Pratylenchus smoliki, a new nematode species (Pratylenchidae: Tylenchomorpha) from the Great Plains region of North America.

Kanan Sakai,Timothy Todd,Thomas Powers,Mehmet Ozbayrak,Ann Macguidwin,Peter Mullin,Tim Harris,Rebecca Higgins,Kirsten Powers

doi:10.21307/jofnem-2021-100

Abstract

Pratylenchus smoliki is a new species of root-lesion nematode described from corn-soybean production fields in the Central Great Plains of North America. It is characterized by populations with relatively abundant males, two lip annuli, females with a round functional spermatheca and a conoid to subcylindrical tail with a non-crenate, smooth terminus. In host preference tests, corn and wheat produce the largest nematode populations, whereas sorghum and soybeans produce less than 20% the numbers observed on corn. Scanning electron microscopy reveals that the en face patterns compare to those seen in Pratylenchus pseudocoffeae, P. scribneri, P. hexincisus, and P. alleni. The pattern is described as rectangular to trapezoidal subdorsal and subventral lips adjoining oral disc, but with a clear demarcation between the oral disc and the subdorsal and subventral sectors. A Maximum Likelihood COI tree recognizes P. smoliki as a moderately-well-supported clade with several haplotype subgroups. A Maximum Likelihood partial 28S tree provides strong support for the P. smoliki clade and reinforces the close relationships between species with similar en face patterns. Topotype specimens of P. alleni were demonstrably different from P. smoliki using DNA markers. The geographic range of P. smoliki overlaps with the ranges of P. alleni, P. scribneri, P. neglectus, P. hexicisus, and P. dakotaensis. The observed host range (corn, rye, sunflower, and wheat) suggests that P. smoliki may be native to the tallgrass prairie region of the Great Plains.

Highlights

Identity might be Pratylenchus alleni (Ferris, 1961), another two-lipped species with males, led to the collection of that species at its type locality in Saline County, Illinois
We describe a second of those undescribed species, previously referred to as Pratylenchus sp. 2 in Ozbayrak et al (2019), described as Pratylenchus smoliki n. sp
We have constructed a maximum likelihood tree of cytochrome oxidase subunit I (COI) that includes P. smoliki n. sp., 22 other described species that are represented by a minimum of two specimens, and nine other described Pratylenchus species that are represented by a single specimen

Summary

Introduction

Identity might be Pratylenchus alleni (Ferris, 1961), another two-lipped species with males, led to the collection of that species at its type locality in Saline County, Illinois. Is characterized by an offset lip region bearing two annuli which are distinctly narrower than the head region immediately posterior, SEM face divided into clearly-demarcated oral disc, with separate lateral and submedial lip sectors forming an obtuse, doubly bent angle with the labial disc, corresponding to pattern I in Subbotin et al (2008), stylet 15 (14-16) μ m long, with rounded knobs, pharyngeal overlap fairly short (1-2 corresponding body diameters in length), lateral field faintly and occasionally areolated as viewed in light microscopy, and with four incisures plus additional striae, especially at midbody, body annulation moderate, spermatheca round, filled with sperm, vulval lips slightly protruding, tail conoid to subcylindrical with blunt, usually smooth terminus, males common, with slightly smaller stylet (14 [13-15] μ m), lateral field with 4 lines, spicules 17 (15-19) μ m in length and ventrally curved, bluntly pointed tail.

Results

Conclusion