New species of Chimerothalassius Shamshev & Grootaert (Diptera: Dolichopodidae: Parathalassiinae) from the West Indies and Costa Rica Author Brooks, Scott E. Author Cumming, Jeffrey M. text Zootaxa 2018 2018-02-28 4387 3 511 523 journal article 30625 10.11646/zootaxa.4387.3.6 dc004088-b648-4c94-bd4b-81131365cecf 1175-5326 1187707 A55E7D25-7617-484E-B288-69B83F7CBED1 Chimerothalassius sp. (Figs 10, 17, 18, 19, 22) Material Examined. COSTA RICA : Herradura , 21.X.1993 , light trap (UV flourescent on white sheet) at edge of ocean beach, A. Borkent , CD1628 ( 2♀ , CNC ) ; Caldera , 24.viii.1993 , swept rocks amidst sand strip along ocean, A. Borkent , CD1548 ( 1♀ , CNC ) . Diagnosis. Minute (wing length 1.0– 1.1 mm ); head, thorax and abdominal tergites with dense grey pruinosity mostly covering brownish ground colour; abdominal sternites mostly pale and concolourous with adjacent membrane, sternite 6 with weak grey pruinosity; legs mostly pale or weakly infuscate, tarsi infuscate apically; setae of body and legs white; head with lower 5–7 postocular setae long; palpus large, broadly subtriangular, lacking FIGURES 7–10. Wings (dorsal surface). 7. Chimerothalassius runyoni sp. nov. , specimen of unknown sex from Rodney’s Rock, Dominica . 8. Same, female paratype from Woodlands Beach , Montserrat . 9. Same, male paratype from Woodlands Beach , Montserrat . 10. Chimerothalassius sp., female from Herradura, Costa Rica. Abbreviations: C—costa; cua—anterior cubital (=anal) cell; h—humeral crossvein; M1, M4—medial veins; R1, R2+3, R4+5—radial veins. ventral bristles; fore coxa with prominent setae on anterior surface, lower 2–3 setae long; fore femur with series of 3–4 long setae ventrally; wing about 2X longer than wide (Fig 10); costal section between R2+3–R4+5 shorter than R4+5–M1 section; female terminalia with tergite 8 medially divided, narrowly fused with sternite 8 anterolaterally; tergite 10 divided medially with three acanthophorite setae on each broadly-tipped hemitergite; cercus with long apical seta and long lateral seta ( Fig. 18 ); spermathecal duct an unsclerotized tube with broad ridged sperm pump in basal part and conical terminal expansion giving rise to sac-like spermatheca ( Fig. 17 ). Male is unknown. Distribution. This undescribed species is currently known only from two localities on the Pacific coast of Costa Rica ( Figs 19 , 22 ). Remarks. Like the other known species of Chimerothalassius , this species appears to be associated with beach rocks, however the two specimens from Herradura were taken at a UV light trap placed near the shoreline.