Macrobrachium olfersii

Macrobrachium olfersii (Wiegmann, 1836) Palaemon olfersii Wiegmann, 1836: 150. Macrobrachium olfersii.— Abele & Kim 1989: 10.— Holthuis 1970: 212.— Ramos-Porto & Coelho 1998: 33.— Bowles et al. 2000: 165.— Hernández et al. 2007: 360.— Valencia & Campos 2007: 27. Macrobrachium olfersi.— Holthuis 1952: 95.— Gomes-Corrêa 1977: 65.— Rodríguez 1980: 120.— Melo 2003: 366.— Pileggi & Mantelatto 2012: 427. Material Examined. Suriname. 1 female (CL 8.29 mm) and 1 male (7.15 mm) DZ/ UFRGS661: Suriname river, Kabel station, 21–28 Oct. 1928, collector: Geyskes, D.C; Brazil. Alagoas. 2 males (CL 18.37, 19.38 mm) CIASBM20180192 UFSB: rio Paraíba, Atalaia, 18 Feb. 1995, collector: Alvarenga, S. R.; 1 male (CL 15.52 mm) CIASBM20250012 UFSB: Piranhas, Brazil, 01 June 2022, collector: Coelho Filho, P.; 1 male (CL 14.31 mm) CIASBM2022007 UFSB: Penedinho, 01 June 2022, collector: Coelho Filho, P.; 1 female (CL 8.05 mm) and 8 males (CL 5.36–9.49 mm) CIASBM20250009 UFSB: Penedinho, 01 June 2022, collector: Coelho Filho, P.; 4 males (CL 9.40–11.30 mm) CIASBM20250010 UFSB: Penedinho, 01 April 2022, collector: Coelho Filho, P.; 1 female (CL 5.19 mm) and 8 males (6.11–10.21 mm) CIASBM20250011 UFSB: Penedinho, 01 April 2022, collector: Coelho Filho, P.; 1 male (CL 15.51 mm) CIASBM20250012 UFSB: Piranhas Brazil, collector: Coelho Filho, P .. Bahia: 1 male (CL 11.95 mm) CIASBM2018026 UFSB: rio Tijuípe, Itacaré, 08 April 2017, collector: Nascimento, J. S.; 1 male (CL 11.30 mm) CIASBM20250007 UFSB: rio Burundanga, Itacaré, 02 June 2019, collector: Novais, W. R.; 2 females (CL 9.60 mm and 9.03 mm) and 13 males (5.71–12.72 mm) CIASBM20190127 UFSB: rio Tijuipinho, Itacaré, 16 April 2019, collector: Carvalho, F. L.; 1 male (CL 14.49 mm) CIASBM20170009 UFSB: Serqueiro de Piraúne, Ilhéus, no collection date, collector: not identified; 8 males (CL 9.17–12.49 mm) CIASBM20250013 UFSB: Córrego da Presa RPPN Capitão, Itacaré, 18 March 2022, collector: Novais, W. R.; 1 male (CL 10.19 mm) CIASBM20180259 UFSB: rio Burundanga, Itacaré, 19 May 2017, collector: Carvalho, F. L.; 1 male (CL 11.25 mm) CIASBM20190001 UFSB: Itacaré, no collection date, collector: Carvalho, F. L.; 1 male (CL 08.21 mm) CIASBM20250014 UFSB: rio Cachoeira Ilhéus, 18 March 2022, collector: Novais, W. R.; 1 female (CL 13.12 mm) and 4 males (CL 11.19–17.29 mm) CIASBM20250015 UFSB: Distrito de Derradeira, Valença, 09 Sept. 2017, collector: Abel; 1 male (CL 14.35 mm) CIASBM20180251 UFSB: rio Burundanga, Itacaré, 19 Dec. 2017, collector: Nascimento, J. S. Espírito Santo: 1 male (CL 16.51 mm) DZ/ UFRGS412: Itapemirim, 10 Oct. 1978, collector: Vilela, M.; 3 males (12.23–18.32 mm) DZ/ UFRGS3371: Rio Itapemirim, Jun. 1989, collector: Martins, M. E.; Rio de Janeiro: 3 females (11.43–12.20 mm) and 3 males (CL 8.39–16.41 mm) CIASBM20250016 UFSB: Fazenda Bananal de Baixo, Parati, 07 April 2018, collector: Souza, G. Paraná: 1 male (CL 09.48 mm) DZ/ UFRGS1146: Morretes, 07 Sept. 1988, collector: Buckup. São Paulo: 18 males (7.19–15.56 mm) DZ/ UFGRS3081: Juréia, 14 Dec. 2000, collector: Rocha, S.; Rio Grande do Sul: 3 males (CL 10.82–12.95 mm) DZ/ UFRGS709: Tramandaí, 30 Oct. 1994, collector: Rocha, S: