1. Male with elongate loop-shaped or elongate uni-spiral amphids. Female with elongate loop-shaped or uni-spiral amphids.. 2
- Male with doubled elongate spiral amphids. Female with doubled circular or elongate spiral amphids.................. 10
2. Male and female with longitudinally areolated annules on swollen pharyngeal region............................... 3
- Male and female without longitudinally areolated annules on swollen pharyngeal region............................. 7
3. Male with precloacal Acan-set or Corn-set. Female with 15–20 SvAT............................................ 4
- Male without precloacal Acan-set or Corn-set. Female with 24–30 SvAT................................ P. spinosum
4. Male with 1 subventral pair of precloacal Acan-set. Female with 12–14 SlAT...................................... 5
- Male with single ventral precloacal Corn-set. Female with 17–18 SlAT.................................... P. hopperi
5. Male and female with prominent eyespots................................................................. 6
- Male and female with obscure eyespots........................................................ P. singaporense
6. Male with cylindrical cloacal region and conical tail gradually narrowing................................ P. floridense
- Male with remarkably enlarged cloacal region and conico-cylindrical tail abruptly narrowing...... P. pachylumbus sp. nov.
7. Male and female with Ceph Acan-set on posterior 1 / 3 of rostrum............................................... 8
- Male and female with Ceph Acan-set about mid-rostrum...................................................... 9
8. Male with single ventral precloacal Corn-set. Female with elongate loop-shaped amphids................. P. meridionale
- Male with 1 subventral pair of precloacal Corn-set. Female with uni-spiral amphids.......................... P. newelli
9. Male with single ventral precloacal Acan-set. Female with 21–22 SvAT............................... P. californicum
- Male without precloacal Acan-set or Corn-set. Female with 15–18 SvAT................................ P. maggentii
10. Male and female with 1 pair of Ceph Acan-set and no eyespots......................................... P. jejuense
- Male and female with 2 pairs of Ceph Acan-set and prominent eyespots............................... P. antarcticum