Tag Archives: Dytiscidae

Allodessus skottsbergii (Zimmerman)

Skottsberg’s Diving Beetle (Allodessus skottsbergi)  

Skottsberg’s Diving Beetle was described in 1924, it is known only from the island of Rapa Nui.

The species reaches a body length of about 0,2 to 0,23 cm and is yellowish to ferruginous colored, males and females are superficially identical.  

The beetle inhabits the crater lakes of Rapa Nui, where it lives among algae, it is a predacious species. [1][2]  


The beetle is known already from subfossil core samples, where its remains can be found at a depth of about 15,5 m, in sediments that were deposited before the first Polynesian settlers appeared, which means that the species indeed is at least native to Rapa Nui, perhaps even endemic. [4]


Skottsberg’s Diving Beetle was apparently not recorded during recent field studies and may in fact already join the list of extinct species. [3]



[1] A. Zimmermann: Coeloptera-Dytiscidae von Juan Fernandez und der Osterinsel. in The Natural history of Juan Fernandez and Easter Island, edited by Carl Skottsberg. Vol. 3: 299-304., Zoology. Uppsala: Almqvist & Wiksells Boktryckeri, 1921-1940 
[2] Michael Balke; Ignacio Ribera: Jumping across Wallace’s line: Allodessus Guignot and Limbodessus Guignot revisited (Coleoptera: Dytiscidae, Bidessini) based on molecular-phylogenetic and morphological data. Australian Journal of Entomology 43(2): 114-128. 2004  
[3] Konjev Desender; Léon Baert: The Coleoptera of Easter Island. Bulletin de l’Institut royal des Sciences naturelles de Belgique. Entomologie 66: 27-50.1996
[4] M. Horrocks; M. Marra; W. T. Baisden; J. Flenley; D. Feek; L. González Nualart; S. Haoa-Cardinali; T. Edmunds Gorman: Pollen, phytoliths, arthropods and high-resolution 14C sampling from Rano Kau, Easter Island: evidence for late Quaternary environments, ant (Formicidae) distributions and human activity. Journal of Paleolimnology 50(4): 417-432. 2013


edited: 11.12.2018

Megadytes ducalis Sharp

Giant Diving Beetle (Megadytes ducalis)

The Giant Diving Beetle, described in 1882, was originally known only from a single specimen, which was collected in 1880 (?) at an unknown location in Brazil.

The species was considered extinct.


However, another ten specimens were discovered in 2019 in different historical museum collections, including drawers with unsorted diving beetle accessions of the Muséum National d’Histoire Naturelle in Paris, France. These specimens were labeled as having been collected in what today is the municipality of Condeúba in the state of Bahia in northeastern Brazil. 

The species is still officially considered extinct, but searches with the intention to rediscover the species are currently underway. [1]



[1] Lars Hendrich; Michael Manuel; Michael Balke: The return of the Duke – locality data for Megadytes ducalis Sharp, 1882, the world’s largest diving beetle, with notes on related species (Coleoptera: Dytiscidae). Zootaxa 4586: 517-535. 2019


edited: 29.04.2021

Siettitia balsetensis Abeille de Perrin

Perrin’s Cave Diving Beetle (Siettitia balsetensis)  

This species, which was described in the year 1904, is known from only two localities, the commune of Le Beausset and the town of La Seyne-sur-Mer in the Provence-Alpes-Côte d’Azur region in southern France.  

The species inhabited caves, where it depended on a habitat providing stagnant groundwater and constantly low temperatures, a habitat that was low in oxygen but rich in carbon dioxide, without any light and vegetation.  

Perrin’s Cave Diving Beetle is now regarded as extinct.


edited: 11.10.2020