Morphology and life cycle of a new species of Psilocladus Blanchard, 1846 (Coleoptera, Lampyridae, Psilocladinae), the first known bromeliad-inhabiting firefly

Abstract

Fireflies (Coleoptera: Lampyridae) are soft-bodied beetles usually associated with mesic and hydric habitats. As such, terrestrial firefly larvae are commonly found in marshy environments and stream banks, while aquatic larvae might dwell in ponds, streams, mangroves, and even brackish water. Larval biology is especially important in fireflies, as the majority of species are extremely semelparous – that is, adults rely on resources gathered during larval stages. Despite their crucial relevance in firefly biology, larvae of only near 1% firefly species have been studied, and the majority of species remain known only from adult stages. That is especially true in the Neotropical region, where they are most diverse. Here, we describe Psilocladus costae sp. nov. after the study of adults and immature stages, the latter reported for the first time for the monotypic subfamily Psilocladinae McDermott, 1964. Interestingly, adults were first obtained by rearing the larvae, the former usually fly fairly high (ca. 10 m) and are therefore seldom collected at ground level by conventional methods (e.g., active search, Malaise traps). The new species is found in the Brazilian Atlantic Rainforest, inhabiting canopy bromeliads, an unprecedented habit for fireflies.

A comprehensive review and call for studies on firefly larvae

“…, cantharid Macromalthinus Pic, 1919 ( Biffi & Casari, 2017 ) and Jurasaidae species ( Rosa et al, 2020 )). Under laboratory conditions, Psilocladus larvae of two species studied by our group readily ate termite workers, consistent with the possibility that their relatives live on termites in the field ( Vaz, Silveira & Rosa, 2020 ; S Rosa, 2021, pers. obs.).…”

“…1C , e.g. , Psilocladus Blanchard , 1846, Lamprigera Motschulsky, 1853) (e.g., Costa, Vanin & Casari-Chen, 1988 ; Novák, 2018a ; Novák, 2018b ; Vaz, Silveira & Rosa, 2020 ).…”

“…Even marine fireflies prey on gastropods ( e.g. , Micronaspis gabrielae Vaz, Silveira & Rosa, 2020 — Vaz et al, 2021 ). Firefly larvae mastered gastropod-eating through a menagérie of complex behaviors, including snail-riding (climbing the shell and biting from above, e.g.…”

“…In fact, Lampyris larvae have been spotted crawling in daytime, searching for pupation sites ( Tyler, 2002 ). During the day, terrestrial larvae are presumed to rest in soil, leaf litter, and under stones ( McLean, Buck & Hanson, 1972 ; Faust, 2017 ), rock crevices ( Vaz et al, 2021 ), or inside bromeliads ( Vaz, Silveira & Rosa, 2020 ). At night they appear on the surface, crawling among grass, weeds, and sometimes climbing up a few inches on stems, particularly if the weather is damp ( Faust, 2017 ).…”

Hide-and-Seek with Tiny Neotenic Beetles in One of the Hottest Biodiversity Hotspots: Towards an Understanding of the Real Diversity of Jurasaidae (Coleoptera: Elateroidea) in the Brazilian Atlantic Forest

“…Many interesting insects were reported from the Atlantic Forest, including the bioluminescent larvae of Keroplatidae fungus gnats (Diptera) [ 64 ] and rove beetles (Staphylinidae) [ 65 ], the first Neotropical meropeid Mecoptera [ 66 ], ant-brood parasitizing scuttle flies (Phoridae) [ 67 ], and many others. The late discovery of Jurasaidae in the Atlantic Forest might seem surprising at first sight, but considering high numbers of recently reported new lineages in other soft-bodied elateroids, including Lampyridae [ 56 , 57 , 68 , 69 , 70 , 71 , 72 , 73 , 74 ], Lycidae [ 19 , 75 ], and Phengodidae [ 76 , 77 ], it is much less surprising. For example, Silveira et al [ 57 ] examined the diversity of fireflies (Lampyridae) in the Serra do Órgãos (a subrange of the Serra do Mar), and, for the first time, collected 58 previously described species along with another 42 yet-undescribed species, which makes the Serra do Órgãos one of the richest firefly hotspots on Earth.…”