T. S. Harris

Phylogenetic relationships of Nygolaimina and Dorylaimina (Nematoda: Dorylaimida) inferred from small subunit ribosomal DNA sequences

Phylogenetic reconstructions based on 18S rDNA sequence data indicate that Dorylaimida, comprising the suborders Nygolaimina and Dorylaimina, is a monophyletic lineage, but that there is a deep division within Nygolaimina, giving rise to the possibility that Nygolaimina is paraphyletic. A well-supported clade comprising members of the traditional orders Mermithida and Mononchida (including Bathyodontina) forms the sister taxon to the Dorylaimida. Inferred relationships within this clade indicate that Mermithida shares more recent common ancestry with Mononchina than does Bathyodontina. Vertebrate parasites within Dorylaimia (Dioctophymida and Trichinellida) are reconstructed in a sister-taxon relationship with the Mononchida/Dorylaimida lineage. The enigmatic order Isolaimida (represented by Isolaimium) appears to be ancestral to all other Dorylaimia sampled. Expanded taxon sampling for phylogenetic analyses of the subclass raises new possibilities for the reconstruction of hypothetical character states in the common ancestor of Dorylaimia.

First Report of Columbia Root Knot Nematode (Meloidogyne chitwoodi) in Potato in Texas

Columbia root-knot nematode, Meloidogyne chitwoodi Golden et al. (1) was identified from potatoes, Solanum tuberosum L., collected from Dallam County, Texas in October 2000. Seed potatoes are the most likely source for this introduction. This nematode is currently found infecting potatoes grown in California, Colorado, Idaho, New Mexico, Nevada, Oregon, Utah, and Washington. Some countries prohibit import of both seed and table stock potatoes originating in states known to harbor M. chitwoodi. Lesions on the potatoes had discrete brown coloration with white central spots in the outer 1 cm of the tuber flesh. Female nematode densities averaged 3 per square centimeter of a potato section beneath the lesions. Nematodes were morphologically identified as M. chitwoodi based on the perineal pattern of mature females and the tail shape of juveniles per Golden et al. (1). Using polymerase chain reaction-RFLP of the rDNA ITS1 region and the mtDNA COII-16S rRNA region (2), individual juveniles were identified as M. chitwoodi based on their restriction fragment patterns. This is the first report of Columbia root-knot nematode infecting potatoes in Texas. The distribution of this nematode in potato fields throughout central United States should be determined. References: (1) A. N. Golden et al. J. Nematol. 12:319, 1980. (2) T. O. Powers and T. S. Harris. J. Nematol. 25:1, 1993.

Description of Mesocriconema ericaceum n. sp. (Nematoda: Criconematidae) and notes on other nematode species discovered in an ericaceous heath bald community in Great Smoky Mountains National Park, USA

A new species of Mesocriconema and a unique assemblage of plant-parasitic nematodes was discovered in a heath bald atop Brushy Mountain in Great Smoky Mountains National Park. Mesocriconema ericaceum n. sp., a species with males, superficially resembles M . xenoplax . DNA barcoding with the mitochondrial COI gene provided evidence of the new species as a distinct lineage. SEM revealed significant variability in arrangement of labial submedian lobes, plates, and anterior and posterior annuli. Three other nematodes in the family Criconematidae were characterised from the heath bald. Ogma seymouri , when analysed by statistical parsimony, established connections with isolates from north-eastern Atlantic coastal and north-western Pacific coastal wet forests. Criconema loofi has a southern Gulf Coast distribution associated with boggy soils. Criconema cf. acriculum is known from northern coastal forests of California. Understanding linkages between these species and their distribution may lead to the broader development of a terrestrial soil nematode biogeography.

DNA Barcode of Thief Ant Complex (Hymenoptera: Formicidae)

Abstract The thief ant, Solenopsis molesta (Say), a common nuisance species found throughout the United States is genetically related to red imported fire ants, S. invicta Buren. Therefore, its identification at the molecular level is very important. The deoxyribonucleic acid (DNA) barcoding, a recent technique was used to identify thief ant complex at species and subspecies levels using a short DNA sequence from the cytochrome oxidase subunit 1 (COI) mitochondrial region. The DNA from thief ants collected from 9 states was extracted using Qiagens Gentra PUREGENE® DNA Isolation Kit. The polymerase chain reactions (PCR) were run on the extracted DNA to amplify partial sequence of COI using primers Lep-F1 (forward) and Lep-R1 (reverse). The resulting DNA products were concentrated, purified and sequenced. The 600 bp sequences of the COI generated were submitted to GenBank that issued accessions numbers from HM179641 to HM179653. The sequences associated with these accession numbers were used as DNA barcodes for distinguishing species and subspecies. Based on this molecular analysis, thief ants collected from New York, Indiana and 1 location in Nebraska were separated in 1 group as S. molesta validiuscula (Emery) and another with ants from Louisiana identified as S. carolinensis (Forel). The third group was comprised of ants from South Dakota, Washington, New Jersey, Tennessee, Kansas and 2 other locations in Nebraska was identified as S. molesta molesta (Say).