Aspidytidae is a family of aquatic beetles of the suborder
Adephaga, described in 2002 from specimens in
South Africa and
China.[2] There are only two known species in the family and these were originally described in the genus Aspidytes,[2][3] but later the new genus Sinaspidytes was erected for the species found in China.[4] The family can also be referred to by its trivial name cliff water beetles.[5]
Description
Cliff water beetles have a streamlined body that is dorsally convex. Their size ranges from 4.8 - 7.0 mm in length.
Dorsal side is predominantly black and cuticle is shiny.[3] The head is laterally rounded and shortened with the
compound eyes integrated in the outline. Legs lack swimming hairs.[2]
Larvae and adults of both A. niobe and S. wrasei are found in or in close proximity of hygropetric habitats[3] - meaning they require a rock surface covered by a thin layer of water. Both adults and larvae are likely predacious. Eggs and pupa are yet unknown.[3]
Phylogeny and evolution
The phylogenetic placement of Aspidytidae within the superfamily Dytiscoidea is still under debate, and even whether the family is monophyletic or paraphyletic with respect to
Amphizoidae.
Initially both species were categorized in the same genus – Aspidytes. Later Sinaspidytes was erected for S. wrasei following a phylogenetic analysis using 11 genes that recovered Aspidytidae as praphyletic. [4]
Later studies using genomic data have been inconclusive. A study using ultraconserved elements (UCE) still recovered Aspidytidae as paraphyletic, but with a different arrangement between the two species and Amphizoidae. [7]
^Balke, M., Ribera, I. & Beutel, R. G. 2002 "Aspidytidae: on the discovery of a new family of beetles and a key to fossil and extant adephagan families." In Water beetles of China, vol. 3 (ed. M. A. Jäch & L. Ji). Vienna: Zoologisch-Botanische Gesellschaft in O ¨ sterreich and Wiener Coleopterologenverein (In the press.)