Qu e k e tt J o wrnal of M icr o s cop y, 2Q 1,2, 4 7, 67 9 -69 4 679

An introduction to the branchiopod

PHILIP M. GREAVES

(Third Presidential Address delivered 15 May 2a12)

Summary For a full account of the , the reader is directed to the work of Dumont and The Branchiopods are a diverse and ancient class Negrea [2]. of crustaceans occurring in freshwaters, marine and (some genera) in hyper-saline environments. Classification They include the (or water fleas), fairy and brine , tadpole shrimps and The classification of the Branchiopoda has a clam shrimps. Morphologically heterogeneous, long and mixed history. The term Branchiopoda they are united by the structure of thoracic was established by Latreille in 1817. Three sub- limbs which have flattened structures associated orders were recognised by Sars tn 1867; the with respiration and swimming. An overview of Phyllopoda (the 'large' branchiopods), the class is provided, including both extant and Cladocera (the 'water fleas') and Apistodostraca extinct orders, together with notes on their (= Branchiura, no longer considered economic importance and the British fauna. Branchiopods). Sars later modified this scheme one that contains most of the extant Introduction lt"H:],r. The Branchiopods are an ancient and diverse Suborder Phyllocarida (now classified with class of the Crustacea characterised by flattened the Malacostracan crustaceans) and foliaceous thoracic appendages (thoracopods); these structures have Suborder Phyllopoda ^ (tadpole shrimps) respiratory (as well as other) function hence the - Conchostraca (clam or seed shrimps) name branchio- (breathing) poda (legs). The - (fairy shrimps) Class includes the Cladocera ('water fleas') and - the 'phyllopod' orders; tadpole shrimps, fairy Suborder Cladocera (water fleas) shrimps and clam shrimps, and has around 1,200 - Calyptomera living in 30 classes; a recent study has - determined that there may actually be over - Anompoda twice this number of species [1]. The majority of - Gymnomera species live in freshwaters varying from stagnant - ephemeral pools to lakes and weakly-running - Haplopoda. waters. A number of species occur in saline Revision the classification branchiopods waters, including inland hyper-saline lakes and of of continued throughout the late 19'h and 2O'h world . Most species are filter feeders, modern basis for although the tadpole shrimps are benthic centuries until the classification was developed Fryer 1982 who omnivores, several species are predators and by in [3], dispensed supra-ordinal hierarchic one, Ancbistropws emarginatws is an ectoparasite, with the levels and proposed eight extant and two feeding on the ectodermof Hydra. Many species orders: of the Cladocera are small to microscopic and are amongst the smallest crustaceans known Order Anostraca (Alonella nana for example, typically has an Order Lipostraca (extinct) adult body length of less than 0.2 mm) whilst Order Spinicaudata the 'phyllopod' species are macroscopic, and Order Laevicardata can grow up to 70 mm (e.g. cancriformis) Order or 100 mm in the case of the fairy Order Ctenopoda gigas. Order Onychopoda Order Haplopoda PHrrrp M. GnnevBs

Order Notostraca in . The majority are planktonic or Order Kazacharthra (extinct). benthic in freshwater , ranging from temporary puddles and ditches to continental Since Fryer's publication, further studies have lakes; other habitats include wet mosses on the been performed using DNA analysis e.g. for [4] floor of cloud forests and tree trunks. extant orders, and cladistics analysis for both Approximately 2a% of species are now known living and extinct orders. One of the most recent to occur in ground-waters (possibly retreating phylogenies is Olssen who performed by [5] there during adverse conditions) and a few cladistics analysis 19 living and 6 fossil on species are stygbiotic (cave-dwe11ing). However, species, scoring each against 80 morphological the 'typical' habitats for Cladocera are large, features. No doubt there wiil continue to be permanent lakes where all habitats are exploited minor revision phylogeny the to the of including the pelagic, the littoral, the benthos branchiopods but is generally accepted that it and water-p1ant zones. the la:ry shrimps (Anostraca) are afl ancient sister group to the other seven branchiopod Most species reproduce parthogenetically orders (Fig.1). most of the time. Embryo development begins and is usuaily completed in the brood chamber, The'Small' Branchiopod Orders a space between the body and the . Egg clutch size typically varies with the size of the The 'small' branchiopods comprise the species, from one or two eggs in the smallest of Cladocera - those loosely termed 'water species up to tens (or hundreds) of eggs in the fleas' and comprising the Anomopoda and largest of species. Live young are usualiy borne Ctenopoda, which are predominantly filter which have the same appearance as the adult. feeders, and two predatory orders, the Growth is by moulting. Under conditions of Onychopoda and Haplopoda. In size they vary environmental stress, such as reduction in the from approximately 0.2mm tn Alonella to 1.Amm availability of food, over-crowding, or reduction

