DISCOVERYOF PARASTENOCARIDIDAE(COPEPODA, HARPACTICOIDA)IN INDIA,WITH THEDESCRIPTIONOF THREENEW SPECIES OF PARASTENOCARIS KESSLER,1913, FROM THE RIVER KRISHNAA TVIJAYAWADA 1/

BY

Y.RANGA REDDY 2/ Departmentof Zoology,Nagarjuna University, Nagarjunanagar 522 510, India

1/Thispaper is dedicatedto the fond memory of myelder brother ,YenumulaV enkataRanga Reddy, who,a towerof strengthto myfamily, passed away while this work was in progress .

ABSTRACT Inatwo-yearstudy of thefamily Parastenocarididae in the River Krishna at Vijayawada,South India,Ž vespecies belonging to the genus Parastenocaris Kessler,1913, have been met with. Of these,three are new to science: P. gayatri n. sp., P. savita n. sp., and P. sandhya n.sp.The Ž rsttwo ofthesebelong to the brevipes-group,the last one to the sioli-group.This paper gives an illustrated descriptionof thesenew taxa, and also brie y discussestheir afŽ nities and ecology. The other two species,viz., P.curvispinus Enckell,1970, and Parastenocaris sp.,will be dealtwith elsewhere. This istheŽ rstreport on Parastenocarididae from India. Incidentally,it has also been found that parastenocaridids constitute a ratherfavoured item in thediet of the postlarvae of a commerciallyimportant gobioid Ž sh, Glossogobiusgiuris (Hamilton, 1822).A briefnote of this Ž ndinghas been made.

RÉSUMÉ Aucours d’ uneé tudede deux ans sur la famille des Parastenocarididae, provenant du  euve Krishnaà Vijayawada,Inde du Sud, cinq espè ces appartenant au genre Parastenocaris Kessler, 1913,ont é térencontré es. Parmi elles, trois sont nouvelles pour la science: P. gayatri n. sp., P. savita n. sp. et P. sandhya n.sp. Les deux premiè res appartiennent au groupe brevipes,latroisiè me au groupe sioli.Cetravail donne une description illustré e deces nouveaux taxons, ainsi qu’ une brè ve discussionde leurs afŽ nité s etde leur é cologie.Les deux autres espè ces, P.curvispinus Enckell, 1970 et Parastenocaris sp.seront traité es par ailleurs. Ceci constitue la premiè re é tudesur les Parastenocarididaede l’Inde. Parailleurs, il aétémis en é videnceque les Parastenocarididae constituent un é lément appré cié dansl’ alimentation de la post-larve d’ unpoisson d’ importancecommerciale, Glossogobiusgiuris (Hamilton,1822). Une note courte relative à cettetrouvaille est fournie.

2/ e-mail:[email protected] m

c KoninklijkeBrill NV ,Leiden,2001 Crustaceana 74(8):705-733 ° 706 Y.RANGA REDDY

INTRODUCTION Parastenocaridids are small harpacticoids (length0.2-0.6 mm), inhabiting the space betweensediment particles ofunderground and subsoil waters. Aidedby their minute,vermiform body and short limbs, theycan crawl orswim freely in the capillary system ofthe interstices betweensand grains. Thefamily Parastenocarididae contains about200 species in Žvewell-recog- nizedgenera: Parastenocaris Kessler, 1913, ForŽcatocaris Jakobi,1969, ParaforŽ - catocaris Jakobi,1972, Potamocaris Dussart, 1979,and Murunducaris Reid, 1994. Of these, Parastenocaris is the most speciose genusand has aworld-widedistribu- tion,whereas all othergenera, containing few species, are exclusively Neotropical (Reid,1994). The family is ‘primarily freshwater’and only about a dozenspecies inhabit marine andbrackish coastal subsoil water (Wells, 1986).In the wholeof Asia, onlyabout 20 species haveso far beenrecorded (see Dussart &Defaye, 1990),but, surprisingly, none from India, as conŽrmed by H.K.Schminke(pers. comm.). Inthe courseof a two-yearstudy of parastenocaridids ofthe River Krishna at Vijayawada,I havecome across Žvespecies, viz., Parastenocaris gayatri n. sp., Parastenocaris savita n. sp., Parastenocaris sandhya n. sp., Parastenocaris curvispinus Enckell,1970, and Parastenocaris sp.The three newspecies will bedescribed below; accounts of the othertwo species foundwill bepublished elsewhere.

STUDY AREA TheRiver Krishnais oneof the major rivers ofIndia. Originating near Mahabaleswarat analtitude of1360 m in the Western Ghatmountains, only about60 km from the ArabianSea, the river owsacross almost the entire peninsularIndia from the west tothe east overa distance ofapprox. 1300 km beforedischarging into the Bayof Bengal. It enters the sea bytwoprincipal mouths andhas built upa large,very fertile delta continuouswith that ofthe Godavari River to the northeast.In the deltaic region,numerous artiŽ cial habitats suchas tanks,ponds, canals, etc., are fedby the river.Theriver derives its water from the monsoonrains andhas several tributaries, ofwhich the Bhima(north) and the Tungabhadra(south) are the largest ones.It has acatchment area ofabout 233,229 km2. At the headof the delta at Vijayawada(16 ±310N 80±E)there is animportant barrage,named Prakasam Barrage,which was constructedin 1955 for regulating the owof water in asystem ofirrigation canals, andwhich is situated 80km from the river mouth.The river narrowsbetween two hills ofgneiss andthen spreads PARASTENOCARIDIDAE FROMINDIA 707 overalluvial plains. Thechannel there is 1.2km wide.During summer, the river, downstreamof the barrage,becomes a narrowstream, with depthsbarely reaching 1.5m. Thedepth, however, rises to as muchas 13m during oodingtimes. Thesampling site at Vijayawadais located nearthe southernend of a road- bridgeacross the river,called KanakaDurga V aradhi,about 2.5 km downstream ofPrakasam Barrage.Here the river bedhas adeposit ofŽ nesand and detritus particles, butwith little ornoclay,andis almost devoidof macrophyticvegetation. Purefreshwater conditionsprevail throughoutthe year.During the present study, anunprecedented  oodwas witnessed in the monthof October, 1998, which causedserious damageto the benthiccommunities. Thetemperature regime was: air 30-38±C,water 28-35 ±C.

