Systematics, Distribution, and Ecology of Colorado Hirudinea

Abstract

Between 1964 and 1968, 20 species of Hirudinea were collected in Colorado, 12 of which are new records for the state. A wide variety of sites were visited in all 63 Colorado counties, including 87 lotic and 443 lentic stations. A total of 6726 leeches were collected from 32 lotic sites and 261 lentic sites. Some species are geographically or altitudinally restricted; others are widely distributed. Helobdella stagnalis is the most abundant and widely distributed leech in Colorado. Erpobdella punctata, Haemopis mar- morata, Glossiphonia complanata, Placobdella ornata, and Theromyzon rude are also widespread. Batracobdella phalera is found only in the foothills zone and montane zone, whereas B. picta occurs from the foot- hills zone into the alpine zone; both species are found in the western half of the state. Dina dubia is common in the northern half of Colo- rado, excluding the Great Plains, but Nephelopsis obscura is prevalent in the western half. The plains zone is characterized by Illinobdella moorei, Helobdella fusca, and Theromyzon tessulatum. Seven species show highly restricted distributions: Dina parva, D. fervida, D. lateralis, D. microstoma, Placobdella parasitica, Macrobdella decora, and Haemopis kingi. The frequency, abundance, and altitudinal distribution are recorded for each species. Erpobdella punctata has the greatest frequency and abundance for lotic species, and Helobdella stagnalis for lentic species; however, both are abundant in standing and running waters. Helobdella stagnalis has the greatest altitudinal range (1080-3099 m) for lotic leeches, and Glossiphonia complanata (1044-3610 m) for lentic leeches. Limiting factors are distinctive for lotic and lentic species. Small lakes and ponds between 1700 and 3300 m with abundant gyttja and f6rna and with color values greater than 20 contain the greatest number of species of any habitat.