Dicharax alticola, 2017

Asami, Takahiro, 2017, Revision of the Alycaeidae of China, Laos and Vietnam (Gastropoda: Cyclophoroidea) I: The genera Dicharax and Metalycaeus, Zootaxa 4331 (1), pp. 1-124 : 14-21

Dicharax (?) alticola Páll-Gergely & Hunyadi n. sp.

FIGUrEs 8A , 9A–D , 10A–B , 11 , 12A–B , 13A–B .

Type material. HOLOTypE HNHM 99702 ( Ex COLL. J.U. OTaNI), JUO/2 paraTypEs (sHELLs aNd ETHaNOL-prEsErvEd bOdIEs) , OKA /1 paraTypE, PGB/1 paraTypE ( Ex COLL. K. OkUbO), 20130913A CHINa, SICHUaN, LIaNGsHaN YIzU ZIzHIzHOU, YaNyUaN XIaN, BaINIaO ZHEN, KEdENG RONGdONG (CavE), 2618 m, 27°43.103'N, 101°31.021'E, LEG. K. OHara, K. OkUbO, & J.U. OTaNI, 13 SEp 2013 ; HA/15 paraTypEs, 2015/59 CHINa, SICHUaN, LIaNGsHaN ZHOU, YaNyUaN XIaN, BaINIaO ZHEN, wEsTErN EdGE Of KEdENG CUN, 2640 m, 27°43.897'N, 101°31.208'E, LEG. A. HUNyadI & M. SzEkErEs, 11 JUNE 2015 ; OKA /5 paraTypEs, PGB/2 paraTypEs ( Ex COLL. OkUbO), 20040520A YUNNaN, NINGLaNG YIzU ZIzIxIaN, HONGqIaO XIaNG, arOUNd THE GUyI RONGdONG (CavE), 2650 m, 27°31.352'N, 100°48.214'E, LEG. K. OkUbO, 20 May 2004 .

Etymology. THE NamE alticola Is a rEfErENCE TO THE HIGH aLTITUdE wHErE THE spECIEs was fOUNd.

Diagnosis. A smaLL TO mEdIUm sIzEd spECIEs wITH sTraIGHT, LOw, bUT sHarp rIbs ON R2, wHICH arE fUsEd NEar THE TUbE, rEGULarLy rIbbEd R1 aNd R3, aNd a rOUNdEd, NOT CrENULaTEd pErIsTOmE wITH sHarp OUTEr LIp.

Description. SHELL ( FIGUrE 8A ) IvOry, aLTHOUGH mOsT avaILabLE sHELLs Had rEddIsH dIrT bETwEEN THEIr rIbs; sHELL OUTLINE raTHEr rOUNdEd frOm dOrsaL vIEw, spIrE ELEvaTEd, EdGE Of bOdy wHOrL rOUNdEd; prOTOCONCH ( FIGUrEs 10A–B ) LOw, sEEmINGLy smOOTH bUT raTHEr maTTE; wITH 1.5 Or vEry sLIGHTLy fEwEr wHOrLs; R1 CONsIsTs Of 1.25–1.5 wHOrLs, raTHEr rEGULarLy rIbbEd; NO spIraL LINEs vIsIbLE bETwEEN rIbs; dENsITy Of rIbs ON R1 CONsIsTENT; TraNsITION bETwEEN R1 aNd R2 NOT CONspICUOUs bUT vIsIbLE, bECaUsE rIb dENsITy Of R2 HIGHEr THaN THaT Of R1; R2 + R3 apprOxImaTELy a qUarTEr Of wHOrL LONG; THEy arE abOUT EqUaL IN LENGTH, Or R3 Is sLIGHTLy LONGEr THaN R2; rIbs ON R2 LOw, NOT CUrvEd, raTHEr sHarp, CONNECTEd TO EaCH OTHEr NEar TUbE ( FIGUrEs 9A–B ); THE CrOss sECTION Of R2 was ExamINEd IN ONE spECImEN ( FIGUrEs 9C–D , 68E ): aNTErIOr CrUsT fOrms a rELaTIvELy LOw, bLUNT, NOT CavErNOUs, NEarLy sTraIGHT rIb; aNTErIOr aNd pOsTErIOr CrUsTs ONLy TOUCH EaCH OTHEr (aNTErIOr CrUsT dOEs NOT fOLd OvEr THE pOsTErIOr ONE); CrOss sECTIONaL vIEw Of mICrOTUNNEL sLIT-LIkE; rIb dENsITy Of R3 sImILar TO THaT Of R1, rIbs raTHEr rEGULar HErE as wELL; CONsTrICTION mOdEraTELy CONspICUOUs bETwEEN R2 aNd R3; R3 wITH a bLUNT swELLING ON ITs mIddLE; apErTUrE rEGULarLy rOUNdEd, OUTEr LIp sTraIGHT, ExpaNdEd bUT NOT rEfLECTEd, sHarp; INNEr LIp vEry sLIGHTLy THICkENEd, sOmEwHaT prOTrUdING aNTErIOrLy; bOUNdary bETwEEN THE TwO LIps CLEarLy vIsIbLE.

