Aselloidea Latreille, 1802

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Suggested Common Name: Waterslaters and Rubyreds
Number of subordinate taxa: at least 427 species in 2 families worldwide, over 140 species in both families in our area.
Etymology: after Asellus Geoffroy, 1762, see that account for more information. Common name refers to the two consituent families
Taxonomic History: Aselloidea Latreille, 1802 [origin of modern usage not yet determined]. The families Microcerberidae and Atlantasellidae were formerly placed in Aselloidea but have been placed in their own suborder due to unique characteristics not found in other asellotes.
Description: Penes elongate, far-seperated.♂️ pleopod 1 smaller; protopods seperate; endites seperate. ♂️ pleopod 2 small; exopod large, circular, often fringed with setae; endopod generally "tucked" behind pleopod 1. ♀️ pleopod 2 not fused, usually small. Pleopod 3 operculate.
Type taxon: Asellidae Latreille, 1802
Notes: Aselloidea is a relict superfamily with an intrequing biogeography. Due to the superfamily's restriction to freshwaters and extremely low dispersal rate, the split biogeography between the Old World and North America indicates ancestors similar to modern relatives existing before the division of Pangaea. Stenasellidae in particular appears to have existed in its modern form since the Triassic, with the two American genera seemingly being closer to some African genera than other old world genera. 

Subordinate taxa: Asellidae, Stenasellidae

Key to families
1 a. Pleon with 2 well-developed segments free; ♂ pleopod 2 endopod distinctively 2-segmented, strongly elbowed so the basis points nearly anteriorad; body pigmentless but often colored reddish by hemoglobin-rich haemocoel; Gulf of Mexico periphery from Florida to Chiapas --> Stenasellidae
b. Pleon segments poorly developed, mostly fused with telson; ♂ pleopod 2 endopod segmentation indistinct to absent, slightly elbowed (often with a large spur at basiolateral corner); body pigmented brownish or unpigmented with a slight magenta hue; Nearctic from NE Alaska (Asellus) and Nova Scotia to Guatemala --> Asellidae


Kensley, B., & Schotte, M. (1989). Guide to the marine isopod crustaceans of the Caribbean. Smithsonian Institution Press.

Magniez, G. (1999). A review of the family Stenasellidae (Isopoda, Asellota, Aselloidea) of underground waters. Crustaceana, 72(8), 837-848.

Wilson, G. D. F. (1987). The road to the Janiroidea: Comparative morphology and evolution of the  asellote isopod crustaceans. Journal of Zoological Systematics and Evolutionary Research, 25(4), 257-280.

Published: Jan 1, 2023

Modified: Oct 25, 2023