METHODS Coresamples wereregularly collected oncea monthfor two consecutive years, i.e.,January 1998 to December1999, using plastic tubes of70cm lengthand 4 cm diameter. Onafewoccasions, a metal corerwas also employed.Moist, exposedas well as submergedparts ofthe riverbedwere sampled. Each time, sampling was doneat Žvesites inc. 100 m 2,andat eachpoint about ten cores weretaken from the sediment surface toa depthof 10-30cm, pooled into a bucketand vigorously stirred with Žltered habitat-water.Thesupernatant was Žltered througha plankton net madeof bolting silk (mesh size 70 ¹m).The Ž ltrate was thenŽ xedin 10% formalin andpreserved in a 5%formalin solution.A fewsamples werealso Žxed in 20%alcohol and preserved in 70%alcohol. The water collected in dug-out pits nearthe water’s edgedid not yield anyparastenocaridids. Specimens were dissected in lactophenol,using a Getnerstereoscopic microscopeat 90 ; the parts £ weremounted under cover slips andsealed with Araldite. All measurements of preservedanimals weremade with acalibrated eyepiecemicrometer, anddrawings weremade with a camera lucida mountedon a Meoptacompound microscope at magniŽcations of270 , 450 or 675 .Someparatypes were largely dissected £ £ £ beforedrawing the appendages;lateral views weregenerally drawn in situ. Body lengthwas measuredfrom the base ofthe rostrum tothe endof the caudalrami. All typematerial has beendeposited in TheNatural History Museum,London. 708 Y.RANGA REDDY

DESCRIPTIVE PART

Parastenocarisgayatri n.sp. (Ž gs. 1-4)

Parastenocaris sp.:Reddy, 1977: 337-341, Ž gs.1-10.

Materialexamined. — Holotype(adult ,0.47mm), allotype (adult ),paratypes(25 , 25 ),allundissected and preserved in 70% alcohol, deposited in TheNatural History Museum, London;registration numbers: holotype 2000.1280; allotype 2000.1281; paratypes 2000.1282-1331. Severaldissected and undissected paratypes are kept at the Department of Zoology, Nagarjuna University.T ypelocality. River Krishna at Vijayawada, South India, 16 ±310N 80±E;closeto the southernend of KanakaDurga V aradhi,a road-bridgeacross the river, from Ž nesand,about 10 m fromthe water’ s edgeat a depthof 10to 30 cm.11 February1999; water temperature 29 ±C.

Description anddrawings are basedon the studyof the c.75 specimens that constitute the type-series. Adultmale. —Total length(excluding caudal setae) ofholotype 0.47 mm, of paratypes0.42-0.52 mm, average 0.47 mm ( N 30).Body elongate, subcylin- D drical, vermiform,about 9 times as longas wide,slightly taperingposteriorly andwithout ornamentation. Cephalothorax, excluding rostral projection,as long as next2 somites combinedand with somewhatspherical integumental window. Urosomites 2-5with 1distinct rectangular,integumental windoweach; window onurosomite 2relatively short andtrapezoidal. Anal operculum smooth, posterior borderstraight, notreaching end of anal somite. Caudalrami parallel and40% shorter thananal somite; eachramus 3times as longas maximumwidth, subcylindrical, distal third narrow.Armature consisting of7setae: dorsal seta inserted almost oppositeto a groupof 3poorlydeveloped, unequallateral setae, located behindthe middle ofoutermargin, and 1 posterolat- eral and2 terminal setae, outerterminal strongest and4.3 times as longas caudal ramus; posterolateral seta longerthan, and inner terminal seta as longas, caudal ramus. Rostrum(Ž g. 1a, b) prominent,subcylindrical, not deŽ ned at base,and tipped with stubby,modiŽed seta (spine?); nosensilla discernible. Antennule(Ž g. 2a)haplocer, 7-segmented; segment 2longest,segments 3and4 enlarged;segment 4with dentiform,lateral process,carrying 1 short seta; segment 6withstrong, lateral, spinousprocess; segments 1-7with 0, 5, 2, 3, 0, 0, and 7setae; segment 4withlong aesthetasc, constricted at midlengthand reaching beyondtip ofantennule,segment 7with short aesthetasc. Antenna(Ž g. 2b). Coxa small, unarmed.Allobasis 3.6times as longas max- imum width,with 2groupsof minute spinules onanterior margin.Exopodite 1-segmented,cylindrical, 4times as longas wide,with 1 apical seta, longerthan its segment.Endopodite about half as longas allobasis, with 2spines andsome PARASTENOCARIDIDAE FROMINDIA 709

Fig. 1. Parastenocarisgayatri n.sp.,male. a, holotype habitus, dorsal; b, rostrum; c, habitus, lateral; d,analsomite and caudal rami, dorsal; e, rightcaudal ramus, lateral. Scale f fora, c; scaleg forb, d, e;scalesequal 50 ¹m. spinules onanterior edge;distal endwith 5setae, 3ofwhichgeniculate, and with 1spinule at distal posterior corner. Mandible(Ž g. 2c).Gnathobase not studied in detail. Palp 1-segmented,4 times as longas wide,with 2apical setae ofnearlyequal length. 710 Y.RANGA REDDY

Fig. 2. Parastenocarisgayatri n.sp.,male. a, antennule,dorsal; b, antenna;c, mandible;d, maxillule; e,maxilla;f, maxilliped;g, leg 1; h, leg 2; i,leg3, posterior; j, do.,exopodite (under cover slip), lateral;k, do., distal exopodite-segment (under cover slip), lateral; l, leg 4, posterior; m, n, do., differentviews of distal part of endopodite; o, leg5. Scaleequals 50 ¹m. PARASTENOCARIDIDAE FROMINDIA 711

