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Outside of the states of Texas and Alabama, the distribution of limnoterrestrial tardigrades in the American Deep South is poorly known. There are no published records from the states of Louisiana and Mississippi, while in Arkansas only one species has been reported. As part of a long-term study of tardigrade distribution and ecology in the region, I began sampling for Louisiana and Arkansas tardigrades in the spring of 2000. In Louisiana, I sampled mosses and lichens from two sites in Calcasieu Parish and one in Natchitoches Parish. No tardigrades were found in ground mosses (Sphagnum sp.). From mosses and lichens on trees I identified seven species of tardigrade, belonging to four genera. No sample contained more than two species of tardigrade. Mosses and lichens obtained from trees and rocks in the Ouachita and Ozark Mountain regions of western Arkansas contained fifteen species of tardigrade. The number of species per sample ranged from one to six.

The distribution of tardigrades in North America remains poorly known. Although a few areas have been intensively sampled, much of the continent has never been surveyed. Only four species have been reported in the state of Michigan: Macrobiotus hufelandi and Isohypsibius prosostomus on Isle Royale in Lake Superior, and Hexapodibius pilatoi and Diphascon {Adropion) belgicae in soil from the Lower Peninsula. In July 2005 I collected cryptogams from woodlands in the Upper Peninsula. Sites in all of the Upper Peninsulas 15 counties were sampled. Eleven tardigrade species were present in these mosses and lichens: the heterotardigrade Echiniscus virginicus and the eutardigrades Diphascon (Diphascon) iltisi, D. (D.) stappersi, Hypsibius arcticus, H. calcaratus, Ramazzottius baumanni, Macrobiotus echinogenitus, Macrobiotus cf. hufelandia, Macrobiotus tonollii, Minibiotus intermedius, and Milnesium tartigradum. The most widely distributed tardigrades were the cosmopolitan species Milnesium tardigradum and Minibiotus intermedius. The known distribution of Echiniscus vinginicus and D. (D.) stappersi in North America was hitherto limited to the southeastern United States.

The distribution of limnoterrestrial tardigrades in the American south is poorly known. This is especially true in the Gulf Coast states. There is only one published record of tardigrades from Louisiana. Nine species were found in two sites in southwestern Louisiana. We collected samples of lichens and mosses from fifteen sites in southeastern Louisiana, encompassing all parishes east of the Mississippi River. Sampling was not quantitative. The sites chosen included both natural woodlands and highly disturbed habitats. The collected material was soaked in deionized water overnight, allowing anhydrobiotic tardigrades to become active. Tardigrades were then mounted in Hoyer's medium for identification. The species collected included Echiniscus cavagnaroi, E. kofordi, Milnesium tardigradum, Macrobiotus cf. hufelandi, M. tonollfi, M. cf. harmsworthi, Minibiotus intermedius, Minibiotus fallax, Doryphoribius citrinus, and one Macrobiotus sp. new to science. D. citrinus has not previously been found in North America. The other species found in southeastern Louisiana are found in similar habitats in Florida.