Heterorhabditis
sonorensis
Summary - A new Heterorhabditis species was isolated
from nymphal stages of the seasonal cicada Diceroprocta ornea (Walker)
in an asparagus field in the state of Sonora,
Mexico.
Concomitantly, another isolate of the same nematode species was also collected
from an oak woodland habitat in the Chiricahua mountain range in southeastern Arizona. Morphological
and molecular studies together with cross-hybridization tests indicate these
two isolates are conspecific and represent a new undescribed Heterorhabditis sp. This new species
is distinguished from other species in this genus by a combination of several
qualitative and quantitative morphological traits. Key diagnostic features
include: presence of a pronounced post-anal swelling in the hermaphrodite; male
with nine pairs of bursal rays, with pairs 4 and 7 bent outwards and one pair
of papillae placed on the cloacal opening, value of D% (average: 79);
infective juveniles with a well developed cuticular tooth, long tail (average:
105 lm) and values of D% (average: 90) and E% (average: 99). In
addition to these diagnostic characters, cross-hybridization tests between the
new species with H. bacteriophora and H. mexicana yielded no fertile
progeny. Comparison of ITS rDNA sequences with other available sequences of
described species depicted the two isolates as a new species. Phylogenetic
analysis of these sequence data placed H. sonorensis n. sp. as a member of
the indica-group.