UPPER ORDOVICIAN BRACHIOPODS FROM KAZAKHSTAN 



Glyptomena onerosa Popov, 1980 PI. 2, figs 5-9 



1980 Glyptomena onerosa Popov: 152, pi. 2, figs 5-7. 



HOLOTYPE. CNIGR 50/1 1523, Anderken Formation, from Sample 

 100b, Anderkenyn-Akchoku section. 



Material. 14 ventral and 24 dorsal valves from Samples 100b, 

 843 (BC 57387), 8135, 8137, 8235 (BC 57386), Anderkenyn- 

 Akchoku section; Sample 7613 (BC 57388), Kujandysai section; 

 Samples 8229 (BC 57385), 8257 (BC 56864-65), Buldukbai- 

 Akchoku section; Sample 1018, 7 km SW of Karpkuduk well, 

 Kotnak Mountains. 



Description. Shell concavoconvex, semielliptical in outline, about 

 60% as long as wide, with maximum width at the hinge line. Cardinal 

 extremities slightly acute. Anterior commissure rectimarginate. Ven- 

 tral valve moderately convex in lateral profile with maximum 

 thickness at about one-third valve length. Ventral interarea low, 

 apsacline, with small apical pseudodeltidium. Dorsal valve flattened 

 with dorsal geniculation at about 75% of valve length from the 

 umbo. Dorsal interarea low, anacline with well developed, broad, 

 convex chilidium. Radial ornament inequally parvicostellate with up 

 to three generations of accentuated ribs separated by 2-5 

 parvicostellae in the interspaces. Number of ribs along the anterior 

 margin of mature specimens varying from 11 to 15 per 3 mm. 

 Concentric ornament of fine, regularly spaced concentric fila, about 

 20-25 per mm. 



Ventral interior with strong teeth bearing rows of crenulations on 

 the outer side and long, widely divergent dental plates. Ventral 

 muscle field heart-shaped about one-third as long as the valve with 

 strongly impressed diductor scar somewhat longer, but not enclosing 

 slightly raised, narrow triangular adductor track. Dorsal interior with 

 bilobed cardinal process on a low notothyrial platform and widely 

 diverging socket ridges subparallel to the hinge line. Sockets deep, 

 transverse, bearing strong vertical ridges on the anterior slope. 

 Adductor scars weakly impressed, bisected by the fine median 

 septum extending anteriorly about 60% of valve length. Pair of inner 

 side septa about the same length as the median septum, slightly 

 divergent proximally and curved towards the anterior of the median 

 ridge near the mid-valve. Outer side septa very fine or completely 

 absent in some specimens. 



DISCUSSION. This species is similar to Glyptomena sculpturata 

 Cooper, 1956, but differs in having a geniculated dorsal valve and 

 more densely accentuated ribs. 



Limbimurina? sp. 



35 

 PI. 3, fig. 1 



Material. One ventral and five dorsal valves from Samples 100, 

 626 (BC 57395), 8223b (BC 56867-68), Anderkenyn-Akchoku 

 section; Samples 628 and 2538 (BC 56866), Kujandysai section. 



Description. Shell flattened, transverse, subrectangular in out- 

 line; strongly geniculate ventrally with a trail up to 4 mm long 

 inclined at nearly right angles to the commissural plane. Cardinal 

 extremities nearly right angled. Ventral valve strongly flattened 

 posteriorly to the geniculation. with gently convex umbonal area. 

 Ventral interarea low, planar, apsacline with apical pseudodeltidium. 

 Dorsal valve with strong angular concentric rugae accentuating the 

 geniculation. Dorsal interarea anacline. Radial ornament unequally 

 parvicostellate with 4-5 parvicostellae per mm along the anterior 

 margin. Concentric ornament of oblique rugellae crossing each other 

 at less than 30-40° and covering all the valve surface between hinge 

 line and geniculation. Interior of both valves unknown. 



Measurements, dorsal valve, L= 1 4. 1 , W=29.0. 



Discussion. Generic assignment of the Kazakh specimens to 

 Limbimurina is based mostly on the distinctive shell shape, with 

 strong geniculation enhanced by the characteristic concentric frill 

 and the irregular oblique rugellae forming an interference pattern 

 with concentric rugae in the posterior half of the shell. The speci- 

 mens from the Anderken Formation differ from Limbimurina 

 brevilimbata Cooper, 1956 from the Edinburg Formation of Virginia 

 and L. insueta Cooper, 1956 from the Rodman Formation of Penn- 

 sylvania in the strongly transverse outline of the shell. The trail in the 

 Kazakh shells is considerably higher than in L. insueta, but not as 

 high as in L. brevilimbata. 



Similar shells were also described as Limbimurina 1 . sp. from the 

 Dulankara Regional Stage (Upper Caradoc) of north Betpak-Dala 

 (Nikitin & Popov 1996). They differ from the Anderken specimens 

 in their more densely spaced parvicostellae, which vary from 1 1 to 

 14 per mm along the anterior margin. 



A similar species is Bellimurina quadrata Fu, 1982, from the 

 Pinling Formation of Northwest China, which also possesses a 

 geniculation as well as a characteristic concentric frill, and irregular 

 oblique rugellae forming characteristic interference patterns; but 

 precise comparision is difficult because of the short description and 

 insufficient illustrations. It most likely belongs to Limbimurina, but 

 no detailed information was provided on the dorsal interior (Fu 

 1982:122, pi. 35, figs 20-21). 



Family LEPTAENIDAE Hall & Clarke, 1894 

 Genus LIMBIMURINA Cooper, 1956 



TYPE SPECIES. Limbimurina insueta Cooper, 1956, from the 

 Nealmont Formation (Caradoc), Pennsylvania, U.S.A. 



Family CHRISTIANIIDAE Williams, 1952 

 Genus CHRISTIANIA Hall & Clarke, 1892 



Type species. 

 of the U.S.A. 



Leptaena subquadrata Hall, 1 883, from the Caradoc 



PLATE 2 



Figs 1-4 Furcitellinae gen. et sp. indet. 1, 2, 4. Sample 100. Anderkenyn-Akchoku section; 1, 2, BC 57382, dorsal radial ornament and exterior, x 5. x 2; 

 4, BC 57384, ventral internal mould, x 2. 3, Sample 1041a, Burultas Valley, BC 57383, ventral exterior, x 2.5. 



Figs 5-9 Glyptomena onerosa Popov. 5, Sample 7613, Akchoku Mountain, Kujandysai section, BC 57388, dorsal valve ornament, x 3. 6. Sample 8229, 

 Buldukbai-Akchoku section, west side of Kopalysai, BC 57385. ventral internal mould, x 2. 7, Sample 8235, Anderkenyn-Akchoku section, BC 57386, 

 ventral internal mould, x 3. 8, Sample 100b, Anderkenyn-Akchoku section, CNIGR Museum, dorsal internal mould, x 4. 9. Sample 843, Anderkenyn- 

 Akchoku section, BC 57387, dorsal exterior, x 1.5. 



Figs 10-20 Teretelasmella chugaevae sp. nov. Anderkenyn-Akchoku section. 10-13, 19, 20, Sample 100; 10-13, 19, BC 57391, conjoined valves, anterior, 

 posterior, dorsal, lateral and ventral views, x 1.5; 20. BC 57390, conjoined valves, posterior view, x 2. 14-18, Sample 626. BC 57392, conjoined valves, 

 holotype, dorsal, posterior, lateral, ventral and anterior views, x 1.5. 



