The Puzzling Falcomurus Mandal (Collembola, Orchesellidae, Heteromurinae): A Review

Simple Summary Springtails are tiny microarthropods found mainly in soil habitats around the globe. Falcomurus is a genus of Heteromurinae (Orchesellidae), currently with a single species from India. Here, we revise the genus, transferring Dicranocentrus litoreus Mari-Mutt and D. halophilus Mari-Mutt to Falcomurus and describing two new taxa from marine littoral habitats in Australian archipelagos. We discovered the morphology of Falcomurus is quite similar among its species, but some characters of its chaetotaxy (the distribution and morphology of body chaetae) are useful to clearly separate them from each other. Falcomurus Mandal is currently a monotypic genus of Heteromurinae described from India in 2018. Its key characters are the first antennal segment subdivided, the second undivided and the third annulated; the first abdominal segment lacking macrochaetae; and the presence of a sinuous modified macrochaeta on the proximal dens. Some details of its morphology were recently put in doubt, and so its genus status and affinities remain uncertain. Here, we revise the genus based on the type material of Dicranocentrus litoreus Mari-Mutt, as well as provide the description of two new species from Australian archipelagos and a reinterpretation of the chaetotaxy of Falcomurus chilikaensis Mandal and D. halophilus Mari-Mutt. After our revision, Falcomurus shows a well-conserved chaetotaxy and overall morphology, which allowed us to provide an updated generic diagnosis. While the antennae morphology of Falcomurus resembles that of Dicranocentrus Schott, its dorsal sensillar and macrochaetotaxy suggest it is closely related to Heteromurus Wankel, as originally stated by Mandal. The main features useful to separate Falcomurus species are the head, mesothorax and fourth abdominal segment chaetotaxy. We also provide a key to its five species, a comparative table and notes on the affinities and distribution of Falcomurus.

Automated summary

Springtails are tiny microarthropods found mainly in soil habitats around the globe. The genus Falcomurus, consisting of a single species from India, has been revised to include new species from Australian archipelagos. The morphology and chaetotaxy of Falcomurus are important for species differentiation, and its affinities within the Heteromurinae subfamily have been reevaluated.