Metalycaeus latecostatus (Möllendorff, 1882)

FIGUrE 47B.

Alycaeus Nipponensis (error, non Reinhardt, 1877) Gredler, 1881: 129. Alycaeus latecostatus — Möllendorff, 1882: 346, pl. 10, fig. 7.

Alycaeus (Orthalycaeus) latecostatus — Möllendorff, 1886: 171.

Alycaeus (Chamalycaeus) latecostatus — Kobelt & Möllendorff, 1897: 148. Alycaeus (Chamalycaeus) latecostatus — Kobelt, 1902: 358.

Chamalycaeus latecostatus — Yen, 1939: 29 –30, pl. 2, fig. 34.

Chamalycaeus (Chamalycaeus) latecostatus — Zilch, 1957: 143, pl. 5, fig. 11.

Types examined. LECTOTypE SMF 39215, 2 paraLECTOTypEs SMF 39299, 8 paraLECTOTypEs SMF 39216, 2 paraLECTOTypEs SMF 39301, 3 paraLECTOTypEs SMF 39217, COLL. BOETTGEr, CHINa: LO-fOU-sCHaN (KwaNGTUNG), LEG. MöLLENdOrff, COLL. KObELT.

Museum material examined. SMF 192408 /4, CHINa: KaNTON, COLL. C. BOsCH Ex COLL. H. ROLLE; NHMUK 1891.3.17.789–190/2, LOfOUsHaN, LEG. HUNGErfOrd; NHMUK 20150486 /6, CaNTON, CHINa, LEG. MöLLENdOrff, COLL. GOdwIN-AUsTEN; NHMUK 20150486 /1, CaNTON, E.R. SykEs COLL., 1954; NHMW 40501/18, LO-fOU-sHaN, COLL. MöLLENdOrff; NHMW 71640/O/7353/2, LO-fOU-sHaN, COLL. ObErwImmEr Ex COLL. MöLLENdOrff.

Diagnosis. A mEdIUm sIzEd spECIEs wITH rarELy, rEGULarLy rIbbEd R1, sHOrT R2 HavING wIdELy-spaCEd, raTHEr bLUNT rIbs, mOdEraTE R3 aNd sLIGHT swELLING ON R3. PErIsTOmE CONspICUOUsLy THICkENEd aNd THE bOdy wHOrL Is sLIGHTLy aNGULaTE.

Description. SHELL (FIGUrE 47B) OCHrE; sHELL OUTLINE rOUNdEd frOm dOrsaL vIEw, wITH apErTUrE rEGION ExpaNdEd ("TUba"-LIkE); spIrE ELEvaTEd, bOdy wHOrL sLIGHTLy aNGULaTEd; prOTOCONCH ELEvaTEd, CONsIsTING Of 1.5–1.75 wHOrLs, NEarLy smOOTH, THE LasT HaLf wHOrL wITH fINE spIraL LINEs; R1 rEGULarLy rIbbEd, wITH fINE spIraL LINEs ON THE fIrsT HaLf wHOrL Of R1; TraNsITION bETwEEN R1 aNd R2 CLEarLy vIsIbLE; R2 aNd R3 sLIGHTLy mOrE THaN a qUarTEr wHOrL LENGTH COmbINEd, R3 abOUT 1.5 TImEs LONGEr THaN R2; rIbbING ON R2 abOUT 3 TImEs as dENsE as IN R1; R2 wITH rELaTIvELy bLUNT, wIdELy-spaCEd rIbs; CrOss sECTION Of rIbs COULd NOT bE ExamINEd; TraNsITION bETwEEN R2 aNd R3 sUddEN, INdICaTEd wITH a sLIGHT CONsTrICTION; R3 aLmOsT smOOTH Or wITH IrrEGULar GrOwTH LINEs; apErTUrE NEarLy rOUNdEd wITH sLIGHT UppEr INCIsION (rEsULTs IN a TEardrOp-sHapEd apErTUrE), bOUNdary Of TwO LIps UsUaLLy CLEarLy vIsIbLE; INNEr LIp THIN aNd prOTrUdING, OUTEr LIp sIGNIfICaNTLy wIdENEd bUT NOT rEfLECTEd, ExpaNsION mOsT CONspICUOUs IN dIrECTION Of UmbILICUs.

Measurements (in mm). D = 4.1–4.3, H = 2.8–2.9 (N = 2).

Operculum. THE OUTEr sUrfaCE Of THE LECTOTypE was ExamINEd, wHICH Is GLOssy, Has NO ELEvaTEd LamELLa, bUT THE mULTIspIraL sUrfaCE Is CLEarLy vIsIbLE.

Variation in specimens. NO NOTabLE INTraspECIfIC varIabILITy was fOUNd.

Differential diagnosis. MOsT pOpULaTIONs Of Metalycaeus heudei HavE LarGEr sHELLs THaN THOsE Of M. latecostatus. MOrEOvEr, M. heudei Has a swELLING ON R3, Has mOrE dENsELy rIbbEd R1 aNd pOssEssEs mOrE rOUNdEd wHOrLs. Metalycaeus oharai n. sp. Has mOrE rOUNdEd wHOrLs, LONGEr R2 aNd a rEfLECTEd pErIsTOmE. Metalycaeus muciferus Has mOrE bULGING wHOrLs THaN M. latecostatus. MOrEOvEr, spECImENs assIGNEd TO M. muciferus LaCk THE CONsTrICTION aT THE bOrdEr bETwEEN R2 aNd R3, aNd HavE sLImmEr pErIsTOmEs. SEE aLsO UNdEr M. rathouisianus aNd D. depressus.

Distribution. THIs spECIEs Is kNOwN frOm THE TypE LOCaLITy ONLy (FIGUrE 56).