Systematic relationships and the evolution of host associations in the mite family Sarcoptidae (Acari:Astigmata).

Abstract

A phylogenetic analysis of relationships among the 117 recognizable species of the mite family Sarcoptidae is carried out based on 215 morphological and ontogenetic characters. The outgroups are the putative sister family of the Sarcoptidae, the family Rhyncoptidae, and some more distantly related families in the Sarcoptoidea. Due to the large quantity of missing data and the overall size of the matrix the phylogenetic analysis is carried out in parts. Initial analyses, including only those taxa for which the amount of missing data is low, are used to establish a hypothesis of relationships between the larger subgroups. Relationships within each subgroup are analyzed separately. Rooting of these partial analyses is by the use of hypothetical ancestors constructed based on the initial analyses. A new classification of the Sarcoptidae is proposed based on the results of the phylogenetic analysis. The family is subdivided in three subfamilies, the Diabolicoptinae (2 genera, 3 species), Sarcoptinae (4 genera, 8 species) and Teinocoptinae (10 genera, 106 species). The Teinocoptinae include the formerly recognized families Teinocoptidae Fain, 1959 and Bakerocoptidae Fain, 1962, as well as the subfamily Notoedrinae Fain, 1968 (Sarcoptidae). Two new genera and 18 new species are described, and data on ecology, pathology and host associations are summarized for all species in the family. The evolution of host associations in the Sarcoptidae is studied using the methods of historical ecology. The history of the association is characterized by association by descent. However, the potential for colonization is retained in all lineages, and at least 9 colonization events (=26% of the nodes for which a hypothesis of process could be generated) have to be hypothesized. Speciation by the mites independent of speciation of the hosts is quite common and is hypothesized for 9 nodes (=26%). Body contact between the old and the potential new host appears required for colonization to occur. This restriction to initial transfer is hypothesized to be the major factor limiting the number of colonization events in Sarcoptidae. Factors restricting the probability for establishment after the initial transfer (e.g., coevolutionary processes) further limit the probability of successful colonizations.