Metalycaeus rathouisianus ( Heude, 1882 )

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 : 98-103

Metalycaeus rathouisianus ( Heude, 1882)

FIGUrEs 55A–C , 63A–B , 65A–B .

Alycaeus rathouisianus Heude, 1882: 7 , pl. 12, figs 12, 12a.

Alycaeus rathouisianus — Möllendorff, 1882: 345.

Alycaeus (Orthalycaeus) rathouisianus — Möllendorff, 1886: 169. Alycaeus dolomiticus Heude, 1890: 130 , pl. 38, fig. 1. n ew synonym. Alycaeus (Chamalycaeus) rathouisianus — Kobelt & Möllendorff, 1897: 149. Alycaeus (Chamalycaeus) dolomiticus — Kobelt & Möllendorff, 1897: 148. Alycaeus (Chamalycaeus) dolomiticus — Kobelt, 1902: 355.

Alycaeus (Chamalycaeus) rathouisianus — Kobelt, 1902: 362.

Chamalycaeus rathouisianus — Yen, 1939: 30, pl. 2, fig. 36.

Chamalycaeus (Chamalycaeus) rathouisianus — Zilch, 1957: 145.

Types examined. 29 syNTypEs (MCZ 167209) Of A. dolomiticus CHINa, TCHEIN-kIaNG (KIaNG-sOU); 23 syNTypEs (MCZ 167143) Of A. rathousianus , CHINa, TsING-p'ON; 5 syNTypEs (SMF 39243) aNd 3 syNTypEs (SMF 39303) Of A. rathouisianus , SUNG-kIaNG: CHINa, COLL. MöLLENdOrff Ex COLL. HEUdE. ACCOrdING TO JOHNsON (1973) paraTypEs Of dolomiticus (INv. NUmbEr: 472335), aNd A. rathousianus (INv. NUmbEr: 472338) arE aLsO prEsENT IN THE NMNH. THEsE wErE NOT ExamINEd by Us.

Museum material examined. MCZ 180900 /10, CHINa, CHEkIaNG, PrOv . TUNG-LU, COLL. BryaN WaLkEr, Ex DavId D. THaaNUm, JaN. 1947 ; SMF 39242/6, CHINa, SHaNGHaI , COLL. MöLLENdOrff; SMF 109787 /2, CHINa, SHaNGHaI , LEG. SCHmaCkEr, COLL. K.L. PfEIffEr Ex COLL. JETsCHIN ; SMF 192409 /6, CHINa: KIaNGsU , COLL. C. BOsCH Ex COLL. H . ROLLE; SMF 39245/3, CHINa, PrOvINCE S. HUNaN , COLL. O. BOETTGEr Ex COLL. MöLLENdOrff ; NHMW 19622 /3, HILLs by SHaNGHaI , COLL. SCHmaCkEr, PETErsEN dON.; NHMW 75000 /E/37114/6, SHaNGHaI , COLL. EdLaUEr Ex COLL. BLUmE ; MCZ 384423 (1 sHELL; rEmOvEd frOm THE syNTypE LOT Of A. fargesianus = MCZ 167229 , THaT OrIGINaLLy CONTaINEd 4 spECImENs), CHINa, TCHEN-k'EOU ; MCZ 384425 (1 sHELL; rEmOvEd frOm THE syNTypE sampLE Of A. sinensis = MCZ 167216 , THaT OrIGINaLLy CONTaINEd 3 spECImENs), CHINa, TONG-LIEOU.

Diagnosis. A smaLL spECIEs wITH sOmEwHaT ELEvaTEd spIrE, mOdEraTELy LONG R2 aNd R3, R3 wITH TypICaL Metalycaeus - TypE rIbs, R3 wITH bLUNT swELLING.

