Date of Award

12-8-2023

Document Type

Thesis

Degree Name

Bachelor of Science

Department

Biology

First Advisor

Amy Treonis

Abstract

Panagrolaimus namibiensis n. sp., a bacterivorous nematode from the family Panagrolamidae, was extracted and cultured from soils collected from under Arthraerua leubnitziae (Pencil bush) in the Namib Desert of Namibia. The extraordinarily arid nature of this environment poses interesting questions concerning the nematode’s physiological adaptations to such conditions. Here, I provide a rigorous morphological characterization of this nematode including anatomical character measurements, scanning electron (SEM) micrographs, differential interference contrast (DIC) light images, and ancillary line drawings. While all Panagrolaimus species described to date share highly similar ultrastructural and interior features, P. namibiensis n. sp. is distinguished by having a conspicuous posterior deirid, a wide tail-base, and a hook-shaped stegostomal dorsal tooth, in addition to several other characteristics and anatomical proportions. Bayesian phylogenetic analysis using 18S and 28S genes confirms P. namibiensis n. sp. as being part of the Panagrolaimus genus, but the two trees reconcile the relationship to closely-related species differently. In a laboratory-induced desiccation experiment, P. namibiensis n. sp. survived exposure to 0% relative humidity for 24 h, demonstrating the anhydrobiotic ability of this species. This finding supports its evident persistence in the extremely arid and desiccated environment of the Namib Desert. Panagrolaimus nematodes have been collected from and studied across the globe, and this characterization of P. namibiensis n. sp. promotes future study of this nematode to better understand the role of anhydrobiosis in its ecology and survival.

Additional Files
2023-Rawson-form.pdf (231 kB)
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