Dicharax Asami, 2017, n. sp.
Creators: name: Asami, Takahiro
Publisher: name: Zenodo
Year: 2017
Subjects: Biodiversity
Taxonomy
Animalia
Mollusca
Gastropoda
Architaenioglossa
Alycaeidae
Dicharax

description: Dicharax (?) immaculatus Páll-Gergely n. sp.
FIGUrEs 8C, 12G–H, 13F, 17C–F.
Type material. HOLOTypE (= sHELL aNd bOdy IN ETHaNOL, HNHM 99707), JUO/1 paraTypE (sHELL + bOdy IN ETHaNOL), JUO/3 paraTypEs + 1 paraTypE (CrOss sECTION Of rIbs ObsErvEd), PGB/1 paraTypE (R2 rIbs ObsErvEd wITH SEM) + 1 paraTypE (INNEr sIdE Of THE OpErCULUm ObsErvEd wITH SEM) (bOTH Ex. COLL. JUO) + 1 paraTypE (sHELL, bOdy IN ETHaNOL, radULa ON dOUbLE-faCEd adHEsIvE TapE), 20110420E CHINa, GaNsU, WEN XIaN, TIELOUzaNGzU XIaNG, SaNjIaOyaN, 1646 m, 32°53.180'N, 104°24.672'E, LEG. Y. NakaHara, K. OkUbO & J.U. OTaNI, 20 Apr 2011; samE LOCaLITy aNd COLLECTOr; JUO/6 paraTypEs, PGB/1 paraTypE (OUTEr sIdE Of OpErCULUm ObsErvEd wITH SEM, Ex COLL. J.U. OTaNI), JUO/1 paraTypE (sHELL, bOdy IN ETHaNOL, radULa IN ETHaNOL), 20110420D CHINa, GaNsU, WEN XIaN, TIELOUzaNGzU XIaNG, abOvE pOwEr LINE (OppOsITE sHOrE), 1558 m, 32°53.716'N, 104°25.831'E, LEG. Y. NakaHara, K. OkUbO & J.U. OTaNI, 20 Apr 2011.
Etymology. THE NamE ImmaCULaTUs (LaTIN: ImmaCULaTE, sTaINLEss) rEfErs TO THE pErfECT LOOkING, pUrE, bEaUTIfUL sHELL Of THE NEw spECIEs.
Diagnosis. A smaLL, fLaT spECIEs wITH smOOTH R1, NOrmaLLy LONG R2 aNd R3; R2 wITH ExTrEmELy fINE, LOw rIbs (aNTErIOr CrUsT LOw, CUrvEd IN pOsTErIOr dIrECTION); R3 wITH LOw, bLUNT swELLING; pErIsTOmE rOUNdEd.
Description. SHELL (FIGUrE 8C) rEddIsH bEIGE; sHELL OUTLINE OvaL frOm dOrsaL vIEw, spIrE vEry LITTLE ELEvaTEd, sHELL NEarLy fLaT; EdGE Of bOdy wHOrL rOUNdEd; prOTOCONCH LOw, CONsIsTING Of 1.75 wHOrLs, GLOssy; bOUNdary bETwEEN prOTOCONCH aNd R1 HardLy vIsIbLE; R1 CONsIsTs Of abOUT 1.5 wHOrLs, aLmOsT COmpLETELy smOOTH, wITH ONLy vEry INCONspICUOUs, IrrEGULar GrOwTH LINEs, wHICH arE vIsIbLE UNdEr HIGH maGNIfICaTION ONLy; TraNsITION bETwEEN R1 aNd R2 vEry CLEarLy vIsIbLE UNdEr mICrOsCOpE; R2 ExTrEmELy dENsELy rIbbEd (FIGUrEs 17C–D), wITH LOw, bLUNT rIbs; CrOss-sECTIONaL vIEw Of R2 was ExamINEd IN ONE spECImEN (FIGUrEs 17E–F, 68F): aNTErIOr CrUsT fOrms a LOw, bLUNT, OCCasIONaLLy sLIGHTLy HOLLOw rIb, sTrONGLy bENT OvEr pOsTErIOr CrUsT (aNTErIOr CrUsT NOT bENT IN aNTErIOr dIrECTION, as IN mOsT OTHEr Dicharax spECIEs); CrOss sECTIONaL vIEw Of mICrOTUNNELs NEarLy rOUNdEd drOp sHapEd; COmbINEd LENGTH Of R2 aNd R3 sLIGHTLy mOrE THaN 90 dEGrEEs; R2 aNd R3 arE Of abOUT THE samE LENGTH, Or R3 vEry sLIGHTLy LONGEr; TraNsITION bETwEEN R2 aNd R3 CLEarLy vIsIbLE bECaUsE Of CHaNGE Of sCULpTUrE, CONsTrICTION bETwEEN R2 aNd R3 vEry sLIGHT; R3 smOOTH aNd GLOssy, wITH LOw, bLUNT swELLING; apErTUrE ExaCTLy rOUNdEd; pErIsTOmE OvEraLL vEry THIN, bOUNdary bETwEEN LIps CLEarLy vIsIbLE, OUTEr LIp vEry sLIGHTLy rEfLECTEd; INNEr LIp THIN, bUT IN sOmE spECImENs qUITE sTrONGLy prOTrUdING (THErEfOrE TwO LIps sITUaTEd far frOm EaCH OTHEr).
