02786nas a2200193   4500008004100000245016800041210006900209260008700278300001200365490000700377520194500384100001902329700001702348700002802365700002602393700002102419700001502440856013702455       2010                        eng d00aLinking DNA sequences to morphology: cryptic diversity and population genetic structure in the marine nematode Thoracostoma trachygaster (Nematoda, Leptosomatidae)0 aLinking DNA sequences to morphology cryptic diversity and popula  aCOMMERCE PLACE, 350 MAIN ST, MALDEN 02148, MA USAbWILEY-BLACKWELL PUBLISHING, INC  a276-2890 v393 aRecent taxonomic and population genetic studies have revealed the presence of substantial cryptic diversity through sequence analysis of nematode morphospecies classified in different major clades. Correct interpretations of intra- and interspecific genetic variation require certainty about the conspecificity of the sequenced specimens, which in turn must depend on appropriate protocols with built-in verifiability procedures. In this study, we performed a population genetic study in the free-living marine nematode Thoracostoma trachygaster, a member of one of the earliest major clades to diverge in nematode phylogeny. We collected 367 nematodes from 11 populations located in the Californian Bight, all of which were video captured before DNA extraction to document and verify their individual morphology. Sequences for the cytochrome c oxidase subunit 1 (COI), D2D3 and 18S genes showed eight deeply divergent clades, and using a reverse taxonomy approach, six of these clades proved to be other morphospecies than T. trachygaster. Phylogenetic analyses of COI, internal transcribed spacer and D2D3 showed evidence for two sympatrically distributed cryptic species within the morphospecies T. trachygaster. Population genetic analyses of the most widespread cryptic species showed a moderate genetic structuring (Theta(ST) = 0.28), and 18% of this genetic variation was caused by differences between populations north and south of Point Conception. Within the southern Californian Bight, some genetic differentiation could be attributed to differences between populations north and south of Malibu, supporting the idea of a barrier to gene flow near Los Angeles region. The results for T. trachygaster support the contention that species diversity within free-living nematodes is underestimated, and that dispersal of marine nematodes from tidal environments associated with kelp holdfasts is substantial at scales of a few 100 km.1 aDerycke, Sofie1 aDe Ley, Paul1 aDe Ley, Irma, Tandingan1 aHolovachov, Oleksandr1 aRigaux, Annelien1 aMoens, Tom  uhttps://nematoda.myspecies.info/content/linking-dna-sequences-morphology-cryptic-diversity-and-population-genetic-structure-marine-n02015nas a2200253   4500008004100000245010500041210006900146260009100215300001200306490000700318520110300325653002001428653002501448653001101473653001501484653001801499653000801517653001301525100002601538700002501564700002801589700001701617856012701634       2008                        eng d00aNematodes from the Gulf of California. Part 2. Ceramonema nasobema sp n. (Nematoda: Ceramonematidae)0 aNematodes from the Gulf of California Part 2 Ceramonema nasobema  aPLANTIJNSTRAAT 2, P O BOX 9000, 2300 PA LEIDEN, NETHERLANDSbBRILL ACADEMIC PUBLISHERS  a835-8440 v103 aAn unusual new ceramonematid, Ceramonema nasobema sp. n., is described using light and scanning electron microscopy. It is particularly characterised by the presence of a perioral tube projecting 5.5-7.0 mu m anterior to the lips, moderately long body (0.86-1.09 mm), relatively small number of body annules (121-134), weakly developed zygapophyses, absence of intracuticular vacuoles, pronounced sexual dimorphism in amphid shape with the male ventral amphidial branch extending as far posterior as the 55-80th annule (no extension in females), barrel-shaped stoma, sigmoid and anteriorly inclined vagina without sclerotisations, gubernaculum with dorsal apophyses and relatively uniform cloacal annules. The new species differs from all other known species of Ceramonema especially by the shape of the amphid in males, the strongly projecting perioral tube and the inclined, sigmoid, vagina. Additional data on morphology of Ceramonema algoensis (from Natal Bay, South Africa) are also provided as this species has the most prominent perioral tube among previously described members of the genus.10aBaja California10aCeramonema algoensis10aMexico10amorphology10amorphometrics10aSEM10ataxonomy1 aHolovachov, Oleksandr1 aMundo-Ocampo, Manuel1 aDe Ley, Irma, Tandingan1 aDe Ley, Paul  uhttps://nematoda.myspecies.info/content/nematodes-gulf-california-part-2-ceramonema-nasobema-sp-n-nematoda-ceramonematidae