Bollettino Della Societnpaleontologic a Itatiana

Bollettino della SocietnPaleontologic a Itatiana

Pubblicatosotto gli auspici del ConsiglioNazionale delle Ricerche

Volume43rr. 1-2r2004

Proceedingof the r, MEETINGOF THE ITALIAIVOSTPACODOL( ,,IA{MEMORY OF GIULIAI{O RUGG Rimini,February I 2-I 4, 2003

Editors: Elsa Gliozzr Antonio Russo

MUCCHI MODENA Bollenino della Societi Paleontologica ltaliana 43 (r-2),2004rssN0375-7633 297-306 2 pls. Modena, Novembre 2004

First British record of Potamoryprishumilis (Sars, ostracod with a,disjunct distribution in Europe a

David J. HonNe RobinJ. SulrH Dept of Geography Departmentof Earth Sciences Queen M"ry Universiryof London, UK KanazawaUniversiry Japan

KEY WORDS - Osnacoda,Freshwaten Britain, Europe,South Africa.

ABSTRACT - Thefeshwater ostracodCyprilla humilis SArs,1924 wasfrst describedfro* fow'Brady, other species ofcqirilla Sars,1924, a genussubsequently considered by otberauthors to be, 1870. It wasargred that Cyprilla himilis at a iingle--transportedlocality 9ry thi southerncoast of Fint perhaps'ago originati"g fo* a singlepirthenogenetic female, fom soutlternAfrica "localitj by mt ind otferu,intTr"in the Cafiehrouince."subse{uent records fom tfi, ,o*, Finnish anc that it wasa long-termresideit that had simply beenouerlooked. Our discoueryof a popuhtion in of Scotlandproiides thefrst British record'oitdan opportunityfor further desiripiiin and illus iharacteristicsinclude: long swimmingsetae on the aniinnae; adult carapacewith a sharplytrunct 'prominentpined ornAment; prominint anterioi and posterouentralmarginal fknges in the adu'lt-lefi uar tubercfeswhich are com?letetyobttnt in adults. Noie of ihesicharacteristicsis cinsider a separategenus or subgenus,hoitrtr.' W, considerpossible expknations for its dirjunct distri ostracodsby birds.

RIASSUNTO- fPrimo ritrovamento^-per la Gran Bretagnadi Potamocyprishumilzs (Sars zione disgiunta in Europa e Sud Africa] L'ostrAcofud'aciua dolceCypiilla humilis Sars, Afica, insiemead alne tptiit di Sars,1924, un gen( Prouincia"delcapo .in Sui .qultno ,Cyprilii sottogenere,o un stnonrmoJunion di PotamocypriJBrady,' 1870. E iin ipotiz,zatoche il itroo detti costameridionale deik Finhndia potesserappreseriart una popolazionedi recenteinsediar 'Successiuipartenogenetica trasportata dal Sud Africa da tttine migranici ili n;difcaryo nellArcipekgo..!"all'i, ritrouaminti nella stessatoiatiti fnhndes, tf in un'abra uicina hanno porioto insediateda lungo tempoe semplicementenon ancorasegnakte. Il nostroritrouamtrto di una po, lnrgo deth costi occidintaled;lla Scoziacostituisce la /rima segnahzioneper h Gran Bretagni mirfologichee per lo studio dell'ontogenesi-bruscamentedi questa spicie. I caranerisalieiti sono:lunghe sete na degi; ad.uhi con margineposteriore troncato e fortementeornAmentato con cauiti; aiteriore e posterouentrale;larue con carapaceprouuisto di euidenti tubercoli, completamentc caratteristicfiei tunauia consideratasfficiente per mantenereCyprilla comegenere o sottogeneres questadistribuzione disgiunta e uienediscussa la dispersionedi osnacodiad operadi uccelli.

