A replacement name for Macrobrachium aemulum madhusoodani Pillai & Unnikrishnan, 2013, a junior homonym of Macrobrachium madhusoodani Unnikrishnan, Pillai & Jayachandran, 2011 (Decapoda: Palaemonidae) .

Macrobrachium aemulum madhusoodani Pillai & Unnikrishnan (2013) was recently described based on material from the Neyyar River, Kerala, India as a new subspecies of M. aemulum (Nobili, 1906). As however, both species and subspecies names are considered part of the species-group for nomenclatorial purposes (ICZN, Art. 45.1), the name is a junior homonym of Macrobrachium madhusoodani Unnikrishnan, Pillai & Jayachandran (2011) and requires a replacement name. Herein, the name of Macrobrachium aemulum keralauni nom. nov. is erected as the replacement name for the junior homonym, M. aemulum madhusoodani Pillai & Unnikrishnan, 2013. The proposed name, ‘keralauni’ is an abbreviation for University of Kerala, Thiruvananthapuram (Kerala, India) and is an arbitrary combination of words to be used as a noun in apposition. For the convenience of researchers, the distinctive characters of the subspecies are reiterated: Rostral formula 9-13/2 with 4-5 postorbital teeth; carapace smooth; distal end of rostrum directed upwards and upper margin convex. Second pereiopods robust, dissimilar in shape and unequal in size. Larger second pereiopod with merus shorter than carpus and about half length of chela; carpus shorter than chela, palm longer than fingers, width of palm slightly greater than width of distal carpus; palm of larger chela narrower than smaller chela; fingers stout and equal; movable finger with two large denticles present on the proximal part and six small denticles on distal part (similar in non-movable finger). Smaller second pereiopod with merus shorter than carpus and about half-length of chela; carpus shorter than chela, palm longer than fingers; width of palm greater than width of distal carpus; fingers stout, equal, unarmed and with wide gap when closed; numerous setae present on the inner margin of both fingers. Four pairs of plumose setae present between inner movable spines of distal margin of telson.