Measurements (in mm). D = 3.5–4.1, H = 2.5–2.9 (N = 4).

Operculum. THE OpErCULa Of TwO spECImENs wErE ExamINEd. THE OUTEr sIdE Of bOTH OpErCULa wErE COvErEd IN mUd; bECaUsE CLEaNING mIGHT rEsULT IN dEsTrUCTION Of THE OrIGINaL sTrUCTUrE THEy wErE NOT ExamINEd. HOwEvEr, NO ELEvaTEd spIraL baNd Is vIsIbLE ON THE OUTEr sUrfaCE. THE INNEr sIdE ( FIGUrE 11 ) Has a sIGNIfICaNTLy ELEvaTEd, CENTraL NIppLE. THE OpErCULUm Is rELaTIvELy THICk OvEraLL.

Anatomy. ONE maLE spECImEN was aNaTOmICaLLy ExamINEd (paraTypE frOm THE TypE LOCaLITy, COLL. JUO). THE pENIs Is LarGE (mUCH LONGEr THaN THE rIGHT TENTaCLE) aNd fLaT wITH TrapEzOId ENd ( FIGUrEs 12A–B ).

Radula. THE radULa Of ONE spECImEN was ExamINEd (samE as THE aNaTOmICaLLy ExamINEd spECImEN). RadULa TypICaL CaENOGasTrOpOd, sImILar TO sOmE OTHEr aLyCaEId radULaE (sEE VENmaNs 1956). RadULar TEETH arraNGEd IN vsHapEd rOws, EaCH TraNsvErsE rOw wITH sEvEN TEETH (2-1-1-1-2). CENTraL TOOTH sTrONGLy CONsTrICTEd IN ITs mIddLE parT, wITH fIvE sHOrT, raTHEr bLUNTLy pOINTEd CUsps, Of wHICH THE CENTraL ONE Is THE LarGEsT. BasE Of pLaTE CONCavE, aNTErIOr marGIN rOUNdEd aNd sINUOUs IN THE mIddLE . THE LaTEraL aNd THE TwO marGINaL TEETH dO NOT HavE THE mEdIaN CONsTrICTION Of THE pLaTEs, aNd arE sEEmINGLy LONGEr aNd mOrE sLENdEr THaN THE CENTraL TOOTH. LaTEraL TEETH wITH THrEE sTrONGLy dEvELOpEd, OvaTE, pOINTEd CUsps , THE mIddLE ONE bEING mUCH LarGEr THaN THE OTHErs. THE marGINaL TEETH HavE fOUr pOINTEd, TrIaNGULar CUsps ( FIGUrEs 13A–B ).

Variation in specimens. NO NOTabLE varIabILITy was dETECTEd wITHIN aNd bETwEEN pOpULaTIONs.

Differential diagnosis. Dicharax alticola n. sp. dIffErs frOm D. cristatus by THE fINE sTrUCTUrE Of THE rIbs ON R2. NamELy, aLL D. cristatus pOpULaTIONs HavE TypICaL Dicharax -LIkE rIbs (CUrvEd TOwards THE apErTUrE), wHErEas THE rIbs Of D. alticola n. sp. arE LOw, sTraIGHT, aNd NEar THE TUbE THE NEIGHbOUrING rIbs arE fUsEd. FUsEd R2 rIbs HavE bEEN ObsErvEd ONLy IN JapaNEsE spECIEs Awalycaeus aNd Cipangocharax spECIEs, bUT IT sEEms UNLIkELy THaT Dicharax alticola n. sp. Has a CLOsE pHyLOGENETIC rELaTIONsHIp wITH THOsE spECIEs. Dicharax fargesianus Is sImILar TO D. alticola n. sp. IN TErms Of THE GENEraL sHapE Of THE sHELL, aNd THE prOpOrTIONs Of THE rEGIONs. THE NEw spECIEs, ON THE OTHEr HaNd, Has a mOrE ELEvaTEd spIrE, THINNEr pErIsTOmE, aNd LEss rEGULar rIbs ON R2. Dicharax dolichodeiros Is aLsO sImILar TO D. alticola n. sp. IN GENEraL sHELL sHapE. HOwEvEr, THE rIbs Or D. alticola n. sp. arE LEss rEGULar, wHICH arE IN CONTaCT wITH EaCH OTHEr NEar THE TUbE, aNd Has a sHOrTEr R2. SEE aLsO UNdEr D. robustus n. sp.