INTRODUCTION tic of the other four speciesof Cyprilln described by Sars, this might be a valid reason to separateit from In the summers of 1945 and 1947, while basedat Potamorypris.Considering the occurrence of this spe- the Tvirminn e Zoological Station in the Gulf of Fin- cies so far outside its African distributional area,Puras- land, K.J. Purasjoki undertook a survey of ostracods joki (1948) proposed that his Tvdrminne population in rock pools on some of the many islandsin the area. must have been transported directly to Finland by In rain-fed pools on a small, baie rock island called migratory birds, citing Common and fuctic terns, both Storshundsharenhe found a specieswhich he assigned of which migrate by coastal routes, winteritg in the to Potamocypris,noting that it differed from other southern hemisphere and nesting in the Tvirminne Europe3 speciesof thE genus in details of its shell. archipelago.The specieswas subsequentlyfound again Purasjoki sent some specimensto the German ostra- in the Tvirminne area by Hagerman (1967) on Stor- cod specialistWalter Klie who identified it as Cyprilla shundsharen and also on a second island, Spikarna; humilis, a speciesdescribed by Sars (1924) from the recordi.g it as Potamocypris (Cyprilla) humilis (Sars) Cape Province of South Africa and not previously re- he expressedreservations about the idea of transport corded in Europe (Purasjoki, 1948). Noting that Klie by birds from Africa, suggesting that the possibiliry (pers. comm. to Purasjoki) considered Cyprilk to be, that it was native to the Gulf of Finland should not at most, a subgenus of Potamocypris,Purasjoki drew be overlooked. Here we report on the first recorded attention to the distinctive ornament of the juvenile occurrence of Cyprilla humilis Sars, 1924 in the Brit- stages (which exhibit pointed tubercles not seen in ish Isles,taking the opportuniry to supplement its de- the adult) and suggestedthat, if this was a characteris- scription (with particular attention to the ontogenetic 298 D.T,HORNE, RJ, SMITH

