Key to species of males of Rheumatobates from Eastern Tropical Pacific

Modified of Polhemus & Manzano (1992)

1. First antennal segment greatly thickened, expanded distally (Fig. 6). Hind femur articulated to the trochanter on the anterior 1/ 3 (Fig. 7)............................................................. R. probolicornis Polhemus & Manzano

- First antennal segment fusiform (Fig. 9) or slightly modified (Figs. 3, 12). Hind femur articulated directly to trochanter..... 2

2. Abdominal sternites set with brushes of long setae........................................................... 3

- Abdominal sternites set with scattered short setae or lacking setae............................................... 6

3. Abdominal sternites IV −VII or VI −VII set with brushes of long setae; antennal segment III curved but not strongly sinuate, with several rows of stout setae........................................................................... 4

- Abdominal sternites, or only abdominal sternite IV, set with brushes of long setae (Fig. 11); antennal segment III strongly sinuate, with three long stout setae (appearing as a spine) on the basal part (Fig. 9).................................. 5

4 Abdominal sternites IV −VII set with brushes of long setae; abdominal sternite IV produced into a median anteriorly directed tubercle, sternites II −VI medially covering this tubercle (Fig. 13)............................... R. prostatus Polhemus

- Only abdominal sternites VI −VII set with brushes of long setae; abdominal sternite IV not produced into an anteriorly directed tubercle, sternites II −VI not medially modified............................................ R. aestuarius Polhemus

5. Only abdominal sternite IV set with brushes of very long setae (Figs. 8, 11)......... R. longisetosus Polhemus & Manzano

- All abdominal sternites set with brushes of long setae.................................. .. R. carvalhoi Drake & Harris

6. Middle femur excavate medially, set with several closely set rows of erect stiff setae; hind leg not modified; abdominal sternites not set with brushes of long setae, two hooks visible ventrally in the apex of abdominal segment VII (Fig. 14)................................................................................... R. ornatus Polhemus & Cheng

- Middle femur not excavate medially, set with at most one row of erect setae, hind leg, much modified.................. 7

7. Base of segment antennal II with an expansion ventrally; hind femur strongly widened into a laterally bowed curvature; hind tibia with a longitudinal concavity (Fig. 12)................................................. R. bergrothi Meinert

- Base of segment antennal II not expanded ventrally; hind femur not bowed laterally; hind tibia without a longitudinal concav- ity (Figs. 2−5); abdominal sternites with small, semirecumbent setae................ .. R. peculiaris Polhemus & Spangler