A new genus of railroad-worm beetles from the Atlantic Rainforest from Brazil (Coleoptera: Phengodidae, Mastinocerinae)

Here we describe a new genus, Cleidella gen. nov., and two new species, C. picea sp. nov. and C. silveirai sp. nov., all from Rio de Janeiro State, Brazil. The new genus is characterized by the interantennal distance subequal to scape length, antenna with 11 antennomeres, IV to X with two long symmetrical branches; mandibles long, projected and not crossed, pointed forward obliquely from head; maxillary palpi 4‑segmented, last segment digitiform; labial palpi 2‑segmented; posterior tentorial pit consisting of a single small fossa; elytron surpassing from the fourth to fifth abdominal segment, 3.3‑3.9× longer than wide; first tarsomere of protarsus with a ventral comb as long as the tarsomere length; wing with radial cell closed and transverse, vein r4 interrupted; aedeagus with paramere symmetrical, apex unevenly round, toothed inward, with short and scarce bristles. We provide a key to Mastinocerinae genera with 11 antennomeres, as well as illustrations for the diagnostic features for this new genus and a key to its species.