UPPER ORDOVICIAN BRACHIOPODS FROM KAZAKHSTAN 



37 



Cristiania egregia Popov, 1985 PI. 3, figs 2-6, 8 



1985 Christiania egregia Popov: 60, pi. 2, figs 7-1 1 . 



HOLOTYPE. CNIGR 25/11989, dorsal internal mould from the 

 Anderken Formation, Sample 1018, 7 km south-west of Karpkuduk 

 Well, Kotnak Mountains. 



Material. Eight pairs of conjoined valves. 17 ventral and 30 

 dorsal valves from Samples 100 (BC 56875-81), 843, 626 (BC 

 56869-70), 8214 (BC 56871-2), Anderkenyn-Akchoku section; 

 Samples 7613, 628 (BC 56587, 56886-89), Kujandysai section; 

 Sample 1041a (BC 57396-98), Burultas Valley; Sample 1024b, east 

 side of Karatal River near Sorbulak well; Sample 1018 (BC 56873- 

 74), 7 km south-west of Karpkuduk well, Kotnak Mountains. 



Description. Shell concavoconvex, strongly elongated, suboval 

 in outline, about 160% as long as wide with maximum width about 

 two-thirds valve length from the hinge line. Cardinal extremities 

 subrectangular, usually slightly alate. Anterior commissure broadly 

 uniplicate. Ventral valve moderately convex in lateral profile with 

 maximum thickness at about one-third valve length, about 20% as 

 thick as long. Ventral interarea strongly apsacline to orthocline with 

 a large convex pseudodeltidium perforated apically by a minute, 

 circular foramen. Very weak ventral sulcus originating at the umbonal 

 area. Dorsal valve gently concave with hypercline interarea and 

 complete, convex chilidium. Radial ornament finely parvicostellate, 

 rarely preserved. 



Ventral interior with strong, transverse teeth and low, widely 

 diverging dental plates. Muscle field weakly impressed, bilobate, 

 with short, linear adductor scars bisected by a fine median ridge. 

 Dorsal interior with bilobed cardinal process, low, curved socket 

 ridges subparallel to the hinge line and two pairs of strong side septa. 

 Dorsal median septum very fine, about 61% as long as the valve. 

 Adductor scars bordered anteriorly by strong muscle bounding 

 ridges curved posteriorly. 



Discussion. Detailed discussion of this species was provided by 

 Popov (1980: 61). Among the Kazakh species it is most similar to 

 Christiania tortuosa Popov, 1980 from the Lidievka Formation 

 (Llandeilo-LowerCaradoc) of north-central Kazakhstan, but differs 

 in having a weak ventral sulcus, very fine radial ornament and a long 



dorsal median ridge extending far beyond the mid-valve. There are a 

 large number of nominal Christiania species known globally, and 

 the genus as a whole is due for revision. 



Christiania aff. sulcata Williams, 1962 PI. 3, figs 7, 9-17 



Material. Three pairs of conjoined valves, 23 ventral and 10 

 dorsal valves from Samples 8223 (BC 56585-6), 8223a, 8223b (BC 

 57399, 57401), Anderkenyn-Akchoku section; Sample 8215 (BC 

 56583^1), west side of Ashchisu River; Samples 628 (=K- 1 07/1 970) 

 (BC 56593), 2538 (BC 56579, 81, 89), 8217 (BC 57400), 8220 (BC 

 56592), Kujandysai section. 



Description. Shell concavoconvex, elongate and subtrapezoidal 

 in outline, as long as wide with maximum width at three-quarters 

 valve length. Hinge line about 85% of maximum shell width. Cardi- 

 nal extremities near right-angled and slightly alate. Lateral 

 commissures near straight, slightly diverging anteriorly. Anterior 

 commissure gently uniplicate. Ventral valve strongly convex in 

 profile with maximum thickness at about one-third valve length. 

 Ventral interarea strongly apsacline to near orthocline with narrow 

 convex pseudodeltidium perforated apically by a minute rounded 

 foramen. Lateral sides of the valve steep inclined near right angle 

 towards the commissural plane. A shallow sulcus v-shaped in cross- 

 section originating near the umbo and flanked by two distinct 

 plications rounded in cross-section. Dorsal valve moderately con- 

 cave with low and narrow median fold. Dorsal interarea hypercline 

 with a convex chilidium. Shell surface finely and equally 

 parvicostellate with 1 6 to 1 8 parvicostellae along the anterior margin 

 of mature specimens. 



