Macrobrachium carcinus (Linnaeus, 1758)

Santana, Laira Lianos Michelle Mollemberg Laurindo André Rodrigues Michelle Pinheiro Vetorelli William, 2018, Checklist of the species of Macrobrachium Spence Bate, 1868 (Decapoda: Caridea: Palaemonidae) from the lower Parnaíba River basin, Piauí, Brazil, Nauplius (e 2018017) 26, pp. 1-8 : 4-6

Macrobrachium carcinus (Linnaeus, 1758)

( Fig. 4A–D )

Material examined. Brazil, Piauí: Parnaíba River , 23.iii.2018, 1 male [ CZDP ( F2 ) 0061], 1 male [ CZDP ( F2 ) 0062] .

Distribution. This species is found in Brazil in the states of Amapá, Pará, Piauí, Pernambuco, Alagoas, Espírito Santo, Rio de Janeiro, São Paulo, Santa Catarina, Paraná and Rio Grande do Sul ( Melo, 2003; Sampaio et al., 2009; Pimentel and Magalhães, 2014; present work).

Remarks. As for M. amazonicum, Ramos-Porto and Coelho (1998) and Ferreira et al. (2010) cited the occurrence of M. carcinus in Piauí but without mention the material examined and locality. This is the first documented record of M. carcinus in the Parnaíba River basin. Macrobrachium carcinus is the most important freshwater species economically and socially in the Brazilian northeast region. Populations of this species are in decline in several Brazilian hydrographic basins due to over-exploitation and habitat loss ( Almeida et al., 2008).However, no studies about population estimation quantify the population reduction of this species, which motivated the categorization of this species as Insufficient Data in the last evaluation of the threatened crustacean species of the Brazilian fauna ( Mantelatto et al., 2016), although most fishermen agree that this species is threatened in at least some regions ( Almeida et al., 2008). In addition, the practice of uncontrolled cultivation of other Macrobrachium species in nonnative areas, with the possibility of species dispersal, may represent a future concern for local biodiversity ( Mantelatto et al., 2016). Macrobrachium carcinus is easily recognizable through its short rostrum and the carpus of the second pereopod distinctly shorter than the merus, and with a single, large, triangular tooth on the cutting edges of the dactyl and propodus.

Figures

Figure 4. Macrobrachium carcinus (Linnaeus, 1758), male [CZDP (F2) 0061]. A, Detail of the anterior region of the carapace; B, habitus, lateral view; C, detail of the telson and uropods, dorsal view; D, habitus, dorsal view. Scale bar: 2 cm.