Helobdella blinni sp. n. (Hirudinida, Glossiphoniidae) a new species inhabiting Montezuma Well, Arizona, USA

A new leech species , is described from Montezuma Well, an isolated travertine spring mound located in central Arizona, USA. In its native habitat, had been previously identified as (Linnaeus, 1758), which was later reclassified to (Verrill, 1872). Similar to the European and North American , has six pairs of testisacs, five pairs of smooth crop caecae, one lobed pair of posteriorly-directed crop caecae, one pair of eyes, a nuchal scute, and diffuse salivary glands. However, the pigmentation of this new species ranges from light to dark brown, unlike which tends to be light grey in color. Also, produces a clutch of 12--35 pink eggs, whereas produces smaller clutches of white eggs (7-14, 0.5 ± 0.15 mm, N = 7) and consequently broods fewer young (1-14, 7 ± 3.3 mm, N = 97). are also able to breed year-round due to the constant warm water conditions in Montezuma Well. Their breeding season is not restricted by seasonal temperatures. These species are morphologically similar, however, comparing the COI mtDNA sequences of with sequences from nearby populations of and other species from GenBank indicate that is genetically distinct from these other populations.