Description of African Scutellonema brachyurus Type B populations as Scutellonema afribrachyurus n. sp. (Tylenchida: Hoplolaimidae) based on integrative taxonomy

Summary Distinguishing Scutellonema species based on morphology alone is particularly challenging, especially within the S. brachyurus complex. Although Type A (America, Europe, Asia) and Type B (Africa) are geographically isolated and exhibit clear molecular divergence, their morphological differentiation has remained ambiguous. However, a newly compiled dataset, integrating comprehensive morphological and molecular data from multiple crops and countries, with a focus on finger millet populations in Kenya, provides stronger evidence for their separation. Molecular analysis of the D2-D3 region of 28S rDNA and COI of mtDNA confirmed that Type B represents a distinct species, with species delimitation methods (bPTB, GMYC and Rosenberg’s PAB) supporting this distinction. A combination of morphological traits such as the number of lip annuli and basal lip blocks, secretory-excretory pore position, c′ ratio, tail length and male stylet length, c and o ratios, further differentiates the two species. Scutellonema brachyurus Type B population is described as Scutellonema afribrachyurus n. sp. and is characterised by a lip region with usually three (exceptionally five) annuli and basal lip annulus with 8-20 blocks, stylet length of 21-32 μ m, ratio a = 20-34, ratio c′ = 0.5-1.4, S-E pore located rarely opposite the middle to mostly posterior part of the pharyngeal lobe, lateral field areolated at scutellum level, spermatheca small, rounded and empty, tail bluntly rounded, and dorsally convex with 9-17 annuli.