1 Pleon shorter than pereonites 46 combined length..................................................... 2
Pleon longer than pereonites 46 combined length....................................................... 3
2 Pereonite 2 only 0.25 times longer than pereonite 1............................... Colettea sp. C
Pereonite 2 almost twice as long as pereonite 1....................................... C. humboldti
3 Uropods long (about as long as half of pleotelson)...................................................... 4
Uropods short (less than ¼ of pleotelson)................................................................... 6
4 Body short (7 times longer than wide) .......................................................... C. minima
Body long (11–15 times longer than wide)................................................................. 5
5 Pereonite 2–3 longer than wide, exopod uropod longer than half length of endopod proximal article............................................................................................. C. elongata
Pereonite 2–3 wider than long, exopod uropod shorter than endopod proximal article half length..................................................................................................... C. lilliputa
6 Pleon clearly shorter than pereonites combined length............................................... 7
Pleon at least as long as all pereonites combined length............................................ 15
7 Chela fixed finger with one seta................................................................................... 8
Chela fixed finger with two setae.............................................................................. 11
8 Pleotelson about as long as wide. Cheliped merus and carpus with 1–2 long seta(ae) ventrally.................................................................................................... C. longipedia
Pleotelson clearly longer than wide. Cheliped merus and carpus without setae.......... 9
9 Carapace elongated twice as long as wide; antennule article 1 clearly longer than rest articles combined length................................................................................ C. subtilis
Carapace short, no longer than 1.5 of width; Antennule article 1 clearly shorter than rest articles combined length....................................................................................... 10
10 Pereonites 1–3 subequal. Carapace longer than pereonite 13 combined length................................................................................................................................... C. wilsoni
Pereonite 2 and 3 longer than pereonite 1. Carapace shorter than pereonite 13 com bined length........................................................................................... Collettea sp. B
11 Pleotelson as long as pleonites combined length .............................. C. rotundicaudata
Pleotelson shorter than pleonites combined length................................................... 12
12 Uropod endopod one articulated .................................................................. C. pegmata
Uropod endopod biarticulated.................................................................................. 13
13 Cephalothorax short (shorther than 1.25 width) ........................................ C. cylindrata
Cephalothorax long (about 1.5 as long as width)....................................................... 14
14 Pereonite 4 and 5 as wide as long, pleon shorter than pereonites 25 combined length
.......................................................................................................................... C. alicjae Pereonite 4 and 5 clearly wider than long, pleon as long as all pereonites combined length.......................................................................................................... C. antarctica 15 Pereonite 6 square or longer than wide...................................................................... 16
Pereonite 6 wider than long........................................................................................ 17
16 Pleotelson longer than pleonites 3–5 combined length......................... C. longipleona
Pleotelson shorter than pleonites 3–5 combined length........................ C. vermiformis
17 Pereonite 5 longer than wide..................................................................................... 18
Pereonite 5 wider than long............................................................... C. cylindratoides
18 Pereonite 6 subequal to 4 th......................................................................................... 19
Pereonite 6 much shorter 4 th.................................................................... C. larviformis
19 Cephalothorax short, about 1.25 times longer than wide, cheliped fixed finger with short and long seta ventrally........................................................................ C. arnaudi
Cephalothorax long, more than 1.5 times longer than wide, cheliped fixed finger with two long seta ventrally.......................................................................... Collettea sp. A