Maxillule (Žg. 2d). Arthrite ofpraecoxawith 1modiŽed jointed seta onabcoxal surface and4 terminal spines, increasing insize distally, as Žgured.Coxa with a single terminal, thick seta. Basis with 2thickterminal setae. Exo-and endopodite absent. Maxilla (Žg. 2e). Syncoxa with 2endites, eachcarrying 2 apical setae, one ofwhich strongly reduced. Basis with 1strongclaw fusedto it. Endopodite representedby 2unequal,slender setae. Maxilliped (Žg. 2f).Basis small, bare.First endopodite-segmentsubcylindrical, 5times as longas wide,bare. Second segment small, with 1short claw. Leg1 (Žg. 2g).Coxa bare. Basis witha fewsmall spinules ona lobeat mid-inner margin; outerseta short.Exopodite 3-segmented; Ž rst segment distinctly longer thanthird segment,with 1spine anda fewspinules ondistal outermargin; second segment shortest andwithout spine; last segment with2 geniculate setae and2 spines; outermargin of distal 2segments spinulose.Endopodite 2-segmented, extendinga little beyondend of exopodite; Ž rst segment morethan twice as longas second,spinulose alongdistal lateral margins andwithout seta. Second segment with 1spinuleat aboutmid-inner margin, and 1 geniculate seta and1 spine apically. Leg2 (Žg. 2h). Coxa bare; basis with 3or4 spinules onproximalouter margin. Exopodite3-segmented; Ž rst segment stouter, butshorter thannext 2 segments combined;third segment with 3setae; Žrst andthird segments with ‘fringed’ distomedial corner.Endopodite 1-segmented, slender, 7 times as longas wide, reachingover 2/ 3lengthof Ž rst exopodite-segment;apex with oneobliquely directed seta and3 spinules. Leg3 (Žg. 2i-k).ModiŽ ed but not complicated. Coxa unarmed. Basis with small lobeat proximalouter corner, carrying 1 strongouter seta and1 posteriorly directed spinule; 1obliquerow of Žnespinules at distal outerangle; 1short slender seta nearinner distal corner,probably representing endopodite. Exopodite, in posterior view(Ž g. 2i), consisting roughlyof 2 segments, Žrst segment muchlarger than second,slightly dilated proximallyand armed with the followingstructures: inner marginwith 1large triangular hyalinelobe at midlength,1 large dentate process close to it and1 small chitinous knobproximally; distal outercorner with 1strong butshort modiŽed seta (‘thumb’), whichis shorter thandistal segment and3 or4 spinules occurringnear thumb. Second segment, in lateral view,much expanded distomedially (Žg. 2j,k) andarmed with 1biŽd chitinous lobeat innerdistal angle (hook-likein posterior aspect) and1 apical, sturdy, straight orslightly curved, pointedspine. Leg4 (Žg. 2l-n). Coxa bare. Basis with usual outerseta onshort papilla. Exopodite3-segmented; Ž rst segment modiŽed, incurved, distally dilated with usual spine neardistal outercorner and 1 thumb-like,unfringed lobe at inner 712 Y.RANGA REDDY distal angle; third segment with2 apical setae and1 small spinule inplace of ‘fringe’at distal innercorner .Endopoditeslender, linguiform, extending beyond posterior borderof Ž rst exopodite-segment,apical regiontapering to bluntor sharppoint; 1 obliquerow of minute spinules dividingdistal half into2 unequal lobes; 1longitudinalrow of 4or5 longspinules orsetules at aboutmidlength in posterolateral view.Basal sclerotized part (stippled area) differentiated into 1large incurvedclaw and1 small, nearlyspherical lobe; also, 1slender seta occurringat base ofendopoditeon inner side. Leg5 (Žg. 2o).Small, nearlycircular plate, with 4setae onuneven distal border; outer(proximal) seta longest,others short,unequal, spiniform. Leg6 (Žg. 1c) bare, posteriorly directed,subconical, pointed protrusion. Adultfemale. —Total lengthof allotype 0.50mm, of paratypes 0.43-0.50 mm, average0.47 mm ( N 30).Habitus similar to male in generalappearance. D Cephalothoraxwith ovatedorsal integumental window.Window on genital double- somite large,trapezoidal inoutline. Anal somite with transverse rowof Ž nesetules and1 sensillum oneither side at distal outercorner of dorsum(Ž g. 3c-e); another dorsal sensillum oneither side anterior to operculum(Ž g. 3c). Anal operculum as in male. Genital Želd (Žg. 4a)extending to midlengthof genital somite. Caudalrami (Žg. 3c-k)same as in male in setal armature,but ornamented with microsetules andspinules, as illustrated; generalshape of caudalrami ofallotype as inŽ g.3a; bothlength and shape varying widely among paratypes; inlateral view,outer margin always straight, butinner margin variously dilating (Žg. 3g-k). Antennule(Ž g. 4b)7-segmented, with 0, 4,4, 2, 1,0,and9 setae; segments 4and 7eachwith aesthetasc; aesthetasc onsegment 4slightly constricted at midlength andextending beyond tip ofantennule; that onsegment 7relatively short and slender. Othercephalic appendages(not illustrated) andleg 1(Žg. 4c)as in male. Leg2 (Žg. 4d). Basis with agroupof 4 small spinules onproximal outer margin.Exopodite 3-segmented; Ž rst andthird segments with fringedfrill at eachdistomedial corner;inner margin of Ž rst exopodite-segmentwith setules. Endopoditeslender, slightly bentat midlengthand with 1curvedseta and2 spinules. Leg3 (Žg. 4e).Basis with 1longouter seta and3 or4spinules nearits base. Exopoditeslender, 2-segmented, each segment producedinto small, triangular, fringedlobe at its innerdistal angle; secondsegment with 2setae. Endopoditeslen- der,lanceolate, slightly shorter thanŽ rst exopodite-segmentand apparently naked. Leg4 (Žg. 4f).Basis withthe usual,single outerseta and2 or3spinules near its base.Exopodite 3-segmented; Ž rst andthird segments withfringed, triangular process at innerdistal angle; third segment with 2apical setae. Endopoditeslender, PARASTENOCARIDIDAE FROMINDIA 713

Fig. 3. Parastenocarisgayatri n.sp., female. a, allotypehabitus, dorsal; b, rostrum; c, partof anal somiteand left caudal ramus (under coverslip), dorsal; d, e,g-k, left caudal ramus, lateral; f, right caudalramus, ventral. Scale l fora; scale m forb-k; scales equal 50 ¹m. elongate,doubly curved, reaching midlength of secondexopodite-segment; lateral margins ofdistal half spinulose andwith asmall circle of4or5small spinules at midlength. 714 Y.RANGA REDDY

Fig. 4. Parastenocarisgayatri n.sp., female. a, leg 5 andgenital somite, ventral; b, antennule,ventral; c,leg 1; d, leg2; e, leg3; f, leg4; g, leg5. Scaleh fora; scale i forb-g; scales equal 50 ¹m.

Leg5 (Žg. 4g) subquadrate, distal innercorner produced into sturdyspinous process; obliquedistal marginwith 4 setae in2 groups;proximal seta longest,all others short,spiniform; secondproximal seta shortest. PARASTENOCARIDIDAE FROMINDIA 715

Etymology.—Inthe Vedic literature, the term “Gayatri”s. str.is genderless, signifyingthe cosmic energy;proposed here as anounin appositionto the generic name. Remarks andafŽ nities. —Twosolitary males of Parastenocarisgayatri n. sp. wereŽ rst noticedby me wayback in 1974 in planktonsamples ofthe River Krishna andwere later briey described(see Reddy,1977).One of these, thendesignated the paratype,was depositedin whole in TheNatural History Museum,London (registration no.1983: 72). Themembranous endopodite of leg 4in the male stronglyfavours the inclusion of P. gayatri in Lang’s (1948) brevipes-group,by possessing heavilysclerotized structures at the base,a seta at the innerproximal corner, and a longitudinalrow of 4or5 spinules. However,these latter spinules, unlikein otherspecies ofthe group in whichthey are present,occur well belowthe apexof the endopodite. Within the Indiansubcontinent, the followingŽ vespecies, all describedby Enckell(1970) from Sri Lanka,also belongto the brevipes-group,which possibly has its epicentre intropical Asia (Reid,1995): P. irenae Enckell,1970, P. noodti, Enckell,1970, P. brincki Enckell,1970, P.lanceolata Enckell,1970, and P. sing- halensis Enckell,1970. A critical comparisonof the newspecies with these andthe otherAsian members ofthe brevipes-groupreveals that it has the closest similarity to P. noodti in the structural details oflegs 2,4,and5 in bothsexes. However,it dif- fers from P. noodti in several respects. Forexample, the anal operculumis straight instead ofbeingconvex; the ornamentationof the anal somite andthe formof the caudalrami differ in the twospecies; the endopoditeof leg 2in the male andof leg 3in the female are longer;in the male leg 3,the basis has aninner and an outer seta, andone spinule, all ofwhich are absent in P. noodti;in leg 4,the endopodite is different in shape,and the armature consists offour or Žvesetules in additionto spinules; the setules are wantingin P. noodti;leg 5in bothsexes ofthe newspecies has fourinstead ofthree setae, butwithout spinules onthe innermargin, and in the female, the spinousprocess at the distal innercorner is larger.Nocomparison ofthe integumental windowsof the somites is possible becausethey are notde- picted for P. noodti.Theintegumental windowsof the somites ofthe newspecies are somewhatsimilar to those of P. brevipes,despite differences in shapeof these windowsbetween the twotaxa (see Reid,1995). Theprehensile capacity ofthe male antennulesin the newspecies is greatly enhancedby a powerfulclaw-like lateral process (notan artifact, Ibelieve) on the Žfth segment (reminiscent ofa comparablestructure frequentlyfound on the antepenultimate segment ofthe modiŽed right antennuleof diaptomid males), and adentiformprocess onthe fourthsegment. Coincidentally, this character is shared bythe Indonesian P.feuerborni Chappuis,1931, another member of the brevipes- group(no information on this pointis available forother members). 716 Y.RANGA REDDY

