Macrostomum lankouensis Lin & Wang, 2017

Lin, Yi-Tao, Feng, Wei-Tao, Xin, Fan, Zhang, Lv, Zhang, Yu & Wang, An-Tai, 2017, Two new species and the molecular phylogeny of eight species of Macrostomum (Platyhelminthes: Macrostomorpha) from southern China, Zootaxa 4337 (3), pp. 423-435 : 429-434

publication ID	https://doi.org/ 10.11646/zootaxa.4337.3.7
publication LSID	lsid:zoobank.org:pub:DC8D40D7-CD12-4165-8988-A342E3635987
DOI	https://doi.org/10.5281/zenodo.6028613
persistent identifier	https://treatment.plazi.org/id/03D587BE-3712-FFA2-C4C4-46C56022FCCF
treatment provided by	Plazi
scientific name	Macrostomum lankouensis Lin & Wang
status	sp. nov.

Treatment

Macrostomum lankouensis Lin & Wang View in CoL , n. sp.

( FIgS. 4–6 View FIGURE 4 View FIGURE 5 View FIGURE 6 )

Material examined. HOlOTYpE: PLA-MA0030, mOUNTED SpEcImENS. THIS NEw SpEcIES wAS cOllEcTED frOm A cOUNTrY brOOk IN HEYUAN, GUANgDONg PrOvINcE, CHINA (2358'39"N, 11502'44"E), bY ZHANg Lv . PArATYpE: PLA- MA0031~0032, mOUNTED SpEcImEN. PArATYpE: PLA-MA0033~0036, SErIAl SEcTION. PArATYpE: PLA-MA0037~0039, mOUNTED pENIS STYlETS. All THE TYpE SpEcImENS ArE DEpOSITED IN THE INSTITUTE Of ZOOlOgY, CHINESE AcADEmY Of ScIENcES ( IZCAS), BEIJINg, CHINA.

Etymology. THE NAmE Of THIS NEw SpEcIES IS DErIvED frOm THE NAmE Of THE LANkOU TOwN IN DONgYUAN COUNTY, HEYUAN, GUANgDONg PrOvINcE, CHINA.

Description. WHEN mOvINg, THE rOD-SHApED bODY IS DOrSOvENTrAllY flATTENED. THE lENgTH AND wIDTH Of THE bODY ArE 1,050–1,400 µm AND 200–300 µm, rESpEcTIvElY (N=6) ( FIgS. 4A View FIGURE 4 , 5A View FIGURE 5 , 6A View FIGURE 6 ). THE bODY HAS DENSE cIlIA (2–4 µm IN lENgTH, N=3) AND SENSOrY HAIrS (1–3 HAIr pEr bUNDlE, 8–10 µm IN lENgTH, N=5) ON ITS SUrfAcE. NUmErOUS rHAbDITES cOvEr THE SUrfAcE Of THE wHOlE bODY. THE DISTANcE bETwEEN THE rOUNDED ANTErIOr END Of bODY AND THE pAIrED blAck rENIfOrm EYES ArE 140–180 µm (N=6), AND THE DISTANcE bETwEEN EYES IS 10–20 µm (N=6). THE pHArYNX IS 110–150 µm IN lENgTH (N=6), AND pHArYNgEAl glANDS ArE lOcATED ON EITHEr SIDE Of IT ( FIgS. 4B View FIGURE 4 , 5C View FIGURE 5 ). THE lENgTH Of THE INTESTINE IS 520–580 µm (N=6). THE pOSTErIOr END AND ADHESIvE glANDS ArE IDENTIcAl TO THOSE Of M. shiyanensis ( FIgS. 4A View FIGURE 4 , 5A, 5D View FIGURE 5 , 6A View FIGURE 6 ).

