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

作者：Joseph Maosa, David Kihoro Sirengo, Phougeishangbam Rolish Singh, Marjolein Couvreur, Dirk De Waele, Wim Bert · 发表于：Nematology · 年份：2025 · DOI：10.1163/15685411-bja10436 · 被引用次数：2 · 研究领域：Parasite Biology and Host Interactions

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...