Anostraca Lipostraca t

Notostraca Kazacharthra ?G o Laevicaudata q 0 tg F Spincaudata ? -() tl og. s - (! c ! L Gyclesthridia t - I o s E Anomopoda G & ! Lo o Ctenopoda () (,o LLTl(E o o onychopoda E I FO t! ? I s Haplopoda I .i5 tt (J Frc. 1 Current phylogeny of the Branchiopoda [after Olssen]. An introduction to the branchiopod crustaceans 681

in photoperiod, males are produced asexually families. Anomopods have a bivalve carap^ce which fertilise haploid eggs in the brood that protects the trunk and limbs of which there chamber. The diploid egg undergoes several ce1l are five or six pairs, of variable shape and size. division cycles after which development is The head is protected by a head-shield, which is arrested (diapause). These resting '.eggs' are usually well-developed (Fig.Z). In most resistant to freezrng and drying and are further circumstances, the Anomopoda are the most protected by an ephippial case, formed from a common order of cladocerans, and include the thickened part of the carapace. Most genera Dapbnia, Chydorws and . sink and attach to the substrate; those of tend to float where they may be Ctenopoda ingested by birds or as an aid to dispersal. Ephippia may survive for several years or The Ctenopoda (Fig.3) are distinct from the Anomopoda having head-shields decades; development of the embryo is in not and always stimulated by water, increasing day length and having six pairs of trunk limbs which are high concentrations. In the Haplopoda, similar in shape although the 6'h pair is reduced however, the eggs hatch into nauplius larvae, in size. There are only two families; the rather than the miniature adults seen in other with 50 described species in 8 genera and Cladocera. Holopediidae with one and two species.

Anomopoda Onychopoda

The Anomopoda is the largest Order within the The Onychopoda (Fig.4) are all predatory Cladocera characterised Branchiopoda, with about 560 species in 10 and are by a much- reduced carapace leaving the limbs uncovered and typically large heads of which the eye occupies the major portion. They are very

Frc. 3 Ctenopod cladoceran; Sid.a ctystalline \X/idespread but not particularly common; occurs in Frc. 2 Amonopod cladoceran; Simocepbalus aetulus larger lowland lakes, attached to the underside or stems Commonly found associated with vegetation. Grizedale of aquatic plants. Virginia 'Water, Surrey, UK. Body Forest, Cumbria, UK. Body length 1.6 mm. length 2.95 mm. 682 Pnrrrp M. Gnrevps

Frc.,l Onychophorna cladoceran; A predatorv member of the of largcr lakes. Coniston rVateq Cumbria, UK. Body length 2.4 mm excluding caudal spine.

Frc. 5 Haplopod cladoceran; Leptodora kindtii The most hyaline non- marine organism, found in larger lakes. Very rsvg i.,h. south and east. Coniston lffateq Cun-rbia, UK. Bod,v length 9.7 mm.