Ventral interior with small, bilobed muscle field, fine teeth and 

 rudimentary dental plates. Dorsal interior with a double cardinal 

 process, low, curved socket ridges, thin median septum extending 

 somewhat anterior of mid- valve and two pairs of strong side septa. 



Measurements. (457/12375) ventral valve, L=8.2, Iw=5.7, 

 W=6.8, T=3.8, Sw=3.2; 458/12375), dorsal valve, L=5.6, Iw=5.2, 

 W=5.3, Sw=2.2 



DISCUSSION. These specimens resemble Christiania sulcata 

 Williams, 1962, from the Stinchar Limestone (Upper Llandeilo- 



PLATE 3 



Fig. 1 Limbimurina sp. Sample 626, Anderkenyn-Akchoku section, BC 57395. ventral exterior, x 1.5. 



Figs 2-6, 8 Christiania egregia Popov. 2, 3, Sample 1041a, Burultas Valley, BC 57396, lateral and ventral views of exterior, x 2. 4, Sample 1018, area 7 

 km west of Karpkuduk well, Kotnak Mountains, south Betpak-Dala, CNIGR 22/1 1989, latex cast of dorsal interior, x 2. 5, Sample 1041a, BC 57397, 

 dorsal valve interior, x 2. 6, Sample 1018, CNIGR 23/1 1989, ventral internal mould, x 2. 8, Sample 1041a, BC 57398, conjoined valves dorsal view 

 showing interareas, x 4. 



Figs 7, 9-17 Christiania aff. sulcata Williams. 7, Sample 628, west side of Kujandysai, BC 56593, dorsal exterior, x 4. 9, Sample 8223b, Anderkenyn- 

 Akchoku section, BC 57399, ventral exterior, x 3. 10, Sample 8217, BC 57400, ventral exterior, x 3. 11-16, Sample 2538, Akchoku Mountain, 

 Kujandysai section; 11, BC 56589, dorsal external mould, x 3; 12-14, BC 56579, conjoined valves, posterior view, x 8, dorsal and ventral views, x 6; 15, 

 16, BC 56581, dorsal internal mould and latex cast, x 5. 17, Sample 8223b, BC 57401, ventral internal mould, x 3. 



Figs 18-23, 25 Foliomena prisca sp. nov. 18, 19, 21-23, Sample 8255, Anderkenyn-Akchoku section; 18, BC 57402, latex cast of dorsal exterior, x 4; 19, 

 BC 57403, latex cast of dorsal exterior, x 4; 21, BC 57404. latex cast of dorsal exterior, x 4; 22, 23, BC 57405, holotype, latex cast and dorsal internal 

 mould, x 4. 20, Sample 100, Anderkenyn-Akchoku section, BC 57407, dorsal exterior, x 4. 25, Sample 8217, Kujandysai section, BC 57408, ventral 

 internal mould, x 4. 



Fig. 24 Kassinella (Kassinella)? sp. Sample 2531, Anderkenyn-Akchoku section, BC 56497, dorsal internal mould, x 8. 



Figs 26-34 Craspedelia tata Popov. 26-28, Sample 626, Anderkenyn-Akchoku section, BC 57409, conjoined valves, dorsal, lateral and ventral views, x 4. 

 29-30, Sample 100, BC57410, dorsal exterior and anterior views, x 3. 31, Sample 8238, CNIGR 9/12361, ventral exterior, x 2. 32-34, Sample 626; 32, 

 34, BC 5741 1, dorsal anterior and exterior view, x 3; 33, BC 57412, conjoined valves, dorsal view, x 5. 



Fig. 35 Isophragma imperator Popov, Sample 1018, 7 km southwest of Karpkuduk well, Kotnak Mountains, south Betpak-Dala. CNIGR 22/1 1522, latex 

 cast of dorsal interior, x 2. 



Figs 36-40 Acculina kulanketpesica sp. nov. 36, Sample 8231^10. Buldukbai-Akchoku section, BC 57416, ventral exterior, x 2. 37^M), Sample 1041a, 

 Burultas Valley; 37, BC 57415, posterior view of ventral and dorsal interareas, x 5; 38, BC 12903, ventral interior, x 2; 39, 40, BC 12904, holotype, 

 conjoined valves, ventral and dorsal views, x 3. 