P. gayatri n.sp. stands outfrom its congenersby ,inter alia, the prominent rostrum,the distinct integumental windowsas seen inhabitus, and the various subtle characters oflegs 2-5in bothsexes. Thecaudal rami are sexually dimorphic;the rami inmales are subject tolittle orno variation, but highly variable in females, as caneasily beobserved in lateral view.Such variation, according to Schminke(1991), is notuncommon in Parastenocarididae. Distribution. —Knownfrom the typelocality only;its sympatric occurrence witha large numberof allied euryhalineforms in different seasons (see under “Co-occurringfauna” , below)points to the possibility ofthis species tobe found all alongthe lowerreaches ofthe river,including the brackishenvironment.

Parastenocarissavita n.sp. (Ž gs. 5-7)

Materialexamined. — Holotype(adult ,0.47mm), allotype (adult )andparatypes (15 , 5 ),allundissected and preserved in 70% alcohol, deposited in The Natural History Museum, London;registration numbers: holotype 2000.1384; allotype 2000.1385; paratypes 2000.1386-1405. Severaldissected and undissected paratypes are kept at the Department of Zoology, Nagarjuna University.T ypelocality. River Krishna at Vijayawada, South India, 16 ±310N 80±E;closeto the southernend of Kanaka Durga V aradhi,a road-bridgeacross the river; from Ž nesand, about 10 m fromthe water’ s edgeat a depthof 2to25 cm,31 August1998.

Description andŽ guresare basedon the studyof the c.35 specimens that constitute the type-series. Adultmale. —Total lengthexcluding caudal setae ofholotype 0.47 mm, of paratypes0.42-0.48 mm, average 0.45 mm ( N 20).Body elongate, vermiform, D onlyslightly taperingposteriorly ,8times as longas maximumwidth near posterior borderof cephalothorax,without ornamentation. Cephalothorax as long as next2 somites combined,and with faintly marked,circular integumental window.Urosomites 3-5each with indistinct, subquadrateintegumental window inproximal half; windowon urosomite 3relatively large; nowindowdiscernible onurosomite 2.Analoperculum smooth, and in holotypeposterior borderslightly convex,not reaching posterior endof anal somite (Žg. 5a, e); in aparatype, posterior borderconcave midway and extending a little beyondposterior endof anal somite (Žg. 5h). Caudalrami divergent,35% shorter thananal somite; eachramus morethan 3times as longas maximumwidth (Ž g. 5e-h) or somewhat shorter (Žg. 5g), subcylindrical,distal third alittle narrow.Caudal armature, as usual,consisting of 7setae; 3anterolateral, in group,located slightly behindmiddle ofouter margin, 2 ofthese setae well developed;dorsal seta inserted almost oppositeto anterolateral setae andshorter thanlongest anterlolateral setae; posterolateral seta sickle-shaped, PARASTENOCARIDIDAE FROMINDIA 717

Fig. 5. Parastenocarissavita n.sp., male. a, holotypehabitus, dorsal; b, same, lateral; c, rostrum; d,pediger5 andurosomite 1, lateral; e, anal somite and caudal rami, dorsal; f, g, analsomite and left caudalramus, lateral; h, analsomite (in part) and caudal rami, dorsal; i, spermatophore. Scale j for a,b; scale k forc-i; scales equal 50 ¹m. 718 Y.RANGA REDDY longerthan caudal ramus; outerterminal seta sturdiest, 4.8times as longas caudal ramus,and in oneparatype, basal part dilated (Žg. 5h). Rostrum(Ž g. 5c)small, notdeŽ ned at base; with acomparativelylong sensillum oneachside ofacute tip. Antennule(Ž g. 6a) haplocer, 7-segmented, with 0, 5, 2, 2, 0, 0, and 7 setae; spinousprojection on segment 6short andbroad; aesthetasc onsegment 4 constricted midwayand extending well beyondtip ofantennule; aesthetasc on segment 7small, onlyhalf as longas that onsegment 4. Antenna(Ž g. 6b). Exopodite 1-segmented, 2.6 times as longas wide,with 1 apical seta, 2.6times longerthan its segment.Endopodite with 2spines andsome spinules onanterior margin; distal endwith 5setae, 3ofwhich geniculate. Mandible(Ž g. 6c).Palp 1-segmented, 2.3 times as longas wide,with 2apical setae ofunequal length. Maxillule (Žg. 6d). Arthrite ofpraecoxawith 1modiŽed jointed seta onabcoxal surface and4 terminal spines, increasing insize distally, as Žgured.Coxa with a single terminal, thick seta. Basis with 2thickterminal setae. Exo-and endopodite absent. Maxilla (Žg. 6e). Syncoxa with 2endites, eachcarrying 2 apical setae, one ofwhich strongly reduced. Basis with 1strongclaw fusedto it. Endopodite representedby 2unequal,slender setae. Maxilliped (Žg. 6f).Basis small, bare.First endopodite-segmentsubcylindrical, 5times as longas wide,bare. Second segment small, with 1short claw. Leg1 (Žg. 6g). Basis with short outerseta. First exopodite-segmenta little longerthan third one. First endopodite-segmentnearly twice as longas second one,and about as longas Žrst 2exopodite-segmentscombined; 1 minuteseta (or spinule?) at distal thirdof inner margin and 2 short,transverse rowsof minute spinules nearouter margin. Leg2 (Žg. 6h, i). Basis with slender spinules onouter edge. First exopodite- segment withfringed triangular lobeat distomedial corner;outer spine rela- tively long,extending beyond distal endof second segment; third segment with small spinousprocess instead offringed lobe at distomedial corner.Endopodite 1-segmented,59% shorter thanŽ rst exopodite-segment,gradually dilating apically, somewhatspatulate inoutline, lateral anddistal margins nearlystraight, with1 obliquelydirected seta and3 spinules at distal outercorner. Leg3 (Žg. 6j-m). Coxa unarmed. Basis subquadrate,wider than long, with long seta nearproximal outer corner, 8 or9 longspinules in obliquerow in distal half and1 short seta ondistal innermargin, perhaps homologous to endopodite. Exopoditelarge, elongately oval, dilated at midlengthin lateral view(Ž g. 6k), innermargin lined withirregular hyalinelamella (Žg. 6l, m); 1spinule occurring neardistal outercorner and small dentiformstructure onproximal inner margin; PARASTENOCARIDIDAE FROMINDIA 719

