Key to Genera of Ptomaphagini of Latin America (modified from Gnaspini, 1998 and Salgado, 2008b)

1a Anterior tibiae with distinct comb of short spines on outer margin, as well as apex; mesepisternum transverse, as wide as inner edge as at outer edge; Mexico, West Indies..............................Subtribe Ptomaphaginina: Proptomaphaginus

1b Anterior tibiae with comb of short spines only at apex; mesepisternum trapezoidal, wider on outer edge than inner edge................................................................................... Subtribe Ptomaphagina ... 2

2a Ventrite VI with a longitudinal keel............................................................ Adelopspeleon

2b Ventrite VI without a longitudinal keel.................................................................... 3

3a Last segment of maxillary palp conical, much shorter than penultimate segment; antenna mostly slender, giving an impression of being elongate; widespread.................................................................. Paulipalpina

3b Last segment of maxillary palp conical, subequal and a little longer than penultimate segment; antenna normal, may be elongate in troglobitic species................................................................................... 4

4a Aedeagus short, with ventral opening............................................................... Peckena

4b Aedeagus short or elongate, with opening always dorsal, cutting from medially to the left side........................ 5

5a Aedeagus with opening cutting medially; flagellum of internal sac longer than aedeagus............................. 6

5b Aedeagus with opening cutting left side; flagellum of internal sac shorter than or subequal to aedeagus................. 7

6a Extremely long flagellum, which rests completely coiled inside the aedeagus; Venezuela ..................... Amplexella

6b Flagellum longer than aedeagus, with basal bulb resting outside aedeagus; widespread................. Parapaulipalpina

7a Aedeagus short and broad, opening cutting left side, right of the apical setae; spiculum gastrale of genital segment broad (rectangular or saddle-shaped plate); widespread......................................................... Adelopsis

7b Aedeagus elongate, opening cutting left side, left of the apical setae; spiculum gastrale of genital segment straight and thin, sometimes elongate; Mexico to Brazil ........................................................... Ptomaphagus