A New Species Of Polycelis (Platyhelminthes, Tricladida, Planariidae) From China Author Dong, Zi-Mei Author Chen, Guang-Wen Author Zhang, He-Cai Author Liu, De-Zeng text Acta Zoologica Academiae Scientiarum Hungaricae 2017 2017-07-21 63 3 263 276 http://dx.doi.org/10.17109/azh.63.3.263.2017 journal article 10.17109/AZH.63.3.263.2017 2064-2474 Polycelis yangchengensis sp. n. (Figs 1–8) Materialexamined – Holotype : CQ1,onesetofsagittalsectionson 5 slides,Cheng- qianggenofTaihangMountainsinYangchengCounty, ShanxiProvince, 05 July 2002 , alt. 1658 mat 112°09.133 ′ E , 35°16.398 ′ N ; watertemperature 5.5–10.5°C, pH 6.0. Paratypes : CQ2, ChengqianggenofTaihangMountainsinYangchengCounty, Shanxi Province , 05 July 2002 , sagittalsectionson 8 slides; CQ3–4, ibid, transversesectionson 9, and 10 slides, respectively; CQ5–6, ibid, horizontalsectionson 6, and 8 slidesrespectively . Othermaterial : RB1–2,RenbiRutofTaihangMountainsinYangchengCounty, Shanxi Province , 06 July 2002 , alt. 1371 mat 112°08.424 ′ E , 35°16.251 ′ N ; watertemperature 5.5–10.5°C, pH 6.0, sagittalsectionson 9, and 8 slides; RB3, 4, 5, ibid, horizontalsectionson 6, 8, and 9 slidesrespectively; RB6–7, ibid, transversesectionson 15, and 10 slidesrespectively . Diagnosis – Prepharyngealtestes, fillingmostofthedorso- ventralspace extendingfromtheleveloftheovaries. Penisalongconewithwell-developed musculature.Boundarybetweenpenisbulbandpenispapillavague.Bulbar cavitynotobserved.Twospermductsenteringtotheejaculatoryductsepa- ratelyatthe 1/3rd–1/4thaslongasthepenisnearthedistalportion. Bursal canalwithaninnerwell-developedcoatofcircularmusclesandathinouter longitudinalone. Chromosomecomplementconsistingofadiploidnumber of 38 chromosomes, withkaryotypeformula 2n = 38 = 24m + 14sm. Etymology – Thisspeciesisnamedafterthegeographiclocation (Yangchengcounty) whereitstypespecimenwasfound. Externalcharacters – Thegeneralappearanceofthelivingspecimensofthisspecies isshowninFigs 1A, B. Thelivingsexuallymatureindividualsmeasureupto 12–17mm inlengthand 1.5–2.5 mminwidth. Inlife, theheadhasabroad, subtriangularformand frontalbodymarginprovidedwithamedianbulge, withapairofratherpointedauricles extendinganterolaterally. Posteriorlytotheauricles, thebodyisslightlynarrowerand thengraduallywidensagain. Afterthis, thebodyremainsaboutthesamewidthuntilthe regionofthecopulatorycomplex. Posteri- orlytothecopulatorycomplex, thebody graduallybecomesnarrowertoendina blunt tail (Figs 1A, B). Thecoloroflivingspecimensistawny todarkchocolate- brownofthedorsalside, while, theventralsideisslightlylighterthan thatofthedorsalbodysurface. Thecolorof fixedspecimensisgraywhite. Inlivingfully sexuallymaturespecimens, thecopulatory bursa, thepenisandapartofspermiducal vesiclecanbeseenfromtheventralside (Figs 1A, B). Thespeciespossessesnumerous smalleyesarrangedintwobands (80–140 intotal) neartheanteriorandthelateral marginsofthehead. Therearenoeyesin themid- dorsalpartofthehead. Theseocu- larbandsarewidestattheleveloftheau- riclesandterminatesomedistancebehind theauriclesattheanteriorone- fifthlevel Fig. 1. Photographsof Polycelisyangchengen- oftheprepharyngealregion. Withineach sis , livespecimens: A = sexuallyimmaturein- bandthesmalleyesaredistributedirregu- dividual, B = sexuallymatureindividuallarly (Figs 1A, B). Thepharynxisinsertedintheposteriorhalfofthebody. Itislongandstrongly musculaturewithalengthnearly 1/3–1/4thaslongasthebodylengthandwithawidthof nearly 1/3rdofthebodywidth. Themouthislocatedatthehindendofthemiddle 1/4th ofthebody. Thegenitalporeisfoundinthemidlineatratherposteriorlevelofthemiddle ofthepostpharyngealregion, theratioofthedistancesbetweenmouthtogonoporeand genitalporetotheendofthetailis 4:3 (Figs 1A, B). Internalcharacters – Thepharynxhasastructuretypicalofthegenus Polycelis inthe familyPlanariidae, themusculatureofthepharynxconsistsoftwolayers: outerepithelium ofpharynxunderlainbyalayeroflongitudinalmuscles, followedbylayerofcircularmuscles. Athicklayerofcircularmuscleunderinnerpharynxepitheliumisfollowedbyathin layeroflongitudinalmusclefibers. Theanteriorintestinaltrunkhas 6–10 pairsoframus; eachoftheposteriortrunks shows 12–16 ramus. Thenumeroustestesarewell-developed, large, andovalinshape. Fullysexuallyma- tureindividualshave 50–60 testesintotal, distributedintotwolongitudinalbands, oneon eachsideoftheanteriorintestinaltrunk (Fig. 2C).Thetestesextendfromthelevelofthe