mobile animals, rapidly searching for, and in plankton collections it is only detectcd by the grasping, prey. There are three families and a water currents created by its swimming motion. total ol ll described species. The species is planktonic, usually restricted to larger lakes, although the author has found Haplopoda individuals in both the Liverpool and Manchester canals, and Rousselet reported the There is only one genus and species within the species as present on two occasions in the Haplopoda. Leptodora bindtii (Figure 5) differs Regent's Cana1, London 16]. from other 'water fleas' in having a very elongated body, an elongated head with a single The'Large' Branchiopod Orders large complex eye consisting of approximately 500 specialised, radially arranged ommatidia. The '1arge' branchiopods - fairy and brine Leptodora is predatory and is reputedly the shrimps, tadpole shrimps and clam or seed most hyaline (transparent) non-marine ; shrimps - occupy onlv waters where fish cannot An introdwction to tbe branchiopod crustaceans 683 survive (although there are reports of mitigated by large branchiopods in two ways. In co-existence of the tadpole shrimp Lepidwrus some species egg hatching when wetted is arcticus with fish in some deep Norwegian delayed, with hatching taking around 5 days iakes). This restricts the large branchiopods to whilst in other species the population of eggs temporary or vernal waters such as freshwater contains a distribution of individuais that rock pools, puddles and clay pans which are require several cycles of wetting and drying subject to cycles of flooding and drying and, in before the eggs hatch. two genera of fairy shrimps, to hyper-saline environments such as inland salt lakes. The The Tadpole Shrimps - Notostraca distribution of large branchiopods is therefore Tadpole (Fig.6), restricted to regions where these habitats occur; shrimps when present, are the although somc species occur in remperate largest and most easily recognised of the fauna countries species diversity is greatest in the of temporary ponds. The body is elongated with regions of and Vestern a large flattened head covered by a thick cuticle Australia. Species diversity is reduced in regions and a trunk of 24-44 rounded segments. The of regular or high rainfall. Environments subject eyes are paired at the front of the head, and an ocellus There to regular freezing can also support large is present. are about 15 species (except branchiopod populations; the author has found and distribution is world-wide ) Notostraca less than 600 miles from the North in fresh- and sometimes brackish Pole (in the Svalbard archipelago) and the clam temPorary waters. shrimp Ewlimnaddia in thermal pools in The tadpole shrimps have a fossil record Yellowstone, Vyoming. Large. branchiopods all extending back at |east220 million years. Mostly survive in temporary water bodies by laying disarticulated or telsons are found resistant eggs which can survive for several years (e.g. Fig.7) but well-preserved entire animals are in dry sediment; survival periods of 5 to 25 years sometimes uncovered (Fig.8). Morphologically have been recorded. Once rain arrives, the eggs some of these are very similar to the hatch, growth to sexual maturity is rapid and living genus Triops, which has consequently the life cycle completed with resting eggs laid been termed a '' (or relict) species before the water dries out. One problem with [e.g. 20]. F{owever, this has been discredited by such a life cycle is predicting if sufficient water Hegna [Z] who compared decay experiments on has flooded the to allow the life cycle to recentiy-deceased individuals with fosstl Triops be completed before the water dries. This risk is and by Vanschoenwinkel et al [8] who concluded

Fic. 6 Tadpole shrimp (Notostraca); A typical inhabitant of temporary waters. Raised from a commercial kit. Body length approx. 56 684 Purrrp M. Gne,{vns

Ftc.7 Fossil Notostracan furca , Victoria Land, Antarctica. Housed in the Natural Historl' Museum, London. Photograph by the authot copyright Natural History Museum. Approx. length of segments presenr 0.55 mm.

from genetic analysis that the living species of tadpole shrimp are the result of a relatively recent radiation in the Cenozoic era and that similarities to 'ancient' Notostracan fossils are as a result of the highly conserved morphology within this group.

The Fairy and Brine Shrimps - Anostraca Fairy shrimps are devoid of any form of carapace and have a distinct short head bearing stalked compound eyes, thoracic and abdominal regions with a total of 19 to 27 segments. The thoracic segments bear swimming legs which are used for filter-feeding whilst the abdominal region contains genitai segments and terminates in two terminal lobes termed cercopods. There are approximately 290 anostracan species of which the majority are restricted to freshwaters. However, the genera Artemia of worldwide occurrence (except Antarctica and Australia before its introduction) and , restricted to Australia (Figure 9) occur in saline and hyper-saline waters. Fairy shrimps have the unusual habit of swimming upside-down. This has been claimed Frc. 8 Fossil Notostfttca; Cbenops yixianensis by the evolutionist Richard Dawkins [9] to be a Early , , Hebei Provir"rce, recent adaptation and that, after tens of millions China. Housed at the Capitol Normal University, of years of evolution, anatomical features of the Beijing. Photograph by and copyright of Thomas A. fairy shrimp would have changed sufficiently to Hegna. Body lcngth approx. 45 n-rm. challenge our concepts of dorsal and ventral. An introduction to tbe brancbiopod crustaceans 685

Frc. 9 Fairy Shrimp (Anostraca); Parartemia contr/tctd (specimen kindly identified by Prof. Brian Timms, University of New South rilales, Australia). Saline lake approximately 3 km NE of Hyden, 'Western Australia. Body length approx. 11 mm.

