Abstract
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 µm, hemispherical lip region with 6 to 7 annules, stylet length 19 to 21 µm, irregularly areolated lateral fields, oval spermatheca filled with rounded sperm, intestine not overlapping the rectum, and tail length 103 to 149 µm, 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 µm. 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.
Highlights
IntroductionWith the exception of H. gracilis (Luc and Goodey, 1964; de Man, 1880), the genus Hirschmanniella is considered a harmful pest and is a quarantine taxon for the European Union (Karssen, 2009)
Genus Hirschmanniella contains 29 valid species as revised by Khun et al (2015)
The new species is characterized by its body length, 1,582 to 1,929 μm, hemispherical lip region with 6 to 7 annules, stylet length 19 to 21 μm, irregularly areolated lateral fields, oval spermatheca filled with rounded sperm, intestine not overlapping the rectum, and tail length 103 to 149 μm, usually with ventral projection with subterminal notch
Summary
With the exception of H. gracilis (Luc and Goodey, 1964; de Man, 1880), the genus Hirschmanniella is considered a harmful pest and is a quarantine taxon for the European Union (Karssen, 2009). These species occur in diverse habitats and hosts in all continents except for Antarctica, and they appear to be well adapted to a broad range of moisture conditions, with a preference for periodically or permanently saturated soils and for graminaceous root systems (Tandingan De Ley et al, 2007). It was not identified at the species level, one Hirschmanniella sp. was isolated from cattail (Typha spp.) along the Colorado River in Yuma, Arizona (Tandingan De Ley et al, 2007)
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