Text-fig. I Aooendasesof Potarnocynrishurnilis, adult femalesfrom Harris,Scodand (BMNH nos).l) anr ;664.i28i;;ir;; ;fflte five long srvimmingsetae is shownat full lengrh);f) magdiF"!* : .o*", 2004.426;i ma:rillularendotodite and Endites, 2004.427;6) ma:rillular branchial.plate t[[p64; zoo+.+lri sl detailof endbpodite(p"lp) of fifth limb, 2004.430,rotated 90'relitive pm). FIRSTBMTISH RECORDOF POTAMOCYPRISHUMILIS 299 development of its valve ornamentation), review its fHE GENUSCYPRILLA SARS, 1924 generic assignment and consider explanations for its bi-hemisphericaldistribution. Sars (1924) described the new genus Cyprilla on the basis of five new species,all obtained from sam- MATERI-ALAND METHODS ples, or raised from dried mud, collected at localities in the Cape Province of South Africa: C. arcuata, C. on 8'h 2002, C. deflexa, C. humilis and C. producta. Cyprll- Our specimens were collected'West J,rly gibbuh, from a rock pool on the coast of Harris in the la arcuata, being the first to be described, may be Outer Hebrides, about 300 m South of a small head- regarded as the rype speciesalthough it was nqt desig- land called Rubha Romaigidh and immediately South nited as such by Sars. Cyprilln may be considered to of a small rocky b"y called Gebdha Martainn (lat. 57" be a valid genus (e.g. Sars, 1924; McKenzie, I97la, 5I' 20" N, long. 60 59' 59" \tr; British Nationd Grid 1977; Ghetti 6( McKenzie, 1981), or it may be re- reference: NG 03496I). Ostracods were collected by garded as subgenus(e.g. Hagerman, 1967) or a junior sweepinga hand-held sieve(7 5 pm mesh size)through synonym of PotamocyprisBrady (e.g. Gauthier, 1939a, the watel and the sediment on the bottom of the pool; b; Meisch, 1985); Martens et al. (1996), assigninga the animals thus obtained were kept alive in a screw- South African speciesto Cyprilla humilis (Sars, 1924), topped jar, filled with water from the pool, until the noted all three possibilities.Sars (1924) commented evening of the same d^y, when they were examined on the similariry of Cyprilla rc Potamocypris,consider- under a binocular microscope before being extracted i^g the rwo genera to differ in the general appearance with a pipette; specimenswere then preservedin eth- of the shell and its ornament as well as in the valve anol (approximately 70%) fot future study. T!. pool, overlap relationships.His generic description of Cyp- measuring approximately 2 x I m at the surface and rilk draws attention to the fact that the right valve is 0.1 m deep, is on bare rock (Lewisiangneiss), xD esti- generally higher than the left, overlapping it along mated 3-5 m above extreme high water mark (judging much of the dorsal margin, while the left valve overlaps by the intertidal algae and supratidal lichens at the the right anteriorly and posteroventrally(by virtue of site) and at the foot of a gende grassyslope extenditg the left valve'sprominent marginal flanges).Another up to the road. It contained dark brown mud (pt.- characterthat may be of genericsignificance, not men- dominantly fine organic detritus) and loose stoneson tioned by Sars (1924), but described and illustrated the bottom but no algae or aquatic plants; the mar- by Purasjoki (1948), is the occurrenceof prominent gins were a mixture of bare rock and patchesof grass. tubercles on the valves "f juvenile instars (A- I and A- At the time of sampling (mid-afternoon) the water 2) in C. humilis from Finland. In our material from temperature was 19'C. On the d^y of our collection Scotland we have identifi.d juveniles back to the A-5 the water in the pool was fresh; however, although stage;the A-5 to A- 1 instars all bear tubercles (Pl. 2) t protected to some extent by the island of Taransay to includirg e rather swollen one in the anterodorsal the Northwest and the headland of Gob an Tobha to (post-ocular)region and a particularly prominent pos- the Southwest, the rocky coast at Rubha Romaigidh terodorsal group which appear to be enlarged pore is exposed to Atlantic swell approaching from due conuli, but there is no trace of tuberclesin adults (Pl. 