01851nas a2200121   4500008004100000245011100041210006900152300001200221490000800233520130700241100002301548856015801571       1985                        eng d00aSetal Morphology and Its Intraspecific Variation in Dero digitata and Dero nivea {(Oligochaeta:} Naididae)0 aSetal Morphology and Its Intraspecific Variation in Dero digitat  a45–510 v1043 aDero digitata and Dero nivea were observed by scanning electron microscopy and light microscopy to have intermediate teeth in needle setae which gave them either a trifid or pectinate condition. There were seasonal differences in the percentages of worms having at least one intermediate-toothed needle seta for D. digitata. Overall, 48.1% of D. digitata and 100% of D. nivea examined had intermediate teeth. Percentage of needle setae with intermediate teeth per worm ranged from 41.3-68.4% for D. nivea and 1.4-4.8% for D. digitata. Plumosity on hair setae was observed for both species; projections giving the plumose appearance were up to 20 Âµm long in D. digitata and those of D. nivea were up to 10 Âµm long. Generally, there was 100% plumosity of hair setae per worm if plumosity was present. Seasonal differences also were seen for plumosity in percentage of worms having this character. There was no correlation {(P} {\textgreater} 0.05) of seasonal differences to environmental physico-chemical parameters and no anterior to posterior trends for either setal character. The appearance of these previously undescribed setal characteristics in D. digitata and D. nivea and their intraspecific variation shed doubt on the validity of these taxonomic characters as used in the subgenus Dero.1 aSmith, Michael, E.  uinternal-pdf://Smith 1985 - setal morphology of Dero digitata and Dero nivea-1532555274/Smith 1985 - setal morphology of Dero digitata and Dero nivea.pdf