Fig. 6. Parastenocarissavita n.sp., male. a, antennule,dorsal; b, antenna;c, mandible;d, maxillule; e,maxilla; f, maxilliped; g, leg 1; h, leg 2; i, do., endopodite, enlarged; j, leg 3; k, do., lateral; l,m,do., posterolateral, in different paratypes; n, leg4; o, leg5. Scaleequals 50 ¹m. 720 Y.RANGA REDDY distal endcarrying 2 elongate,unsegmented branches of equal length; outerone slender,dilated at subapical innermargin and produced apically intoshort, spinous process.Inner branch thicker, subcylindrical, apex rounded and provided with hyalinelamella (Žg. 6j), varying in size andshape (Ž g. 6l, m). Leg4 (Žg. 6n). Coxa bare. Basis with short outerseta. First exopodite-segment curved,distal thirddilated; distal innercorner without any lobe; outerdistal spine relatively thick.Third segment with 2apical setae andshort, simple, spinous process at distal innerangle. Endopodite short, roughly 2-segmented, barely reachingdistal endof Žrst exopodite-segmentand ending in 2short,apical spines, formingbeak-like structure; basal sclerotized part consisting of1 verysmall, crescented lobeat proximalouter corner and 1 large,triangular lobe,projecting inwardinto short hook-likeprocess; also, 1short,stout spine occurringat inner proximalcorner of endopodite and another small spine lyingadjacent toit and overlappingendopodite. Leg5 (Žg. 6o)small, subquadrateplate; distal borderuneven, with 4slender, dissimilar setae; outermost seta longest,and seta nextto it shortest. Leg6 (Žg. 5d)bare, posteriorly directed,subcylindrical protrusion,ending in acute tip. Most ofthe males examinedshowed 1 reniformspermatophore (Ž g. 5i) in their body. Adultfemale. —Total lengthof allotype 0.46mm, of paratypes 0.44-0.47 mm, average0.46 mm ( N 9).Body (Ž g. 7a) closely resembling male in gen- D eral appearanceexcept for maximum width occurring on genital double-somite. Cephalothoraxas longas next2 somites combinedand with vague,circular, in- tegumental window.Genital double-somiteand succeeding 2 somites eachwith indistinct, subquadrateintegumental windowin their proximalhalf. Anal oper- culumsmooth, with straight posterior border,not reaching posterior endof anal somite (Žg. 7a).Caudal rami as well as their setal armature (Žg. 7a,c, d), and the rostrum same as in the male. Antennule(Ž g. 7e) 7-segmented, with 0, 4, 4, 2,1, 0, and 8 setae; aesthetasc onsegment 4constricted midwayand extending beyond tip ofantennule,that on segment 7shorter andslenderer thanthat onsegment 4. Othercephalic appendages(not illustrated) andleg 1(Žg. 7f) as in the male. Leg2 (Žg. 7g, h). Basis with arowof 4 small spinules onproximal outer margin.Exopodite as in male exceptfor fringed distomedial projectionof Ž rst exopodite-segmentbeing longer .Endopodite1-segmented, 38% shorter thanŽ rst exopodite-segment,slender, slightly dilated distally,with 1seta and3 spinules; in oneparatype, seta directed outward. Leg3 (Žg. 7i). Basis with 1longouter seta and1 spinule onouter edge. Ex- opodite2-segmented, proximal segment producedinto short Žnger-like,fringed PARASTENOCARIDIDAE FROMINDIA 721

Fig. 7. Parastenocarissavita n.sp.,female. a, allotype habitus, dorsal; b, leg 5 andgenital double- somite,ventral; c, anal somite (in part) and left caudal ramus, dorsal; d, do., left caudal ramus, lateral;e, antennule, ventral; f, leg 1; g,leg 2; h,do.,endopodite, another paratype; i, leg3; j, leg4 (endopoditeenlarged); k, leg5. Scalel forb; scalem forc-k; scale n fora; scalesequal 50 ¹m. 722 Y.RANGA REDDY process at innerdistal angle; secondsegment with 2apical setae andshort, un- fringed,spinous process at innerdistal angle.Endopodite 1-segmented, spiniform, somewhatlanceolate, incurved,as longas Žrst exopodite-segment,proximal third slightly thicker,apparently naked. Leg4 (Žg. 7j).Basis with1 outerseta. Exopodite3-segmented; Ž rst andthird segments producedinto unfringedspinous process eachat distal innercorner; third segment with2 apical setae. Endopoditerelatively stout, outcurved,lanceolate, extendingbeyond middle ofsecondexopodite-segment; lateral margins ofdistal half spinulose,a small circle of4or5 small spinules at midlength. Leg5 (Žg. 7b,k) subrectangular,1.6 times as longas wide,distal innercorner producedinto strong, outcurved, claw-like structure; 3spinules lyingon inner marginnear base ofclaw; distal marginwith 4 setae; outermost seta longest,seta nextto it shortest. Etymology.—Inthe Vedic literature, the term “Savita”s. str. is genderless, denotingthe transcendental energybetween the cosmic andthe universal energy; proposedhere as anounin appositionto the genericname. Remarks andafŽ nities. — Parastenocarissavita n.sp. also belongsto the bre- vipes-group,and seems rather close tothe precedingspecies. Themorphological similarity betweenthe twotaxa, especially with regardto the female habitus andappendages, is quite impressive. Yet, the natureof the rostral projection, ornamentationof the caudalrami, relative size andshape of the endopoditeof leg 2,and shape and ornamentation of leg 5,etc., caneasily separate these females. Further,the caudalrami of P. savita showlittle variation andthe integumental windowsare vague,as comparedwith the conditionsin P. gayatri.Asto the male morphology, P. savita is distinctly different.The antennuleis less prehensile,owing to muchreduced lateral projections onsegments 4and6. Theendopodite of leg 2 is shorter anddilated apically.Inleg 3,the basis is armedwith an oblique row of longerspinules, andthe exopoditeends in twobranches, instead ofone, and has alarge hyalinelamella onthe innermargin. The endopodite of leg 4is shorter andmore simpliŽ ed; the sclerotized basal regionis reduced,the spinules andthe subapical setules are absent,and the seta at the proximalinner corner is strongand spiniform. Thecaudal rami showno sexual dimorphism.The variation inshape and positionof the anal operculumin males, as opposedto females, is worthnoting in this species. Within the brevipes-group, P. savita is distinctive especially bythe following features ofthe male: the spatulate endopoditeof leg 2,the exopoditeof leg 3ending into twobranches, and the simpliŽed structure ofthe endopoditeof leg 4. Distribution. —Knownfrom the typelocality only. PARASTENOCARIDIDAE FROMINDIA 723

