Monophyletic group |
Both morphological and molecular characters support the monophyly of Criconematoidea (van Megan et al., 2009). Recently Bert et al., (2008) in a phylogenetic analysis of Tylenchina using female gonad structure and 18S rDNA found strong support for the group (posterior probabilities of 100) in Bayesian inferences that included eight criconematoid species. They stated that “the absence of a well separate spermatheca and a uterus not arranged in regular rows is a distinct apomorphic characteristic for Criconematoidea”. Yet the remarkable overall similarity in gonad structure did not shed light upon the “uncertain position” of subgroups within the superfamily. This theme of group monophyly with poorly resolved relationships among subgroups was echoed by Subbotin et al., (2006) in a phylogenetic analysis of Tylenchida using partial 28S rDNA. Eleven criconematid taxa, representing eleven nominal genera (one species per genus) were strongly supported collectively as one of seven main lineages in Tylenchida. Relationships within the suborder, however, were not well-resolved except a grouping combining representatives of Ogma Southern, 1914 and Criconema Hofmänner & Menzel, 1914. An expanded phylogenetic analysis of Criconematina conducted by Subbotin et al., (2005) using the same gene region arrived at the same conclusion. This study included 23 nominal taxa from 11 genera. The geographic coverage of the 38 samples included two from North America, 12 from Venezuela, and the remaining specimens from Europe. The authors stated “none of the phylogenetic analyses of the D2-D3 dataset allowed resolution of the relationships between main lineages.” |
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