ovariestotherootofthepharynx (Figs 2C, 4A, B). Mosttestesfillalmostcompletelythe dorso- ventralspace (Figs 2A, B). Thetwospermductsenlargetoformspermiducalvesicles oneithersideoftheposteriorpartofthepharynx, whichdecreaseindiameterbeforepen- etratingtheproximal, anterolateralwallofthepenis ( Fig. 3A ). Withinthepenis, thesperm ductsrunseparatelyforaconsiderabledistance, andthenenterintotheejaculatoryduct respectivelyonlyatthe 1/3rd–1/4thaslongasthepenisnearthedistalportion ( Figs 3B–F ). Apairofmoderatelysizedovariesissituatedintheusualventralspacejustbehind thebrainandbetweenthesecondandthirddiverticulaoftheanteriorintestinaltrunk; it Fig. 2. Photomicrographsshowingthetestesindifferentsectionsof Polycelisyangchengensis : A = specimenRB7-2, transversesection, B = specimenRB2-5, sagittalsection, AandB showingthetestesfillingthedorso- ventralspace, C = specimenRB4-3, horizontalsection showingthetestesextendingtotherootofthepharynx Fig. 3. Photomicrographsshowingthetwospermductsindifferentsectionsalongthepe- nisof Polycelisyangchengensis : A = specimenCQ5-2, horizontalsectionshowingtheen- tranceoftwospermductsintothepenis, B = specimenRB4-2, horizontalsectionshowing thetwospermductsalongthepenis, C = specimenRB5-1, horizontalsectionsshowing twospermductsinpenis, D = specimenCQ4-5, horizontalsectionshowingthetwosperm ductsandejaculatoryductinthepenispapilla, E = specimenCQ2-4, sagittalsectionshowingthesinglespermductalongthepenis, F = specimenCQ4-9, transversesectionshowing thetwospermductsandejaculatory posteriorpart (thepositionofthepenispapilla) hastheshapeofanelongatedcone, and itsdorso- ventrallipissymmetrical, theejaculatoryductisratherwideandopensattipof penis (Figs 5, 6A–C). Themusculatureofthepenisiswell-developed, consistingofavery thicklayerofinnercircularfibersandathinlayerofouterlongitudinalone (Figs 5, 6D). Karyology – Weexamined 100 well-dispersedmetaphaseplatesof Polycelisyangchengensis .In 69.82. % ofthemetaphaseplatesthechromosomenumberwas 2n = 38. Karyotype parameters, includingtherelativelength, armratio, andcentromereindex, aregiveninTa- ble 1. AchromosomalplateandtheidiogramofthekaryotypeareshowninFigs 7A, Band C. Theresultsindicatethatthekaryotypeof Polycelisyangchengensis showsadiploidnumberof 38, withakaryotypeformulaof 2n = 38 = 24m + 14sm, inwhichNos 6, 9, 10, 13, 14, 16 and 19 aresubmetacentricandtheothersaremetacentric. Thefirstpairofchromosomes isclearlylargerthantheotherpairsbeing 5.37 timesaslargeasthesmallestchromosome. Distributionandecology – Thisspeciesisdistributedabovealt. 1100 m andshowstheobviousverticaldistribution (Figs 8A, B). Theywerefound togetherwith Dugesia speciesataboutalt. 1000 m , the Dugesia speciesaredistributedbelowalt. 1000 minthesamemountain. Uptothepresent, wehave notobservedfreshlyregeneratedanteriororposteriorendsbothinthelocality andthelaboratoryculture, so, wepresumethatthisspeciesreproducesonly sexually. Itsbreedingseasonisusuallyfromautumntothenextspring (Octo- bertoFebruaryofnextyear). Thenewlylaidcocoonsarered- brown (Fig. 8C), andthenturnbrownishdarkafter 2 to 3 days, theyhatchabout 70–110 days Fig. 5. Polycelisyangchengensis : HolotypeCQ1, sagittalreconstructionofthecopulatoryapparatus (anteriortotheright) Table 1. Karyotypeparametersof Polycelisyangchengensis .

No. ofRelativelengthArmratioCentromereChromosome chromosomeindextype
1	15.14±0.54	1.04±0.014	48.93±0.35 m
2	7.29±0.03	1.29±0.016	43.85±0.29 m
3	6.71±0.59	1.52±0.011	39.81±1.82 m
4	5.55±0.14	1.26±0.025	44.56±0.47 m
5	5.25±0.09	1.36±0.011	42.53±0.21 m
6	5.20±0.16	2.22±0.06	31.82±0.57 sm
7	5.11±0.01	1.52±0.03	40.01±0.45 m
8	4.98±0.02	1.66±0.03	37.92±0.46 m
9	4.93±0.05	2.38±0.06	30.25±0.58 sm
10	4.71±0.12	1.75±0.02	36.48±0.31 sm
11	4.59±0.20	1.20±0.01	45.45±0.21 m
12	4.47±0.26	1.33±0.016	43.08±0.31 m
13	4.41±0.19	2.64±0.03	27.63±0.24 sm
14	4.15±0.08	1.92±0.02	34.36±0.27 sm
15	4.14±0.18	1.32±0.012	43.23±0.22 m
16	3.73±0.02	2.18±0.013	31.45±1.91 sm
17	3.48±0.12	1.36±0.08	42.44±1.62 m
18	3.32±0.20	1.47±0.017	40.52±0.29 m
19	2.82±0.05	1.79±0.016	35.94±0.22 sm

±: Meanvaluesandstandarddeviation afterlayingat 4°Cinthelaboratoryand 50–80 daysinthefieldlocations, 4 to 6 juvenilesemergefromonecocoonandtheyare 3–5 mmlongand 0.6–1.0 mm wide. Thecocoonissphericalinshape (2–2.5 mmindiameter) andwithout astalk, thenewjuvenileplanariansarewhiteandtranslucent, theyattainthe colorofmaturespecimensinthecourseofthefirstmonth (Fig. 8C).