Integrative taxonomy of Meloidogye ottersoni (Thorne, 1969) Franklin, 1971 (Nematoda: Meloidogynidae) parasitizing flooded rice in Brazil

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Inglés. A root-knot nematode (RKN) parasitizing rice (Oryza sativa L.) and causing damage in Santa Catarina (SC), Rio Grande do Sul (RS) and Paraná (PR) states (Brazil) was identified as Meloidogyne ottersoni (Thorne 1969) Franklin 1971. The species is redescribed from the Brazilian population from Meleiro (SC) and compared with the description of M. ottersoni from Wind Lake (Wisconsin, USA) with additional morphological, biochemical and molecular characterization. The female and male bear smaller stylets: 10-12 μm, 14-16 μm, respectively, when compared with M. graminicola: 12-14 μm, 16-18 μm, and M. oryzae: 14-16 μm, 18-20 μm. Meloidogyne ottersoni presents perineal patterns located on the contour of a slight protuberance. Striae are mostly continuous, never raised by transverse irregular striae, as frequently observed in M. graminicola and M. oryzae. Meloidogyne ottersoni belongs to the RKN group 11 described by Jepson (1987); the reproduction is by meiotic parthenogenesis and the somatic chromosome number is 18. The tail of second-stage juveniles is very long and thin, and tapers to a long, narrow, irregular hyaline terminus (M. ottersoni, 20.5 μm vs M. graminicola, 17.9 μm and M. oryzae, 22.0 μm, respectively). The ability of the Brazilian M. ottersoni population to parasitize canary grass, Phalaris arundinacea L. (type host), and barnyard grass, Echinocloa crus-galli, was confirmed. Biochemically, the esterase profile of M. ottersoni lacks any band (Est Ot0, Rm=0), which differentiates it from M. graminicola and M. oryzae (Est VS1, Rm=0.70 and Est O1, Rm=1.02, respectively). In Maximum Likelihood analysis of ITS, D2D3 and COXII-16S rRNA sequences, populations of M. ottersoni from different states of Brazil clustered together and were separated from other Meloidogyne spp., thus confirming that all four populations are very similar and conspecific.