'West, and it is therefore probable that the introduction I ), which bear only the finely reticulate/pitted orna- to the pool of salt spray from breaking waves is a ment seen in all the instars. Purasjoki (1948), men- fairly frequent occurrence. The pool appeared to be tioning Gauthier's (1934) doubts about the validiry of fed partly by rain and partly by seepage from the grassy Cyprilla, stated that Klie (pers. comm. to Purasjoki) slope above it; the possibility that it dries out cohsideredit to be at most a subgenusof Potamoryp- occasionallycannot be ruled out but the fact that it ris. However, noting that tuberculate juveniles are not was full in summer (J"ly) suggeststhat drying is known in any speciesof Potamocypris,Purasjoki sug- infrequent. gestedthat if they could be shown to be characteristic Associated ostracod taxa were lbotyPris bradyi Sars, of other speciesof Cyprilh then there would be a good 1890 and Cypria ophtalmica (Jurine, 1820), both of case for keeping the rwo genera separate.Gauthier which are common in the British Isles;a similar, slight- (1939a, b) later concluded that Cyprilla should be syn- ly larger pool at the same localiry was also sampled onymised with Potamocypris.Hagerman (1967) con- but yielded only Cypria ophtalmica. sidered Cyprilln to be a subgenusof Potamocypris,prob- South African specimens were provided by Koen ably followitg the opinion of Klie as cited by Purasjo- Martens (Royal Belgian Institute of Natural Sciences, ki. Meisch (1985) assignedC. humilis rc Potamorypris, Brussels)who has collected P humilis at severallocali- considering it to have the diagnostic features of the ties in the Cape Province; the specimens illustrated latter genus: the ventral overlap of the right valve over herein are from near Blinkvlei, Van Rhynsdorp (sam- the left, the anterior and posterior flanges of the left ple no. RSA/011004),lat. 31"43' 55" S, long. 18' 55' valve, and the spatula-like distal podomere of the max- 3I" E, collectedon 7'h September200I. illular palp (seeText-fig. 1). He noted, nevertheless, "somewhat Illustrated specimens have been deposited in the that it was set apart in the genus" (Meisch, Natural History Museum, London (BMNH nos). 1985; p. 74) by the carapaceshape with its nearly 300 D.l. HORNE, R.J.SMITH straight dorsd margin and especially by. ,h1 tubercu- in the field and under ^ low-power binocular micro- late brttament of ihe iuveniles. Recently George 6( scope later the same da, to be active swimmers. (2002) have described a new speciesof Pota- The question of the-significance of the tuberculate Martens '.'Cn- juveniles, however, remiins unresolved. Purasjoki mocyprisfrom India, which they assigned!o the '(1948) and suggestedthat if this character were demon- rilla" group becauseof its prominent'We anterior Pos- terior-flanges in the left valve. concur with their strated in 6-ther Cyprilk spP. juveniles, it would pro- argument ihat the characteristic cited by plevious au- vide a good reason to maintain Cyprilk as..aseParate th6rs in support of the generic or subgeneric status of genus.\7e have been unable to find any indication, in Cyprilla (pidminence ofleft valve flan-ges)ditrers only- ih. available literature, of the Presenceor absenceof in'degree from the left valve margin characteristics of such ornalnent in the juveniles of the other four sPe- all Pitamocypris species. IntermedJate forms exist; the cies assigned rc^Cypriik by Sars (1924), of, for that European Potamicypris unicaudata Sch?ifer, 1943, for maffer, in any Po.iimorypris species.Such ornament is (it is seen .*"-p1., has a left valve in which the selvage is P:- not uncommon ln cypiiaoidean ostracods in adults and juveniles of mayy lbocyPris species,fot ripheial anteriorly (so that there. is .no. flang9, &s in many Potamorypris) but posteriorly displaced inwards example), but the total loss of prominent tubercles in ftal moult appears to be uhusual, althougt it has resulting"of in a- prominent^right flange which overlaps ,tt. the margin the valve (as-in Cypr/k) (M.isgh, been reported in- other taxa, for example in llXoryPrh 2006). Remarkin[ on other variable characters (in- bradyiSars, 1890 (Scharf,1981; Meisch,2000). cluding long or short swimmitg-of setae on the antennae, "id thE number and form setae on the distal SYSTEMATICS marillul^ry palp segment) George 6c Martens (2002) concluded th"f Cylrilk is potentially a pqlyphyletic Order PooocoPIDA Sars, 1866 to(on which should not be used as a formal genus or Suborder CwruoocoPINRJones, 1901 subgenus. In accordancewith this opinion we assign Superfamily CvpruooIDEABaird, 1845 humilis to Potamoqtpris. Family CvpruoIDAEBaird, L845 There are two groups of Potamorypris, one com- Subfamily CwRIDoPSINAEKaufmann, 1900 -tennae,prising species with- short swimmitg sEtaeon the an- ihe other group having lgtg swimmi."g.setae PornvocYPRISHUMILIs (Sars, 1924) -8; (Meisch, 1984, l9B 5); P humilis belongs to the latter Pl. l, figt I-14; Pl. 2, figt I Text-figs l-2 group (seeText-fig. I ). In our collection from Harris, Soth-adults and juveniles were observed (by hand lens Typt material - Sars Collection, Zoological Muse-

