Tag Archives: Elmidae

Peloriolus brunneus (F. H. Waterhouse)

Brown Riffle Beetle (Peloriolus brunneus)

This species was described in 1879, it is apparently known only by the material that was collected by Charles Darwin himself in 1836, allegedly on the island of Saint Helena, where it has never been found again.

The species might be extinct, or, which is in fact more likely, it was just mislabeled and did in fact originate from southern Africa, where all other species of that genus live, and where Darwin had been just prior to his arrival at Saint Helena. [1] 



[1] C. Hänel; M. A. Jäch: Beetles of the Tristan da Cunha Islands: Poignant new findings, and checklist of the archipelagos species, mapping an exponential increase in alien composition (Coleoptera). Koleopterische Rundschau 83: 257-282. 2013


edited: 29.05.2021

Heterelmis stephani Brown

Stephan’s Riffle Beetle (Heterelmis stephani)

Stephan’s Riffle Beetle was described in 1972; it was restricted to Madera Canyon on the western flank of the Santa Rita Mountains in south-east Arizona, USA.

The species was only ever found at two locations: Sylvester Spring and Bog Spring; in the last location it is known to have inhabited wet areas near a leaking pipe that diverted water from a spring to the Bog Spring Campground.

Stephan’s Riffle Beetle was last seen in 1993 and was officially declared extinct in 2016.


Depiction: United States Fish and Wildlife Service

(public domain)


edited: 23.08.2022