Introduction Conchostracans are called clam shrimp because their body is completely enclosed within a somewhat transparent carapace that resembles the shape of clam valves. Mature specimens of the two Lyriceus species known to occur in Alberta obtain a length of almost 5 mm ( Plate 23.1 ). Cyzicus mexicanus, the other conchostracan of Alberta, can be much larger, mature specimens reaching a length of 15 mm ( Plate 23.1
). Lynceus is found throughout most of the province in vernal ponds; but occasionally L. brachyurus maintains a population into mid or late summer. Cyzicus is possibly restricted to the southern half of Alberta. Most clam shrimp, including Cyzicus, have claws (cercopods) at the end of the telson, but the telson of Lynceus does not bear claws.
Conchostracans feed mainly on minute organic material, especially detrital particles. Periodicity is similar to that of typical anostracans and notostracans. Females carry eggs between the carapace and the dorsum of the trunk. The fertilized egg hatches into a nauplius larva. See Mattox (1959) and Pennak (1978) for keys to all North American conchostracans. Martin and Belk (1988) have recently reviewed the Lynceidae.
Species List
- Family Cyzicidae
- Cyzicus mexicanus (Claus)
- Family Lynceidae
- Lynceus brachyurus Muller
- Lynceus mucronatus (Packard)
Some Taxa Not Reported From Alberta
As indicated in the CONCHOSTRACA pictorial key, members of Limnadiidae
(Limnadia and Eulimnadia) and Caenestheriella (Cyzicidae) have not been reported from Alberta, although Caenestheriella possibly occurs here. There are
also two genera with more southerly distributions that have not been reported
from Alberta. These are Leplestheria (Leptestheriidae) and Eocyzicus (Cyzicidae).
Survey of References
The following references pertain to clam shrimp of Alberta: Chengalath (1987),
Johansen (1921), Retallack (1975) and Retallack and Clifford (1980).
Pictorial Keys
Plates
Plate 23.1
Upper, let to right: Artemiopsis stephanssoni (Anostraca) [9 mm]—male and female, Artemiopsis franciscana (=salina) (Anostraca) [10 mm].
Middle, left to right: Cyzicus mexicanus (Conchostraca) [10 mm] [note: the posterior "spine" is the cercopod of the telson not a spine from the carapace], Lynceus sp. (Conchostraca) [4 mm].
Lower: Lepidurus couesii (Notostraca) [20 mm]