# 50 pm

- Scotland,BMI Texr-fig.2 Appendagesof -Potqmocyprishumilis, adult femalefrom Harris, 2i se'"enittti-b (cleaningleg); 3) furca;4) genitalhook; all x460 (scalebar = 50 pm). FIRSTBRITISH RECORD OF POTAMOCYPRISHUMILIS 301 urrr, Oslo, Norway, slide no. F10922, Mp464 (4 syn- are lesselongate, have a more sharply truncated poste- rypes); South African Museum spirit tube no. S.A.M. rior margin,-and have narrower marg_inalflanges than Al 1306 (2 poorly preserved synrypes); no holorype either the Scottish or the South African specimens. designated.This rype material was examined by M:t_t.h The Scottish specimensare, in turn, slightly lesselon- ( 1995) who did not consider it necessaryto establish gate and slightly more tapered posteriorly, in lateral have a lectorype. ii.*, than ihor. from South Ahi.", 'Webui they somewhat broader marginal flanges. have had no Upt locality Dam at Faure, Cape Flats, South opportuniry to examine variation in large populations, Africa, lat. 33" 52' S, long. 18" 22' E. hbwever, and in comparison with the range of in- traspecific variation described for other Potqrygcypris Diagnosis- Adult carapace in lateral view with a speCies(e.g. Meisch, 1985) the above-noteddifferenc- long, stiaight (left valve) to slightly convex (right valve) el seem quite minor. To the best of our knowlgdg., j.ty.- dorial maigin sloping down to a distinctively truncat- the presenceof spiny tuberculate ornament 'Wein ed posterior margin,-with which it makes an angle of nileJ but not adults is unique to P humilis. offer approx. I l0o; anterior margin broadly rounded, ven- rwo tentative functional explanations for the ontoge- tial margin weakly concave. Maximum height one netic development of the ornament. Firstly, it may be quarter of the length from the anterior. External sur- to protect juveniles againstpredators that do not prey face of carapacepitted/finely reticulate, with numer- on-the larger adults. Secondly (and much more spec_u- ous normal pores from which sensilla extend, giving latively), ihe spinose tubercles may render juveniles the carapacesa hirsute appearance.Normal pores tend- more easily caught among birds' feathers,thus facili- irg to form small pore conuli, especiallynear the mar- tating their dispersal (see discussion of distribution gifrs of the valves. Right valve overlapsieft valve along below); adults are likely to be either about to lay eBBs, dorsal and ventral margins; left valve with anterior or havitg laid them, have no further reproductivepo - and posterior marginal"flanges extendi.g beyond a tential, so would gain no advantagefrom being picked well-developed selvage,especially prominent in the up and dispersed,whereas juveniles thus transported posterovential cornei and the lower rwo-thirds of the to another pond could survive to reach adulthood and anterior margin, so that the left valve overlapsthe right reproduce. in these regions; selvageperipheral along the ventral margin. Vbak dorso-median (post-ocular) sulcus in DISJUNCTDISTRIBUTION OF POTAMOCYPRISHUMILIS left valve only. Antenna with long natatory setae extenditg well As already mentioned, Purasjoki (1948) proposed past ends of the terminal claws. Beta setaof mandibu- transport by migrat ory Arctic and Common terns to Iar palp broad, leaf-shapedwith marginal setules.Fe- explain the occurrence of P humilis in Finland and mal-ecbpulatory hook proxim ally straight, with maxi- South Africa. The potential for dispersalof ostracods mum curvature in the distal third. by migratory birds is well known (e.g. McKe nzie, Juvenile carapaceswith prominent tuberclesin ad- 1971b; Sandberg-Siddiqui, 6{ Plusquellec, 1974; De Deckker, dition to pitted/reticulateornament: a prominent swol- 1977; Grigg & 1993). Cyptidoidean (and len post-ocular tubercle (near the dorsal margin j,tft at least sorne cytheroidean) ostracods are predisposed behind the dorsal angle at maximum height) distally to such passived,ispersal by virtue of their desiccation- pointed and slightly curved towards the posterior; a resistant eggs (which can remain viable for years) ald cluster of pointed tubercles (near the dorsal margin, the abilirlof adults to survive adverseconditions (fot close to the angle with the posterior margin) which at least days or weeks) in a torpid state (Horne & overhang the dorsal margin in the lateral view; a ven- Martens, 1998). Eggt and individuals (especiallysmall tro-lateril row of severalsmall, rounded tuberclessub- juveniles) might easily become stuck to the feet or parallel to the ventral margin; and severalother small, feathers,or survive passagethrough the digestive tracts icattered tubercles.The majoriry of the tubercles ap- of birds that bathe, drink or feed in the water bodies pear to be formed by the expansion of certain po{e inhabited by the ostracods. However, although some Lonuli and the associatedreticulation. A distinct ad- ostracod distributions have been shown to match the ductor muscle node is also developed in smaller juve- routes of bird migrations (see,e.g. De Deckker, 1977), niles (A-3 A-5). Reticulation relatively coarser in the evidence for such dispersal remains circumstan- smallerjuveniles (A-4, A-5), with developmentof sec- tial. Proof of a specific ostracod being dispersed in ondary pitting in the fossae,especially in the anterior this way by " specific bird has yet