Paramerlinius shamimi n. sp. (Nematoda: Merliniidae) from India with a tabular key for the genus Paramerlinius

The population of the genus Paramerlinius was discovered from potato rhizosphere in a government potato seed farm, located in Tiksen, Munsiari, Pithoragarh, Uttarakhand, India. It is here described as Paramerlinius shamimi n. sp. based on morphological, morphometric and molecular data. The new species is characterised by having a body length of 841.8-1208.8 mu m, continuous head bearing 7-8 annuli, a prominent stylet (28.4-32.3 mu m) with well-developed posteriorly sloping basal knobs, six lateral incisures at the mid-body, a well-developed median bulb, a secretory-excretory (S-E) pore (123.5-160.7 mu m) almost at the level of basal bulb, hemizonid covering 2-3 annuli that are located 3-4 annuli above the S-E pore, phasmids located in the front half of the tail, tail subcylindrical, having a hemispherical smooth terminus (62.7-94.1 mu m) with 38-48 tail annuli, males common, spicule arcuate (27.4-31.4 mu m), gubernaculum curved ventrally (8.8-9.8 mu m) and peloderan bursa. Molecular characterisation of the population was performed by sequencing nuclear ribosomal DNA (rRNA) genes, viz. ITS-1, 18S (partial) and D2-D3 region of 28S rRNA. Maximum likelihood and Bayesian phylogenetic analyses of P. shamimi n.sp. using the D2-D3 region show it forms a distinct clade with other unidentified Paramerlinius spp. and P. neohexagrammus and, using 18S rRNA, groups it in the same clade as P. hexagrammus. A tabular key for 13 species including P. shami1mi n.sp. under the genus Paramerlinius is given.