Key to Garthambrus species

1. Posterior edge of metabranchial region with a raised triangular patch and anterior epibranchial margin with well- separated evenly-spaced teeth each bearing minute spinules .............................................................. G. complanatus

- Posterior edge of metabranchial region without raised triangular patch and anterior epibranchial margin otherwise 2

2. Posterior edge of metabranchial region with several tubercles, which can be stellate or granular leading to edge of posterior margin .......................................................................................................................................................... 3

- Posterior edge of metabranchial region with either a spine or tubercle, not leading to edge of posterior margin ..... 4

3. Dorsal surface of carapace with paxillate tubercles; tubercles on upper margin of ambulatory legs rounded at tip; tubercles on surfaces of ambulatory legs well spaced .................................................................................. G. poupini

- Dorsal surface of carapace with stellate granules; sharp tipped tubercles on upper margin of ambulatory legs; tuber- cles on surfaces of ambulatory legs very close together ............................................................................... G. allisoni

4. Upper margin of ambulatory legs cristate ................................................................................................................... 5

- Upper margin of ambulatory legs tuberculate ............................................................................................................ 7

5. Subhepatic region not excavated ............................................................................................................... G. lacunosus

- Subhepatic region excavated ...................................................................................................................................... 6

6. Hepatic tooth absent. Hepatic cavity broad and deep ............................................................................ G. darthvaderi

- Hepatic tooth present. Hepatic cavity narrow and shallow .................................................................... G. pteromerus

7. Upper margin of ambulatory legs with only one or two rounded tubercles on proximal and distal portion, middle portion smooth .............................................................................................................................................. G. posidon

- Upper margin of ambulatory legs with well-spaced tubercles on entire upper margin .............................................. 8

8. Dorsal surface of carapace densely covered with granulate tubercles, ambulatory legs with spines ......... G. stellatus

- Dorsal surface of carapace not densely tuberculate, ambulatory legs without spines ................................................ 9

9. Distal tubercles of upper margin of ambulatory leg meri flattened laterally, sub-cristatiform. Hepatic tooth cristati- form. Teeth on anterior epibranchial margin narrow, well-spaced from each other .......................................... G. tan i

- Distal tubercles of upper margin of ambulatory leg meri not flattened laterally. Hepatic shoulder forms right-angle not cristatiform. Teeth on anterior epibranchial margin broad, bases almost adjacent ............................................. 10

10. Lateral tooth at epibranchial corner short, not elongated. Tubercles on dorsal surface of carapace paxilliform .......... ........................................................................................................................................................................ G. c i d a r i s

- Lateral tooth at epibranchial corner elongated, tip acute. Tubercles on dorsal surface of carapace not paxilliform ..... ................................................................................................................................................................... G. undulatus