Monographs Details: Potamogeton pusillus L. subsp. pusillus
Authority: Haynes, Robert R. & Holm-Nielsen, Lauritz B. 2003. Potamogetonaceae. Fl. Neotrop. Monogr. 85: 1-52. (Published by NYBG Press)
Synonyms:Potamogeton panormitanus Biv., Potamogeton aschersonii A.Benn., Potamogeton berteroanus Phil., Potamogeton tenuifolius Phil.
Description:Subspecies Description - Leaves 1-3-veined, 1.4-6.5 cm x 0.5-1.9 mm, the apex acute or rarely apiculate, rarely with a bristle, lacunae absent or to 2 rows each side of midrib; ligules usually connate. Peduncles filiform to cylindrical, 1-3 per plant; spikes cylindric, usually interrupted. Fruits obovate, the sides usually centrally depressed; beak forward, rarely central.

Discussion:Bennett (1893), in the protologue of Potamogeton aschersonii, listed eight collections, citing none as the type. The gatherings he listed are Philippi from Chile, Bridges from Chile, Hieronymus from Argentina, Tweedie from Argentina, Gibert from Uruguay, Jameson from Colombia, Gardner from Brazil, and Glaziou from Brazil. Every collection is a syntype for the name. We have examined collections by Gardner, Gibert, Glaziou, and Philippi. Although none of the specimens we examined by these collectors were from BM or K, the two herbaria visited most frequently by Bennett, we believe these are the collections, if not the sheets, cited by Bennett. All specimens represent the same taxon. All are acceptable sheets for type specimens. Choosing one over another would not change current usage. Horn af Rantzien, while preparing a treatment of Latin American pondweeds that was never published, annotated the Gardner collection at P as the type and the Glaziou collection at P as the isotype. Obviously, neither can be correct. Glaziou’s original herbarium is at P and Gardner’s is at BM. We have examined the Glaziou specimen from P, but as stated earlier, we have not examined Gardner’s specimen from BM, although we have examined the BM material. We have chosen to designate the Glaziou specimen at P as the lectotype, since it is in his original herbarium. That very likely is the material that Bennett examined, and Horn af Rantzien had already indicated this specimen as an isotype.
Distribution:Mexico North America| Aguascalientes Mexico North America| Baja California Mexico North America| Distrito Federal Mexico North America| Durango Mexico North America| Hidalgo Mexico North America| Jalisco Mexico North America| Michoacán Mexico North America| Morelos Mexico North America| Puebla Mexico North America| San Luis Potosí Mexico North America| Tamaulipas Mexico North America| Veracruz Mexico North America| Belize Central America| Guatemala Central America| Izabal Guatemala Central America| Quiché Guatemala Central America| Quezaltenango Guatemala Central America| Sololá Guatemala Central America| Honduras Central America| Comayagua Honduras Central America| Morazán Honduras Central America| Nicaragua Central America| Jinotega Nicaragua Central America| Matagalpa Nicaragua Central America| Río San Juan Nicaragua Central America| Costa Rica South America| Alajuela Costa Rica Central America| Cartago Costa Rica Central America| Guanacaste Costa Rica Central America| Limón Costa Rica Central America| San José Costa Rica Central America| Colombia South America| Antioquia Colombia South America| Boyacá Colombia South America| Cundinamarca Colombia South America| Risaralda Colombia South America| Santander Colombia South America| Venezuela South America| Barinas Venezuela South America| Mérida Venezuela South America| Ecuador South America| Azuay Ecuador South America| Carchi Ecuador South America| Imbabura Ecuador South America| Loja Ecuador South America| Morona-Santiago Ecuador South America| Napo Ecuador South America| Pichincha Ecuador South America| Cusco Peru South America| Lima Peru South America| La Libertad Peru South America| Brazil South America| Alagoas Brazil South America| Bahia Brazil South America| Ceará Brazil South America| Goiás Brazil South America| Mato Grosso do Sul Brazil South America| Minas Gerais Brazil South America| Rio de Janeiro Brazil South America| Paraná Brazil South America| Pernambuco Brazil South America| Rio Grande do Sul Brazil South America| Santa Catarina Brazil South America| São Paulo Brazil South America| Bolivia South America| Beni Bolivia South America| Cochabamba Bolivia South America| La Paz Bolivia South America| Chile South America| Aconcagua Chile South America| Atacama Chile South America| Concepcion Chile South America| O'Higgins Chile South America| Santiago Chile South America| Valdivia Chile South America| Valparaíso Chile South America| Paraguay South America| Central Paraguay South America| Argentina South America| Buenos Aires Argentina South America| Córdoba Argentina South America| Corrientes Argentina South America| Entre Ríos Argentina South America| Jujuy Argentina South America| Mendoza Argentina South America| San Juan Argentina South America| Salta Argentina South America| Santiago del Estero Argentina South America| Tucuman Argentina South America| Uruguay South America| Montevideo Uruguay South America| Rocha Uruguay South America|