Water fleas

Code OG019999

SIDIIDAE: A family of the Cladocera (water fleas). This family is characterised by six pairs of trunk appendages, all but the last being foliacious. However, this character is hidden by the carapace and cannot readily be seen without dissection.

External identifying features include a large head, feathery antennae, and setae along all or part of the valve margin. The 'face' is concave with the anteroventral part protruding as a rostrum (as also in most Daphniidae), or else it is rounded (as in Moinidae, Illocryptidae, and Macrothricidae). The posteroventral corner of the carapace is not developed as a spine (a spine occurs in many rostrate Daphniidae, also in Bosminidae). The antennae are large and are not retractable into the carapace (in Chydoridae they are small, partially hidden by the rostrum, and retractable). On the postabdomen, the furcal claw is long and curved, with three small spines at its base.

Rostrate Sidiidae can be distinguished from most Daphniidae by lack of a posteroventral spine, and from the remaining Daphniidae (in all of which the rostrum is very small) by the relatively well-developed rostrum. Non-rostrate Sidiidae can be distinguished from other non-rostrate cladocerans by the unique postabdomen and furcal claw.

Sidiidae of both the rostrate and non-rostrate type are distinguished from Bosmiidae by the overall shape of the head together with lack of a posteroventral spine, and from the Chydoridae by head and body shape together with having large, well-developed antennae.

References:

Korovchinsky, N.M. (1992) The Sidiidae and Holopediidae (Crustacea: Daphniiformes). Guides to the Identification of the Microinvertebrates of the Continental Waters of the World. 3: 1-82. SPB Academic Publishers, The Hague.

Shiel, R.J. (1995) A Guide to Identification of Rotifers, Cladocerans and Copepods from Australian Inland Waters. Co-operative Research Centre for Freshwater Ecology Identification Guide No. 3., Albury, NSW.

Smirnov, N.N. and Timms, B.V. (1983) Revision of the Australian Cladocera (Crustacea). Records of the Australian Museum Supplement1: 1-132.