Key to the Philippine species of Ancyronyx 1. CL> 1.9 mm; legs very long (length of elytra: metafemur> 0.5); ovipositor (coxite) short and stout (comp. Fig. 16 d) ......................................................................................................................................... 2 - CL 0.5 paramere length) (Fig. 15 a, b) ................................................................................ A. minutulus Freitag & Jäch sp. n. - Elytra with one subapical pair of longitudinal elongate yellowish patch and one pair of round or transversally elongate, yellowish patches or entirely dark (Figs. 3–8); CL usually> 1.1 mm. Aedeagus different; parameres short ( 10 long setae or without long setae (Figs. 11 b, 12b, 13b, 14b) ............................................................................................................................................. 5 5. Pronotum anteriorly with transverse white to yellowish patch or band (Figs. 7, 8); CL 10 long apical setae (Fig. 14 a, b) A. minerva Freitag & Jäch sp. n. - Pronotum entirely dark, without transverse patch or band (Figs. 3–6); CL> 1.35 mm. Aedeagus subapi- cally more or less widened, not conically tapered; parameres with <10 short to moderately long apical setae (Figs. 11 a, 12a, 13a)........................................................................................................................... 6 6. [Determination in dark specimens unambiguously possible by sexual characters only]: Subbasal elytral patches more or less equally round, not reaching posterior or lateral elytral margin; legs entirely dark (Fig. 6). Aedeagal median lobe long and moderately slender, subapically slightly widened (ca. 0.3 times as wide as long); ventral sac almost reaching apex (Fig. 13 a, b) ..................... A. punkti Freitag & Jäch sp. n. - Subbasal elytral patches transversely elongate (cross-stripe-like), at least reaching elytral margin at shoul- der; legs partly yellowish to pale brown (Figs. 3, 5). Aedeagal median lobe subapically distinctly widened; ventral sac not reaching apical 0.1 of aedeagus (Figs. 11 a, b; 12a, b) .............................................. 7 7. Femora predominantly yellowish to pale brown (except for articulations), ventral (inner) side without conspicuous setae; basal elytral patches <0.65 times as long as broad (Fig. 3), in dark specimens medially interrupted, reduced or lacking (Fig. 4). Aedeagal median lobe long and slender (ca. 0.2 times as wide as long; Fig. 11 a) ............................................................................................ A. patrolus Freitag & Jäch sp. n. - Dorsal side of femora entirely dark brown; ventral side with conspicuous setae; basal elytral patches large, ca. 0.8 times as long as broad (Fig. 5). Aedeagal median lobe short and stout (ca. 0.4 times as wide as long; Fig. 12 a) ................................................................................ A. pseudopatrolus Freitag & Jäch sp. n.

Published as part of Freitag, Hendrik & Jäch, Manfred A., 2007, The genus Ancyronyx Erichson, 1847 (Coleoptera, Elmidae) in Palawan and Busuanga, (Philippines) with descriptions of six new species, pp. 37-59 in Zootaxa 1590 on pages 40-41, DOI: 10.5281/zenodo.178539