The status of Demodex cornei: description of the species and developmental stages, and data on demodecid mites in the domestic dog Canis lupus familiaris

Abstract

Demodecosis canina is one of the most important dog parasitoses, but its aetiology is still not well known. There are currently two known species of demodecid mite specific to the domestic dog Canis lupus familiaris Linnaeus, 1758 (Carnivora: Canidae). These are Demodex canis Leydig, 1859 (Acariformes: Demodecidae) and Demodex injai Desch & Hillier, 2003. There have also been many reports of the so-called 'short form', considered to be a separate species functioning under the name Demodex cornei nomen nudum, for which, however, no formal valid description has been documented. Taxonomic analysis of short forms of dog demodecid mites, associated with the stratum corneum, was performed, in line with the taxonomic criteria of Demodecidae systematics. This form was found to be a distinct species with features that differ from those of the other known species of this family. The species, including the adult and immature stages, is described. It is likely that different Demodex species parasitizing the domestic dog may be responsible for differentiated symptoms and different courses of demodecosis. However, the basis for clarifying this issue should be the correct, unambiguous identification of the species causing parasitosis.

Diagnosis and treatment of demodicosis in dogs and cats

“…The female adult mites were approximately 50% longer and males 100% longer than adult D. canis mites respectively. A short‐bodied mite was named D. cornei by some authors because it was supposedly found more superficially . Genetic comparisons revealed only one or two different species of Demodex in the dog: D. canis and D. injai .…”

“…In one report it was suggested that D. cornei are dead or near‐dead D. canis mites, further supporting that only two species of mites exist . However, a taxonomic analysis found the short‐bodied mite to be a distinct canine species …”

Demodex: a skin resident in man and his best friend

“…Demodex injai is substantially larger than D. canis , with adult males and females reported as approximately 100% and 50% larger than D. canis , respectively, 16 and genetically distinct 17 . Demodex cornei is shorter than D. canis , and in a recent study focusing on taxonomic features such as the shape and position of the female opisthosomal organ, the authors concluded that D. cornei could be distinguished from D. canis and D. injai 18 . However, D. cornei was 98% identical to D. canis in a study of the mites mitochondrial 16S rDNA sequence, though D. injai was only 77% identical to D. canis 17 …”

Morphological and ontogenetic characteristics of Miridex putorii (Acariformes: Demodecidae), a new genus and species of skin mite specific to the European polecat Mustela putorius

“…The Demodecidae (Acariformes: Prostigmata) of carnivoran mammals have been relatively poorly studied. Most information regarding mites of the genus Demodex concern domestic animals, dogs and cats, each harboring four species; however, some of these have been discovered only in recent years ( Izdebska and Rolbiecki, 2018 , 2020 ; Morita et al, 2018 ). The majority of known information concerns the clinical signs of the parasitosis in the hosts, canine demodecosis and feline demodecosis , respectively.…”