Revision of the amphiamerican genus Mysidium Dana, 1852 (Crustacea: Mysida: Mysidae), with descriptions of two new species and the establishment of two new subgenera Author Wittmann, Karl J. Author Wirtz, Peter text European Journal of Taxonomy 2019 2019-02-05 495 1 48 journal article 28548 10.5852/ejt.2019.495 db716632-f55b-4a04-b3cd-918eea1c92c9 2584868 65CC1141-E560-4979-97E5-F0701563C84B Genus Mysidium Dana, 1852 Mysidia Dana, 1850 : 130 (junior homonym, see Discussion). Mysidium Dana, 1852 : 638 , 653 (published in synonymy, see Discussion). Themisto – Dana 1850 : 130 (quoted as homonym). Macromysis – Dana 1852 : 638 , 652, 653 (subjective junior synonym, see Discussion); 1853: 1435; 1855: pl. 43, fig. 5. — Czerniavsky 1887 : 85 (in synonymy). — Tattersall & Tattersall 1951 : 376 (in synonymy). Mysidium – Czerniavsky 1882 : 16 , 50 (in key); 1887: 85 (diagnosis, synonymy). — W.M. Tattersall 1951 : 223 (synonymy, key to species). — Brattegard 1969 : 89 (key to species). — Mauchline 1980 : 36 (in key). — Băcescu & Ortiz 1984 : 22 (key to species). — Harrison & Bowman 1987 : 678 . — Fukuoka 2006 : fig. 1. — Petrescu & Wittmann 2009 : 64 . — Ortiz et al. 2012 : 985 ; 2017b: 72. — Wittmann et al. 2014 : 339 . — Ortiz & Lalana 2018 : 67 . Mysidia – Czerniavsky 1887 : 85 (in synonymy). — Gerstaecker & Ortmann 1901 : 665 (in citation). — Zimmer 1915b : 211 , 215; 1918: 24. — Illig 1930 : 599 (in list). Diamysis – Zimmer 1915a : 214 (invalid subsequent assignment). Type species Macromysis gracilis Dana, 1852 , currently acknowledged in revised combination as Mysidium gracil e ( Dana, 1852 ). Diagnosis Compiled with the reservation that not every one of the following characters is known in Mysidium iliffei Băcescu, 1991 (see Discussion): Anisomysini with eyes normal, eyestalks and cornea well developed. Antennular trunk terminally with the usual two flagella in both sexes, no accessory flagellum developed.Appendix masculina large, setose. Antennal scale lanceolate, without spines, but setose all around, with small terminal segment. Mandibles normal, palp three-segmented, cutting edges with well-developed pars incisiva, lacinia mobilis and pars molaris. Distal segment of maxillary palp with setae, but without denticles. Thoracopods essentially normal, endopods with 2- or three-segmented carpopropodus. All pleopods of females and pleopods 1–3, 5 of males are vestigial, setose, uniramous, unsegmented. Male pleopod 3 larger than pleopods 1–2, 5. Male pleopod 4 even longer, modified, with distinct sympod, unsegmented endopod and 3- or 4-segmented, slender exopod. Terminal two segments of exopod each bearing a large modified seta, remaining segments usually without setae, at most with one small seta on the basal segment. Uropods setose all around, without spines; exopods longer than endopods. Telson longer than broad, with entire or incised terminal margin; with spines and laminae on distal half. Etymology Derivation and gender of Mysidia and Mysidium not stated by Dana (1850 , 1852 ). Neutral gender of Mysidium implicitly fixed by Czerniavsky (1887: 85) upon proposing the revised combination Mysidium gracile ( Dana, 1852 ) . Subgenera included Mysidium Dana, 1852 , nominotypical subgen., east and west coasts of America Orientomysidium Wittmann subgen. nov. , east coast of America Occimysidium Wittmann subgen. nov. , west coast of America Species included West Atlantic (32° N to 24° S): Mysidium ( Mysidium ) gracile ( Dana, 1852 ) Mysidium ( Mysidium ) integrum W.M. Tattersall, 1951 Mysidium ( Mysidium ) cubanense Băcescu & Ortiz, 1984 Mysidium ( Mysidium ) rubroculatum Băcescu & Ortiz, 1984 Mysidium ( Mysidium ) triangulare Wittmann sp. nov. Mysidium ( Orientomysidium ) columbiae (Zimmer, 1915) comb. nov. Mysidium ( Orientomysidium ) antillarum Wittmann sp. nov. Mysidium iliffei Băcescu, 1991 East Pacific (21–25° N): Mysidium ( Mysidium ) rickettsi Harrison & Bowman, 1987 Mysidium ( Occimysidium ) pumae Ortiz, Hendrickx & Winfield, 2017 comb. nov.