Monday, August 12, 2019

[Entomology • 2019] Neoceroplatus betaryiensis • the First Record of A Bioluminescent Fungus-gnat (Diptera: Keroplatidae) in South America

Neoceroplatus betaryiensis Falaschi, Johnson & Stevani

in Falaschi, Amaral, Santos, Domingos, Johnson, et al., 2019. 

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.

Figure 1: Different locations and habitats where larvae of Neoceroplatus betaryiensis nov. sp. were photographed.
(A) Decaying log where larvae were collected. (B) Larvae on the surface of the log surrounded by a web-like mucus. (C) Association of a larva with a Favolus brasiliensis (Fr.) Fr. mushroom raised in a terrarium. (D) Photo of a typically translucid N. betaryiensis sp. nov. (E) Details of the larva head and (F) last abdominal segment.

Figure 2: Life cycle of Neoceroplatus betaryiensis nov. sp. (A) Pupal stage. (B) Emerged adult female. (C) Emerged adult male.

Figure 3: Bioluminescence of Neoceroplatus betaryiensis nov. sp. larvae.
(A) Light emission under illumination and (B) in the dark. (C) Detailed view of the two photophores located laterally on the first thoracic segment.

Neoceroplatus betaryiensis Falaschi, Johnson & Stevani nov. sp.

Diagnosis and comments: Neoceroplatus betaryiensis nov. sp. can be distinguished from the other Neotropical Neoceroplatus¸ especially from N. dissimilis, its closest species, by the shape of the genitalia, particularly the gonostylus (Figs S3E, S4B,C) and the absence of spines in the gonostylus as appears in N. paicoenai.

Etymology: The specific epithet refers to the Betary brook, in whose banks the specimens were collected.

Here we report the discovery of the first bioluminescent species of fungus-gnats of the family Keroplatidae in the Neotropical region. Similar to the Palearctic and Oriental Keroplatus species, N. betaryiensis also lives under dead logs and is probably sporophagous. The bioluminescence is blue, and likely shares the same luciferin-luciferase system of the North-American Orfelia fultoni, and possibly of the Palearctic Keroplatus spp. These findings show how Neotropical biodiversity is still poorly known, despite being recognized as the most diverse biogeographic region on the planet. Unfortunately, the anthropic pressure on natural areas has been increasing, causing disturbances in different habitats, with damage in megadiverse countries such as Brazil. These threats affect especially small invertebrates, which have been extinguished at a much faster rate than their discovery and description. This reinforces the need for conservation policies for areas such as the Betary Reserve, a place that provides new taxa for science, the Keroplatidae being one of them.

Rafaela L. Falaschi, Danilo T. Amaral, Isaias Santos, Adão H. R. Domingos, Grant A. Johnson, Ana G. S. Martins, Imran B. Viroomal, Sérgio L. Pompéia, Jeremy D. Mirza, Anderson G. Oliveira, Etelvino J. H. Bechara, Vadim R. Viviani and Cassius V. Stevani. 2019. Neoceroplatus betaryiensis nov. sp. (Diptera: Keroplatidae) is the First Record of A Bioluminescent Fungus-gnat in South America. Scientific Reports. volume 9, 11291.