Mikrotrichodactylus Pretzmann, 1968

Genus Mikrotrichodactylus Pretzmann, 1968

Dilocarcinus View in CoL — Ortmann 1893: 491 [part].

Trichodactylus View in CoL — Nobili 1896: 2. — Ortmann 1902: 310 [part]. — Colosi 1920: 10, 11 (in key) [part]. — Lopretto 1976: 68 (in list) [part]. — Pretzmann 1978 b: 165. — Holthuis 1986: 614 (in list) [part]. — Bisbal 1987: 121. — Rodríguez 1992: 42 [part]. — Morrone and Lopretto 1996: 71 [part]. — Magalhães and Türkay 1996 a: 67 (in list), 71 (in key), 73 [part]. — Sternberg 1997: 55 (in tab.), 57, 58 (in fig.). — Magalhães 1998: 520 [part]. — Magalhães 2003: 199 (in key), 246 [part.]. — Campos 2005: 13, 24 [part]. — Ng et al. 2008: 188 [part]. — De Grave et al. 2009: 42 (in list) [part]. — Campos 2014: 251 [part]. — César and Damborenea 2015: 4 [part]. — Rogers et al. 2020: 942 (in key) [part].

Trichodactylus (Valdivia) — Rathbun 1906 a: 43 [part]. — Rathbun 1906 b: 503 [part]. — Coifmann 1939: 111 [part].

Trichodactylus (Trichodactylus) — Coifmann 1939: 111 [part]. — Pretzmann 1968: 70 [part]. — Bott 1969: 14 [part]. — Lopretto 1976: 68 (in list) [part]. — Pretzmann 1983 a: 307. — Pretzmann 1983 b: 320.

Trichodactylus (Mikrotrichodactylus) Pretzmann, 1968: 71.

Mikrotrichodactylus — Rodríguez 1992: 55.

Type species.

Mikrotrichodactylus borellianus Nobili, 1896 , by original designation.

Diagnosis.

Carapace: lateral margin devoid of teeth or usually with up to 5 teeth of variable development (vestigial, small or well-developed teeth) in antero- and / or postero-lateral margins. Efferent branchial channel: aperture with yugal lateral lobe present. P 2 – P 5: dactyli and propodi covered by felt-like pubescence; Pleon: pleonal somites free; male pleon usually very wide. Telson (male): anterior margin as broad as or slightly shorter than posterior margin of pleonal somite VI. G 1: simple, straight, positioned more or less diagonally in the sternopleonal cavity; distal half subcylindrical, with or without distinct lobes on lateral and / or mesial surfaces; distal opening wide, V-shaped, fusiform or subtrapezoidal, directed mesially, apex regularly convex, slightly concave or produced mesodorsally. G 2: longer than G 1. Small-sized species (up to 30 mm CW).

Distribution.

Atlantic drainage in northern, center and southern South America (in the Amazon basin, the Paraguay-lower Parana River system, as well as in some coastal river basins of southern Brazil and Uruguay).

Composition.

Mikrotrichodactylus borellianus ( Nobili, 1896) ; Mikrotrichodactylus panoplus (Martens, 1869) ; Mikrotrichodactylus faxoni (Rathbun, 1906 a) , comb. nov.; Mikrotrichodactylus parvus ( Moreira, 1912) , comb. nov.; Mikrotrichodactylus ehrhardti ( Bott, 1969) , comb. nov.; Mikrotrichodactylus kensleyi ( Rodríguez, 1992) , comb. nov.

Remarks.

Mikrotrichodactylus was erected by Pretzmann (1968) as a subgenus of Trichodactylus to accommodate M. borellianus and M. panoplus . Rodríguez (1992) raised it to generic status and kept these same species in the genus. Magalhães and Türkay (1996 a) did not follow the decisions of Pretzmann (1968) and Rodríguez (1992) and treated Trichodactylus and Mikrotrichodactylus as synonyms in their classificatory system. As the present study corroborated the validity of Mikrotrichodactylus , and since different authors have followed either Rodríguez’ (1992) or Magalhães and Türkay’s (1996 a) proposals, we prefer not to treat M. borellianus , and M. panoplus as new combinations herein.