A new species of Chaetiliidae (Crustacea: Isopoda: Valvifera) from the Río de la Plata estuary, Argentina-Uruguay, and reconsideration of Macrochiridothea and Chiriscus Author Poore, Gary C. B. text Zootaxa 2009 2119 51 65 journal article 10.5281/zenodo.188066 ab6365d5-73f9-4961-b482-3020feb144a3 1175-5326 188066 Chiriscus giambiagiae ( Torti & Bastida, 1972 ) new combination Macrochiridothea giambiagiae Torti & Bastida, 1972 : 16 –22, figs 1, 2. — Harrison-Nelson & Bowman, 1990 : 127 –129, fig. 1. — Carvacho, 1997 : 51 (list). Material. Holotype : Mar del Plata (Playa Peralta Ramos), Buenos Aires, Argentina , 0–2 m , 38°03´S , 57°32´W , MACN 27514 (male, 4.3 mm , examined by AS ). Paratypes : collected with holotype , MACN ( 4 females ), MNHN Is3849 (female, examined by GCBP ). Distribution. Rio de Janeiro, Brazil (23°S), to Mar del Plata, Argentina (38°S); 2–7 m depth. Remarks. As pointed out by Harrison-Nelson & Bowman (1990) the species was overlooked by Poore (1984) and other authors who dealt with Macrochiridothea . The limbs of M. giambiagiae are almost indistinguishable from those of Chiriscus australis and Carvacho (1997) thought it very possible that the two species were synonymous. The most significant differences are in the shape of the head (more angled in C. giambiagiae ) and the presence (in female and male C. giambiagiae ) and absence (in female C. australis ) of a lateral incision in the head. Harrison-Nelson & Bowman (1990) noted only small differences between their material from Copacabana Beach, Rio de Janeiro, Brazil , and that from the more southern type locality.