Dicharax Kobelt & Mollendorff 1900
Creators: name: Asami, Takahiro
Publisher: name: Zenodo
Year: 2017
Subjects: Biodiversity
Taxonomy
Animalia
Mollusca
Gastropoda
Architaenioglossa
Alycaeidae
Dicharax

description: Dicharax (?) dolichodeiros (Heude, 1890)
FIGUrEs 8D–E, 9E–F, 10E–F.
Alycaeus dolichodeiros Heude, 1890: 129, pl. 38, fig. 3.
Alycaeus (Chamalycaeus) dolichodeirus (sic!)— Kobelt & Möllendorff, 1897: 148. Alycaeus (Chamalycaeus) dolichodirus (sic!)— Kobelt, 1902: 355.
Types. NO TypE spECImENs wErE rEpOrTEd by JOHNsON (1973). THE ONLy sHELL wE fOUNd IN mUsEUm COLLECTIONs LabELLEd as D. dolichodeiros was fIGUrEd by YEN (1939, pL. 2, fIG. 37; SMF 39254). ALTHOUGH THE wIdELy-spaCEd rIbs Of THE OrIGINaL fIGUrE dO NOT maTCH wITH THE spECImEN LIsTEd HErE (sEE DIsCUssION abOUT THIs IssUE), THE sHELL sHapE aNd sIzE sUGGEsTs THaT THE TwO pOpULaTIONs LIsTEd HErE rEprEsENT Alycaeus dolichodeiros.
New material examined. HA/1, 2013/6 CHINa, GUaNGxI, HECHI SHI, Bama XIaN, CLIffs NEar JIaOLE CUN, 590 m, 24°7.045'N, 107°7.847'E, LEG. A. HUNyadI & M. SzEkErEs, 10 SEp 2013, HNHM 99710; HA/4, 2016/100 CHINa, CHONGqING, CHENGkOU XIaN, LaNTIaN XIaNG, mOUNTaIN abOvE LaNxI CUN (NOrTHErN sIdE), 1215 m, 31°55.399'N, 108°53.421'E, LEG. A. HUNyadI, 0 8 JUNE 2016.
Diagnosis. A smaLL spECIEs wITH LOw, smOOTH prOTOCONCH, sHOrT R2 HavING wIdELy-spaCEd, sTraIGHT rIbs, bLUNT swELLING ON R3 aNd rOUNdEd apErTUrE.
Original description. "TEsTa dIsCOIdEO-TrOCHOIdEa, LaTE UmbILICaTa, spIra apICULaTa, aNfraCTIbUs 3½, rEGULarITEr CrEsCENTIbUs, sUTUra ImprEssa jUNCTIs, TUbO sUTUraLI CONsTrICTIONE TErmINaLI LONGUa, CONICa; pErIsTOmaTE dUpLICI, aNTICO prOTraCTO pOsTICO sUbdILaTaTO.—DIam.: 3; aLTIT.: 2½ mILL.".
Description of specimens from Chongqing. SHELL (FIGUrE 8E) wHITE; sHELL OUTLINE rOUNdEd frOm dOrsaL vIEw, spIrE sLIGHTLy ELEvaTEd; EdGE Of bOdy wHOrL rOUNdEd; prOTOCONCH LOw, CONsIsTING Of 1.5 wHOrLs; sCULpTUrE NEarLy smOOTH, bUT raTHEr maTTE; R1 CONsIsTs Of Ca. 1.75 wHOrLs, raTHEr rEGULarLy, rarELy rIbbEd; rIbs fEwEr TOwards R2; R2 wITH wIdELy-spaCEd, LOw, bUT sHarp rIbs; CrOss-sECTIONaL vIEw Of R2 COULd NOT bE ExamINEd, bUT prObabLy sImILar TO THOsE Of Metalycaeus spECIEs; TraNsITION bETwEEN R2 aNd R3 NOT CONspICUOUs, bUT vIsIbLE bECaUsE Of sLIGHT CONsTrICTION afTEr THE OrIGIN Of THE TUbE; rIbbING ON R3 mOrE wIdELy-spaCEd THaN ON R1; R2 + R3 apprOxImaTELy Of 85–90 dEGrEEs; R2 Ca. HaLf LENGTH Of R3; R3 pOssEssEs bLUNT CENTraL swELLING; apErTUrE rOUNdEd, wITHOUT kNOTs; OUTEr LIp ExpaNdEd bUT NOT rEfLECTEd, INNEr LIp sHarp aNd prOTrUdING.
Measurements (in mm). D = 3.3, H = 1.9–2.1 (N = 2, HOLOTypE aNd paraTypE).
Operculum. UNkNOwN.
Variation in specimens. TwO pOpULaTIONs arE kNOwN. THE TwO spECImENs frOm GUaNGxI arE sLIGHTLy dIffErENT frOm EaCH OTHEr IN TErms Of spIrE HEIGHT. THE spECImENs frOm CHONGqING dO NOT sHOw NOTabLE varIabILITy IN TErms Of sHELL CHaraCTErs. THE sHELLs frOm GUaNGxI HavE sOmEwHaT wEakEr rIbs aNd mOrE ExpaNdEd OUTEr pErIsTOmE THaN THOsE Of THE sHELLs frOm CHONGqING.
Differential diagnosis. SOmE Metalycaeus spECIEs (E.G. Metalycaeus muciferus, M. sinensis) mIGHT rEsEmbLE Dicharax dolichodeiros bECaUsE Of THE aTypICaL rIbs ON R2, bUT aLL Of THEsE spECIEs dIffEr frOm D. dolichodeiros by THE spIraL sTrIaTION Of THE prOTOCONCH aNd THE TELEOCONCH. SEE aLsO UNdEr D. alticola n. sp.
Distribution. TwO GEOrEfErENCEd pOpULaTIONs Of THIs spECIEs arE kNOwN, ONE IN GUaNGxI, aNd aNOTHEr IN CHONGqING. THEsE TwO pOpULaTIONs arE sITUaTEd apprOxImaTELy 880 km frOm EaCH OTHEr (FIGUrEs 7 aNd 14). SEE aLsO CONCLUdING REmarks (BIOGEOGrapHy).
Remarks. Dicharax dolichodeiros Has a bLUNT aNd smOOTH prOTOCONCH, wHICH Is CHaraCTErIsTIC fOr THE GENUs Dicharax. HOwEvEr, THE wIdELy-spaCEd, sHarp rIbs ON R2 arE CHaraCTErIsTIC fOr THE GENUs Metalycaeus. WE CLassIfy THIs spECIEs IN Dicharax bECaUsE THE rIbbING ON R2 Is sOmEwHaT varIabLE IN aLL GENEra ExamINEd by Us (Alycaeus, Chamalycaeus, Dicharax, Metalycaeus), wHErEas THE prOTOCONCH sHapE aNd sCULpTUrE Is mUCH LEss varIabLE aCrOss spECIEs.
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 22-23, DOI: 10.11646/zootaxa.4331.1.1, http://zenodo.org/record/1009725