Parastenocarissandhya n.sp. (Ž gs. 8-11)

Materialexamined. — Holotype(adult ,0.37mm), allotype (adult )andparatypes (25 , 25 ),allundissected and preserved in 70% alcohol, deposited in TheNatural History Museum, London,registration numbers: holotype 2000.1332; allotype 2000.1333; paratypes 2000.1334-1383; severaldissected and undissected paratypes are kept at the Department of Zoology, Nagarjuna University.T ypelocality, River Krishna at Vijayawada, South India, 16 ±310N 80±E;closeto the southernend of Kanaka Durga V aradhi,a road-bridgeacross the river; from Ž nesand, about 10 m fromthe water’ s edgeat a depthof 5to50 cm,31 August1998.

Description andŽ guresare basedon the studyof the c.75 specimens that constitute the type-series. Adultmale. —Total lengthexcluding caudal setae ofholotype 0.37 mm, of paratypes0.31-0.36 mm, average 0.35 mm ( N 20).Body elongate, vermiform, D graduallytapering in posterior direction; 7times as longas maximumwidth and withoutornamentation or integumental windows.Cephalothorax shows maximum bodywidth near posterior borderand is longerthan next 2 somites combined.Anal somite with Žnelyspinulose distal innercorners on ventral aspect (Žg. 8f,g). Anal operculumsmooth, with straight posterior border,not reaching posterior endof anal somite. Caudalrami divergentand as longas anal somite; eachramus nearlyof uniform width,4 times as longas wide,with generally convex inner and concave outer margins; size andshape varying in paratypes(Ž g. 8a-g). Armature consisting of7 setae; 3anterolateral setae conspicuousand located nearbase oframus; dorsal seta inserted at aboutdistal third ofinner margin and about as longas longest anterolateral seta; outerterminal seta strongest, plumose,2.6 times as longas caudalramus; posterolateral seta generallysickle-shaped, longer than inner terminal seta, butshorter thancaudal ramus. Rostrum (Žg. 8a)small, nipple-like protuberance,undeŽ ned at base andwith 2 minute sensilla. Antennule(Ž g. 9a,b) haplocer, 7-segmented, with 0, 5, 2,2,0, 0,and7 setae; segment 6withoutspinous projection; segment 5endingin short,blunt process. Segment4 with aesthetasc, constricted at distal thirdand not reaching tip of antennule;segment 7with short aesthetasc, 0.7as longas that onsegment 4. Antenna(Ž g. 9c). Exopodite 1-segmented, 3.5 times as longas wide,with 1 apical seta, longerthan segment. Endopodite with 2 spines andsome spinules on anterior margin; distal endwith 5setae, 3ofwhich geniculate. Mandible(Ž g. 9d).Palp 1-segmented, 4.3 times as longas wide,with 2 apical setae ofnearlyequal length. Maxillule (Žg. 9e).Arthrite ofpraecoxa with 1modiŽed jointed seta onabcoxal surface and4 slender,terminal spines, increasing in size distally,as Žgured.Coxa 724 Y.RANGA REDDY

Fig. 8. Parastenocarissandhya n.sp.,male. a, holotype habitus, dorsal (rostrum enlarged); b, do., lateral(leg 6 enlarged);c, anal somite and caudal rami, dorsal; d, e, right caudal ramus, lateral; f,g, right caudal ramus, ventral; h, spermatophore. Scale i fora, b; scale j forc-h; scales equal 50 ¹m. PARASTENOCARIDIDAE FROMINDIA 725

Fig. 9. Parastenocarissandhya n.sp., male. a, antennule, ventral; b, do., in another paratype (armatureomitted); c, antenna; d, mandible;e, maxillule;f, maxilla; g, maxilliped; h, leg1; i,leg 2 (endopoditeenlarged); j, thirdpair of legs, posterior; k, rightleg 3, posterior,in another paratype; l,leg 4 (endopoditeenlarged); m, leg 5. Scale equals 50 ¹m. witha single terminal, thick seta. Basis with 2thick terminal setae. Exo-and endopoditeabsent. Maxilla (Žg. 9f). Syncoxa with 2endites, eachcarrying 2 apical setae, oneof whichstrongly reduced. Basis with 1strongclaw fusedto it andwith 1subapical 726 Y.RANGA REDDY spinule,as Žgured.Endopodite represented by minute segment,carrying 2 unequal, slender setae. Maxilliped (Žg. 9g).Basis small, bare.First endopodite-segmentsubcylindrical, 5times as longas wide,bare. Second segment small, with 1short claw. Leg1 (Žg. 9h). Basis with minute spinules nearslender, lateral seta. First exopodite-segmentshort, as longas third segment.First endopodite-segment almost twice as longas secondsegment, only slightly shorter thanexopodite; 1obliquerow of spinules in proximalhalf and1 minute seta ondistal innermargin; secondendopodite-segment without lateral spine. Leg2 (Žg. 9i).Basis with minute spinules alongouter margin and oblique row ofsomewhatlong spinules nearbase ofendopodite.First exopodite-segmentwith fringed,triangular lobeat distomedial corner;third segment with small spinous process instead offringed lobe at distomedial corner.Endopodite 1-segmented, basal part narrow,distal 2/3expanded,with 1doubly-curvedapical seta ankedby 2short spiniform setae; crescented rowof c. 10 spinules in distal half. Leg3 (Žg. 9j) modiŽed. Coxa short, unarmed, heavily chitinized. Basis also chitinized, nearlyrectangular, longer than wide, with small butarticulate lobe onproximal outer margin, carrying 1 verylong apical seta and1 short spine nearits base; innermargin with 1spine proximallyand 1 small hyalinelobe at distal end.Distal part ofleg (‘pincers’) less chitinized, consisting of1 outerand 1innerelement, bothbent inward and partly overlappingeach other; also, 1spine occurringclose to base ofouter element; outerelement muchlonger than inner one,distal half taperingto acute point;inner element bell-shaped,with acutely roundedtip andshort subapical innerspine; innerelement, insome paratypes, undifferentiatedas in Žg.9k. Leg4 (Žg. 9l). Basis with spinules ondistal margin; outerseta slender, arising fromshort papilla. Exopodite3-segmented; Ž rst segment unmodiŽed, with small thumb-like,fringed lobe at distal innercorner; outer spine slender,barely reachingmidlength of second segment; third segment with 2apical setae andshort, unfringed,spinous projection at distal innercorner .Endopoditemuch reduced in size, 1-segmented,digitiform, bare. Leg5 (Žg. 9m) small, squarish plate, distal innercorner produced into short, outcurvedhook; 2 spinules oninner margin near base ofclaw; distal convexmargin with 4slender setae; proximalseta longest; innermost seta slender andcontiguous with its neighbour. Leg6 (Žg. 8b) bare, ventrally directed,ovate protrusion, ending in small, pointed beak. Most males examinedcontained 1 reniformspermatophore (Ž g. 8h) in their body. PARASTENOCARIDIDAE FROMINDIA 727

