【摘要】 文中描述采自南黄海7井叶肢介化石,分别是Yunmenglimnadia huanghaiensis(sp.nov.),Y.subrhombica(sp.nov.),Y.brevis(sp.nov.)和Perilimnadia?cf.P.taizhouensis Chen。其地层时代为早古新世。更多还原

【Abstract】 The fossil conchostracans described in this paper were collected from the Southern Yellow Sea drilling core no.7,1 464.5—1 466.7mof the uppermost Taizhou Formation(Zhai,1990).They are:Yunmenglimnadia huanghaiensis(sp.nov.), Y.subrhombica(sp.nov.),Y.brevis(sp.nov.) and Perilimnadia?cf.P.taizhouensis Chen, showing the early Paleocene in age(Chen et al. 2012). DESCRIPTION OF NEW SPECIES Family Perilimnadiidae Chang and Chen,1975 Genus Yunmenglimnadia Chen,1975 Yunmenglimnadia huanghaiensis Chen(sp.nov.)(Pl.Ⅰ,figs.1—6) Derivation Huanghai,fossil locality. Holotype pl.Ⅰ,fig.1,Cat.No.NIGP 70530,Col.No.1464.5-③. Materials Two specimens(1464.5,1465.8), several carapaces on each specimen.Cat.No. NIGP 70530—70535. Description Carapace moderate to large in size,elliptical in outline,6.4—14mm in length, 5—9.8 mm in height;dorsal margin slightly arched upward;protoconch large,about one-half the size of whole valve,with marked elliptical adductor muscle scar and shell glands in antero-dorsal part;anterior margin straight,posterior margin rounded,ventral margin slightly arched downward; anterior height greater than posterior height,posterior end of valve strongly contracted; 5—8growth lines with a groove in the central for each,growth bands broader and flat,both protoconch and growth bands with shallow and crowded honeycomb sculpture,crowded pustulate structures present on external mold of valve. Comparison This species closely resembles Yunmenglimnadia yingchengensis Chen,but differs in shape and location of the shell glands.It differs from Yunmenglimnadia hubeiensis Chen and Yunmenglimnadia gansuensis Chen in having more growth bands and obvious contraction of posterior end of valve. Yunmenglimnadia subrhombica Chen(sp.nov.)(Pl.Ⅰ,fig.9;pl.Ⅱ,figs.1—3) Derivation subrhombica,Latin,means subrhombic. Holotype Pl.Ⅱ,fig.1,Cat.No.NIGP 70538, Col.No.1464.5-①. Materials Three specimens(1464.5,1466.7, 1465.8),Cat.No.NIGP 70538—70541. Description Carapace small in size,subrhombic in outline,5.2—7mm in length,5—6mm in height,length and height near equal;dorsal margin short and straight,protoconch very large,only 3 growth bands near ventral margin;adductor muscle scar and shell glands large and obvious,elliptical in outline,located in antero-dorsal part of protoconch and slightly oblique extended to posterior ventral part;both of anterior and posterior margins relative straight and nearly parallel,ventral margin rounded,anterior height greater than posterior height;growth bands and protoconch with crowded honeycomb sculpture,very irregular pustulate structures present on external mold ofvalve. Comparison This species is more closely allied to Yunmenglimnadia rhombica Chen from the Gonganzhai Formation of Hubei,but differs in the shape and location of shell glands. Yunmenglimnadia brevis Chen(sp.nov.)(Pl.Ⅰ,figs.7,8) Derivation brevis,Latin,means short. Holotype Pl.Ⅰ,fig.7,Cat.No.NIGP 70536, Col.No.1464.5-⑦. Materials Two carapaces on the same specimen(1464.5-⑦ ⑧),Cat.No.NIGP 70536, 70537. Description Carapace moderate to large in size,short ovate in outline,9.2—12 mm in length,7—9 mm in height;dorsal margin medium,protoconch also short ovate in shape,about one-half size of the whole valves,adductor muscle scar and shell glands elliptical in outline,located in antero-dorsal part of protoconch;anterior margin relative straight,ventral and posterior margin rounded,anterior height greater than posterior one;post end of valve obviously contracted,10— 15growth bands narrow;protoconch and growth bands with honeycomb sculpture. Comparison Yunmenglimnadia brevis and Yunmenglimnadia huanghaiensis are very similar each other,but the differing only in shape of short oval valve,smaller protoconch,and more growth bands for the former.更多还原