Additional information on Meloidogyne polycephannulata and its proposal as a junior synonym of M. incognita

Abstract

Summary The type population of Meloidogyne polycephannulata is synonymised with M. incognita based on morphological and morphometric characters, as well as biochemical, molecular and phylogenetic studies. Morphological variability and a wide host range were reported for M. incognita during its first description and later re-description. Meloidogyne polycephannulata was described in Brazil from specimens collected in a carrot field (type population). The esterase phenotype (Est) characterised for this species was identical to the phenotype Est I2 of M. incognita, the most ubiquitous phenotype used for diagnostics. Morphological and morphometric characters of the descriptions of the two nominal species showed major similarities, as well as variability within the range of variation detected in M. incognita. In PCR assays, three SCAR markers species-specific for M. incognita (incK14 F/R, Mi/FR and incB06 F/R) amplified the same fragments of 399 bp, 955 bp and 1200 bp, respectively, for populations in both species. In phylogenetic studies based either on concatenated sequences of ITS1-5.8S-ITS2, D2-D3 rRNA, mitochondrial COII regions or on RAPD and AFLP data, the populations of both species grouped in the same clade with high bootstrap support. Altogether, these results provide congruent evidence that the M. polycephannulata type isolate deposited at the Embrapa Cryopreserved National Collection of Root-knot Nematodes is not a valid species but rather a junior synonym of M. incognita.