Distribution. Dicharax alticola n. sp. Is kNOwN frOm NOrTHErN YUNNaN aNd sOUTHErN SICHUaN PrOvINCEs. THE dIsTaNCE bETwEEN THE TwO kNOwN pOpULaTIONs Is apprOxImaTELy 75 km.

Figures

FIGURE 8. Shells of Dicharax species. A. Dicharax (?) alticola Páll-Gergely & Hunyadi n. sp. (holotype, HNHM 99702). B. Dicharax (?) fargesianus (Heude, 1885) (lectotype, MCZ 167229). C. Dicharax (?) immaculatus Páll-Gergely n. sp. (holotype, HNHM 99707). D. Dicharax (?) dolichodeiros Heude, 1890 (2013 / 6). E. Dicharax dolichodeiros (2016 / 100). Scale represents 5 mm. All photos: B. Páll-Gergely.

FIGURE 9. R 2 ribs of Dicharax species. A – D. Dicharax (?) alticola Páll-Gergely & Hunyadi n. sp. (A – B. 20130913 A, OC 1, coll. JUO, C – D. 20040520 A, coll. PGB). E – F. Dicharax (?) dolichodeiros (2013 / 6). All images: B. Páll-Gergely.

FIGURE 10. Protoconchs of Dicharax species. A – B. Dicharax (?) alticola Páll-Gergely & Hunyadi n. sp. (A. 20130913 A, OC 1, coll. JUO, B. 20040520 A, coll. PGB). C – D. Dicharax (?) fargesianus (Heude, 1885) (lectotype). E – F. Dicharax (?) dolichodeiros (2013 / 6). All images: B. Páll-Gergely.

FIGURE 11. Operculum of Dicharax (?) alticola Páll-Gergely & Hunyadi n. sp. (inner side, 20130913 A, coll. JUO). All images: B. Páll-Gergely.

FIGURE 12. Males of Dicharax species. A – B. Dicharax (?) alticola Páll-Gergely & Hunyadi n. sp., paratype from the type locality, coll. JUO. C – D. Dicharax cristatus (Möllendorff, 1886), 20130911 B, coll. JUO. E – F. Dicharax depressus (Bavay & Dautzenberg, 1912), 20080510 B, coll. JUO. G – H. Dicharax (?) immaculatus Páll-Gergely n. sp. 20110420 E (2 different specimens), coll. JUO. Figures not to scale.

FIGURE 13. Radulae of Dicharax species. A – B. Dicharax (?) alticola Páll-Gergely & Hunyadi n. sp., (paratype from the type locality, 20130913 A, OC 3, coll. JUO). C. Dicharax cristatus (Möllendorff, 1886) (2015 / 56, coll. PGB). D. Dicharax depressus (Bavay & Dautzenberg, 1912) (20080510 B, coll. JUO). E. Dicharax fimbriatus (Bavay & Dautzenberg, 1912) (20081112 B, coll. JUO). F. Dicharax (?) immaculatus Páll-Gergely n. sp (20110420 E, coll. JUO). All images: B. Páll-Gergely.

FIGURE 68. Schematic diagram of cross sections of R 2 of Dicharax and Metalycaeus species. The aperture opens leftwards. A. Dicharax bison Páll-Gergely & Hunyadi n. sp. B. Dicharax robustus Páll-Gergely & Hunyadi, n. sp. C. Dicharax fimbriatus (Bavay & Dautzenberg, 1912). D. Dicharax depressus (Bavay & Dautzenberg, 1912). E. Dicharax (?) alticola Páll- Gergely & Hunyadi n. sp. F. Dicharax (?) immaculatus Páll-Gergely n. sp. G. Dicharax (?) moellendorffi (Kobelt & Möllendorff, 1886). H. Metalycaeus muciferus (Heude, 1885). I. Metalycaeus oharai Páll-Gergely & Hunyadi n. sp. J. Metalycaeus (?) okuboi Páll-Gergely & Hunyadi, n. sp. Abbreviations: a: anterior crust; p: posterior crust; t: tunnel.