Fontana, N. F.; 2 males (8.15, 9.11 mm) DZ/ UFRGS 716: Tramandaí, 11 Apr. 1984, collector: Fontoura, N. 1 female (10.18 mm) and 5 males (10.23–16.28 mm) DZ/ UFRGS810: Tramandaí, 2 Dec. 1985, collector: Bond, G. Morphological Characterization. Rostrum straight with a slight downward tilt, sometimes narrow, extending beyond or not reaching the distal end of the antennular peduncle. Upper margin has 12–16 regularly spaced teeth, often 14, with the proximal tooth slightly more distant from the others. Three to six teeth are located behind the orbit, most commonly five. Lower margin contains two to four teeth. Post-orbital margin is convex. Width of scaphocerite approximately one third of its length. Epistome divided into two lobes with rounded carinae. Carapace smooth, with the hepatic spine being smaller than the antennal spine. First pair of pereiopods with from one half of the carpus to half of the merus overreaching the scaphocerite. Articles are smooth with a few setae. Second pair of pereiopods unequal, with the larger one extending beyond the scaphocerite with half of the carpus to the distal part of the merus and the smaller one overreaching the scaphocerite with half of the propodus to half of the carpus. Larger cheliped of second pair of pereiopods shows variation in finger size, with a gap between fingers and rigid setae. Fixed finger has two to four small teeth in the proximal region of the cutting edge, followed by one larger distal tooth. Propodus slightly or significantly inflated. Longitudinal rows of spines and spinules welldistributed and closer together in the upper and lower parts, with a higher concentration in the median region of the propodus. Velvety pubescence present throughout the propodus, with long, rigid setae. Dorsal part of the chela has many smaller spines in the fixed finger region. Carpus varies in length and is shorter than or equal to the length of the merus. Carpus and merus robust with smaller and more widely spaced spinules ventrally. Ischium is half the length of the merus. Pleonal region smooth. Pleura of the fifth somite rectangular. Internal appendage of the second pair of pleopods is longer than male appendage. Preanal carina small and rounded, with or without apex setae. Telson has a posterior margin with a sharp median tip and two pairs of posterior cuspidate setae, where the inner ones extend beyond the posterior margin of the telson with long setae present between them. Sexual dimorphism: The presence of heterochely was less pronounced in females, with the larger cheliped being less developed than that in males. Females exhibited minimal pubescence. Distribution: Recorded occurrences in the southern United States, Mexico, Costa Rica, Nicaragua, Panama, Colombia, Venezuela, Guyana, Suriname, and along the entire Atlantic coast of Brazil (Ortmann 1897; Holthuis 1952; Holthuis & Provenzano 1970; Anderson & Filingame 1980; Williams 1984; Barros 1995; Melo 2003). Remarks. The presence of morphotypes in M. olfersii was previously identified by Santos et al. (2022). Therefore, the variability observed in the second pereiopod in the present study encompasses the morphotypes described for the species.