UPPER ORDOVICIAN BRACHIOPODS FROM KAZAKHSTAN 



39 



geniculation. Dorsal valve strongly concave with low, planar interarea 

 and notothyrium covered by joined apical chilidial plates. Weak 

 median fold originating anterior to the geniculation. Shell surface 

 smooth with fine growth lines. Ventral interior with strong teeth and 

 vascula media subparallel. Dorsal interior with simple, undercut 

 cardinal process, divided bema, low median ridge and a pair of 

 slightly diverging side ridges bisecting the bema. 



DISCUSSION. This species differs from Craspedelia marginata 

 Cooper ( 1 956) and C. gabata Williams ( 1 962: 1 79), from the Lower 

 Ardwell Formation (Middle Caradoc) of Girvan, in its high (up to 8 

 mm) ventrally directed trail with a well-defined ventral sulcus and 

 dorsal median fold. It differs from C. intonsa Potter, 1991, from 

 Member 1 of the Gregg Ranch Unit (Llandeilo), of California. USA, 

 in having a larger shell, up to 12 mm long, with a less transverse 

 outline and a high trail, which exceeds the thickness of the ventral 

 valve in mature specimens. 



Family LEPTELLINIDAE Ulrich & Cooper 1936 



Subfamily LEPTELLININAE Ulrich & Cooper 1936 



Genus ACCULINA Misius, in Misius & Ushatinskaya,1977 



TYPE SPECIES. Acculina acculica Misius in Misius & Ushatinskaya, 

 1977, from the Tabylgaty Formation (Lower Caradoc: gracilis Zone), 

 Moldo-Too Range, North Kirgyzstan. 



Acculina kulanketpesica sp. nov. PI. 3, figs 36-40, PI. 4, 

 figs 1-5 



Etymology. After Kulanketpes ('donkey cannot escape' in 

 Kazakh) Valley on the way from Lake Balkhash to the type locality. 



Holotype. BC 12904, PI. 3, figs 39, 40, conjoined valves, from 

 the Anderken Formation, Sample 1041a, Burultas section. 



MATERIAL. 50 pairs of conjoined valves, 13 ventral and 10 dorsal 

 valves from Samples 100 (=K98/1970) (BC 56493-5, 56485-90, 

 BC 57414), 620 (BC 56937-39), 626, 8128, Anderkenyn-Akchoku 

 section; Sample 823 1-^0 (BC 57416, 18), Buldukbai-Akchoku; 

 Sample 1041a (BC 12900-7,57413, 15, 19), Burultas Valley; Sam- 

 ples 85258 (BC 56491-2, 56941-6), 2538 (BC 56501-02), 

 Kujandysai. 



Description. Shell resupinate, transverse, semielliptical in out- 

 line, about 70% as long as wide and 35% as thick as long. Cardinal 

 extremities near right-angled or slightly acute. Anterior commissure 

 rectimarginate. Ventral valve gently to moderately concave in the 

 anterior half and slightly convex posterior to the mid- valve. Ventral 

 interarea apsacline with a narrow, convex pseudodeltidium. Dorsal 

 valve flat and gently sulcate between the umbo and mid-length, 

 becoming moderately convex anteriorly. Interarea anacline with a 

 narrow, convex chilidium completely covering the notothyrium. 

 Radial ornament unequally parvicostellate with 7 accentuated costae 

 in the umbonal area and 27-30 accentuated costellae along the 



Table 10 Basic statistics of complete shells of Acculina kulanketpesica 

 sp. nov. from Sample F- 104 la. Burultas valley. 





Lv 



Ld 



W 



T 



Lv/W 



LdAV 



T/Lv 



N 



6 



5 



6 



5 



6 



5 



5 



X 



15.5 



14.7 



22.6 



5.4 



68.9% 



65.6% 



34.5% 



S 



0.89 



0.92 



0.85 



1.13 



1.9 



2.1 



7.0 



MIN 



14.0 



13.5 



21.3 



3.8 



65.7 



63.4 



24.1 



MAX 



16.4 



16.1 



23.5 



7.0 



71.2% 



68.5% 



42.9% 



anterior and lateral margins in full grown specimens. Interspaces 

 between the accentuated costellae occupied by fine parvicostellae 

 about 7-10 per mm along the anterior margin. Fine, closely spaced 

 growth lamellae form comae crossed by accentuated ribs in the 

 anterior half of the shell. 



