Key to species of Holocephalus (adapted from Smith & Génier 2001)

Sentences between "quotes" were transcribed ipsis litteris from Smith & Génier (2001) and illustrations of other species are available also in this work.

1. “Eyes reduced, ventral portion narrow. Posterior portion of cephalic horn strongly rugose, with well defined V-shaped carina. Elytron short, semicircular when viewed laterally. Hind wing brachypterous, not reaching apex of elytron; flightless". Brazil, Paraguay ................................................................................................................................................. Holocephalus cristatus (Gillet)

- “Eyes normal, ventral portion fully developed. Posterior portion of cephalic horn at most slightly rugose, lacking carina, with poorly defined swelling. Elytron longer, dorsally flattened when viewed laterally. Hind wing fully developed, folded, capable of flight" Brazil, Paraguay .................................................................................................................................................................... 2

2. Pronotum with coarse ocellate punctures of anterior declivity extending beyond outer edge of eyes (Fig. 1 C).............................. 3

- Pronotum with coarse ocellate punctures set in triangular region of anterior declivity, largely restricted to anteriomedian depression.................................................................................................................................................................................................... 4

3. “Pronotum anteriorly with tubercle on each side of subrectangular median protuberance". Anterior angles evenly rounded and lacking carination. Cephalic carina bituberculate, tubercle on each side of carina. Brazil ................ Holocephalus sculptus (Gillet)

- Pronotum anteriorly lacking tubercles on median protuberance. Anterior angles acute, produced into fine carina (Figs. 1 A–C). Cephalic carina trituberculate (Fig. 1 C). Paraguay (Chaco)......................................... Holocephalus pokornyi new species (Fig. 1)

4. “Cephalic process with median portion depressed, lateral angles produced into acute, conical tubercles. Apical portion of cephalic process less then half head width. Pronotum with median protuberance narrow, less than half pronotal width, arcuate in dorsal view". Brazil ....................................................................................................................... Holocephalus eridanus (Olivier)

- “Cephalic process with median portion raised or not depressed compared with lateral angles. Apical portion of cephalic process more than half head width. Pronotum with median protuberance wide, more then half pronotal width, straigth in dorsal view" .. 5

5. “Elytral striae 1 and 2 shallowly impressed apically, lacking distinct punctures. Paramere with ventral portion not extending beyond lateral edge in dorsal view". Brazil ............................................................................ Holocephalus simoni Smith & Génier

- “Elytral striae 1 and 2 deeply impressed apically, with distinct punctures. Paramere with ventral portion extending beyond latera edge in dorsal view". Brazil ................................................................................................... Holocephalus julieni Smith & Génier