Description of Hirschmanniella dicksoni n. sp. (Nematoda: Pratylenchidae) from rhizosphere soil of limpograss from Florida, USA

Abstract

Hirschmanniella dicksoni n. sp. isolated from the rhizosphere soil of limpograss is described and illustrated based on morphology and molecular characters. The new species is characterized by its body length, 1,582 to 1,929 mu m, hemispherical lip region with 6 to 7 annules, stylet length 19 to 21 mu m, irregularly areolated lateral fields, oval spermatheca filled with rounded sperm, intestine not overlapping the rectum, and tail length 103 to 149 mu m, usually with ventral projection with subterminal notch. Males are similar to the females except for their shorter body length and presence of secondary sexual characteristics, with spicules length 19 to 30 mu m. The new species is closely related with H. mucronata, H. belli, and H. oryzae. Compared with these three species, the new species has a relatively longer tail and a terminus shape tail with a ventral projection with a subterminal notch. Other morphological and morphometric characteristics that separate these species are as follows: lip region, number of lip annuli, and spicules length. Molecular sequence analysis using the D2-D3 expansion segments of 28S and the ITS rRNA sequences showed that the new species is genetically distinct. D2-D3 sequence of H. dicksoni n. sp. showed 99 and 95% sequence homology with an undescribed species of Hirschmanniella isolated from the Colorado River in Yuma, Arizona, and H. oryzae, respectively. ITS sequence of the new species also showed 88% sequence homology with H. oryzae. The phylogenetic analysis of D2-D3 and ITS region grouped H. dicksoni n. sp., as sister species, with H. oryzae.