The taxonomy of Geomydoecus (Mallophaga: Trichodectidae) from the Geomys bursarius complex (Rodentia: Geomyidae)

Abstract

A revision was undertaken of the members of the genus Geomydoecus parasitizing plains pocket gophers of the Geomys bursarius complex. Prior to this revision, 5 specific and subspecific taxa of lice were recognized from Geomys bursarius. Approximately 20,000 lice were obtained and examined; these were from all described subspecies of G. bursarius and represented 590 individual hosts from 427 localities. In addition to a study of qualitative features, 28 morphological characters were quantified for both adult male and female lice. The measured or counted characters that proved useful taxonomically are reported along with their ranges, means, and standard deviations. Three programs in the BMDP series were used for the multivariate statistical analysis: principal components analysis (BMDP4M), discriminant function analysis (BMDP7M), and cluster analysis (BMDP2M). The Geomydocus on Geomy bursarius proved to be quite variable geographically; however, there was little intrapopulation variability. This geographical variation is best represented taxonomically by recognizing 8 distinct monotypic species of lice. The previously described species, Geomydoecus geomydis, G. ewingi, G. illinoensis, and G. oklahomensis, are all recognized as valid species. A population previously described as a subspecies of G. geomydis is elevated to specific status, G. subgeomydis, and 3 new species are described: G. heaneyi on Geomys bursarius llanensis and G. b. texensis; G. nebrathkensis on Geomys bursarius lutescens; and G. spickai on Geomys bursarius missouriensis. These 8 species of lice cluster as 2 distinct groupings; the 1st, here termed the “northern” group, is composed of G. geomydis, G. illinoensis, G. nebrathkensis, G. oklahomensis, and G. spickai; the 2nd, the “southern” group, is composed of G. ewingi, G. heaneyi, and G. subgeomydis. In no case did a single population of pocket gophers have more than 1 species of Geomydoecus parasitizing it. Two species of Geomydoecus were obtained on Long-tailed Weasels, Mustela frenata; these host records are considered primary contamination, a result of the weasel's obtaining the lice directly from pocket gophers. A key is presented to the 15 specific and subspecific taxa of Geomydoecus that parasitize pocket gophers of the genus Geomys.