This suggestion has been firmly rebutted by antennae which can be extended from the Fryer [10], who notes that fairy shrimps have carapace. There are around 225 species ofwhich been swimming in this way for at least 130 Laevicaudata (e.g Fig.10) and Spinicawdata are million years (from the fossil record) and 'typical' large branchiopods occurring in probably for all of the estimated 400 million temporary freshwaters and of worldwide years of existence of the order! distribution (except the polar regions). Cyclestberida, however, are generally smaller The Clam Shrimps - Laevicaudata, (around 3 mm) and occur in both temporary Spinicaudata and Cyclesthrida and permanent waters, often associated with vegetation and appear restricted to the equatorial The three orders of clam shrimps are typically and tropic regions. 2-L6 mm long and have iO- 32 pairs of thoracic legs enclosed in a carapace that wraps around Like the Notostraca, clam shrimps have an the entire body. They swim with the legs down extensive fossil record, extending at least to the or forward, and swimming is performed in the , although usually only carapaces same way as the Cladocera, using the second (and not whole animals) are found (Fig.11).

Frc. 10 (Laevicaud ata); Ewlimnadia spp. Thermal lake at Mary Bay, Yellowstone National Park, USA. Body length approx. 5.5 mm. 686 PHrrrp M. Gnnavns

Frc.11 Fossil clam shrimps, Eustbeia spp Coal measures, Cefn Coed Colliery, Breconshire, UK. Housed in the Natural History Museum, London. Photograph by the author, copyright Natural History Museum. Body length approx. 1.1 to 1.4 mm.

Extinct Orders - Lipostraca and Between 4A0 to 420 million years ago, the region Kazacharthra was geothermally active with hot springs and temporary pools where porous sinter rock was Lbostra.ca infused with silica, trapping communiries of plants and microscopic animals. The resulting The first fossil order to be recognised was chert is a semi-transparent rock, from which identified by Scourfield in chert from Rhynie, fossils of a branchiopod-like animal were Scotland 111, 121. Rhynie is a small village identified, similar to but distinct from the fairy approximately 5O miles north-wesr of Aberdeen. shrimps. Scourfield erected the Order

Frc. 12 Fossil Lipostraca;

L ep i d o c aris rlry ni e n s is Housed in the Natural History Museum, London. Photograph by the author, copyright Natural History Museum. Rhynie chert field, Rhynie, Scotland. Approx. length of segments present 0.45 mm. An introduction to tbe brancbiopod crustacedns 687

Frc. 1l Reconstruction of the extinct Lepidocaris rhyniensis (fron'r Scourfield, 1927), founci in the Rh,vnic chert fossil beds.

Lipostraca, and named the animal Lepidocaris (Fig.1a). Morphologically the Kazachrathra rhyniensis (Figs.12,13). Rescarch on thc Rhynie have many sirnilarities with the Notostraca and beds and nearby Vindyfield chert continues at are classified as a sister group. They arc however the University of Aberdeen and several nerv generallv much larger (carapace length up to 5 branchiopod and branchiopod-like crustaceans cm) and the carapace is uniquely shaped and have recently been identified. more sclerotized.

Kazacharthra Economic Aspects The order Kazacharthra is only known from Jurassic and fossils found in Kazakhstan, The economic impact of the branchiopods has Mongolia and parts of China. Currently about not been calculated, but is certainiy very high. 25 species in 7 genera have been identified, of Cladocera in particular serve as a n-rajor food which Almatium gusevi is the most comrion source for larval fish in both natural freshwater