THE fEmAlE rEprODUcTIvE SYSTEm Of Macrostomum lankouensis n. sp . IS SImIlAr TO THAT Of M. shiyanensis N. Sp .. THE OvArIES, 230– 230 µm IN lENgTH AND 35–48 µm IN wIDTH (N=12), ArE lOcATED ON EITHEr SIDE Of THE INTESTINE AT 50% Of THE bODY lENgTH. THE fEmAlE ATrIUm IS lOcATED pOSTErIOr TO THE INTESTINE ( FIgS. 5A View FIGURE 5 , 6A View FIGURE 6 ), AND THE fEmAlE gONOpOrE OpENS AT THE vENTrAl SIDE Of THE fEmAlE ATrIUm. ( FIgS. 5D View FIGURE 5 , 6B View FIGURE 6 ). AS fOr mAlE rEprODUcTIvE SYSTEm, THE TESTES, 195–250 µm IN lENgTH AND 30–50 µm IN wIDTH (N=12), ArE lOcATED ON EITHEr SIDE Of THE INTESTINE AT 33–50% Of THE bODY lENgTH. THE ArrANgEmENT Of vAS DEfErENTIA, fAlSE vESIcUlA SEmINAlIS (92–112 µm IN lENgTH, 23–45 µm IN wIDTH, N=6), vESIcUlA SEmINAlIS (AbOUT 55 µm IN DIAmETEr, N=6) AND vESIcUlA grANUlOrUm IS AlSO SImIlAr TO THAT Of M. shiyanensis n. sp. ( FIgS. 4C View FIGURE 4 , 5D View FIGURE 5 , 6B–C View FIGURE 6 ). THE C-SHApED pENIS STYlET IS 110–135 µm IN lENgTH, AND DIAmETErS Of ITS bASE rEgION AND DISTAl OpENINg ArE 30–40 µm AND 5–6 µm (N=3), rESpEcTIvElY. ITS pOSTErIOr END IS A C-SHApED cUrvE, wHIlE THE DISTAl cIrcUlAr OpENINg pOINTS rIgHT JUST IN frONT Of THE mAlE gONOpOrE, wHIcH lIES bEHIND THE STYlET ( FIgS. 5D View FIGURE 5 , 6B View FIGURE 6 ).

SImIlAr TO M. shiyanensis N. Sp. , THE lENgTHS Of THE mATUrE SpErm, THE SHAfT, AND THE brUSHES Of M. lankouensis n. sp. ArE 75–80, 35–40, AND 3.5–5 µm (N=3), rESpEcTIvElY. HOwEvEr, THE pAIrED brISTlES ArE 8–9 µm IN lENgTH (N=3), lONgEr THAN THOSE Of M. shiyanensis n. sp. ( FIgS. 4J View FIGURE 4 , 6E View FIGURE 6 ).

Taxonomic comparison. AmONg THE rEcOrDED SpEcIES Of THE gENUS Macrostomum , 19 SpEcIES HAvE THE C- SHApED pENIS STYlET, wHIlE EIgHT Of THESE 19 SpEcIES HAvE AN ADDITIONAl DISTAl cUrvE bESIDES THE C-SHApED cUrvE, wHIcH IS SImIlAr TO THAT Of M. lankouensis n. sp. ( TAb. 4). AmONg THE EIgHT SpEcIES, THE DISTAl cUrvE Of M. bicurvistyla ArmONIES et al., 1987 pOINTS TO THE cONcAvE SIDE Of THE C-SHApED cUrvE, wHIlE THE DISTAl OpENINgS Of M. gilbert FErgUSON, 1939; M. pithecusae PApI, 1959; AND M. sinensis WANg, 2005 ArE SHArp. IN cONTrAST, THE DISTAl cUrvE Of M. lankouensis n. sp. pOINTS TO THE cONvEX SIDE Of THE “C” cUrvE AND THE OpENINg IS cIrcUlAr. IN M. johni YOUNg, 1972, THE pENIS STYlET IS 80–98 µm lONg. THE DISTAl cUrvE bENDS ApprOXImATE bY 90, wHIlE IT OpENS TOwArDS THE ANTErIOr END Of SpEcImEN. THE DIAmETEr Of THE DISTAl OpENINg IS 4.4–5.4 µm. AS fOr M. leptos AN-DEr-LAN, 1939, DEScrIpTION Of ITS pENIS STYlET IS NOT THOrOUgH, bUT OvErAll IT IS IN “C” SHApE AND ITS DISTAl pArT bENDS SlIgHTlY TOwArDS THE cONvEX SIDE Of THE C-SHApED cUrvE. IN cONTrAST, THE lENgTH Of THE STYlET Of M. lankouensis n. sp. IS 110–135 µm. THE EXTErIOr SIDE Of THE DISTAl cUrvE IS SEmIcIrcUlAr IN SHApE AND THE DISTAl END OpENS TOwArDS THE pOSTErIOr END Of SpEcImEN. Macrostomum gallicum AX, 2008 AND M. heyuanensis SUN et al., 2015 ArE mOST SImIlAr TO M. lankouensis n. sp. IN THE mOrpHOlOgY Of THEIr pENIS STYlE. IN THESE THrEE SpEcIES, THEIr pENIS STYlETS All HAvE DISTAl bENDS TOwArDS THE cONvEX SIDE Of THE “C”-SHApED cUrvE, wHIlE THEIr DISTAl OpENINgS ArE All cIrcUlAr. HOwEvEr, THE DISTAl ENDS Of THE pENIS STYlET Of M. gallicum AND M. heyuanensis ArE bOTH THIckENED, wHIlE SImIlAr THIckENINg IS AbSENT IN M. lankouensis n. sp. BASED ON THE DISTINcT mOrpHOlOgIcAl cHArAcTErISTIc Of pENIS STYlET Of M. lankouensis , IT IS EvIDENT THAT THIS SpEcIES IS A NEw SpEcIES wITHIN THE gENUS Macrostomum .