Adultfemale. —Total lengthof allotype 0.33mm, of paratypes 0.33-0.39, av- erage0.35 mm ( N 25).Body (Ž g. 10a) broadly elliptical, with greatest widthat D aboutmidlength; 6 times as longas maximumwidth; withoutornamentation, ex- cept forsome ventral spinules at distal innercorner of anal somite; nointegumental windowsnoticed. Cephalothorax slightly longerthan next 2 somites combined,but

Fig. 10. Parastenocarissandhya n.sp., female. a, allotype habitus, dorsal; b, rostrum, enlarged; c-g,anal somite and caudal rami, dorsal; h, rightcaudal ramus, lateral; i, do.,ventral; j-l, left caudal ramus,lateral. Scale m fora; scale n forb-l; scales equal 50 ¹m. 728 Y.RANGA REDDY ofsame widthas either ofthem; pediger4 dilating posteriorly; pediger5 andgen- ital double-somitealmost equalin size; othersomites graduallytapering behind. Analoperculum of allotype (Žg. 10a, c) notdifferent fromthat ofholotype,but its shapeand position varyingin paratypes(Ž g. 10d-g). Genital Želd as in Žg.11a;

Fig. 11. Parastenocarissandhya n.sp., female. a, leg 5 andgenital double-somite, ventral; b,antennule,ventral; c, leg1; d,leg 2; e, f, do.,endopodite in differentparatypes; g, leg 3; h,leg 4 (endopoditeenlarged); i, leg 5. Scaleequals 50 ¹m. PARASTENOCARIDIDAE FROMINDIA 729 ventral surface ofdouble-somiteornamented on either side ofmedianaxis, as il- lustrated. Caudalrami divergent,as longas anal somite, about3 times as longas wide; armature as in male, butshowing greater variation in form(Ž g. 10j-l). Rostrum (Žg. 10a)as in female. Antennule(Ž g. 11b)7-segmented, with 0,4,4,2, 0, 0,and 8 setae; segments 4 and7 eachwith aesthetasc; aesthetasc onsegment 4somewhatslender, constricted at aboutmidlength and reaching tip ofantennule; that onsegment 7as longas, but slenderer,than the oneon segment 4. Othercephalic appendages(not illustrated) andleg 1(Žg. 11c)as in male. Leg2 (Žg. 11d). Basis with afewspinules at proximalouter corner; distal spinules absent.Exopodite as in male exceptfor outer spine onŽ rst exopodite- segment beinglonger and bare. Endopodite small, spatulate, with 1apical seta and 2spinules; shapeslightly varyingin paratypes(Ž g. 11e, f). Leg3 (Žg. 11g). Seta onbasis long.Exopodite short, 2-segmented; Ž rst segment withoutfringed extension at innerdistal corner;second segment with small, unfringedspinous process at innerdistal cornerand 2 apical setae. Endopodite stronglyreduced, being represented by very small, at chitinous thickening, coveredby minute hairs. Leg4 (Žg. 11h). Basis with short outerseta anda fewspinules close to distal outermargin. Exopodite as inmale. Endopodite1-segmented, stronger than in male, spiniform,with acute tip. Leg5 (Žg. 11i)small, rectangularplate; lateral margins nearlystraight; distal innerangle produced into upright,slender spinousprocess; 2spinules occurring ondistal innermargin. Distal convexborder with 4slender setae; outermost seta longest; othersetae dissimilar in size.

Etymology.—InV edic philosophy,the term “Sandhya”s. str.is genderless, signifyingthe junctionbetween the past andthe future; proposedhere as anounin appositionto the genericname. Remarks andafŽ nities. — Parastenocaris sandhya n.sp. comes veryclose to the sioli-group,established byNoodt (1963) for three Neotropicalspecies: P. sioli Noodt,1963, P. jakobi Noodt,1963, and P. digitata Noodt,1963 (I am unaware ofany additions orallocations tothis grouphaving been made subsequently). Noodt(1963) characterized the sioli-groupas follows: Verysmall andslender parastenocaridids (c.11 times as longas wide).Caudal rami simple, cylindrical, withoutessential sexual dimorphism; eachramus with 2outermarginal setae in the proximalsection. Operculumsmooth. Anal somite unarmed.Rostrum small. Legs1 and2 practically withoutsexual dimorphism.Endopodite of leg 2with 1outermarginal spine and3 terminal elements. Leg3 inmale strong,pincer- like, sometimes subdividedand hand-like. Endopodite of leg 3in female almost 730 Y.RANGA REDDY completely reduced.Basis ofleg 4in male with setae oninner margin, endopodite verysmall. Endopoditeof leg 4in female strong,with long, ornamented terminal spine,almost reachingend of second exopodite-segment. Leg 5 in bothsexes similar, small, plate-like, with 3-4elements; bothlegs ofa pair close to eachother . Leg6 in male triangular,small. P. sandhya differs fromthe diagnosis ofthe sioli-groupespecially with regardto the endopoditeof leg 2,which is sexually dimorphicand lacking the outermarginal seta. Comparedwith the three knownspecies ofthis group,the newspecies has a closer similarity to P. jakobi,thoughthe innerelement ofthe ‘pincers’of leg 3 is muchreduced, and leg 5endsin ashort,hooked projection at the innerdistal corner.Outside the sioli-group,pincers, though different fromthat of P. sandhya, are also foundin P. chelifer Delachaux,1923, from Surinam, and P. cruzi Noodt &Galhano,1969, from Portugal (H. K.Schminke,pers. comm.). It maybe recalled herethat ina parallel case, Enckell(1970) has, perforce, assigned P.curvispinus fromSri Lankato Noodt’ s (1963) remanei-groupof species fromSouth America, “ althoughthe geographicaldistribution indicates that aclose relationship betweenthis species andthe SouthAmerican ones is unlikely”. The same logic seems to holdfor P. sandhya as well. Noclear-cut sexual dimorphismis noticedin the caudalrami of P. sandhya, thoughthe rami are moreprone to variation inthe females thanin the males. Similarly,the shapeand position of the anal operculumalso varyin the females alone. Distribution. —Knownfrom the typelocality only.