Frc. 1'{ Fossil Kazacharthrai Almatium guset:i Latc Triassic, Xinjang lJygur Autonomous region, NlV China. Housed in the Zoological Muscum, lJnir.ersity of Copenhagcn. Photograph by and cop,r'right of Thomas A. Hegna. \Xlidth oi carapacc approx. 2.2 mm. PHrrrp M. Gnsavps environments and commercial farming of where rice is sown directly into the paddy, freshwater species. Cultivation of cladocerans, Triops can be a pest due to the same foraging especially Daphnia species (D. pulex and D. behaviour; Triops granarius was officially listed magna) for the aquarium and trade as a pest species in Swaziland for this reason. appears largely to be a 'back yard' industry and Triops nezaberryihas also been investigated as a the global value of this market has not been potential biological conrrol agent of immarure recorded. Some water utility companies actively mosquitoes [14]. manage fish stocks in drinking water reservoirs Artemia cysts, harvested to encourage large populations of Cladocera, either from wild stocks cultivated which control algal density by filter feeding; rhis or as part of solar sea-salt significantly reduces the filtration requirements production, are supplied in large quantities for of the water during treatment. use in fish and shrimp farming; the cysts are hatched and raised to nauplius or adult stage as As recently as 1989 tribes in the Fezzan feed. The largest source of supply has been the region of the Libyan Sahara have been recorded , at Salt Lake City, . This eattng Artemia which occur in shallow hyper-saline lake occupies an area of dense populations in the salt lakes of that region; approximately 1.,7a0 square miles, although the the tribes are called locally the Dawada, literally total area fluctuates annua11y. Only two meaning the 'worm earers'. It is also likely that arthorpods survive in the lake in any numbers; native Americans also practiced such dietary the brine flies Epbydra byans and E. cinerea and utilisation of brine shrimp although this does the brine shrimp (Figure not seem to have been documented. Brine 15). Harvesting of Artemia cysts, which float in shrimp are reported as having similar nutritional drifts on the lake's surface, is performed on an value to the larger Malacostracan shrimps. industrial scale, and is dghtly regulated by the Utah State Division of Vildlife who issue Triops species are economically important in harvesting permits and monitor cyst levels to the cultivation of rice. In Japan, where rice is prevent over-harvesting . The harvest season planted into paddy fields as youngplants,Triops extends from 1 October to 3 1 each year, have been used as a biological agent ro control January with spotter planes locating 'siicks' of cysts weed growrh [13]. They achieve this by which are then collected using oil containment disturbing the sediment surface whilst foraging booms. Whilst the harvest varies significantly or laying eggs, which uproors young weed each yea;r due to environmental factors, seedlings; the consequent increase in water significant quantities are extracred annually; the turbidity also cuts down light for weed 2008 2009 season harvested some 19,600,000 photosynthesis and the seedlings themseives - pounds of raw material. After processing (to may be eaten by the omnivorous Triops. remove waste material) the cysts are sold on to Conversely, in California and other regions

Frc. 15 The brine shrimp Artemia franciscana From the Great Salt Lake, Utah, USA, where it occurs in significant densities and is the basis for industrial- scale harvesting of cysts for frsh and farming. Body length approx. 9 mm. An introduction to tbe brancbiopod crustaceans 689 hatcheries for the fish farming industry. Prices is exceptionally rare in the fluctuate annually, with the 2008 price being UK. Brady [16] described the species as present reported as $11 per pound [15]. Due to variable in a pond on Bexby [?Bexley] Common and in yields from the Great Salt Lake, har-vesting Devonshire; Scourfield [17] writing just over 50 operations have been extended to other hyper- years later stated that the species has "not been saline lakes in Russia, Iran and . The total found apparently (in the UK) for more than half global market in processed Artermia cysts has a century" and questioned whether it should be been estimated at around 2,000 tonnes annually. included in any modern list of British species. Fortunately, for most of the second half of the 2O'h century, Triops cancriformis was known Fauna The British from one protected pond in the northern New The British Isles has a diverse fauna of 'small' Forest in Hampshire and the animal is protected branchiopods but a very impoverished 'large' under Schedule 5 of the Countryside and branchiopod fauna. Surprisingln the group has \Tildlife Act (1981). It was therefore ^ great not been considered as a whole since Brady's surprise when a second population was work of 1850; publications since then have discovered at the Caeriaverrock Wildfowl and focused almost exclusively on the freshwater Wetland Trust in Scotland in 2A04. Two 'cladocera'. Brady [16] listed 3O species of additional populations have since been Cladocera (including one marine) and 2 large discovered at the same location and funding has branchiopods. Scourfield in i903 and 1905 [6, recently been secured to undertake a 3 year 17) listed 83 species (including large search for other UK populations [21]. branchiopods exclusively freshwater but A third large branchiopod species also species); next major work was by Scourfield the occurred in the UK, but is now considered freshwater cladocerans and Harding, listing 89 extinct. The brine shrimp was their most recent edition Recent work in [18]. first described by Schlosser in 1,756 from salt to by the Cladocera Interest Group [19] pans in the salterns at Lymington, Hampshire. records has resulted in a total of 94 consolidate At that time, Lymington was the main producer freshwater ciadoceran species 50 genera; in of sea sait in the UK; the industry possibly dated combined with records for marine cladocerans back to Roman times. Sea water was run into large species present and the two branchiopod large lagoons and allowed to partially evaporate 97 in the UK results in a total of species [20]. It before the brine boiled in metal pans until the as genetic is highly likely this list will expand, moisture was evaporated. Brine shrimp were analysis reveals that some currently recognised still present when Brady wrote his monograph complex. species are, in fact, species for the Ray Society in 1850 but disappeared The number and diversity of cladoceran when the sea salt industry collapsed due to species is perhaps surprising, with all four competition from cheaper rock salt. Some of the Orders represented and nearly one sixth of all saltern works at Lymington are still visible but currently known species present. Unlike many the brine shrimps have gone. As other groups, species diversity of the cladocerans populations of Artemia have been allocated to increases away from the tropics, and peaks in other species, Fryer [10] considers Artemia the temperate zones [1]. salina now to be effectively extinct in the wild, with the possible exception of one population in Only two species of large branchiopods are Sardinia. now present in the UK; the fairy shrimp Cbirocepbalws diaphanows and the tadpole Acknowledgements shrimp Triops cancriformis. Clam shrimps are not represented in the UK fauna. Chirocepbalus I am indebted to Claire Mellish, Natural History diaphanous is found in temporary puddles and Museum, London for enabling access to the wheel tracks and appears randomly distributed Museum's fossil branchiopod collections and in the south and east of the country usually for permission to publish photographs; to Bram appearing in late summer afrcr heavy rain. The Vanschoenwinkel of the Universiteit Leuven for most reliable locations for this species are the assistance with references; to Thomas Hegna of New Forest in Hampshire and Salisbury Plain Western Illinois University for assistance with in Wiltshire. references and for provision of Figures [8] and An introdwction to the branchiopod crustaceans 691