to be obtained. regron. The Arctic Tern (Sternaparadisaea) undertakes the most extensive migrations of any bird; its breeding Remarhs- Morphological differences are apparent grounds are circumpolar in the northern hemisphere, berween the adult specimensfrom Finland (illustrated and in the non-breeding seasonit migrates to Antarc- by Meisch, 1985, figt 26,27) Scotland(herein, Pl. 1, tic waters, involvitg a return journey of up to 20,000 figr l, 2, 4, 6, l0) and South Africa (herein,Pl. l, figs km (Monaghan, 2002). Birds from northern Europe 3: 5, 7 -9, I I ). The carapacesof the Finnish specimens follow the western coastsof Europe and Africa. Breed- 302 D.l. HORNE,R.J. SMrrH irg populations have been recorded in Scotland, in- visitor introduced by migrating birds. Sars(1924) gave cluding Harris, in May-August; birds ringed in Brit- no information about tf,. tirie of year in which- his recorded at many locations Cyprilk specimenswere collected,but Meisch (1985) ain and Ireland have'W'est been along the coasts of and South Africa (Text-fig. cit^.d ons collection of humilis in the South African (near 3) from August to June. At least parts of the migra- Museum as having been collected Lilyfontein) tions are believed to occur at high altitude, possibly in September l9t2 by R. Lawrence. More recently, thousandsof metres. Birds ringed on the coast of Fin- Martens et al. (1996) recorded it ("t Cyprilla humilis) land, includitg the Tvirminne area,have subsequent- in a semi-estuarinecoastal lake, Verlorenvlei ('Western ly been reco'tered in the British Isles (Ivlonaghan, Cape, South Africa) in April 1993, during ,tt. dty 2002). The Common Tern (Sterna hirundo) has simi- season;Martens (pers. comm.) has also found it in lar but less extensivemigrations, and birds ringed in this area(near Van Rhynsdorp) in September (speci- Af- mens illustrated herein) as well as in several other Britain and Ireland ha'ne'-beenrecovered in Soulh 'Western rica (Norm an, 2002). The Sandwich Tern (Sternasand- Cape localities in April, September,October uicensis)is a third possibiliry: birds ringed in the Brit- and December, and near Windhoek in Namibia in ish Isles have been recoveredat many locations along September.-'We the coastsof western and southern Africa (Noble-Rollin found no malesin our Scottish population and 6{ Redfern, 2002). The known occurrencesof P hu- none were reported in the Finnish collectionsby Puras- milis thus fall within the migratory routes of three joki (1948) ind Hagerman (1967); Sars(1924) stated speciesof terns, the best match being_with_the Arctic that a single male specimen was Present il the_rype T.rtr (Text-fig. 3). Most records of I?-hu*ilis are from material oT Cyprilla- humilis from Faure (Cape Flats) coastal areas,but the record from Namibia is several in South Africa, but he only illustrated a female, and no other reports of males (Meisch, hundred kilometres inland, in an upland area,which there have'We been might seem to raise an objection to-the hypothesis of 1985). consider it probable, therefore, that Pota- dispersal by terns; however, although the great major- mocypris humilis, like most cypridid ostracods, has iry- of British migrant terns have been recovered in mix-edreproduction and can occur in all-female pop- coastal regions, there are a few inland recovery sites as ulations is well as (more rarely) populations contain- well ('Wernham et al., 2002). irg a mixture of sexualand parthenogeneticindividu- The seasonaldistribution of the birds also corre- als (Martens, 1998). spondswell with that of the ostracodq.P_urasjoki (1948) There is no justification for regarding-been P humilis as described, illustrated and discussed Cyprilla humilis a South African speciesthat has introduced to formally mainly on the basis of specimens-in collected on the is- Europe, simply becauseit was first described land of Storshundsharen the Tvirminne area in the from- a Soutlr African localiry; nor, indeed, is there summer of 1947, adding as a footnote that he had any good reason to prefer the opp-ositeinte_rpretation: also found it on the same island in summer 1945 but that it is a European speciesintroduced to South Afri- had taken little notice of it at the time. An additional ca.'We consider at least equally likely that it is a sPe- collection of about 50 specimensfrom the Tvdrminne cies with a true bi-hemispherical distribution, living area,attributed to K.J. Purasjoki,J,tly 1954, was list- in similar habitats and climatic conditions in both ed by Meisch (1985) as being in the Klie collection (it northern and southern hemispheres,and with inter- is not certain whether this collection was from Stor- changebetween the rwo areasmaintained by.ggs trans- shundsharenor another localiry). In July 1966, it was ported by migratitg birds. The combination of par- found again on Storshundsharenand also on Spika- ihenogenesisind desiccation-resistantgggs (the latter ran, anoiher island in the Tvd.rminne archipelago,by possesiedby most, if not all, cypridoidean ostracods) Hagerman (1967). It has thereforebeen recorded four is highly advantageousfor dispersal,since it only takes timis on the same Finnish island over about 20 years, one egg to start a new population in a new habitat suggestingthat it is not simply a rare or occasional (Horne & Martens, 1998, 1999). The fact that Sars