Ventral valve with strong teeth with central grooves; lacking 

 dental plates. Ventral muscle field small, rounded pentagonal with 

 strongly impressed diductor scars completely divided by slightly 

 shorter, narrow, triangular adductor scars. Ventral mantle canals 

 saccate with slightly diverging vascula media. Dorsal valve interior 

 with trifid cardinal process situated on the low notothyrial platform. 

 Socket ridges low, widely diverging and slightly incurved posteriorly. 

 Dorsal adductor muscle field subquadrate, bordered laterally by low, 

 subparallel ridges. Median ridge high and strongly thickened, ex- 

 tended anteriorly to the mid-valve, merging with high diaphragm 

 bordering the lophophore platform. Dorsal mantle canals lemniscate. 



Discussion. This species also occurs in Betpak Dala, Kazakhstan 

 (the locality in Nikitin & Popov 1996). It differs from Acculina 

 acculica Misius {in Misius & Ushatinskaya 1977: 1 14) in its signifi- 

 cantly larger shell, strongly convex anteriorly transverse profile of 

 the dorsal valve and numerous comae (PL 3, fig. 39) in the anterior 

 part of full grown specimens. It is also similar to A. villosa Nikitina 

 ( 1 985 : 24) from the Rgaity Formation ( Llandeilo-Lower Caradoc) of 

 the Kendyktas Range, south Kazakhstan, in the development of 

 comae, but can be distinguished in having a well-defined peripheral 

 rim in the ventral valve, a somewhat smaller dorsal lophophore 

 platform, which has a subrectangular, not a flabellate outline, and a 

 pair of fine transmuscle ridges dividing the anterior and posterior 

 adductors. Acculina is the only plectambonitoid in the Anderken 

 Formation to possess comae, and its exterior is also normally covered 

 by encrusting girvanellid algae. Two specimens (BC 56502-3, PI. 4, 

 figs 7, 8) from the Kujandysai section from Sample 2538 differ from 

 other Acculina in having a geniculate shell with the lophophore 

 platform less than half the valve length, and probably represent a 

 separate species. 



Genus DULANKARELLA Rukavishnikova, 1956 



Type SPECIES. Dulankarella magna Rukavishnikova 1956, from 

 the Dulankara Formation (late Caradoc), Kazakhstan, Chu-Ili Range. 

 Kazakhstan. 



Dulankarella larga sp. nov. PI. 4, figs 9-25, PI. 5, figs 1-3 



ETYMOLOGY. After largus, Latin - rich. 



Holotype. BC 57421, PI. 4, figs 9, 10, a dorsal valve interior from 

 Anderken Formation, Sample 8231-40, Buldukbai-Akchoku sec- 

 tion. 



Material. 86 pairs of conjoined valves, 3 ventral and 2 dorsal 

 valves, from Samples 100 (=K98/1970) (BC 56514, 16-18, 25-29, 

 57422, 24, 26), 626 (BC 56522-4), 8223a (BC 56511, 56975), 

 Anderkenyn-Akchoku; Sample 8231^10 (BC 57421, 23), Buldukbai- 

 Akchoku; Sample 8228 (BC 56986), east side of Kopalysai River; 

 Samples 1041a (BC 56512, 19-21, 56947-57), 818a, 1041a (BC 

 56967, 57425), Burultas Valley. 



DESCRIPTION. Shell strongly concavoconvex, transverse and 

 semielliptical in outline, on average 73% as wide as long, with 

 maximum width at the hinge line and 45% as thick as long. Cardinal 

 extremities slightly acute. Anterior commissure weakly sulcate. 

 Ventral valve strongly and evenly convex in lateral profile, subcarinate 

 posteriorly in transverse profile. Ventral interarea low, planar, anacline 