A Checklist of the British Branchiopod Crustaceans

THE CLADOCERA INTEREST GROUP

The branchiopods are a well-known class of crustaceans occupying predominantly freshwater environments but also with some marine species. Despite there being an extensive history and literature associated with their study in the British Isles, there has not been a published checklist of the entire British fauna (marine and freshwater) since Brady's monograph of 1850 [1]. Previous checklists for the 'cladoceran' crustaceans have focused on the freshwater species and themselves have not been updated since 1966 [2]. This current checklist has been compiled by the Cladocera Interest Group [3], supplemented with published records of the 'large' branchiopod species and marine cladocerans. It is published here to place on record the current state of knowledge of the British fauna and in the hope that it will encourage further work on the distribution of these animals.

Superorder Sarsostraca Order Anostraca Family Ch iro ceph alus diap b anws Pr6vost 1803

Superorder Calmanostraca Order Notostraca Family Triopodae Triops Triops cancriformis (Bosc,1801)

Superorder Leptodorida Order Haplopoda Family Leptodoridae Leptodora Leptodora bindti (Focke, 1844)

Superorder Cladocera Order Ctenopoda Famiiy Sididae

Diaphanosoma D iap b ano s oma brachy wrwm (Lieven,1848)

Latona Latona setifera (Mriller, 1785)

Sida crystallina (Miller,1776)

Family Holopedidae Zaddach,1855

Order Anomopoda Family Richard,1894 C erio dapb nia laticawdata Mriller, 1862 Ceriodapbnia megops Sars, 1862 C erio daph nia p wlch e lla Sars, 1862 C erio daph nia quadrangula (Miiller, 1785) C erio daph nia quadrangwla f . hamate (Sars) C erio dap b nia r eticwlata (furine,1820) Ceriodapbnia setosa Matile, 1890 692 PHrrrp M. Gnnevps

Daphnia Daphnia ambigua Scourfield,1946 Dapbnia atkinsoni Baird, 1859 Dapbnia cucullata Sars, 1862 Daphnia cwroirostris Eylmann, 1887 Sars, 1864 Daphnia hyalina Leydig, 1860 Miiller, 1785 Dapbnia Tnagna Straus, 1 820 Daphnia obtwse Kurz, L874 Daphnia parvula Fordyce,1901 Dapbnia pulex (DeGeer,1,778) Dapbnia rosea Sars,1862

Megafenestra Megafenestra aurita (Fischer,1849)

Scapholeberis S cap h ole b eris mucronata (Miillea 178s)

Simocephalus Simocephalus exspinosus (Koch,1841)

S i m ocep h a I u s serru I a I u s (Koch,1841) Simocephalws vetulus (Mnller,1776)

