Phylogenetic relationships, distribution and abundance of Charaxes mtuiae Collins Congdon and Bampton, 2017 (Papilionoidea: Nymphalidae: Charaxinae) and its host plant in the Udzungwa mountain forest in southern Tanzania

Abstract

Charaxes mtuiae Collins Congdon and Bampton, 2017 was discovered in 2005 in the Udzungwa Mountains of Tanzania, where the caterpillars feed exclusively on Diospyros natalensis. This study was aimed at determining the abundance and spatial distribution of C. mtuiae and its host plant, as well as its evolutionary history. Field surveys were conducted between April 2017 and December 2018. Stems of the host plant were counted in sampling plots and their diameter at breast height measured, and categorised as mature if the diameter was ≥ 12 cm, otherwise as recruits. Charaxes mtuiae was sampled by searching for immatures on the leaves of the host plant and capturing adults using traps. DNA material of C. mtuiae was extracted, sequenced, and aligned with 63 other species of Charaxes. A total of 1,173 stems of the host plant including 1,064 recruits and 102 mature stems were recorded. One specimen of C. mtuiae found at caterpillar stage was raised to adulthood, and three empty pupa cases of C. mtuiae were recorded. The phylogenetic relationship of C. mtuiae and its sister lineages was concordant with previous descriptions, based on morphology. Our results indicate that C. mtuiae is rare, despite the high abundance of its host plant. Continued research and monitoring of C. mtuiae population to understand its ecological requirements; and expansion of surveys into other parts of the country where the host plant occurs to establish its distribution country-wide are recommended.