Comparative Morphometry and Morphology of Glochidial Shells of Amazonian Hyriidae (Mollusca: Bivalvia: Unionida)

Freshwater mussels from South America: state of the art of Unionida, specially Rhipidodontini

“…Simone (2006) do not presented an explanation to support his decision, and probably for this reason some authors like Pereira et al (2014) don´t followed his suggestions. It is clear that glochidium is a good diagnostic feature in Hyriidae (Parodiz & Boneto 1963, Mansur 1999, Mansur & Silva 1999, Pimpão et al 2012, but is also necessary to find other characteristics on the morphology of adult specimens as well as on molecular aspects to substantiate this division. It is also important to mention that in South America there are many under-sampled areas and undescribed glochidia of Rhipidodontini.…”

“…That is the case of some species recognized in several works as Diplodon rhombeus (= Rhipidodonta rhombea after Simone 2006) ( Figure 5G). There were also some cases of "change" of the glochidium type, after detailed revision; for example, glochidium type in Diplodon suavidicus (d´Orbigny, 1835) ( Figure 5E) was firstly assigned as non-parasite (Simone 2006) and later as parasite (Pimpão et al 2012). Pimpão et al (2012) successfully used the glochidium to differentiate Amazonian species of Hyriidae, thus proving that glochidium can be powerful in species delimitation.…”

“…There were also some cases of "change" of the glochidium type, after detailed revision; for example, glochidium type in Diplodon suavidicus (d´Orbigny, 1835) ( Figure 5E) was firstly assigned as non-parasite (Simone 2006) and later as parasite (Pimpão et al 2012). Pimpão et al (2012) successfully used the glochidium to differentiate Amazonian species of Hyriidae, thus proving that glochidium can be powerful in species delimitation. One concept that appeared in several older works was that of a "group of species" (Simpson 1914, Ortmann 1921, Haas 1930, 1931a, abandoned in more recent works (Haas 1969, Simone 2006, Graf & Cummings 2007.…”

“…Diplodon has glochidium with hooks and an obligate stage as parasite of fishes , Pimpão et al 2012. The life cycle of D. martensi was described by Mansur (1999) and remains as the unique species to have the cycle described in Brazil.…”

“…The glochidium of Rhipidodonta is hookless and the life cycle still poorly known. The glochidium develop at the marsupium and the mussel release a juvenile (Wächtler et al 2001, Mansur & Silva 1999, Pimpão et al 2012. Unfortunately the glochidium type was not described to all species of Rhipidodontini (Table 4).…”