Family Moina brachiata (furine,1820) Moina macrocopa (Straus,1820) Moina micrwra K,arz, 1,874

Family Bosmina Bosmina coregoni Baird, 1857 (MtilleE 1285) Bosmina longirostris var. cornuta (|urine) Bosmina longispina Leydig, 1860

Family

Ilyocryptus I ly o cryptus acwtifrons Sars, 1 862 Ilyocryptws agilis Kurz, L878 Ilyocryptws sordidws (Lieven,1848)

Family Eurycercus Eurycercus glacialis Lilljeborg,1887 Ewrycercws lamellatus (Miiller, 1285)

Family Acroperus harpae (Baird, 1835) Acroperws angustatus Sars,1 863

Alona ffinis (Leydig, 1860) Alona costata Sars, 1 862 Alona elegans Ktrz, 1.874 Alona guttata Sars, 1862 Alona intermedia Sars,1862 Alona karelica Stenroos,1897 Alona quad.rangwlaris (Mrillea 1785) Alona rwstica Scott, 1 895 Alona wehneri Keilhack, 1905 An introdwction to the branchiopod crustaceans 693

Alonella Alonella excisa (Fischer,1854) Alonella exigwa (Lilljeborg, 1853) Alonella nana (Baird, 1843)

Alonopsis Alonopsis elongata Sars, 1 862

Anchistropus Anch istrop us emar ginatws Sars, 1 862

Camptocercus Ca mpt ocercu s lillj eb orgi Schoedler,1862 Ca mpt ocercu s rect iros I ris Schoedler,1852

Chydorus Chydorus gibbws Sars,189O Chydorws latws Sars, 1862 Chydorus ovalis Kurz, 1874 Chydorws spbaericws (Miillea 178s)

Coronatella C oronatella re ctangula (Sars,1862)

Disparalona Disparalona rostrata (Koch,1841)

Dunhevedia Dunhepedia crassa King, 1853

Graptoleberis C rap t o I e b eris t est u d inaria (Fischea 1848)

Kurzia Kurzia latissima (Kur2,1,874)

Leydigia Ley digia acanth o cercoide s (Fischer,1854)

Ley digia ley digi (Schoedler, 1 862)

Monospilus Monospilws dispar Sars, 1 862

Oxyurella Oxywrella tenuicaudis (Sars,1862)

Paralona Paralona pigra (Sars,1 862)

Phreatalona Phreatalona protzi (Hartwig,1900)

Pleuroxus Plewroxus adwncws (iurine,1820) Ple wrox ws denticwlatus Birge,1829 Pleuroxus laer:is Sars, 1 862 Pleuroxus trigonellws (Miiller, 1285) Plewroxws truncates (Mnllea 178s) Pleuroxus wncinatws Baird,185o

Pseudochydorus P se udo ch y dorus glob o s us (Baird,1843)

Rhynchotalona Rhynchotalona falcata (Sars,1862)

Tretocephala Tretocepbala ambigua (Lilljeborg, 1900)

Family Ophyroxidae Ophryoxus Ophryoxus gracilis Sars, 1861 694 PHrr-rp M. Gnenvns

Family Acantholeberidae Acantholeberis Acanth o le b eris c wrv iro stris (Mnller,1,776)

Family Drepanothrix Drepanothrix dentata (Euren,1861)

Lathonura Latb onura re ctirostris (Miiller, 1785)

Macrothrix M acro t h rix h irsuticornis Norman &.Brady, 1.867 Macrothrix laticornis (|urine,1 820) Macrothrix rosea (Jurine,1 820)

Streblocerus S tr e b lo c er u s s erricawdatws (Fischea1849)

Order Onychopoda Family Polyphemidae Polyphemws pedicwlws Linnaeus, 1261

Family Eotadne nordmanni Lov6n, 1836 Pleopsis P le op sis p o lypb emoide s (Leuckart, 1859) Podon intermediws Liljeborg,1853 Podon lweckartii Sars, 1 862

Family Cercopagidae Bythotrephes Bytb otreph e s longimanws Leydig, 1860

References

1 . Baird, \f. 1850. The Natural History of the British Entomostraca. The Ray Socieqz, London. 2. Scourfield, D. J. and Harding. J. P. 1,966. A Key to the British Species of Freshwater Cladocera. Scientific Publication No. 5, 3'd Edition, Freshwater Biological Association, Ambleside. 3. CladoceralnterestGroup:http://www.cladocera.org.uk