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

description: Dicharax bison Páll-Gergely & Hunyadi n. sp.
FIGUrEs 21A, 22, 23.
Type material. HOLOTypE HNHM 99703, PGB/1 paraTypE (Ex COLL. K. OHara), 20070708B CHINa, SICHUaN, DUjIaNGyaN SHI, TaIaNzHEN, QINGCHENGHOUsHaN, SaNLONGsHUIjING RONGdONG, 942 m, 30°55.15418'N, 103°29.72375'E, LEG. Y. NakaHara, K. OHara, K. OkUbO & J.U. OTaNI, 0 8 JULy 2007; HA/5 paraTypEs, 2015/53 CHINa, SICHUaN, CHENGdU SHI, DUjIaNGyaN SHI, QINGCHENGsHaN, FaNGNING BrIdGE, 200 m frOm ZUsHI TEmpLE, 1130 m, 30°54.337'N, 103°33.282'E, LEG. A. HUNyadI & M. SzEkErEs, 0 6 JUNE 2015; HNHM 99728 /1 (fIGUrEd paraTypE: sHELL was brOkEN IN OrdEr TO ExamINE CrOss sECTION Of R 2 rIbs), HA/15 paraTypEs + 2 brOkEN paraTypE spECImENs, 2015/40 CHINa, SICHUaN, CHENGdU SHI, DUjIaNGyaN SHI, QINGCHENGHOUsHaN, TaIaN ZHEN, vaLLEy UNdEr SaNLONG SHUIjING RONGdONG, 1100 m, 30°54.941'N, 103°29.635'E, LEG. A. HUNyadI & M. SzEkErEs, 0 3 JUNE 2015.
Etymology. THE INfLaTEd LasT wHOrL frOm dOrsaL vIEw, EspECIaLLy THE R2 Is rEmINIsCENT Of a bIsON’s HUmp (Bison sp., BOvIdaE). THE spECIEs NamE bison Is UsEd as a NOUN.
Diagnosis. A mEdIUm sIzEd spECIEs wITH TypICaL Dicharax - TypE rIbs ON THE INfLaTEd R2, vEry sHOrT R2 aNd R3, rOUNdEd pErIsTOmE aNd aN ELEvaTEd fUNNEL-sHapE sTrUCTUrE ON THE OUTEr sIdE Of THE OpErCULUm.
Description. SHELL (FIGUrE 21A) yELLOwIsH Or sLIGHTLy GrEENIsH IvOry; sHELL OUTLINE rOUNdEd Or sLIGHTLy OvaL frOm dOrsaL vIEw, spIrE raTHEr fLaT, wITH CONspICUOUsLy INfLaTEd R2, EdGE Of bOdy wHOrL rOUNdEd; prOTOCONCH LOw, CONsIsTING Of 1.5 wHOrLs (N = 2), raTHEr maTTE; R1 CONsIsTs Of 1.75–2 wHOrLs, rEGULarLy, dENsELy rIbbEd, rIbs LOw, wITHOUT spIraL LINEs; rIbs bECOmING sLIGHTLy mOrE wIdELy-spaCEd TOwards ENd Of R1; TraNsITION bETwEEN R1 aNd R2 CLEarLy vIsIbLE; R2 vEry dENsELy rIbbEd (FIGUrEs 22A–B), rIbs CUrvEd TOwards THE apErTUrE; CrOss sECTIONaL vIEw Of R2 (FIGUrEs 22C–D) COULd bE ExamINEd IN ONE spECImEN: aNTErIOr CrUsT fOrms a sIGNIfICaNTLy ELEvaTEd, HOLLOw rIb THaT Has a sTrONGEr aNTErIOr aNd wEakEr pOsTErIOr prOjECTION; THE aNTErIOr CrUsT fOLds OvEr THE mUCH wEakEr pOsTErIOr CrUsT THaT Is aLsO HOLLOw; CrOss sECTIONaL vIEw Of mICrOTUNNEL drOp-sHapEd; COmbINEd LENGTH Of R2 aNd R3 sHOrT, apprOxImaTELy 70–80 dEGrEEs ONLy; R2 aNd R3 Of abOUT THE samE LENGTH; TraNsITION bETwEEN R2 aNd R3 CLEarLy vIsIbLE, INdICaTEd by a dEEp CONsTrICTION; R3 wITH swELLING vEry CLOsE TO pErIsTOmE; R3 IrrEGULarLy wrINkLEd, raTHEr smOOTH aNd GLOssy; apErTUrE aLmOsT pErfECTLy rOUNd; bOUNdary bETwEEN TwO LIps HardLy vIsIbLE, OUTEr LIp sTrNGLy ExpaNdEd, sHarp, ONLy sLIGHTLy ExpaNdEd; INNEr LIp vEry wEak.