* Measurement based on images and scales from the references. NA: not available.

Phylogenetic analysis. THE pHYlOgENETIc TrEES gENErATED frOm cONcATENATED 18S AND 28S rDNA bY mAXImUm lIkElIHOOD (ML) AND NEIgHbOr JOININg (NJ) mETHODS ArE SHOwN IN FIgS 7 View FIGURE 7 & 8 View FIGURE 8 . BOTH rESUlTS INDIcATE THAT THE THrEE SpEcImENS Of Macrostomum lankouensis N. Sp ., AS wEll AS THOSE Of M. shiyanensis n. sp., clUSTEr TOgETHEr rESpEcTIvElY, fOrmINg A wEll-SUppOrTED clADE wITH THE OTHEr SpEcIES wITHIN THE gENUS Macrostomum . FUrTHErmOrE, OUr rESUlTS AlSO SHOw THAT THESE TwO NEw SpEcIES ArE clOSElY rElATED TO M. heyuanensis , M. finlandense AND M. sinensis , wHIlE M. acus IS clOSElY rElATED TO M. obtusa . AS SUcH, bOTH pHYlOgENETIc AND mOrpHOlOgIcAl EvIDENcE SUppOrT THE ESTAblISHmENT Of M. lankouensis n. sp. AND M. shiyanensis n. sp. AS NEw SpEcIES wITHIN THE gENUS.

Discussion. THE mOrpHOlOgY Of pENIS STYlETS IS ONE Of THE mOST ImpOrTANT crITErIA fOr THE clASSIfIcATION Of SpEcIES wITHIN THE gENUS Macrostomum (ZHAO et al. 2011). HOwEvEr, THE pENIS STYlET bENDS IN mUlTIplE plANES AND fOrmS A cOmplEX STrUcTUrE IN SOmE SpEcIES, INclUDINg M. xiamenensis WANg, 2004A AND M. zhaoqingensis LIN et al., 2017, wHIlE SOmE Of THEIr pENIS STYlETS ArE qUITE SImIlAr (ScHärEr et al. 2011). THErEfOrE, IDENTIfIcATION Of NEw SpEcIES IS pArTIcUlArlY cHAllENgINg IN SOmE cASES. REcENTlY, A mOrE cOmprEHENSIvE STUDY USINg pHYlOgENETIc ANAlYSIS, TOgETHEr wITH cOmpArATIvE INvESTIgATION Of SpErm AND pENIS STYlET mOrpHOlOgY AND mATINg bEHAvIOr wAS cONDUcTED TO EXAmINE THE EvOlUTION AND cOEvOlUTION Of THE Macrostomum , SUggESTINg THAT IT IS AN EffIcIENT wAY TO ASSESS DIvErSITY AND EvOlUTION wITHIN THE gENUS (ScHärEr et al. 2011). TO DATE, SpErm mOrpHOlOgY HAS ONlY bEEN STUDIED IN A vErY lImITED NUmbEr Of SpEcIES wITHIN Macrostomum , wHIlE mOlEcUlAr SEqUENcES, INclUDINg 18S rDNA, 28S rDNA, COI AND wHOlE mITOcHONDrIA SEqUENcES, IS NOT AvAIlAblE Or AT lEAST NOT cOmplETE IN mANY rEcOrDED SpEcIES. IN THIS STUDY AND THrEE prEvIOUS STUDIES, wE HAvE prOvIDED DETAIlED INfOrmATION IN TErmS Of SpErm DESIgN AND mOrpHOlOgY Of pENIS STYlET IN EIgHT SpEcIES Of Macrostomum , INclUDINg M. heyuanensis , M. dongyuanensis SUN et al., 2015; M. zhujiangensis , M. baoanensis FANg et al., 2016; M. chongqingensis , M. zhaoqingensis LIN et al., 2017 (UNDEr rEvIEw); M. shenzhenensis , M. qiaochengensis WANg et al., 2017. AS fOr pHYlOgENETIc INfOrmATION, OTHEr THAN THE TwO NEw SpEcIES rEpOrTED IN THIS STUDY, wE HAvE AlSO SUpplEmENTED cONcATENATED 18S AND 28S rDNA SEqUENcES Of Macrostomum acus , M. obtusa , M. bicaudatum , M. dongyuanensis , M. heyuanensis AND M. sinensis . AlTHOUgH IT IS STIll fAr frOm prOvIDINg THE OvErAll pIcTUrE Of Macrostomum DIvErSITY AND EvOlUTION wITHIN THE rEgION, THIS STUDY SHOUlD prOvIDE bASElINE INfOrmATION fOr fUrTHEr STUDIES Of THE pHYlOgENY Of THE gENUS.