. The Canadian field-naturalist. 2000 Staton, Metcalfe-Smith, and West: Status of Northern Riffleshell 225. Figure 1. Live specimens of Epioblasma torulosa rangiana found in the Sydenham River near Florence, Ontario in August, 1998. Specimen in the middle of the photograph is a female; specimen at the lower right is a juvenile; other specimens are males. docardinal teeth are small, and the lateral teeth are fairly short and moderately thick. Clarke (1981) adds that the beaks are elevated above the hinge line and moderately excavated. Mature individuals have been reported to vary in shell lengt
. The Canadian field-naturalist. 2000 Staton, Metcalfe-Smith, and West: Status of Northern Riffleshell 225. Figure 1. Live specimens of Epioblasma torulosa rangiana found in the Sydenham River near Florence, Ontario in August, 1998. Specimen in the middle of the photograph is a female; specimen at the lower right is a juvenile; other specimens are males. docardinal teeth are small, and the lateral teeth are fairly short and moderately thick. Clarke (1981) adds that the beaks are elevated above the hinge line and moderately excavated. Mature individuals have been reported to vary in shell length from 45 to 76 mm (Clarke 1981; Cummings and Mayer 1992; USFWS 1994), although surveys in southwestern Ontario in 1997-1998 produced specimens up to 90 mm long. Figure 1 shows five living specimens of E. t. ran- giana from the Sydenham River. Three of the five animals are males (the largest is 59 mm in length); the smaller specimen in the middle of the photograph is a young female (35 mm); and the smallest speci- men (17 mm) is a juvenile of indeterminate sex. Epioblasma torulosa rangiana was originally described by Lea in 1837 and named after the French malacologist Sander Rang (USFWS 1994). The type locality for the subspecies is the Ohio River near Cincinnati, and Yellow Creek of the Mahoning River near Poland, Ohio. Three distinct subspecies of Epioblasma torulosa are generally recognized: E. t. torulosa, E. t. rangiana, and E. t. gubernaculum (Turgeon et al. 1988), but many consider E. t. ran- giana to be the headwater form of E. t. torulosa (USFWS 1994). Neither E. t. torulosa nor E. t. gubernaculum have ever been found in Canada, and both are presumed extinct (Williams et al. 1993). Distribution The Northern Riffleshell was historically known from Alabama, Illinois, Indiana, Kentucky, Michigan, Ohio, Pennsylvania, Tennessee (question- able records), West Virginia, and Ontario (USFWS 1993*); see inset. Figure 2A. Although the sub- species has never been found in New York
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