The anatomy and functional morphology of Diplodon rhombeus fontainianus (Orbigny, 1835) (Mollusca Bivalvia, Hyriidae)

Abstract

Diplodon rhombeus fontainianus (Orbigny, 1835), belongs to the family Hyriidae Swainson 1840, the distribution of which is restricted to South America and Australasia. This species, endemic to Brazil, occurs in the central-southern geographical region, Upper Paraná Basin and Atlantic Microbasins Espirito Santo to Paraná states. The mollusk lives buried in muddy substrata, has similar sized adductor muscles, and is dioecious, lacking sexual dimorphism. The apertures are simple (type AII of Yonge, 1948Yonge, , 1957 as in Diplodon rotundus gratus, Castalia undosa martensi, Castalia undosa undosa and mantle fusion is present only in the base of the exalant aperture. The inhalant aperture exhibits tentacles originating from the inner fold while the exhalant aperture has no tentacles. The ctenidia are type D (of Atkins, 1937). A well-developed marsupium is present in the inner demibranch. The association between the ctenidia and the labial palps belongs to category I (of Stasek, 1963). The stomach constitutes a type IV structure (of Purchon, 1958). The posterior sorting area (psa) presents two pouches in Diplodon rhombeus fontainianus. Among the Hyriidae, the presence of these pouches has also been described in several species of Hyriidae from South America. The organization of the gut in the visceral mass follows the same pattern seen in the Hyriidae already studied: Castalia undosa martensi, Castalia undosa undosa, Diplodon.rotundus (1948, 1957) semelhantes a Diplodon rotundus gratus, Castalia undosa martensi, Castalia undosa undosa e a fusão do manto ocorre apenas na dobra interna na base da abertura exalante. A abertura inalante exibe tentáculos de origem da dobra interna e a exalante não possui tentácu-los. Os ctenídios são do tipo D (de Atkins, 1937). O marsúpio, presente na demibrânquia interna, é bem desenvolvido. O estômago pertence ao tipo IV (de Purchon, 1958

Diplodon Cf. Colhuapiensis (Bivalvia - Hyriidae) in the Santa Cruz Formation (Early-Middle Miocene), at the Río Santa Cruz, Patagonia, Argentina. Stratigraphic and Paleoenvironmental Considerations

“…For example, the species D. chilensis inhabits lentic and lotic waters of the Manso basin that drain into the Pacific Ocean (Bonetto, 1973). In addition, they are commonly seen in shallow waters, close to 30 cm deep (Miyahira et al, 2017), or in association with roots of aquatic plants (Avelar and Cunha, 2009).…”

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

“…Some details of internal morphology was described only to the following species, Diplodon charruanus, D. pilsbry Marshall, 1928, D. besckeanus, D. multistriatus (Lea, 1831, D. rhombeus fontainianus and D. rotundus gratus (Hebling & Penteado 1974, Alvarenga & Ricci 1981, Mansur & Anflor 1982, Ricci et at 1988, Avelar & Cunha 2009). Meyer et al (2012Meyer et al ( , 2014 described the reproductive system of D. expansus (Küster, 1856) and D. ellipticus from a histological perspective.…”

“…They usually start appearing at a depth of 30 cm. They are sometimes found associated to roots of aquatic plants (Avelar & Cunha 2009). They prefer the final sections of the river, due to the highest amount of nutrients, and are rare or absent in headwaters (Pereira et al 2011, Miyahira et al 2017.…”

“…Ricci studied the soft parts and glochidium of Diplodon multistriatus (Ricci et al 1988(Ricci et al , 1990, as well as the morphology of soft parts, glochidium and shell variation of Diplodon besckeanus (Alvarenga & Ricci 1977a,b, 1981. In the field of functional anatomy, there are the works of Wagner Avelar (Avelar & Santos 1992, Avelar 1993, Avelar & Cunha 2009) and Nilton Hebling (Hebling & Penteado 1974, Hebling 1976 concerning Hyriidae and Mycetopodidae species. Simone (1994Simone ( , 1997 described the morphology of two species of Anodontites.…”

Modelling the risk of mortality of Corbicula fluminea (Müller, 1774) (Bivalvia: Corbiculidae) exposed to different turbidity conditions

“…However, while much of the literature involves scientific anatomy and functional morphology of bivalves (Hebling, 1976;Avelar and Santos, 1991;Avelar, 1993;Simone, 1994Simone, , 1997Avelar and Cunha, 2009) or addresses reproductive aspects (Peredo and Parada, 1986;Avelar and Mendonça, 1998;Mansur and Campos-Velho, 2000), there is still no scientific evidence in the literature that addresses the influence of suspended sediments on the mortality rates of bivalve populations.…”