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Genus Synalpheus Bate, 1888
Key to species
[Adapted from Chace, 1972, and Dardeau, 1984]
Family Alpheidae 201
1. Stylocerite not overreaching basal segment of antennular peduncle (except in S.
macclendoni and S. paraneptunus); movable finger of minor first-chela with
prominent fringe of long, distally curved hairs on superior surface (reduced to
single longitudinal row in S. paraneptunus) 2
Stylocerite distinctly overreaching basal segment of antennular peduncle; movable
finger of minor first chela with scattered tufts of straight hairs but without
prominent fringe on superior surface (scaphocerite with well-developed blade,
lateral spine considerably exceeding that of basicerite in length) 14
2. (1) Both pairs of dorsal spines of telson arising in posterior of segment (ocular hoods
blunt, broader than long) S. heardi
Anterior or both pairs of dorsal spines of telson arising in anterior of segment 3
3. (2) Both pairs of dorsal spines of telson arising in anterior of segment (carapace not
distinctly produced at anteroventral angle and not carinate in dorsal midline
posterior to base of rostrum; cardiac notch not well marked; ocular teeth acute, as
broad as long but not much broader than rostrum; basicerite not produced dorsally;
major first chela twisted, immovable finger short, not reaching nearly as far distally
as does movable finger; palm of major first chela armed with sharp distal spine;
movable finger of minor first chela strongly tridentate in lateral view) S. pectiniger
Posterior pair of dorsal spines of telson arising in posterior of segment 4
4. (3) Carpus of second pereopod composed of 4 segments 5
Carpus of second pereopod composed of 5 segments 6
5. (4) Basicerite with strong dorsal spine S. rathbunae
Basicerite unarmed dorsally S. agelas
6. (4) Exopod of uropod with 1 fixed tooth on outer margin, sometimes at distolateral
angle just lateral to movable spine, sometimes distinctly removed from distolateral
angle (basicerite not produced dorsally) .7
Exopod of uropod with 2 or more fixed teeth on outer margin at, and proximal to,
distolateral angle 10
7. (6) Scaphocerite with well-developed blade (fingers of minor first chela not bidentate
distally) 8
Scaphocerite without blade (ocular teeth distinctly broader than rostrum; stylocerite
not reaching as far as distal end of basal antennular segment) 9