GENOMICS AND MORPHOLOGY RESOLVE CHIPMUNK SUCKING LOUSE SYSTEMATICS (GENUS HOPLOPLEURA).

Area of Science:

• Parasitology
• Molecular Phylogenetics
• Ectoparasite Taxonomy

Background:

• Sucking lice (order Phthiraptera) are obligate parasites of mammals, often exhibiting host specificity.
• Previous molecular studies have indicated inaccuracies in current louse taxonomy.
• Chipmunks (Tamias spp.) are hosts to two described species of Hoplopleura lice: H. arboricola and H. erratica.

Purpose of the Study:

• To investigate the phylogenetic relationships between Hoplopleura lice infesting western and eastern chipmunks.
• To clarify the taxonomic status of Hoplopleura arboricola and Hoplopleura erratica using molecular and morphological data.
• To understand the evolutionary history of chipmunk-louse associations.

Main Methods:

• Phylogenetic analysis using 1,107 coding loci with maximum-likelihood and species tree approaches.
• Sequencing of additional genetic data to supplement existing published sequences.
• Morphological examination of louse specimens to identify distinguishing traits.
• Calculation of pairwise distances for the cytochrome oxidase subunit 1 (COI) gene.

Main Results:

• Phylogenetic analyses revealed two well-supported clades within H. arboricola, with H. erratica nested within one of these clades.
• No consistent morphological differences were found to distinguish H. erratica from H. arboricola.
• Genetic distances within H. arboricola clades were greater than distances between H. erratica and H. arboricola clades.
• H. arboricola is relegated to a junior subjective synonym of H. erratica.

Conclusions:

• The genetic and morphological evidence supports the synonymization of Hoplopleura arboricola under Hoplopleura erratica.
• An ancestral louse likely associated with western chipmunks before transferring to the eastern chipmunk.
• These findings highlight host-parasite co-evolution and the utility of phylogenomic analyses in understanding species interactions.