Nematodes from vernal pools in the Santa Rosa Plateau Ecological Reserve, California I. Hirschmanniella santarosae sp. n. (Nematoda: Pratylenchidae), a cryptic sibling species of H. pomponiensis Abdel-Rahman & Maggenti, 1987

Abstract

AbstractHirschmanniella santarosae sp. n. is described from the largest vernal pool in the Santa Rosa Plateau Ecological Reserve, Murrieta, California, USA. The cryptic new species is morphologically very close to H. pomponiensis and H. gracilis as it can be distinguished from the former only by a more anterior excretory pore position and by more flattened as well as laterally expanded stylet knobs, whilst it differs from the latter in the greater distance from phasmid to tail tip and in the bursal alae ending near the phasmids rather than near the tail tip. Analysis of the rDNA small subunit (SSU) and D2D3 expansion segments of the large subunit (LSU) shows that H. santarosae sp. n. is genetically distinct, having respective sequence homology of 98.89% and 95.9% with H. pomponiensis for these loci. Congruence in SSU and D2D3 gene trees as well as unambiguous character autapomorphies further support the new species status of H. santarosae sp. n. and sibling relationship with H. pomponiensis. Although many more isolates and species will need to be studied before informative biogeographic analyses can be performed, the presently available sequence data suggest that some Hirschmanniella lineages have diversified independently on either side of the Atlantic.