EXPLANATION OF PLATE I

FigsI ,2,4,6, 10,12, 13 Potamocyprishumilzi (Sars, 1924), Harris, Scotland; BMNH nos. I ) adult femaleCC left lateral 2) adulifemaleCC dorsalview, 2004.415;4) adult femaleCC right lateralview, 2004.419;6) t internallateral view, 2004.418; l0) adult femaleLV internallateial view, 2004.418; l2) juveni lateralview, 2004.421; l3) juvenile(A-l) CC dorsalview, 2004.416. Figs 1,2,4,6, l0 all x 247 pm); figr 12, 13 x 146 (scalebar = 205 Fm). ' Figs3,5,7-9,ll,14 Potamocypriihumilis (Sars,1924), Blinkvlei,'South Africa. 3) adult femaleLV externallateral 5) adulifemale RV externallateral view, 2004.432;T adult femaleLV dorsalview, 2004.434; RV dorsalview, 2004.434;9)adult femaleRV internallateral view, 2004.433;I l) adult fen lateralview, 2004.433; 14) juvenile (A-l) CC, left lateralview, 2004.435. Figs 3,5,7-9,1I all - 247 pm); fig. 14 x 146 (scalebar = 205 Fm). D.l. HORM, R.J.SMTTH, FIRST BRITISH RECORD OF POTAMOCYPRISHUMILI Pl. 1 304 D.l. HORNE,R.J. SMrTH

Finnish collections were also found in July, would be consistent with the idea that the eggs hatch in M"y- June-South and the new adults lay eggs in luly-August. Th.e African occurrencesfor *hich dates are recorded show that adults can be found berween September and April. The available data are consistent with the notion that this speciesis a seasonalform which grows and lives in the summ erldry season in both hemispheres,^ overwintering as eggs.-ivailable Nevertheless,whili the data offer strong its support for the idea that P humilis owes .dispersal to terns, lt must be emphasized that the evidence is only circumstantial. It is-also worth pointing oyt that while there is a sood match between the distribution of P humilis anJ the migratory routes of the terns' it is perhaps unlikely that-these are the o4y birds re- sponsible for the ostracod'sdispersal. Other, p.ossible ,n..tott include Sandwich Terr (Sterna sanduicensis), (Calidris Sanderling (Calidris 7lba), kd Knot canu- Swallow (Hirundo rustica) (R. Pryt- tus), and-Barn 'Wernham pers. comm.; et al-, 2002)- hI: Jones, "frequent Th. bothesii that P humilis is a traveller" could b. tested by mapping its clonal^genetic diversi.y' U_f means of allozyme analysis(.,8.-Rossi et dl., 1998) and DNA (nuclear and mitochondrial) analysis (e.g. Schon 6c Butlin, 1998). Proof that it is actually transported by terns (ot ^\y other birds) is g"ly^ likely to b. obtained if individuals or eggs can be found on birds arriving after migratory flights.

CONCLUSIONS

Tlt. genus Cyprilla Sars, 1924 is considered to be . a ,unror' synonym of P.otqmoqtprisBrady, 1870. PotAmotyprit humilis has ah ontogenetic-so develop- not been Pobmocyprishumitis ment of carapaceornament that has far * described in iny other cypridoidean species:the pres- O RecoveryofArctic Tems ence in juveniles (at least A-5 to A-l) of prominent ringedin British lsles tubercles,some of them spinose'as well as a fine reticulation/pitting, while adults are 9lly. finely reticulate all ol.t, the lubercles being totally lost in the final - map: stars indicate localities/areas in Text-fig. 3 Distribution moult. which Potamocyiris humilis has been recorded: I ) northern hemi- Scotland; 2) Fi-njand; 3) Namibia; 4) South Africa; Potamoc'yprishumilis is found in the seetext for further details. Circles indicate approxi- sphere in finhnd and Scotland, and in the southern mare locations of recoveriesof Arctic Terns ringed hemisphere in South Africa; it aPPeTSto be a sum- in the British Isles (based on Monaghan, 2002). mer fot- in each hemisphere.This disjunct distribu- e,xplain.d dispersal by season"lly^ tion. may !: .by^ Ti- facil- graung-by seabirdsl possibly-Arctic Terns,-x Process Itated the fa€r that the ostracod has desiccation- resistant eggs and reproduces (mainly) parthenogenet- (1924) actually'humilis) reared four of his five specie_sof .Cyp; rilk (but not from mud sent frbm South Af- ically. rica and placed in aqu aria in Norway is clear evidence that this particular grouP of PotamocyP.r:s,sPeciesPos: ADDENDUM sessesdesiccation-reiistant eggs, even if the dispersal medium in this case was the postal service and not The rockpool near Rubha Romaieidh was revisit- when birds. Nothing is known of the-life-cycle_gf P humilis, ed by the fitit author (DJH) on p'n Jirl e 2004, results but the populition age-structureof.our July collection abundant ostracodswere collected; preliminary (adults juve- in Scotlind (A-5 to A-l juveniles plus adults), togeth- indicate the presence of P humilis and brad.yi and Cypria ophtalmica. On the er with the fact that adults and lale-sta8e iuveniles in niles), Iboryprit D I HOR\VL, R..1..SMI7-H, FIRSI- BRI'I.ISH REC,ORD OF POTAMO(,YPRISH(IMILI Pl.2

