Review of the Hemiosus Sharp and Derallus Sharp of North America, Central America, and the Caribbean (Coleoptera: Hydrophilidae: Berosini) Author Short, Andrew Edward Z. Author Torres, Phillip J. text Zootaxa 2006 1369 1 17 journal article 50294 10.5281/zenodo.174866 15363d41-dba5-4484-addb-9734f619bcf1 1175-5326 174866 Hemiosus exilis ( LeConte, 1852 ) ( Fig. 4 ) Berosus exilis LeConte, 1852 : 211 . Hemiosus toxillus d’Orchymont, 1940 : 181 . New synonomy. Hemiosus exilis : Leech, 1943 : 61 ; Van Tassell, 1964 : 54 . Type material examined. Berosus exilis LeConte : Holotype (male): [colored disc], “ B. exilis / Lec./ Gila”, “ Type / 3081 ” ( MCZ ). Hemiosus toxillus d’Orchymont : holotype (male): “[male symbol]”, “Mex. Mazatlan/ brack, pools 25 / v. 1934 H. Hinton”, “A. d’Orchymont det./ Hemiosus / toxillus m.”, “ TYPE [red card]” ( IRSNB ). Paratype : “Female symbol”, “Sinaloa/ Mex”, “Para-/ type [orange card]”, “ Hemiosus toxillus / Orchymont/ Tete Manque” ( IRSNB ). Additional material examined ( 69 ). MEXICO : Sinaloa: Culiacan, 16 .vii. 1963 , P.J. Spangler leg. ( 60 : AEZS , NMW , USNM ); Jalisco: Rio Cuitzmala, SE of Chamela, 180 ft . asl, 6 .i. 2005 , W.D. Shepard leg. ( 7 : AEZS ); 6.6 km SE Villa Purificacion, Puente El Amorin, 8 .i. 2005 , W.D. Shepard leg. ( 1 : AEZS ); Veracruz: 29 mi . SE Jalapa, 900 ft ., 26 .xii. 1963 , M.J. Tauber & C.A. Tauber leg. ( 1 : EMEC ). Diagnosis. Total length: 2.3–2.8 mm . The broadly testaceous anterior and lateral margins of the pronotum ( Fig. 4 ) serve to distinguish this species in Mesoamerica. Distribution. Mexico , United States (Arizona, Texas). Remarks. See Van Tassell ( 1964 ) for a detailed discussion of the taxonomic history of the species. The synonymy of H. toxillus d’Orchymont with H. exilis (LeConte) was first recognized but unpublished by Van Tassell ( 1966 ) . I have examined the holotypes of both species and concur that H. toxillus d’Orchymont and H. exilis (LeConte) are conspecific. This likely occurred because H. exilis was still placed in the genus Berosus when d’Orchymont ( 1940 ) described H. toxillus . A full description and additional illustrations of this species are given by Oliva ( 1991 ) under the name H. toxillus .