A new species of sucking louse (Phthiraptera: Anoplura: Linognathidae) from Günther's Dikdik (Madoqua guentheri) in Kenya

The fragmented mitochondrial genomes of two Linognathus lice reveal active minichromosomal recombination and recombination hotspots

Evidence for recombination between mitochondrial (mt) minichromosomes has been reported in sucking lice, but it is still not clear how frequent mt minichromosomal recombination occurs. We sequenced the mt genomes of the cattle louse Linognathus vituli and the goat louse L. africanus. Both Linognathus species have 10 mt minichromosomes, and seven of them have the same gene content and gene arrangement. Comparison of mt karyotypes revealed numerous inter-minichromosomal recombination events in the evolution of Linognathus species. Minichromosome merger, gene duplication and gene translocation occurred in the lineage leading to Linognathus lice. After the divergence of L. vituli and L. africanus, duplication, degeneration, deletion and translocation of genes also occurred independently in each species. Most of the recombination events in the Linognathus species occurred upstream of either cox3 or nad2, indicating these two locations were hotspots for inter-minichromosomal recombination. Our results provide an important perspective on mt genome evolution in metazoans.

RETROSPECTIVE ANALYSIS OF MORTALITY CAUSES IN MANAGED KIRK'S DIK-DIKS (MADOQUA KIRKII) IN NORTH AMERICA FROM 1988 to 2019

Kirk's dik-diks (Madoqua kirkii) are the most common dik-dik species managed in North American zoological institutions, but their numbers are declining at a concerning rate, with less than 40 individuals currently housed in accredited institutions. This retrospective study reports the causes of mortality in Kirk's dik-diks in North American zoological institutions from 1988 to 2019. Out of 15 institutions accredited by the Association of Zoos and Aquariums (AZA) currently housing Kirk's dik-diks, nine contributed to this study (60% participation). Eighty-four necropsy records were reviewed to determine the primary affected body system and etiological cause of death across and within age categories. Neonatal death (prior to 1 mon of age) was most common (38.1%), followed by death in adults (29.8%), geriatric animals (19.0%), and juveniles (13.1%). As a whole population, causes of death by body system were multisystemic (47.6%), musculoskeletal (15.5%), respiratory (8.3%), and digestive (8.3%). Neonatal complications accounted for 50.0% of all deaths in animals prior to 1 mon of age. In juveniles, a nutritional cause of death was most common (27.3%) and significantly higher compared to measures of this cause within other age categories. In adults, metabolic etiologies and trauma each accounted for 28.0% of deaths. Degenerative etiologies were most common in geriatric individuals, representing 31.3% of the deaths. Death from infectious disease was found across all ages, representing 11.9% of all mortalities. Results from this study provide a baseline reference for this species and may aid clinicians in decision-making as it relates to the medical care and management of this species during different life stages.