UPPER ORDOVICIAN BRACHIOPODS FROM KAZAKHSTAN 



41 



Table 11 Basic statistics of complete shells of Dulankarella larga sp. 

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





Lv 



W 



T 



Lv/W 



T/Lv 



N 



9 



9 



7 



9 



7 



X 



16.9 



24.6 



7.7 



69.7% 



46.1% 



s 



2.10 



3.57 



1.19 



10.2 



3.2 



MEN 



13.5 



19.1 



5.7 



51.9% 



41.5% 



MAX 



18.8 



31.6 



9.2 



81.3% 



50.0% 



with delthyrium partly covered by a convex pseudodeltidium. Dorsal 

 valve strongly concave and slightly geniculate anteriorly. Dorsal 

 interarea hypercline with chilidial plates joined apically. Sulcus 

 broad and shallow, originating near mid-valve. Radial ornament 

 unequally parvicostellate with 5-7 accentuated ribs originating at 

 the umbo and two or three generations of accentuated costellae, 

 totaling 31-38 in number in full grown specimens. Parvicostellae 

 between accentuated ribs very fine and closely spaced, about 12-16 

 per mm along the anterior margin. 



Ventral valve interior with strong teeth supported by short den- 

 tal plates, thickened at the base. Muscle field bilobed with strongly 

 impressed, rounded subrhomboidal diductor scars separated by 

 short, elongate subtriangular adductor scars. Paired nodose swell- 

 ings anterolateral to the muscle field. Ventral mantle canals saccate 

 with short, divergent vascula media. Dorsal interior with trifid 

 cardinal process bearing a strong, ridge-like median lobe and up to 

 6 fine ridges on the lateral lobes. Socket ridges narrow, widely 

 diverging. Median septum strongly raised and thickened anteriorly 

 with the maximum height at the point of junction with the outer 

 boundary of the lophopore platform accentuated by geniculation 

 of the valve. 



Discussion. This species resembles the later Dulankarella magna 

 Rukavishnikova ( 1956: 139) in size and transverse profile, but differs 

 in having a finer radial ornament with 5-7 strongly accentuated 

 primary ribs and a characteristic rounded subrhomboidal outline of 

 the ventral diductor scars, which only slightly touch each other 

 anteriorly to the adductor scars. The differences from Dulankarella? 

 partita Percival (1979b: 103) are in having a less transverse outline, 

 evenly convex ventral valve, the ventral muscle field lacking a 

 median ridge, and the rhomboidal outline of the ventral diductor 

 scars. 



Kajnaria rugosa sp. nov. PL 5, figs 6-18 



Etymology. After rugosus, Latin - wrinkled. 



HOLOTYPE. BC 5655 1 , PI. 5, figs 12, 1 3, a dorsal internal mould 

 from Sample 628, Kujandysai section. 



Material. 9 pairs of conjoined valves and three ventral valves 

 from Samples 100 (BC 56545-47, 57436, 37), 626 (BC 56548), 

 8223a, Anderkenyn-Akchoku section; Sample 628 (=K107/1970) 

 (BC 56551, 57439), Kujandysai section; Sample 1041a (BC 56543, 

 44), Burultas Valley: Sample 816 (BC 56549-50, 57438), Alakul 

 lake. 



Description. Shell strongly concavoconvex, semielliptical in out- 

 line, about 67-82% as long as wide with maximum width at the 

 hinge line. Cardinal extremities acute and slightly alate in adult 

 specimens. Ventral valve strongly convex in lateral profile, weakly 

 geniculate in some specimens, with maximum thickness posterior to 

 mid-length. Relatively weak umbo. Interarea anacline with narrow 

 convex pseudodeltidium. Dorsal valve moderately and evenly con- 

 vex with hypercline interarea. Notothyrium completely covered by 

 convex chilidium. Radial ornament unequally parvicostellate with 

 5-7 primary accentuated ribs and two to three generations of accen- 

 tuated costellae, with the interspaces between them covered by fine 

 closely-spaced parvicostellae, about 7-14 per mm. Concentric orna- 

 ment of up to 9 undulated rugellae in the posterior half of both valves. 