ECOLOGICAL REMARKS

Parastenocaris gayatri n.sp. is animportant memberof the interstitial commu- nityof the River Krishna.It was commonlyfound in the coresamples (2-30cm), butscarce in the moist, exposedsand. Surface sediments collected nearthe water’s edge,using a planktonnet (mesh 70 ¹m) also yieldedfair numbersof this taxon. It was generallydominant when the habitat was stable followingthe cessation of the monsoonactivity, i.e.,from December onwards, but rare oreventotally absent duringJuly to Octoberwhen the river receives huge,turbid in ows from the catch- ment area.Though no quantitative estimates weremade, visual observationhas conŽrmed the occasional dominanceof this species overall otherparastenocari- dids.However, it showedno consistent seasonal pattern betweenthe twoyears of this study.Frequently, it was also also dominatedby P.curvispinus or P. sandhya. Duringthe summer months,a gobioidŽ sh, Glossogobiusgiuris (Hamilton, 1822)increases its numbersand becomes commercially important.I havefound PARASTENOCARIDIDAE FROMINDIA 731 its early juveniles (lengthc. 4 cm) heavilypreying upon, inter alia, several benthicharpacticoids includingparastenocaridids. A large numberof harpacticoid carcasses, most ofthem in excellent shape,have been found in the guts ofjuvenile Žsh capturedon 25May 1999. The prey species identiŽed are listed below,in the descendingorder of their numerical abundance,which closely correspondedwith that observedin the contemporaneouscore samples: (1) Leptastacus ?euryhyalinus Krishnaswamy,1957,adults, copepodids,and nauplii; (2) Parastenocariscurvi- spinus Enckell,1970, adults; (3) P. gayatri n.sp. adults; (4) Mesochrawolskii Jakubisiak,1933, adults (Harpacticoida); and(5) Chironomus larvae (Insecta). The guts of G. giuris adults, however,contained only strays of M. wolskii and several emptymolluscan shells. It is beyonddoubt that parastenocaridids constitute afavouredand perhaps easy diet forthe juvenile gobioidsin the River Krishna. P. savita n.sp., though co-occurring with other parastenocaridids reported herein,is characterized byits overall sparseness in the river,often with males outnumberingfemales. Likethe precedingspecies, it was neverfound in the exposedsand and was rare inthe surface sediments sampled withthe plankton net. P. sandhya n.sp.,on the otherhand, is morecommon than the precedingtwo species, frequentlyco-occurring with these andoccasionally dominatingthem. This studydoes not reveal anyconsistent seasonal trendin this taxon,either . Ofthe Žveparastenocaridid species recordedin the River Krishna, P.curvispi- nus is the most commonone. Instances ofco-occurrence of all Žvespecies are not rare.However, none of them was noticedin the samples overa monthfollowing un- precedented oodsin October,1998. It was also observedthat the presenceof algal scum onsediments in the shallow channel,as duringsummer, greatly restricted the species compositionand density ofparastenocaridids. Under such apparently un- favourableconditions, P. sandhya and P.curvispinus alonewere noticed, but only as strays. Thepeaks in the parastenocarididoccurrence coincided with the post- monsoonperiod (late Octoberto February)and were due mainly to P.curvispinus , P. gayatri, and P. sandhya.Thoughno quantitative data werecollected, the cores showeda profusepresence of the three newspecies.

Co-occurringfauna Thefollowing species ofHarpacticoida, which are predominantlyeuryhaline, havealready been recorded in plankton samples fromthe River Krishnaby Rad- hakrishna& Reddy(1976): Stenheliamadrasensis Wells, 1971( Stenheliakrish- D nensis Radhakrishna& Reddy,1978), Mesochrawolskii Jakubisiak,1933, Nitokra ?lacustris (Schmankevitsch,1875), Onychocamptuschathamensis (G. O. Sars, 1905), and O. mohammed (Blanchard& Richard,1891 ). Nauplii andcopepodids 732 Y.RANGA REDDY of Pseudodiaptomusbinghami Sewell, 1912,a denizenin the river (Reddy& Rad- hakrishna,1982), were found not infrequently in the present coresamples. Among the interstitial harpacticoids, Leptastacus ?euryhyalinus .Krishnaswamy,1957, generallydominated all the parastenocaridids almost throughoutthe studyperiod. Mesochrawolskii was fairly common,whereas N. ?lacustris and O.chathamen- sis wererather sporadic. Cletocamptusdeitersi (Richard,1897) occurred as strays. Thecyclopoid genera that weresporadically met withinclude Halicyclops , Mi- crocyclops, Eucyclops, Ectocyclops , and Paracyclops .TheCladocera were repre- sented bystrays of Macrothrix sp. and Chydorus sp. Also, Habrobathynella n. sp. andanother unidentiŽ ed parabathynellid species werenoticed but rarely, and in ex- tremely small numbers.Nematodes were sometimes foundin abundance,whereas oligochaetes wererare andfew. On oneoccasion (11 February 1999), a swarm of Chironomus larvae co-existed with variousparastenocaridid species, which,too, werefairly represented,and simultaneously so. Philodina,arotifer, was fairly abundanton three occasions.

GENERAL MORPHOLOGICAL REMARKS Accordingto Schminke(1991), most cases ofsexual dimorphismin the caudal rami inParastenocarididae are dueto the changesexhibited by the females. A sort ofvariation-gradientin the female caudalrami is apparentin the three species describedherein. The variation observedin P. gayatri n.sp. is remarkable,whereas it is tenuousin P. sandhya n.sp.and nearly non-existent in P. savita n. sp. Asrightlyemphasized by Reid (1994),form and location ofthe integumental windowson the bodyare constant within species. While the windowson the body are distinctly markedin P. gayatri,theyexist as vagueimpressions andare ofa slightly different pattern in P. savita,butapparently absent in P. sandhya as in othermembers ofthe sioli-group. Theanal operculumshows no variation in either sex of P. gayatri.However,its formand location varyappreciably in the females of P. savita and,to some extent, in the males of P. sandhya.Idonotknow if suchvariation couldbe an artifact, as consideredby Reid (1995). Aperusal ofthe literature showsthat leg 1andthe antennuleare rarely,if ever, consideredimportant in taxonomy.While it is true that leg 1is generallythe same inboth sexes, the relative proportions,besides ornamentation,of its segments on bothrami seem to provideuseful speciŽc information,as evidencedby the three species in question.Likewise, the relative size ofthe lateral spinousprocess onthe fourthand sixth segments, especially the latter, ofthe male antennule,seems to be species-speciŽc. It is stronglydeveloped in P. gayatri, reduced in P. sandhya, and absent in P. savita.Similarly,the length-widthratio ofthe antennalexopodite as well as ofthe mandibularpalp merits attention. PARASTENOCARIDIDAE FROMINDIA 733

ACKNOWLEDGEMENTS Iwishto express mygratitude to the authorities ofNagarjuna University for providingfunds under a U.G.C.MinorResearch Project, andto Prof. Dr . H.K.Schminke,Oldenburg University ,Oldenburg,for his helpfulcomments on anearlier draft ofthe manuscript.Thanks are also dueto mycolleague, Prof. S.V.Sharma,for identifying the gobioidŽ sh.

REFERENCES

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Firstreceived 23 February2001. Finalversion accepted 4 April2001.