Pachynidae

Lowry, J. K. & Stoddart, H. E., 2012, The Pachynidae fam. nov. (Crustacea: Amphipoda: Lysianassoidea) 3246, Zootaxa 3246 (1), pp. 1-69 : 6

Key to genera of Pachynidae

1. Gnathopod 1 propodus, posterior margin greatly reduced or absent.............................................. 2

- Gnathopod 1 propodus, posterior margin well developed...................................................... 5

2. Antenna 1 accessory flagellum article 1 short (less than twice as long as article 2). Maxilla 1 palp present. Maxilliped inner plate present. Telson shorter than broad............................................................ Acheronia

- Antenna 1 accessory flagellum article 1 long (at least twice as long as article 2). Maxilla 1 palp absent. Maxilliped inner plate absent. Telson slightly longer than broad................................................................... 3

3. Maxilliped palp with 3 articles................................................................. Pachychelium

- Maxilliped palp with 4 articles........................................................................... 4

4. Maxilliped palp article 4 falcate. Gnathopod 1 ischium swollen posteroproximally....................... Ultimachelium

- Maxilliped palp article 4 spatulate. Gnathopod 1 ischium not swollen posteroproximally..................... Smaraldia

5. Antenna 1 peduncular article 1 with large posterodistal spine................................................... 6

- Antenna 1 peduncular article 1 without large posterodistal spine............................................... 10

6. Maxilla 1 outer plate setal teeth smooth, without cusps or sculpturing. Maxilliped inner plate absent. Gnathopod 1 palm defined by simple robust seta...................................................................... Ekelofia

- Maxilla 1 outer plate setal teeth with cusps or sculpturing. Maxilliped inner plate present. Gnathopod 1 palm defined by complex robust seta....................................................................................... 7

7. Maxilliped palp with 4 articles........................................................................... 8

- Maxilliped palp with 3 articles (articles 1 and 2 partially or completely fused)..................................... 9

8. Mandible accessory setal row modified into lamina dentata on at least one side........................... Drummondia

- Mandible accessory setal row not modified into lamina dentata, accessory setae separate........................ Renella

9. Left mandible with accessory setal row partially fused into lamina dentata. Mandibular palp article 3 distally tapered. Pereopods 5 and 6 merus without posteroproximal shoulder................................................. Coriolisa

- Mandibles without lamina dentata. Mandibular palp article 3 not distally tapered. Pereopods 5 and 6 merus with posteroproximal shoulder................................................................................ Prachynella

10. Lateral cephalic lobe small. Maxilla 1 palp with apical robust setae. Maxilliped outer plate small, not reaching palp article 3............................................................................................... Pachynus

- Lateral cephalic lobe large. Maxilla 1 palp with apical slender seta or setae absent. Maxilliped outer plate large, about as long as palp............................................................................................ 11

11. Gnathopod 1 propodus length about 2.5 × breadth; palm defined by complex robust seta. Uropod 3 uniramous.... Sheardella

- Gnathopod 1 propodus length 1.5–2 × breadth; palm defined by simple robust seta or seta absent. Uropod 3 biramous................................................................................................... Figorella