64 



L.E. POPOV, L.R.M. COCKS AND I.F. NIKITIN 



Suborder DALMANELLIDINA Moore, 1952 



Superfamily ENTELETOIDEA Waagen, 1884 



Family DRABOVIIDAE Havlicek, 1950 



Subfamily DRABOVIINAE Havlicek, 1950 



Genus PIONODEMA Foerste, 1912 



TYPE SPECIES. Orthis subaequata Conrad, from the Caradoc of Mis- 

 souri, U.S.A. 



Pionodema opima sp. nov. PI. 12, figs 13, 14, 16-27 



ETYMOLOGY. After opimus, Latin - fat. 



Holotype. BC 57545, PI 12, figs 17-1 8, internal mould of conjoined 

 valves, from the Anderken Formation, Sample 7613, Kujandysai sec- 

 tion. 



Material. Nine pairs of conjoined valves, 70 ventral and 64 dorsal 

 valves from Sample 7613 (BC 57545), Kujandysai section; 

 Sample 8128, Anderkenyn-Akchoku; Sample 8228 (BC 57185, 57547, 

 48), east side of Kopalysai; Samples 1 10, 8229 (BC 57546), 8230 (BC 

 57803), 8257 (BC 57544), Buldukbai-Akchoku section; Sample 818a 

 (BC 57802), Burultas Valley. 



Description. Shell slightly dorsibiconvex, transverse, suboval in 

 outline, about 84% as long as wide and 53% as thick as long. Hinge line 

 slightly shorter than the maximum shell width at mid-length. Anterior 

 commissure uniplicate. Ventral valve gently convex with maximum 

 thickness at the umbonal area. Beak curved, pointed and slightly erect 

 posterior to hinge line. Ventral interarea subtriangular, apsacline, weakly 

 curved in cross-section, with open triangular delthyrium. Shallow 

 sulcus originating near mid-valve. Dorsal valve moderately convex 

 with maximum thickness at quarter valve length. Umbonal area with 

 shallow V-shaped sulcus reversed into a low and narrow median fold 

 flanked laterally by weak plications. Radial ornament multicostellate 

 with 28-30 primary ribs and about 3-5 costellae per mm along the 

 anterior margin of full grown specimens. Growth lines fine, ridge-like, 

 crowded, evenly spaced. 



Ventral interior with teeth and long, diverging dental plates continu- 

 ing into ridges bordering laterally slightly elongate suboval muscle 

 field. Ventral adductor scars narrow and subtriangular. raised anteriorly 

 and somewhat shorter than the strongly impressed elongate suboval 

 diductor scars. Ventral mantle canals lemniscate, straight, widely di- 

 verging. Dorsal interior with high, triangular brachiophores with slightly 

 diverging bases. Fulcral plates variably developed. Cardinal process 

 ridge-like with crenulated myophore. Dorsal adductor scars bisected 

 by fine median ridge and bordered laterally by subparallel ridges 

 starting from the ends of the brachiophore bases. 



Discussion. This species is characterised by a uniplicate ante- 

 rior commissure with low dorsal median fold and shallow ventral 

 sulcus, which is unusual for Pionodema (Cooper 1956), and can 

 be compared only with P. uniplicata Cooper, but differs from that 

 species in its more transverse outline and the weak umbonal dorsal 

 sulcus reversing into a median fold at about mid-length. The 

 Anderken specimens also lack the prominent ridge anterior to the 

 ventral muscle field of P. uniplicata (Cooper 1956: pi. 154, figs 

 31-32). 



Order PENTAMERIDA Schuchert & Cooper, 1931 

 Suborder SYNTROPHIIDINA Ulrich & Cooper, 1936 

 Superfamily CAMARELLOIDEA Hall & Clarke, 1894 



Family CAMARELLIDAE Hall & Clarke, 1894 

 Genus PARASTROPHINA Schuchert & LeVene, 1929 



TYPE SPECIES. Atrypa haemiplicata Hall, 1 847, from the Trenton 

 Limestone (Caradoc), New York, U.S.A. 



Parastrophina iliana sp. nov. 



