Key to species of Pseudothelphusidae from Costa Rica

including the species of Ptychophallus from Panama (based on characters taken from fully grown adult males)

1. Subdistal portion of mesio-cephalic and lateral surfaces of G1 with distinct patch of minute spines or short to large setae (tribe Potamocarcinini).................................................................................... 2

- Subdistal portion of mesio-cephalic and lateral surfaces of G1 smooth, lacking spines or setae (tribe Hypolobocerini)...... 6

2. G1 with well-developed marginal process, rounded (Figs. 71, 75) or subtriangular (Fig. 73); cephalic process present (Figs. 72- 74) (Potamocarcinus)................................................................................. 3

- G1 with rudimentary marginal process (Figs. 64, 69); cephalic process absent (Allacanthos)......................... 5

3. Antero-lateral teeth of carapace large, sharp. Marginal process of G1 subtriangular, projected distally beyond mesial lobe (Fig. 73)......................................................................... Potamocarcinus nicaraguensis

- Antero-lateral teeth of carapace small or minute, blunt. Marginal process of G1 rounded, as long as or shorter than mesial lobe................................................................................................... 4

4. G1 with marginal process slightly shorter than or as long as mesial lobe; cephalic process as one broad, bifid tooth (Fig. 71).................................................................................. Potamocarcinus magnus

-. G1 with marginal process distinctly shorter than mesial lobe; cephalic process as two well separated, sharp teeth (Fig. 75).................................................................................. Potamocarcinus richmondi

5. G1 with marginal suture straight along all stem; subdistal portion of mesio-cephalic and lateral surfaces with a wide subdistal field of minute spines; lateral lobe of apex with rounded tip (Fig. 64)............................. Allacanthos pittieri

-. G1 with marginal suture curved to cephalic side on distal part of stem; subdistal portion of lateral and cephalic sides with a very weakly developed field of scattered minute spines; lateral lobe of apex with sharp tip (Fig. 69)....... Allacanthos yawi

6. G1 slender; apex elongated and slim, not bent cephalically; lateral surface simple; distal portion of caudal surface smooth (Achlidon).......................................................................................... 7

-. G1 stout; apex oblong, bent cephalically; lateral surface with lateral process large and usually bilobed (except P. goldmanni); distal portion of caudal surface with low longitudinal ridge (Ptychophallus)...................................... 8

7. G1 slightly curved towards cephalic side on caudo-mesial view; marginal process rounded, not produced beyond the mesial crest of apex; mesial process weakly developed, rounded (Fig. 1)................................. Achlidon agrestis

-. G1 slightly curved towards latero-cephalic side on caudo-mesial view; marginal process triangular, produced beyond the mesial crest of apex; mesial process strongly developed, reniform (Fig. 6)........................ Achlidon puntarenas

8. Lateral surface of G1 with lateral process variously bilobed................................................... 9

-. Lateral surface of G1 with lateral process very poorly developed, reduced to small lobe distally (Fig. 17); Panama ......................................................................................... Ptychophallus goldmanni

9. G1 with lateral process very well developed, broadly subtriangular, undivided, its border broady convex.............. 10

-. G1 with lateral process more or less developed, weakly or strongly bilobed, its border with a shallow or deep concavity.. 11

10. G1 with apex strongly bent (> 90°) in cephalic direction, usually touching cephalic surface of stem (Figs. 31, 32); central Panama ............................................................................ Ptychophallus lavallensis

-. G1 with apex moderately bent (90° or little less) in cephalic direction, not touching cephalic surface of stem (Figs. 22, 23); central-south Costa Rica ............................................................... Ptychophallus exilipes

11. G1 with lateral process long, at least 60% of stem length (from proximal opening to caudal border of apex), usually slightly shorter than or as wide as lateral end of apex, with a shallow median incision.................................... 12

-. G1 with lateral process of moderate length, usually 60% or less of stem length (from proximal opening to caudal border of apex), usually as wide as or wider than lateral end of apex, usually with a deep median incision....................... 13

12. G1 with mesial process usually broadly rounded to subretangular, transversally projected (not downturned); lateral process weekly bilobed with shallow median incision, proximal lobe rather broader and wider than distal one (Fig. 44); Costa Rica ................................................................................. Ptychophallus paraxantusi

-. G1 with mesial process subtriangular, narrow, slightly directed downwards; lateral process very weekly bilobed with rudimentary median incision or nearly straight (Fig. 10); Costa Rica and Panama ................... Ptychophallus colombianus

13. G1 with mesial process subtriangular, narrow, usually directed downward...................................... 14

-. G1 with mesial process subquadrangular, large, hatchet-shaped (Fig. 39); Costa Rica (questionably from Panama)............................................................................................ Ptychophallus tristani

14. G1 with mesial process with one or two short spines on laterocephalic side..................................... 15

- G1 with mesial process smooth on laterocephalic side...................................................... 16

15. G1 with mesial process bearing one short spine on laterocephalic side (Fig. 34); Panama ....... Ptychophallus micracanthus

- G1 with mesial process bearing two short spines on laterocephalic side, proximal one a little sharper than distal one (Fig. 15); Costa Rica ..................................................................... Ptychophallus costaricensis

16. G1 with lateral process well developed, both proximal and apical lobes wide, separated by a rather shallow median incision................................................................................................... 17

-. G1 with lateral process moderately developed, proximal lobe finger-like and distinctly narrower than apical lobe, separated by deep, wide and rounded median incision (Fig. 9); Panama ................................. Ptychophallus cocleensis

17. G1 with distal lobe of lateral process or as long as or narrower than lateral end of apex in caudo-mesial view............ 18

- G1 with distal lobe of lateral process distinctly wider than lateral end of apex in caudo-mesial view.................. 19

18. G1 with apex strongly bent (approximately 90°) in cephalic direction; lateral process usually as wide as lateral end of apex; distocaudal ridge well developed (Fig. 35); Costa Rica and Panama .......................... Ptychophallus montanus

-. G1 with moderately bent (less than 90°) in cephalic direction; lateral process distinctly shorter than lateral end of apex; distocaudal ridge weakly developed (Fig. 21); Panama ............................................ Ptychophallus kuna

19. G1 with distal lobe much swollen distally on the cephalic surface, its border smooth (Figs. 54, 55); Costa Rica and Panama .................................................................................. Ptychophallus tumimanus

-. G1 with distal lobe strongly swollen distally on the cephalic surface, its border bearing crest-like flange directed distally (Figs. 61, 62); Costa Rica and Panama ....................................................... Ptychophallus uncinatus