Page 141 - The Freshwater Mussels of Oklahoma

Partial Synonymy:
Ptychobranchus clintonense Simpson, 1900,Simpson 1914
Ptychobranchus phaseolus (Hildreth, 1828), Isely 1925
Ptychobranchus fasciolare (Rafinesque, 1820), Isely 1925; Murray and Leonard
1962
Ptychobranchus occidentalis (Conrad, 1836), Valentine and Stansbery 1971;
Buchanan 1980; Johnson 1980; Branson 1984; Oesch 1984; Turgeon and
others 1988; Vidrine 1993
Description:
“Shell oblong, ovate, elliptical or subrhomboid, sometimes subtriangular, solid,
scarcely inflated, rather wider behind; posterior ridge feeble, rounded or slightly double,
ending behind in a faint biangulation; beaks low and not inflated, their sculpture not seen;
surface nearly smooth, yellowish-green covered with delicate, wavy, green, faint rays;
epidermis silky when fresh, but nearly smooth when rubbed; hinge solid; left valve with
two low, small, solid pseudocardinals, the hinder larger and sometimes dentilate, with
two remote laterals; right valve with one pseudocardinal and a vestigial one on each side
of it, with one, sometimes more or less double, lateral; beak cavities shallow; muscle
scars smooth and impressed; nacre bluish-white, often with lurid blotches thicker in
front” (Simpson 1914, p 335).

Table 26. Summary of P. occidentalis shell characters.
Mean H/L Max. Mean W/L
H/L Range Length W/L Range
Location N (%) (%) (mm) (%) (%) Remarks
Arkansas River
Drainage 1 - 60.5 81 - - fossil/subfossil
Neosho River 4 54.6 52.8-56.3 125 - - fossil/subfossil
Verdigris River
(Nowata Co.) 4 58.0 57.1-59.8 103 - 33.3 weathered
Verdigris River
(Rogers Co.) 3 50.7 49.5-52.5 99 29.5 27.1-32.3
Illinois River
Red River Drainage
Mountain Fork River 32 49.1 45.1-55.7 88 30.2 24.1-33.8
Glover River 24 50.4 43.6-61.1 91 29.6 23.3-37.5 2 of 24 “humpback”
Little River 6 53.4 46.3-65.2 76 34.2 24.4-41.9 2 of 6 “humpback”
Kiamichi River 29 53.3 48.5-58.1 87 31.4 26.3-37.1
Blue River 16 52.7 48.7-58.9 99 33.2 31.3-35.6

General Distribution:
Ozarkian region of Mississippi River drainage in southeast Kansas, southern
Missouri, Arkansas and eastern Oklahoma. One record from northern Louisiana.
Oklahoma Distribution:
Found in the Blue, Kiamichi, and Little River systems of southeastern Oklahoma.
In northeastern Oklahoma, most records are for weathered or subfossil shells. The only
recently collected specimens are from the Illinois River.

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