Mejía-Madrid H H, Choudhury A, de León G Pérez-Ponce
Laboratorio de Helmintología, Instituto de Biología, Universidad Nacional Autónoma de México, Mexico City, Mexico.
Syst Parasitol. 2007 May;67(1):1-18. doi: 10.1007/s11230-006-9065-3. Epub 2006 Dec 8.
A phylogenetic analysis of 40 species of Rhabdochona Railliet, 1916, including all 21 valid species in the Americas, resulted in 1733 equally most parsimonious trees and indicates that Rhabdochona is arguably monophyletic. Species from the Americas do not form a monophyletic group, since each of the six clades of Rhabdochona includes species from the Americas and species from other continents. The synapomorphies defining each clade stem from the morphology of the left spicule. Teeth number was consistent in one clade only, suggesting that this character, while useful for taxonomic purposes, is not indicative of phylogeny. Species of Rhabdochona associated with certain host groups, such as salmonids, catostomids and goodeids, do not always form monophyletic assemblages, nor do species associated with smaller discrete areas, such as the Mesa Central of Mexico. This indicates widespread host-switching rather than co-speciation as the main phenomenon in the evolution of this group, at least in the species from the Americas. Phylogenetic patterns reveal an ancient origin for the group that probably pre-dates current continental configurations.
对1916年的40种似蛔线虫属物种进行系统发育分析，其中包括美洲所有21个有效物种，结果得到1733棵同等最简约树，这表明似蛔线虫属可以说是单系的。美洲的物种并不形成一个单系类群，因为似蛔线虫属的六个分支中的每一个都包括来自美洲的物种和来自其他大陆的物种。界定每个分支的共衍征源于左交合刺的形态。仅在一个分支中齿数是一致的，这表明该特征虽然对分类学有用，但并不指示系统发育。与某些宿主类群（如鲑科鱼类、胭脂鱼科鱼类和古氏鳉科鱼类）相关的似蛔线虫属物种并不总是形成单系组合，与较小离散区域（如墨西哥中部台地）相关的物种也是如此。这表明广泛的宿主转换而非共同物种形成是该类群进化中的主要现象，至少在美洲的物种中是这样。系统发育模式揭示了该类群的古老起源，可能早于当前的大陆构造。