Measurements (in mm). D = 3.3–3.9, H = 1.6–2.1 (N = 5).
Operculum. VEry THIN, sTrONGLy CONCavE, yELLOwIsH. THE OUTEr sIdE Is mULTIspIraL wITH apprOx. 4–5 wHOrLs; THE INNEr sIdE Is smOOTH, wITH a sTrONGLy ELEvaTEd NIppLE, wHICH Is NEvErTHELEss smaLL IN dIamETEr.
Anatomy. TwO maLE spECImENs wErE aNaTOmICaLLy ExamINEd (20110420E, COLL. JUO). THE pENIs Is vEry smaLL (mUCH sHOrTEr THaN THE rIGHT TENTaCLE), papILLa-LIkE.
Radula. THE radULa Of ONE spECImEN was ExamINEd (20110420E, sp1, COLL. JUO). THE TEETH arE vEry sImILar TO THOsE Of THE OTHEr spECIEs, bUT aLL CUsps arE bLUNTEr THaN THOsE Of OTHEr ExamINEd spECIEs. THE LaTEraL TEETH arE vEry sImILar TO THOsE Of D. fimbriatus.
Variation in specimens. NO TraITs wErE parTICULarLy varIabLE.
Differential diagnosis. Dicharax immaculatus n. sp. dIffErs frOm THE GEOGrapHICaLLy CLOsELy OCCUrrING pOpULaTIONs Of D. cristatus by THE smaLLEr, fLaTTEr sHELL, THE GLOssy R1 aNd R3, sHarpEr swELLING ON R3 aNd dEEpEr CONsTrICTION bETwEEN R2 aNd R3. MOsT ImpOrTaNTLy HOwEvEr, THE R2 rIbs Of Dicharax immaculatus n. sp. arE CUrvEd IN pOsTErIOr dIrECTION.
THE spECIEs mOsT sImILar TO Dicharax immaculatus n. sp. Is D. fargesianus, wHICH Has sUpErfICIaLLy sImILar rIbs ON R2, aLTHOUGH THEy arE mOrE wIdELy-spaCEd THaN IN D. immaculatus n. sp. THE R1 aNd R3 rEGIONs Of Dicharax fargesianus arE NEvErTHELEss rIbbEd, wHErEas THEy arE smOOTH, GLOssy IN THE NEw spECIEs. MOrEOvEr, THE pErIsTOmE Is mUCH THICkEr IN D. fargesianus aNd IT Has a sHarpEr swELLING ON R3. Dicharax microcostatus n. sp. Is sImILar TO Dicharax immaculatus n. sp. dUE TO THE GLOssy R1 aNd R3 aNd THE rOUNdEd pErIsTOmE. THE TwO spECIEs arE dIsTINGUIsHabLE basEd ON spIrE HEIGHT (LOw IN D. immaculatus n. sp. aNd ELEvaTEd IN D. microcostatus n. sp.), THE mUCH LONGEr R2 IN D. immaculatus N. sp, aNd THE fINE sTrUCTUrE Of THE rIbs ON R2.
Distribution. Dicharax immaculatus n. sp. Is kNOwN frOm TwO NEarby sITEs wITH rOUGHLy 2 km dIsTaNCE INbETwEEN (FIGUrE 7).
description: Published as part of Asami, Takahiro, 2017, Revision of the Alycaeidae of China, Laos and Vietnam (Gastropoda: Cyclophoroidea) I: The genera Dicharax and Metalycaeus, pp. 1-124 in Zootaxa 4331 (1) on pages 26-27, DOI: 10.11646/zootaxa.4331.1.1, http://zenodo.org/record/1009725