PI. 13, figs 30-50; Figs 15, 16 



1956 Camerella haemiplicata (Hall) var. rotunda (Winchell & 



Schuchert); Rukavishnikova: 129, pi. 2. figs l,3(no«fig. 



2). 

 1975 Parastrophina haemiplicata (Hall); Sapelnikov & 



Rukavishnikova: 25, pi. 1, figs 1-8. 

 1986 Parastrophina haemiplicata (Hall): Kolobova & Popov; 



pi. Lfig. 4. 



HOLOTYPE. BC 57557, PI. 13, figs 38^2. conjoined valves 

 from Sample 100, Anderkenyn-Akchoku section. 



Material. 52 pairs of conjoined valves, one ventral and 3 

 dorsal valves from Samples 100 (=K-98/1970) (BC 56643-46, 

 57557), 626 (BC 56634-6), Anderkenyn-Akchoku section; Sam- 

 ples, 628 (BC 56633, 56642, 57559), 2538 (BC 56637^1 ), 8217 

 (BC 57556), 8256 (BC 57558), 85258, Kujandysai Section; Sam- 

 ple 948 (BC 57192-99). Tesik River; Sample 1041a, Burultas 

 Valley. 



Description. Shell dorsibiconvex to biconvex, transverse, 

 semielliptical in outline, about 90% as long as wide and 75% as 

 thick as long. Anterior commissure uniplicate. Ventral valve gen- 

 tly convex with maximum thickness somewhat posterior to 

 mid- valve. Sulcus originating about 5-6 mm from the umbo, 

 deepening anteriorly and terminating in broad, semioval tongue 



PLATE 12 



Figs 1-9 Phragmorthis conciliate! Popov. 1, 2, Sample 1018, area 7 km SW of Karpkuduk well. Kotnak Mountains. CNIGR 10/1 1989. holotype. latex 

 cast and dorsal internal mould, x 4. 3, 5-9, Sample 2538, Akchoku Mountain, Kujandysai section; 3, BC 57538, dorsal exterior, x 4; 5-8, BC 57539, 

 conjoined valves lateral, dorsal, posterior and ventral views, x 4; 9. CNIGR 12/1 1989, latex cast of dorsal exterior, x 4. 4, Sample. 8230. Buldukbai- 

 Akchoku section, west side of Kopalysai, BC 57603, dorsal internal mould, x 5. 



Figs 10-12, 15 Eodalmanella extern Popov. 10, Sample 1018, area 7 km SW of Karpkuduk well, Kotnak Mountains, CNIGR 9/1 1989, ventral exterior, x 

 4. 11, Sample 620, Anderkenyn-Akchoku section, BC 57189. dorsal exterior latex cast, x 5. 12, 15. Sample 843. Anderkenyn-Akchoku section: 12. 

 CNIGR 5/1 1989, dorsal internal mould, x 4; 15, CNIGR 3/1 1989, ventral internal mould, x 4. 



Figs 13, 14, 16-27 Pionodema opima sp. nov. 13, 14, Sample 8257, Buldukbai-Akchoku section, west side of Kopalysai, BC 57544, internal mould, 

 dorsal and ventral views, x 3. 16, Sample 8230, east side of Kopalysai. BC 57803, latex cast of dorsal external mould, x 2.7. 17, 18. Sample 7613, 

 Akchoku Mountain, Kujandysai section, BC 57545, holotype, internal mould of conjoined valves, dorsal and ventral views, x 3. 19-24. Sample 818a. 

 Burultas valley. BC 57802, conjoined valves, detail of radial ornament, x 8, and lateral, ventral, dorsal, posterior and anterior views, x 4. 25, Sample. 

 8229. Buldubai-Akchoku section, west side of Kopalysai. BC 57546. dorsal internal mould, x 3. 26, 27, Sample 8228, east side of Kopalysai: 26, BC 

 57548, ventral internal mould, x 3; 27, BC 57547, ventral internal mould, x 2. 



Figs 28-35 Ilistrophina tesikensis gen. et sp. nov.. Sample 948, Tesik River. 28-31, BC 56824, conjoined valves, lateral, anterior, ventral and dorsal views, 

 x 4. 32-35, BC 56823, conjoined valves, holotype, dorsal, ventral, lateral and anterior views, x 4. 



