also occur nearby the Betary river in the buffer zone of High Ribeira River State Park (PETAR) in the Atlantic Forest of Brazil, where the larvae were found when on fallen branches or trunks enveloped in their own secreted silk. The new species is named Neoceroplatus betaryiensis nov. sp. (Diptera: Keroplatidae: Keroplatinae: Keroplatini) based on a morphological analysis. Neoceroplatus betaryiensis nov. sp. larvae emit blue bioluminescence that can be seen from their last abdominal segment and from two photophores located laterally on the first thoracic segment. When touched, the larvae can actively stop its luminescence, which returns when it is no longer being agitated. The in vitro bioluminescence spectrum of N. betaryiensis nov. sp. peaks at 472 nm, and cross-reactivity of hot and cold extracts with the luciferin-luciferase from Orfelia fultoni indicate significant similarity in both enzyme and substrate of the two species, and that the bioluminescence system in the subfamily Keroplatinae is conserved.

Highlights

The family Keroplatidae comprises of at least 92 genera and approximately 950 species[1,2,3,4,5], distributed in all biogeographic regions
The bioluminescence system of O. fultoni, produced by translucent areas associated with rows of black bodies, involves an unknown heterodimeric 140 kDa luciferase, an unknown luciferin and a Substrate Binding Fraction (SBF), which apparently releases luciferin in the presence of reducing agents[20]
The addition of hot extract of N. betaryiensis nov. sp. to the purified luciferase of O. fultoni resulted in blue light emission. These results indicate that N. betaryiensis nov. sp. and O. fultoni share either very similar or identical luciferin substrates and luciferase enzymes

Summary

Introduction

The family Keroplatidae comprises of at least 92 genera and approximately 950 species[1,2,3,4,5], distributed in all biogeographic regions. The larvae of luminous species such Archnocampa luminosa and Orfelia fultoni are carnivorous, the Japanese Keroplatus nipponicus is fungivorous. They are sticky and, in some cases, poisonous (i.e., contains oxalic acid as in the case of O. fultoni). Bigger arthropods such as cockroaches and ants were found caught in the webs of O. fultoni[14]. Bioluminescence in Diptera is reported only in the Keroplatidae family in the genera Arachnocampa Edwards (Arachnocampinae), Keroplatus Bosc (Keroplatinae: Keroplatini), and Orfelia Costa (Keroplatinae: Orfeliini)[4,16,17]. Within the Keroplatidae there are at least two morphologically and biochemically distinct bioluminescent systems, namely those of Arachnocampa and O. fultoni Fisher[20], whilst the bioluminescent system of Keroplatus species remains unknown. There is no cross-reaction between either the luciferin or the luciferase of Arachnocampa and Orfelia

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Conclusion