Description of the type series of rathouisianus . SHELL ( FIGUrE 55A ) dark IvOry Or bEIGE; prOTOCONCH brOwN Or sOmETImEs pINkIsH; sHELL OUTLINE rOUNdEd frOm dOrsaL vIEw, spIrE sOmEwHaT ELEvaTEd, bOdy wHOrL rOUNdEd; prOTOCONCH ELEvaTEd, CONsIsTING Of 1.25–1.5 wHOrLs (N = 3); LasT 0.75–1 wHOrL spIraLLy sTrIaTEd, prECEdING arEa raTHEr maTTE; R1 CONsIsTs Of 1.5–1.75 wHOrLs (N = 3), raTHEr IrrEGULarLy rIbbEd aNd rEGULarLy spIraLLy sTrIaTEd; spIraL aNd radIaL LINEs apprOxImaTELy Of THE samE sTrENGTH, rEsULTING IN a rETICULaTEd sCULpTUrE; TraNsITION bETwEEN R1 aNd R2 NOT vEry CONspICUOUs bECaUsE THE dENsITy Of rIbs dOEs NOT CHaNGE mUCH, aLTHOUGH rIbs ON R2 mUCH mOrE rEGULar THaN ON R1, aNd sHarpEr ON R2; R2 wITH rELaTIvELy sHarp, wIdELy-spaCEd rIbs; CrOss sECTION Of THE rIbs COULd NOT bE ExamINEd, bUT prObabLy sImILar TO OTHEr Metalycaeus spECIEs HavING wIdELy-spaCEd rIbs; R2 aNd R3 apprOxImaTELy 90–110 dEGrEEs TOGETHEr, R2 bEING sOmEwHaT sHOrTEr; R2 IrrEGULarLy wrINkLEd; dENsITy Of wrINkLEs sImILar TO THaT Of THE ENd Of R1; spIraL sTrIaTION vIsIbLE ON bOTH R2 aNd R3; R3 wITH a bLUNT swELLING aT ITs mIddLE; R3 sEparaTEd frOm R2 by a mOdEraTE CONsTrICTION; apErTUrE rOUNdEd, INNEr LIp sLIGHTLy prOTrUdING, sOmEwHaT sHarp; OUTEr LIp sITUaTEd sOmE dIsTaNCE frOm INNEr LIp IN mOsT spECImENs (IN OTHErs THEy arE NOT sO dIsTaNT); OUTEr LIp sLIGHTLy ExpaNdEd aNd sHarp, ExCEpTIONaLLy sHarp IN THE dIrECTION Of THE UmbILICUs.

Measurements (in mm). D = 3.7–3.9, H = 2.5–2.7 (N = 6, MCZ 167143).

Operculum. MOsT syNTypEs Of Alycaeus rathouisianus (MCZ 167143) pOssEssEd aN OpErCULUm. THE OUTEr sUrfaCE Has a dENsELy COILEd, wrINkLEd LamELLa, wHICH Is UsUaLLy COvErEd by mUd. OfTEN THIs LamELLa Is ENTIrELy Or parTLy mIssING, THUs, THE GLOssy sUrfaCE Of THE OpErCULUm bECOmEs vIsIbLE. MOsT syNTypEs Of Alycaeus dolomiticus aLsO Had OpErCULa. IN THaT sampLE, HOwEvEr, NONE Of THEm Had aN OUTEr LamELLa ( FIGUrEs 65A–B ), bUT aLL THE OUTEr sUrfaCEs Of OpErCULa wErE smOOTH, aNd THE mULTIspIraL CHaraCTEr was CLEarLy vIsIbLE. THE INNEr sUrfaCE was ExamINEd IN ONE OpErCULUm; IT was smOOTH, maTT, wITH a vEry LOw NIppLE IN THE mIddLE.

Variation in specimens. SOmE sLIGHT varIabILITy Is dETECTabLE IN TErms Of spIrE HEIGHT, sHELL sIzE aNd pErIsTOmE THICkNEss.

Differential diagnosis. Metalycaeus latecostatus Has LEss bULGING wHOrLs, sTrONGEr pErIsTOmE aNd mOrE wIdELy spaCEd rIbs. SEE aLsO UNdEr M. oharai n. sp., M. sinensis aNd Dicharax dolichodeiros .

SOmE CONGENErIC JapaNEsE spECIEs ( M. hirasei , M. nipponensis aNd M. satsumanus ) arE vEry sImILar TO M. rathouisianus . THErE arE sOmE mINOr dIffErENCEs bETwEEN M. rathouisianus aNd THOsE JapaNEsE spECIEs, IN THE sHELL sIzE, THE THICkNEss Of THE pErIsTOmE, THE HEIGHT Of THE spIrE Or THE ExTaNT Of THE CONsTrICTION ON R3, bUT THEsE dIffErENCEs COULd raTHEr bE ExpLaINEd by INTraspECIfIC dIffErENCEs. A fUTUrE rEvIsION sHOULd CLarIfy If M. rathouisianus aNd THE abOvE-mENTIONEd JapaNEsE Taxa rEaLLy rEprEsENT dIsTINCT spECIEs.

Distribution. ACCOrdING TO THE OrIGINaL dEsCrIpTION Of A. dolomiticus , THE spECIEs was COLLECTEd NEar TCHENkIaNG (KIaNG-sOU). LaTEr, KObELT aNd MöLLENdOrff (1897) mENTIONEd THE spECIEs frOm KIaNGsI. KIaNG-sOU (= JIaNGsU PrOvINCE) aNd KIaNGsI (= JIaNGxI PrOvINCE) arE sITUaTEd IN IN TwO dIffErENT prOvINCEs, aNd IN THE prEsENT CasE JIaNGxI Is prObabLy ErrONEOUs.

