Morphological and molecular characterisation of Hirschmanniella paramucronata n. sp. associated with rice from India

Populations of Hirschmanniella collected from rice from different states in India were studied using morphological, morphometric, and molecular approaches. All populations were similar and distinctly different from previously known species of Hirschmanniella mucronata from rice. Herein, we describe a new species as Hirschmanniella paramucronata n. sp. This new species is characterised by having body length of 1006–1835 μm, hemispherical lip region with 6–7 annules, a stylet 21.6–25.5 μm in length with a shaft length of 6.8–9.0 μm, the SE pore at 102 to 151 μm from anterior end, a longer oesophageal gland overlapping 211–378 μm from anterior end, vulva near the mid-body, phasmids located 20.6 to 39.2 μm from the tail tip, spicule tylenchoid 25.5–33.3 μm long, and gubernaculum 6.9–11.5 μm long. The new species is morphologically and morphometrically distinct from its closely related species H. mucronata by having a higher number of lip annules (6–7 vs. 5), a lower b-ratio (8.1–15.6 vs. 16–29), and a shorter shaft length (6.8-9.0 vs. 10–13 μm). Molecular characterisation using the D2D3 region of 28 S rDNA, the Internal Transcribed Spacer (ITS) of rDNA, and 18 S rDNA further supported the distinct status of the new species, showing sequence similarities with H. mucronata of 95.27%, 90.33% and 98.53%, respectively. Bayesian phylogenetic analyses of these markers recovered H. paramucronata n. sp. as a well-supported, separate monophyletic lineage forming a distinct sister relationship with H. mucronata.