Benthesicymidae, Wood-Mason, 1891

Wicksten, Mary K., 2012, Decapod Crustacea of the Californian and Oregonian Zoogeographic Provinces 3371, Zootaxa 3371, pp. 1-307 : 17

Key to species of family Benthesicymidae

1. Endopods of second maxillipeds slender. Usually benthic...................................................... 2

– Endopods of second maxillipeds with merus thin, broad, compressed. Usually pelagic.............................. 4

2. Posterior margin of abdominal somite 4 armed with comb-like denticles, teeth................. Benthesicymus laciniatus

– Posterior margin of abdominal somite 4 not armed with comb-like denticles or teeth................................ 3

3. Median carina of abdominal somites 5, 6 terminating posteriorly in small acute tooth............... Benthesicymus tanneri

– Median carina of abdominal somites 5, 6 not terminating in teeth; sixth somite ending in upturned transverse ridge............................................................................................. Benthesicymus altus

4. Podobranchs absent on pereopods 1–3. Telson with single pair mobile lateral spines................................. 5

– Podobranchs present on pereopods 1–3. Telson with more than single pair mobile lateral spines....................... 8

5. Female with orifices of seminal receptacles opening independently, not included in common atrium. Male with distolateral lobe of petasma undivided............................................................................... 6

– Female with orifices of seminal receptacles lying within common atrium. Male with distolateral lobe of petasma divided... 7

6. Female with subtriangular structure present between pereopods 4; two symmetrical protuberances transversely located just anterior of this structure from posterior margin of fifth thoracic sternite, male with external lobe of petasma undivided; distoventral lobe of petasma divided........................................................... Gennadas tinayrei

– Female without such structure, male with external distoventral lobe of petasma undivided............. Gennadas sordidus

7. Female with thelycum provided with subrectangular, tong-shaped projection extending forward from between pereopods 4, reaching to posterior edge of thoracic sternite 6; male with external lobe of petasma much longer than median lobe............................................................................................... Gennadas incertus

– Female without such subrectangular structure, but subtriangular structure on thoracic sternite 5, between pereopods 2; strong transverse crest on anterior part of sternite XIV. Male with external lobe of petasma shorter than median lobe................................................................................................. Gennadas propinquus

8. Cervical and post-cervical sutures not closely approaching each other on dorsal midline......... Bentheogennema borealis

– Cervical and post-cervical sutures closely approaching each other on dorsal midline................................. 9

9. Petasma with large accessory lobe; in mature male, with terminal hook; thelycum with elevated triangular plate on sixth sternite.Telson with only 1 pair terminal-lateral spines.................................... Bentheogennema burkenroadi

– Petasma with smaller accessory lobe, without terminal hook; thelycum without elevated triangular plate on sixth sternite.Telson with 1–3 pairs terminal-lateral spines............................................... Bentheogennema pasithea