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Family Alpheidae
Family Alpheidae
Key to genera and species
[Adapted from Chace, 1972]
1. Movable plate at posterolateral angle of sixth abdominal somite 2
No movable plate at posterolateral angle of sixth abdominal somite 3
2. (1) Rostrum lacking; antennular peduncle long and slender, stylocerite closely
appressed to basal segment; exopod of uropod distally truncate (telson with convex
distal margin; first chelipeds carried with chela flexed against merus, opposable
margins of fingers of major chela dentate) Leptalpheus forceps
Rostral projection present; antennular peduncle short and stout, stylocerite well
separated from basal segment; exopod of uropod distally rounded (first chelipeds
carried extended) AIpheopsis
3. (1) Eyes completely exposed dorsally; movable finger of major first chela without
molar-like tooth fitting into socket in immovable finger., Automate
Eyes concealed from all but anteroventral view by deflexed frontal margin of
carapace; movable finger of major first chela usually provided with large molar-like
tooth fitting into socket in immovable finger 4
4. (3) Posterior margin of carapace without "cardiac notch" at base of branchiostegite;
exopod of uropod without transverse suture (rostral projection lacking, front
unarmed; antepenultimate segment of third maxilliped normal, not unusually
expanded; epipods present on at least 2 anterior pairs of pereopods) Thunor simus
Posterior margin of carapace with "cardiac notch"; exopod of uropod with
transverse suture 5
5. (4) Pereopods without epipods; second pleopod of male without appendix masculina
(front tridentate; antepenultimate segment of third maxilliped normal, not unusually
expanded; dactyli of 3 posterior pereopods biunguiculate) Synalpheus
Epipods present on at least 2 anterior pairs of pereopods; second pleopod of male
with appendix masculina 6
6. (5) Labrum and mandible not unusually enlarged; antepenultimate segment of third
maxilliped not unusually expanded; fourth pereopod with mastigobranch epipod;
appendix masculina normal, not reaching distal end of either endopod or exopod of
male second pleopod Alpheus
Labrum greatly swollen and enveloped by expanded incisor process of mandible;
antepenultimate segment of third maxilliped broadened to form partial operculum
over anterior mouthparts; fourth pereopod without mastigobranch epipod; appendix
masculina greatly enlarged and elongate, overreaching distal ends of both endopod
and exopod of second pleopod Metalpheus rostratipes