b,XPT-ANAI-ION OF I'I-AI'[., 2

Figsl-fl Potuntot-.,rtprishtmtilis (Setrs,1924), Hrrrris,Scotlancl; BMNH nos. l) jtrvenile(A-2) (,(,, lefi late = lttO pirn);2) juvenile(A-3) (,(., left later:rlvicrv, )004.42.J (x 200, scalebrtr = 150 pnr); 2004.4'17(x 167,scale bar = 180 prrn):4)juvenile (A-4) (,(., lcft later,rlvicw 2004.424(x 240, (r) 5) (.(,, left lateralview, 2004.425(x 2U(r,sc,rlc bar = 105 |'rrn); juvertile (A-l ) tV internallate -- 205;,rrn),7) iuvenilc(A-1) RV clctailof p,ostercdorsalrcgion (lateralview) showing exPansio fbrrn tubercles,2004.420(x 545, scalebar= 55 |.rrn);[J) ailult tenralecar:rpace, c-letail of ornan view) showingrericr-rlation, pore conuli and sensilla,2004.415 (x 857, scalebar = 35 prn).

same d^y severalother adiacentpools were sampled taken to be indicativeof the closeproximiry of a breed- and appearedto be barren of ostracods,but a second ing colony; in view of the increasitg agitation of the populatior-rof P humilis was found in another rock- biids further investigationwas consideredinadvisable. pool approximately100 m South of the original one (NG 034960), together with Ilyocltpriscf. bradyi,,Can- A(, KN O\VL E,DG E,M E,NTS dona cf. t-artdida(O.p Mtiller, 1776) and juvenilesof Heterorypriscf . salina (Brady, 1868) Exploring the rocky Koen Marrens (Roval Belgian Institutc fbr Natr.rralSciences) kindlv provided specirnens and distributional data fiont southern I km North towardsAird Niosaboist(NG coastabout Afiica. Scrrnning L,lectron Microscopv w:rs carried oLlt bv Johrr 045976) the frrst author was then mobbed by large Whitraker (ThcJNrttural Historv Museurn), whose expertiseand numbers of terns (probablyArctic Tern), behaviour helpfirl conuncnts were rnuch aprpreciatecl.Iatt l)eters(Roval Soci- 306 D.l. HORNE, R.J.SMITH

ery for the Protection of Birds) and Robert Prys-Jones(The Natu- of the genus Potamocypris(Crustacea, Ostracoda). Part I, species ral History Museum) are thanked for advice on bird migrations. with short swimming setae on the second antennae: Tlav. sci- Ve thank Gianmarco Paris (Milan) and Giampaolo Rossetti (Par- ent. Mus. hist. nat. Luxembourg,3, l-55. 'West ma) for their kind assistancein the preparation of this paper and -, I 985, Revision of the Recent European speciesof the ge- Elsa Gliozzi for facilitating our attendance of the meeting in mem- nus Potamorypris (Crustacea, Ostracoda). Part II, specieswith ory of Giuliano Ruggieri in Rimini, at which the paper was pre- long swimming setaeon the second antennae: Ti'av.scient. Mus. sented. Robin Smith gratefully acknowledges the support of the hist. nat. Luxembourg,6, l-95. Royal Sociery in the form of a Post-Doctoral ResearchFellowship. -, 2000. 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