Timms: A revision of Limnadopsis clam shrimps 
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Sex is easily determined by examining the rostrum (long 
in males and short in females) and by the presence of claspers 
in males. Carapace shape can also be different, especially in 
L. tatei and L. multilineata, and to a much lesser extent in L. 
parvispinus, L. paradoxa, and L. pilbarensis, with carapaces 
being more humped dorsally in females than in males of 
these species. An interesting intersex condition was observed 
in one population of L. parvispinus, in which males had a 
short rostrum and claspers smaller than usual. Of various 
intersex conditions known in limnadiids this is most unusual 
(Sassaman, 1995; S. Weeks pers. comm.). 
Despite this variability, by reference to many character¬ 
istics, species can be delineated, despite overlap in some 
counts such as number of growth lines or telsonic spines. 
More disconcerting is the occasional finding of a specimen 
well outside the normal range in just one character when the 
remaining features all indicate a particular species. This is 
seen mainly in counts of telsonic spines, so that ranges given 
for some species, e.g., L. tatei, L. parvispinus, are much wider 
than normally seen in an attempt to encompass this vari¬ 
ability. Perhaps such oddities are explained by development 
abnormalities. More easily explained are areas of the body 
so damaged during development that they assume a different 
shape or number of parts than usual. Body parts most easily 
damaged seem to be the male rostrum (e.g., Fig. 8B of L. 
parvispinus), carapace edge, and the caudal claws. 
In diagnosing species, the most useful characters, because 
of their consistency between species, are shape of the 
carapace, particularly the convexity of the dorsal margin 
and posterior edge; the relative development of the dorsal 
carinae; the number of body segments; the number of spines 
on the caudal claws; and also the surface morphology of 
the eggs. Also useful in differentiating some species are, 
the number and relative size of the telsonic denticles, the 
curvature of the dorsal telsonic surface, the number and 
expression of the growth lines, the number of spines on the 
dorsal margin of the middle flagellomeres of the second 
antennae, and the number of caudal claw setae. There is little 
difference between species in the macroscopic structure of 
the claspers, although microscopic studies using SEM is 
proving fruitful in Limnadopsis (S. Richter, pers. comm.). 
From the study of the thoracopods of just four of the eight 
species, there seems to be only minor differences between 
species, although all are clearly different from those of other 
spinicaudatan genera. Thoracopods of Limnadopsis (Fig. 
4) are characterized by a long fifth endite, that is of similar 
structure to the endopod, and by a one-segmented palp on 
just the third pair of thoracopods, and in males only. The 
structure of the head, second antenna and to a lesser extent 
the first antennae are conservative throughout the genus and 
of little use in delineating species. 
Limnadiopsium. Novojilov (1958) split the genus 
Limnadopsis (misspelt as Limnadiopsis ) into Limnadiopsis 
(sic) and Limnadiopsium. Novojilov placed Limnadopsis 
tatei into his Limnadiopsium and left Limnadopsis birchii 
(misspelt as L. brichii ) in Limnadopsis. He was apparently 
unaware of Limnadopsis parvispinus and thought L. brunneus 
belonged to a third genus. Furthermore, he erected holotypes 
“on paper” for both species based on the material the original 
authors used in their descriptions (for L. birchii : “Holotype: 
specimen decrit par Baird”; forL. tatei : “Holotype: specimen 
decrit par Spencer et Hall 1896”—Novojilov, 1958:104-105) 
It seems from the text that Novojilov (1958) did not see the 
original descriptions as he quotes Daday de Dees, 1925, fig. 
122 in the case of L. birchii and fig. 123 in the case of L. 
tatei. No type material was designated for these two species 
by their authors and indeed forL. birchii and L. brunneus no 
type specimens of any designation exist (Timms, 2006). For 
L. tatei it is only now that a neotype has been chosen (see 
earlier). The misspelling of just about every name used, the 
erection of invalid holotypes and the omission of the other 
known species of Limnadopsis, is enough to cast doubt on 
this work. 
Novojilov (1958) claimed Limnadiopsium to be distinct 
from Limnadopsis by reason of the smaller number of ap¬ 
pendages, presumably meaning 26 as against 32 inL. birchii; 
spines on the telson being of various dimensions compared 
with uniform spines in L. birchii; the straight dorsal edge of 
the carapace in Limnadiopsium, presumably in contrast to 
the convex edge in Limnadopsis, and the “spines” (= carinae) 
on the dorsal edge of the carapace being present in all stages 
of development in Limnadiopsium but only in the last stages 
in L. birchii. Detailed studies show that all these claims are 
spurious. The extent of development of the carinae varies 
between populations, so that on this character alone, some 
L. tatei and L. birchii populations would be excluded from 
both Limnadopsis and Limnadiopsium because of not having 
carinae even as adults. Also, some populations of L. tatei 
do not have a straight dorsal edge to the carapace, so would 
be excluded, and no female L. tatei has a carapace with a 
straight dorsal edge. As for the telsonic spines, while there 
is a contrast between L. tatei and L. birchii, other species 
show intermediate conditions. Finally, five other species of 
Limnadopsis have 26 trunk segments (25 in some specimens), 
and L. minuta has 24, so that on this character they should be 
aligned with L. tatei, not L. birchii. As shown above they are 
all otherwise distinct from L. tatei. In summary, L. tatei is 
not distinctive enough to warrant removal into its own genus 
Limnadiopsium, so Novojilov’s (1958) work is rejected. 
Biogeography. Two species of Limnadopsis (L. birchii 
and L. tatei ) are widespread in the drier parts of Australia, 
showing no consistent differences across this broad range. 
Eastern Australia is populated by just one local species, 
L. parvispinus but in the west and northwest there are five 
localized species with somewhat different latitudinal distri¬ 
butions (cf. anostracans in Western Australia: Timms, 2002, 
2008). Southern Western Australia has L. paradoxa, the 
mid north and northwest has L. occidentalis, the northwest 
has L. pilbarensis, and the far north has L. minuta and L. 
multilineata. The inland of Western Australia has L. birchii 
and L. tatei. Clouding this picture is the presence of isolated 
populations of the southern Western Australian species L. 
paradoxa in central South Australia and in western New 
South Wales; perhaps it is spreading to the east from its 
base in southern Western Australia. The higher diversity 
of Limnadopsis in the west is typical of many organisms 
of inland waters in Western Australia (e.g., charophytes, 
A. Garcia, pers. comm.; anostracans, Timms, 2002, 2004, 
2008; mytilicyprinid ostracods, Halse and McRae, 2004; 
many cladocerans, Hebert & Wilson 2000, R. Shiel, pers. 
comm.). Despite this diversity in Western Australia, no con¬ 
generic occurrences have been noted, unlike in the Paroo of 
the eastern inland, where L. birchii and L. parvispinus often 
co-occur (Timms & Richter, 2002). 
