A Numerical Phenetic Study of the Quill Mites of the Family Syringophilidae (Acari)

Abstract

A numerical phenetic study, based on 43 OTU's (species) and 83 characters, was carried out on this potentially large but homogeneous group of mites. The MCD values computed from the standardized data matrix were analyzed by cluster analysis and graph (nearest-neighbor) analysis. Successive subdivisions of the Syringophilidae were determined from analysis of the phenogram, graph diagrams, and distributions of the MCD values. The family is divisible into 2 major groups, the Syringophilinae and Picobiinae, new subfamily. The Syringophilinae is comprised of two major generic groups, the Syringophilopsis-group and the Syringophiloidus-group. The latter includes 2 complexes of genera centered about Niglarobia and Syringophiloidus, respectively. The indeterminate relationships of certain genera, especially Syringophilus, is discussed. Principal components analysis of the OTU's appeared to portray relationships rather poorly. The quill mites of the family Syringophilidae are a potentially large but homogeneous group of bird parasites. The mites inhabit the hollow of the calmus of various feathers and have been found on representatives of 16 orders of birds. A preliminary revision of the family (Kethley, 1970) arrayed the 29 recognizable described species in 17 genera. In addition, specimens of at least 200 new species are on loan to or in the collection of the junior author. The tactics of Syringophiloidus minor (Berlese) have been described by Kethley (1971) and, extrapolating from those observations and his experience with patterns of taxonomic discovery in the group, we may predict an eventual known fauna of 5,000 or more species of these mites. Although the number of species discovered is very small relative to the number yet to be found, we regard a numerical phenetic study as an essential step in the advancement of the knowledge of the Syringophilidae. Such studies have been suggested as inappropriate for poorly known groups by Michener (1963) but we believe that the strictly comparative approach demanded in numerical phenetic methods is precisely what is needed for all mite taxa. It is the purpose of this paper to provide quantitative estimates of affinity among members of the Syringophilidae. These estimates should (1) provide a sound basis and direction for future taxonomic work with the family; (2) provide a basis for comparison of taxa and their properties with ecologically Received for publication 22 December 1972. defined groups within the family; and (3) provide a basis for comparison of the classification of quill mites with the classifications of their avian hosts. In this paper we use the ideas and terminology of numerical phenetics without special explanation and definition. For a general introduction to these approaches, the reader is referred to Sokal and Sneath (1963), Blackith and Reyment (1971), or Jardine and Sibson (1971); an introduction oriented toward parasite taxonomy is given by Moss and Webster (1970). Prior numerical phenetic studies of mites have been carried out by Funk (1963, 1964, 1968), Herrin (1969), Manischewitz (1971), Moss (1967, 1968), Petrova (1967), Sheals (1965, 1969), and Wasmer (1971). MATERIALS AND METHODS The 43 OTU's used in this study are listed in Table I with their codes and host names. The choice of specimens was an attempt to provide a wide coverage of the diversity of the family within the limits of the quality of available material. Twenty-nine undescribed species were included and 6 of these were judged, prior to the study, to represent new genera. Because only adult females are known for many taxa, we have restricted our study to that instar and sex. Intensive examination of the chosen material permitted the recognition of 83 characters; the partitioning of these is given in Table II. A complete list of the characters is available upon request from the junior author. There were no missing data for any of the OTU's. The basic (character X OTU) data matrix was transformed by standardization. Similarity (or, conversely, difference) was computed as product-