In the course of two trips to Central America (June 1967 and JulyAugust 1976) I had the opportunity of collecting topotypic specimens of Planorbis nicaraguanus Morelet, 1849, anatomically defined in this paper, and of P. yzabalensis
Crosse & Fischer, 1879, the identity of the latter with Drepanotrema anatinum
(Orbigny, 1835) is confirmed. The following planorbid species were also found: Helisoma trivolvis
(Say, 1817) in Nicaragua, Guatemala, Costa Rica and Belize; H. duryi
(Wetherby, 1879) in Costa Rica; Biomphalaria helophila
(Orbigny, 1835) in Guatemala, Belize, Nicaragua, Costa Rica and El Salvador; B. kuhniana
(Clessin, 1883) in Panama; B. obstructa
(Morelet,1849) in Guatemala, Belize and El Salvador; B. straminea
(Dunker, 1848) in Costa Rica; B. subprona
(Martens, 1899) in Guatemala; D. anatinum
(Orbigny,1835) in Belize, Guatemala, Nicaragua and Costa Rica; D. depressissimum
(Moricand,1839) in Nicaragua, Costa Rica and Panama; D. lucidum
(Pfeiffer, 1839) in Guatemala, Belize and Nicaragua; D. surinamense
(Clessin, 1884) in Costa Rica and Panama; and Gyraulus percarinatus
sp. n. in Panama.
The occurrence of B. kuhniana
and D. surinamense
is first recorded in Central America, and Gyraulus percarinatus
is the first representative of the genus provenly occurring in the American continent south of the United States.
The following synonymy is proposed: Planorbis declivis Tate, 1870 = Biomphalaria helophila
(Orbigny, 1835); Planorbis isthmicus Pilsbry, 1920 = Biomphalaria kuhniana (Clessin, 1883); Planorbis cannarum Morelet, 1849 and Segmentina donbilli Tristram, 1861 = Biomphalaria obstructa (Morelet, 1849); and Planorbis yzabalensis Crosse & Fischer, 1879 = Drepanotrema anatinum
(Orbigny, 1835), confirming Aguayo (1933).