Williamsonia gigas (Lindley & Hutton, 1831) species accepted

Williamsonia amarjolense Sharma, 1968 species accepted

Williamsonia sahnii Gupta, 1943 species accepted

Williamsonia recentior Dawson, 1885 species accepted

Williamsonia guptae Sharma, 1968 species accepted

Williamsonia seniana Bose & Kasat, 1969 species accepted

Williamsonia santalensis Sitholey & Bose, 1953 species accepted

Williamsonia phoenicopsoides Ward, 1899 species accepted

Williamsonia delawarensis Berry, 1907 species accepted

Williamsonia harrisiana Bose, 1968 species accepted

Williamsonia campanulatiformis Sharma, 1969 species accepted

Williamsonia riesii Hollick, 1892 species accepted

Williamsonia elocata Lesquereux, 1891 species accepted

Williamsonia indica Seward, 1917 species accepted

Williamsonia microps Feistmantel, 1877 species accepted

Williamsonia blanfordii Feistmantel, 1876 species accepted

Williamsonia texana Fontaine, 1893 species accepted

Williamsonia smockii Newberry, 1895 species accepted

Williamsonia gallinacea Ward, 1905 species accepted

Williamsonia virginiensis Fontaine, 1889 species accepted

Williamsonia sewardiana Sahni, 1932 species accepted

Williamsonia oregonensis Fontaine, 1905 species accepted

Williamsonia marylandica Berry, 1914 species accepted