 Ventral interior with strong teeth lacking dental plates. Ventral 

 muscle field small, strongly supported by raised muscle bounding 

 ridges which merge centrally and anteriorly. A further pair of strong 

 curved ridges originate posteriorly at one-third of the length of the 

 hinge line on each side of the valve, and curve anterolaterally to form 

 a w-shaped structure which terminates near the end of the bounding 

 ridges at about quarter valve length. Mantle canals saccate with 

 vascula media subparallel in the proximal part and diverging 

 anteriorly. Dorsal interior with erect trifid cardinal process fused 

 anteriorly to a strong median ridge. Sockets large. The median ridge 

 merges near the mid-length with a high subperipheral rim bordering 

 the lophophore platform. 



DISCUSSION. This species differs from Kajnaria derupta in the 

 twice as large shell size and the well defined concentric rugellae in 

 the posterior half of the valves. 



Genus KAJNARIA Nikitin & Popov, 1984 



TYPE SPECIES. Kajnaria derupta Nikitin & Popov in Klenina et al. 

 (1984), from the Bestamak Formation (Lower Caradoc), Chingiz 

 Range, Kazakhstan. 



Genus MABELLA Klenina, 1984 



TYPE SPECIES. Leptellina (Mabella) semiovalis Klenina in Klenina 

 et al. (1984), from the Taldyboy Formation, Dulankara Regional 

 Stage (Upper Caradoc), Chingiz Range, Kazakhstan. 



PLATE 4 



Figs 1-5 Acculina kulanketpesica sp. nov. 1, Sample 1041a, Burultas Valley, BC 57413, dorsal interior, x 2. 2, Sample 8137, Anderkenyn-Akchoku 

 section, BC 57417, latex cast of dorsal interior, x 3. 3, Sample 100, Anderkenyn-Akchoku section, BC 57414, dorsal exterior view of conjoined valves, x 

 2. 4, Sample 1018, area 7 km S W of Karpkuduk well, Kotnak Mountains, ventral internal mould, x 3. 5, Sample 85258, east of Uzunbulak River, BC 

 56491, ventral internal mould, x 2. 



Fig. 6 Glyptambonites sp., Sample 628 (=K-107/70), west side of Kujandysai, BC 56510, ventral exterior, x 3. 



Figs 7, 8 Acculina sp. Sample 2538, Akchoku Mountain, Kujandysai section. 7, BC 56502, latex cast of dorsal interior, x 2. 8, BC 56501. ventral internal 

 mould, x 1.5. 



Figs 9-25 Dulankarella larga sp. nov. 9, 10, 16, Sample 823 1^10 , Buldukbai- Akchoku section, west side of Kopalysai; 9, 10, BC 5742 1 , holotype. 

 dorsal interior, x 2.7; cardinal process and socket plates, x 5; 16, BC 57423, ventral internal mould, x 2. 11-13, 19-21, 24, 25, Sample 1041a, Burultas 

 Valley; 11-13, conjoined valves, lateral, ventral and dorsal views, x 2; 19-21. BC 57425, conjoined valves, ventral, dorsal and lateral views, x 2; 24, 

 Sample 1041a, BC 56512, conjoined valves, posterior view showing interareas. x 6: 25, BC 56967. dorsal view of conjoined valves, x 2. 14, 15, 17, 18, 

 22, 23, Sample 100, Anderkenyn-Akchoku section; 14, BC 56514, incomplete dorsal valve interior, x 3: 15, BC 57422, ventral internal mould, x 2; 17, 

 18, BC 57424, conjoined valves, ventral and dorsal views, x 1.5; 22, 23, BC 57426, ventral valve exterior, anterior and ventral views, x 2. 