Operculum. THE OUTEr sUrfaCE (FIGUrEs 23A–C) Of THE OpErCULUm Is COrNEOUs, mULTIspIraL, bUT NO LamELLa Is vIsIbLE. IN addITION TO THIs sUrfaCE, THErE Is aN ELEvaTEd, dEEp fUNNEL-LIkE sTrUCTUrE HavING rECOGNIsabLE COILs, sTarTING frOm THE EdGE Of THE NUCLEUs. THE EdGE Of THIs "fUNNEL" Is sLIGHTLy bENT IN THE dIrECTION Of THE OpErCULUm. THIs fUNNEL-LIkE sTrUCTUrE Is prObabLy HOmOLOGOUs wITH THE mULTIspIraL LamELLa ON THE OUTEr sUrfaCE Of THE OpErCULUm Of OTHEr aLyCaEId spECIEs. THE INNEr sIdE (FIGUrEs 23D–F) Of THE OpErCULUm Has aN ELEvaTEd, CENTraL NIppLE.
Measurements (in mm). D = 4.6–5.5, H = 2.7–3.4 (N = 9).
Variation in specimens. ExCEpT fOr sHELL sIzE, NO TraITs wErE fOUNd TO bE parTICULarLy varIabLE.
Differential diagnosis. D. bison n. sp. Is sLIGHTLy LarGEr THaN D. planorbulus, Has a sLIGHTLy mOrE ELEvaTEd spIrE, mOrE ExpaNdEd pErIsTOmE, sHOrTEr aNd mOrE INfLaTEd R2 aNd mOrE CONspICUOUs swELLING ON R3. MOrEOvEr D. bison n. sp. Has aN ELEvaTEd rING ON THE OpErCULUm, wHICH Is absENT IN D. planorbulus. THE INdIaN D. rechilaensis Is vEry sImILar TO D. bison n. sp., bUT IT Has LEss dENsE rIbs ON R3, aNd ITs OpErCULUm LaCks THE fUNNEL-LIkE sTrUCTUrE.
Metalycaeus awalycaeoides n. sp. aNd sOmE pOpULaTIONs LIsTEd UNdEr M. muciferus arE sImILar TO D. bison n. sp. IN TErms Of THE INfLaTEd R2, aNd sHOrT R2 aNd R3. THEsE TwO spECIEs dIffEr IN THE sCULpTUrE Of THE prOTOCONCH (smOOTH IN D. bison n. sp. aNd spIraLLy sTrIaTEd IN M. muciferus), THE sCULpTUrE Of THE TELEOCONCH (wITHOUT spIraL sTrIaE D. bison n. sp. aNd wITH spIraL sTrIaE IN M. muciferus), aNd THE R1 THaT Has a swELLING CLOsE TO THE pErIsTOmE IN D. bison n. sp.
Distribution. Dicharax bison n. sp. Is kNOwN frOm THrEE NEarby LOCaLITIEs IN THE vICINITy Of DUjIaNGyaN CITy, SICHUaN PrOvINCE (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 32-34, DOI: 10.11646/zootaxa.4331.1.1, http://zenodo.org/record/1009725