KEY TO THE EXTANT
GENERA OF CRANGONYCTIDAE
1. Pigmented eyes typically
present; lateral lobe of head (interantennal lobe) rather
broadly
rounded
anteriorly, inferior sinus lacking or poorly developed;
coxal plates 1-4 deep,
deeper than
corresponding body segments; posterior corners of pleonal
plates
(especially 1
and 2) produced and/or acuminate
..........................................................................................................................................2
Eyes absent;
lateral lobe of head narrowly rounded anteriorly,
inferior sinus present
but shallow;
coxal plates 1-4 moderately shallow, not deeper than
corresponding body
segments;
posterior corners of pleonal plates rounded, not produced
or acuminate
..........................................................................................................................................4
2. Outer ramus of uropod 3
longer than peduncle, inner ramus present,
scale-like
.........................................................................................................................Crangonyx
Outer ramus
of uropod 3 shorter than peduncle (or occasionally
absent), inner
ramus
lacking
.........................................................................................................................................3
3. Outer ramus of uropod 3 present;
antenna 2 of male bearing calceoli
..........................................................................................................................Synurella
Outer ramus
of uropod 3 absent; antenna 2 of male lacking calceoli
(?)
...........................................................................................................................Lyurella
4. Inner ramus of uropod 3
small, scale-like; outer plate of maxilliped with row
of
blade spineson
inner margin
.......................................................................................................................Bactrurus
Inner ramus
of uropod 3 lacking; outer plate of maxilliped lacking
blade spines on
inner
margin
......................................................................................................................................5
5. Outer ramus of uropod 3
distinctly shorter than peduncle or absent, usually
lacking
lateral
spine(s)
.................................................................................................................Stygobromus
Outer ramus of
uropod 3 equal in length to peduncle, armed with 1 set of
2 spines
and occasionally
another single spine
........................................................................................................................Stygonyx
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