About Cryptolithodes sitchensis Brandt, 1853
The carapace of Cryptolithodes sitchensis is ovate and nearly smooth, and it extends completely over the species' three pairs of walking legs and two chelipeds. The carapace is typically around 5/3 times as wide as it is long, and fully grown adults can reach over 5 cm (2.0 in) in carapace width. Coloration of C. sitchensis ranges from neutral sandy hues to bright oranges, reds, and purples. In adult individuals, the first abdominal segment is fused to the second abdominal segment. The third, fourth, and fifth abdominal segments each consist of one inner (median) plate and a pair of outer (lateral) plates. However, the third abdominal segment has accessory plates located in two small regions, one on the left and one on the right, that are surrounded by the second segment, the third segment's median plate, and the third segment's lateral plates. Males have the same number of these accessory plates on both sides of the median line, but females often have more accessory plates on the left side of the median than on the right.
