Family Sididae

Diaphanosoma birgei Korinek, 1981

Work by Korinek (1981) shows that based on its original description, European specimens of Diaphanosoma leuchtenbergianum Fisher are synonymous with Diaphanosoma brachyurum. North American specimens reported as D. leuchtenbergianum differ significantly in morphology from European specimens, and are now considered a separate species, Diaphanosoma birgei. European populations of D. birgei have slight differences in marginal spinulation and have been given subspecific status, D. birgei ssp lacustris Korinek. Predominantly limnetic, D. birgei is common throughout Canada, the United States and South America.

D. birgei was collected from 11 lakes south of the Thompson River, in the summer and fall months. Specimens were collected from the limnetic zone, with the exception of one benthic sample from Green Lake. Depths ranged from 45 m to surface. A water temperature of 14° C and conductivity of 625 mS/cm were recorded at Shuswap Lake, Salmon Arm. Reported from acidified lakes and swamps with pH between 4.2 and 7.0 (Anderson et al., 1977; Sprules, 1975), D. birgei tends to be acid sensitive below pH 4.5 (Havens & Decosta, 1987; Havens et al., 1993). Although found in saline lakes, mortality rates increase at salinities greater than 6 ‰ (Galat and Robinson, 1983). Observations of D. birgei by Threlkeld (1986) showed positive responses to increased suspended sediment environments.

D. birgei is distinguished from D. brachyurum by characteristics of the head and second antennae: the compound eye is located within a pronounced supraocular expansion along the midventral margin of the head; the second antennae, when reflexed, surpass the posterior margin of the valves, and the spine located at the end of the first exopodial segment extends beyond the tip of the segment.

Collection localities: Osoyoos Lake 993-95-2; Tugulnuit Lake 983-1146-1; Green Lake 983-479-1; Smelter Lakes 983-1046-1; Chain Lake 983-55-3,983-166-3,983-167-2,983-168-4; Link Lake 983-672-2; Okanagan Lake 994-79-1,994-81-1,994-86-1; Nicola Lake 983-816-1,983-817-1,983-821-6,983-822-3,983-826-1,983-828-2,983-830-3,983-836-3; Bleeker Lake 984-738-2,984-739-2; Shumway Lake 983-1019-1,983-1020-2; Shuswap Lake 994-149-2.

Diaphanosoma brachyurum (Lieven, 1848)

European specimens of D. brachyurum are synonymous with Diaphanosoma leuchtenbergianum. However, in North America two species of Diaphanosoma exist. North American specimens reported as D. leuchtenbergianum differ in morphology from D. brachyurum, and have been given full specific status, Diaphanosoma birgei.

Collected primarily from the littoral regions, D. brachyurum was recorded from five lakes and two ponds located in the central and western regions of the study area. No specimens of D. brachyurum were recorded from the south eastern region of the study area. Collections were made at depths of nine metres to the surface. Water temperatures were 15° C in May, rose to 26° C in July and dropped to 19° C in September. Conductivity was less than 350 mS/cm at most locations except for one pond west of Kalamalka Lake with a conductivity of 5000 mS/cm and salinity of 3 ‰. pH ranged 7.5 to 8.8. Substrate varied from mud to gravel.

This littoral species is widely distributed in Canada south to South America, and Europe, from northern Spain eastward to Asia (Balcer et al., 1984; Jaume, 1991). It is absent from alpine lakes (Anderson, 1971; Jaume, 1991). Preferring warmer waters it is most common in epilimnetic waters during the summer months (Balcer et al., 1984; Brandlova et al., 1972).

Characteristics of the head and second antennae separate D. brachyurum from D. birgei: the enlarged compound eye is located along the anterior margin of the head; the second antennae, when reflexed, do not reach the posterior margin of the valves, and the spine at the end of the first exopodial segment is reduced, not reaching the end of the segment.

Collection Localities: pond N of Blue Lake 994-142-8; pond W of Kalamalka Lake 994-201-3; Mara Lake 995-95-5; Caribou Lake 983-255-6; Sawmill Lake 983-1002-1; Thuya Lake 994-228-12; Star Lake 994-229-4,994-230-7,994-232-4.

Latona setifera (O.F. Muller, 1785)

This uncommon species was collected from the nearshore waters of Little White Lake and Thuya Lake during the summer months. Conductivity was low at 25 to 50 mS/cm. Water temperatures measured 17.5° C and 21° C. L. setifera was recorded at pH 7.6 from Thuya Lake, and previously from pH 5.9 to 8.2 (Anderson, 1974; Sprules, 1975).

Occurring in lakes, ponds and swamps of North America and Europe, L. setifera is a benthic species restricted to shallow nearshore waters (Hutchinson, 1967). Locomotion, produced solely by strong antennal strokes, is often followed by prolonged periods of resting on the bottom (Korovchinsky, 1991).

L. setifera is the only representative of the family Sididae with a lateral expansion of the first segment of the dorsal ramus of the second antennae.

Collection Localities: Little White Lake 994-148-9; Thuya Lake 994-228-5.

Sida crystallina (O.F. Muller, 1875)

S. crystallina was recorded from 11 lakes throughout the study area. Specimens were collected at a maximum depth of two metres, from both the limnetic and littoral zones. Substrates were mud with a mixture of sand, gravel and organic debris. Water temperature varied from 14° C to 23° C, with a pH of 6 and 7 recorded at two locations. Berzins and Bertilsson (1990) document the occurrence of S. crystallina between pH 5.8 and 9.4 in Swedish lakes. Conductivity ranged 70 to 625 mS/cm. Generally more abundant in softwater lakes, this species has been reported from lakes with total hardness levels as high as 200 ppm (Anderson, 1974; Carter et al., 1980).

Occurring within lakes and ponds of North America and Europe, S. crystallina is the only known species of the genus Sida. Predominantly littoral, it can occur in open water plankton samples (Brandlova et al., 1972). In inshore waters, it is usually attached to aquatic vegetation but swims well if disturbed (Fairchild, 1981; Korovchinski, 1991).

The largest species of the family Sididae, S. crystallina is characterized by a three segmented dorsal ramus of the second antennae.

Collection Locations: Mara Lake 995-95-3; Shuswap Lake 976-1204-5,994-150-4,994-151-3; Kamloops Lake 992-65-4; Okanagan Lake 991-991-9; Nicola Lake 983-830-2; Mamit Lake 992-70-3; East Barriere Lake 994-219-3; Coquihalla Lakes 995-67-6; Dutch Lake 994-233-4; Burn Lake 994-171-1.

Cladocerans of the Thompson-Okanagan Region  
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