Remarks. Alycaeus rathouisianus was dEsCrIbEd as a spECIEs THaT LaCks spIraL sTrIaE ON ITs sHELL. THIs CHaraCTEr was HIGHLIGHTEd aNd fIGUrEd as a dIffErENCE bETwEEN A. rathouisianus (LaCks sTrIaE) aNd A. sinensis (Has spIraL sTrIaE) ( HEUdE 1882). THIs INfOrmaTION Is, HOwEvEr, NOT IN aGrEEmENT wITH THE TypE sErIEs, bECaUsE THE spIraL LINEs arE vIsIbLE EvEN ON THE wEaTHErEd syNTypEs Of A. rathouisianus . IN faCT, TwO Of THE THrEE syNTypEs Of A. sinensis pOssEss mUCH wEakEr spIraL LINEs THaN THE syNTypEs Of A. rathouisianus (sEE aLsO rEmarks UNdEr M. sinensis ). ONE mIGHT THINk THaT THE syNTypEs aNd LabELs Of A. sinensis aNd A. rathouisianus HavE sImpLy bEEN mIxEd Up. THIs Is vEry UNLIkELy, bECaUsE THE sHELL sHapE Of THE syNTypEs Of A. sinensis maTCH wITH THE OrIGINaL dEsCrIpTION ("dEprEssE OrbICULaTa"). THE samE Is TrUE TO THE syNTypEs Of A. rathouisianus ("dIsCOIdEO-CONICa"). THE rEasON fOr THE dIsCrEpaNCy rEmaINs ObsCUrE, aNd wE rELy ON THE sHELL spECImENs INsTEad Of THE OrIGINaL dEsCrIpTION.

WE fOUNd NO NOTabLE dIffErENCEs bETwEEN THE TypE spECImENs Of A. rathouisianus ( FIGUrE 55A ) aNd A. dolomiticus ( FIGUrE 55B ) IN sHELL sHapE, sCULpTUrE, LENGTH Of THE dIffErENT rEGIONs, apErTUrE aNd pErIsTOmE mOrpHOLOGy, ETC. CONsEqUENTLy, THE LaTTEr Is a syNONyms Of A. rathouisianus .

IN mUsEUm COLLECTIONs (NHM, NHMW, SMF) sHELLs frOm "HUNaN" arE LabELLEd EITHEr Chamalycaeus rathousianus, Or C. rathousianus var. major . THE LaTTEr fOrm Is LarGEr, Has a LONG TUbE, wIdELy-spaCEd rIbs ON R3 (aLTHOUGH NOT aLways), aNd sTrONGLy ExpaNdEd pErIsTOmE, THUs, THEy arE TypICaL Metalycaeus oharai n. sp. sHELLs. THE sHELLs LabELLEd as Chamalycaeus rathousianus OfTEN HavE a sHOrTEr R2 aNd dENsEr R3 rIbs THaN TypICaL M. oharai frOm GUaNGxI aNd YUNNaN. As a CONsEqUENCE, sEEmINGLy THE HIsTOrICaL sampLEs frOm "HUNaN" sHOw TraNsITIONaL sHELL CHaraCTErs bETwEEN TypICaL M. rathouisianus aNd M. oharai n. sp. spECImENs IN sOmE sHELL CHaraCTErs. CONsIdErING THIs, wE prEfEr dIsTINGUIsHING M. oharai n. sp. frOm M. rathouisianus bECaUsE aLL M. oharai n. sp. sHELLs (INCLUdING THE HIsTOrICaL sampLEs frOm "HUNaN") pOssEss mOrE wIdELy-spaCEd R1 rIbs, LONGEr R2, sHarpEr (mOrE ELEvaTEd) aNd UsUaLLy mOrE wIdELy-spaCEd R2 rIbs, aNd a mOrE ExpaNdEd pErIsTOmE. WE rEfEr TO THE M. rathouisianus sHELLs frOm HUNaN as M. Cf. oharai , aNd dO NOT sELECT THEm TO bE paraTypEs. FUTUrE INvEsTIGaTION sHOULd fOCUs ON THE prEsENTLy kNOwN raNGE Of M. oharai n. sp. aNd M. rathouisianus .

Figures

FIGURE 55. Shells of Metalycaeus species. A – C. Metalycaeus rathouisianus (Heude, 1882). A. syntype (SMF 39243) of M. rathouisianus. B. syntype (MCZ 167209) of Alycaeus dolomiticus Heude, 1890. C. MCZ 167222, labelled as Alycaeus neglectus Heude, 1886. D. Metalycaeus sinensis (Heude, 1882) (lectotype, MCZ 167216). E. Metalycaeus (?) ibex Páll- Gergely & Hunyadi n. sp., (holotype, MNHN IM- 2012 - 27042). Scale represents 5 mm. All photos: B. Páll-Gergely.

FIGURE 63. Protoconchs of Metalycaeus species. A – B. Metalycaeus rathouisianus (Heude, 1882) (syntype of A. dolomiticus MCZ 167209). C – D. Metalycaeus oharai Páll-Gergely & Hunyadi n. sp. (holotype, HNHM 99712). All images: B. Páll- Gergely.

FIGURE 65. Opercula of Metalycaeus species. A – B. Metalycaeus rathouisianus (Heude, 1882) (MCZ 167209; syntype of Alycaeus dolomiticus). C – F. Metalycaeus (?) okuboi Páll-Gergely & Hunyadi, n. sp. (holotype, HNHM 99713). All images: B. Páll-Gergely.