UPPER ORDOVICIAN BRACHIOPODS FROM KAZAKHSTAN 



55 



Bicuspina rukavishnikovae Klenina, 1984 PI. 9, figs 5-13 



1984 Bicuspina rukavishnikovae Klenina in Klenina et al.\ 62, pi. 

 5, figs 7, 8. 



1985 Bicuspina attrita Popov: 61 , pi. 3, figs 2-A. 



Holotype. IGNA 41 1/89, conjoined valves, from the Abai For- 

 mation (Lower Caradoc), Ordotas Mountains, Chingiz Range, 

 Kazakhstan. 



Material. Five conjoined valves, one ventral and 9 dorsal valves 

 from Samples 100 (=K-98/1970) (BC 57505), 626, Anderkenyn- 

 Akchoku section; Sample 1018 (including the holotype of B. attrita 

 CNIGR 32/1 1989), area 7 km southwest of Karpkuduk well, Kotnak 

 Mountains. 



Description. Shell dorsibiconvex, about half as thick as long and 

 about 90% as long as wide. Hinge line short, about two-thirds 

 maximum width. Ventral valve gently convex in lateral profile with 

 maximum thickness at about one-third valve length. Beak small, 

 slightly curved. Ventral interarea low, planar, apsacline with small 

 pseudodeltidium bisected by monticulum. Ventral median sulcus 

 originating in umbonal area with flattened bottom and steep lateral 

 sides about 60% valve width. Well-developed semioval tongue. 

 Dorsal valve strongly convex with maximum thickness at mid- 

 length and flattened umbonal area. Median fold high, originating 

 near umbo, with steep lateral slopes. Radial ornament costellate with 

 6-1 1 ribs in the fold and sulcus and 1 3-2 1 ribs on the lateral sides of 

 mature shells. 



Ventral interior with small teeth supported by short diverging 

 dental plates. Ventral muscle field open anteriorly, weakly im- 

 pressed. Umbonal area with a short internal pedicle tube (PI. 9, 

 fig. 10). Dorsal interior with forked cardinal process on a short, 

 thickened shaft, and small curved socket ridges. 



Measurements. (47 1/1 2375) conjoined valves, L=14.0,W=1 6.9, 

 T=6.3, Sw=8.9; (474/12375) conjoined valves, L=20.4, W=21.0, 

 T=11.2, Sw=8.7; (475/12375) conjoined valves, L=22.9, W=24.5, 

 T=10.2, Sw=12.8; (476/12375) conjoined valves, L=16.5, W=19.8, 

 T=6.5, Sw=11.2; (479/12375) conjoined valves, L=10.5, T=6.7, 

 Sw=6.7. 



DISCUSSION. Coarsely ribbed triplesiides are characteristic of the 

 Caradoc of West Gondwana (Havlicek 1950; Melou 1990) and 

 Avalonia (Williams 1963; 1974), but they are apparently absent from 

 China and Australia and very rare in Kazakhstan. Specimens from 

 the Chu-Ili Range were previously known as Bicuspina attrita 

 Popov (1985). They differ from Bicuspina rukavischnikovae, 

 described by Klenina {in Klenina etal. 1984) from the Abai Forma- 

 tion of the Chingiz Range, only in having a slightly uneven lateral 

 profile of the ventral valve with maximum height posterior to mid- 

 length, and in a more apsacline ventral interarea. These differences 



are regarded here as intraspecific, and specimens of Bicuspina from 

 the Chu-Ili and Chingiz ranges are therefore conspecific. Klenina 

 mentioned the presence of a forked cardinal process and internal 

 pedicle tube in the original description of the species, but the 

 interiors of both valves were not illustrated. 



The published Llanvirn age of B. rukavischnikovae in the Ordotas 

 Mountains of the Chingiz Range, which is the type locality, is not 

 supported by analysis of the associated brachiopod assemblage. It 

 co-occurs with Hesperorthis karaadirensis Klenina, which is prob- 

 ably synonymous with Paralenorthis numerosa (Nikitin & Popov) 

 and rhynchonellids, suggesting that the age of the assemblage is not 

 older than Llandeilo to early Caradoc. 



Genus GRAMMOPLECIA Wright & Jaanusson, 1993 



Type SPECIES. Grammoplecia triplesioides Wright & Jaanusson, 

 1993, from the Boda Limestone (Ashgill) of Dalarna, Sweden. 



Grammoplecia wrighti sp. nov. 



PI. 9, figs 14-21 



ETYMOLOGY. After A. D. Wright, to honour his triplesioid studies. 



HOLOTYPE. BC 57509, PI. 9, figs 17, 18, a dorsal valve from the 

 Anderken Formation, Sample 8214, Anderkenyn-Akchoku section. 



Material. Three pairs of conjoined valves, three ventral and 9 

 dorsal valves, from Samples 620 (BC 57100-04, 57506, 07, 10, 1 1), 

 626 (BC 57105-6), Anderkenyn-Akchoku section; Samples 8214 

 (BC 57099, 57508-11), 8215b (BC 57107), west side of Ashchisu 

 River; Sample 628, Kujandysai Section,. 



DESCRIPTION. Shell dorsibiconvex, slightly transverse, sub- 

 rectangular to suboval in outline, about 83% as long as wide. Hinge 

 line straight, not exceeding two-thirds shell width. Anterior commis- 

 sure uniplicate. Ventral valve moderately convex with low, apsacline 

 interarea and flat pseudodeltidium bisected by monticulum. Ventral 

 sulcus originating about 3-5 mm from the umbo, ending in wide, 

 trapezoidal tongue about 83% as wide as the valve. Dorsal valve 

 strongly convex with maximum thickness at about one-third valve 

 length. Strong dorsal median fold, flat centrally with steep lateral 

 slopes. Lateral slopes convex in cross-section, strongly inclined to 

 the commissural plane. Radial ornament of fine capillae about 5-7 

 per mm crossed by fine, closely-spaced concentric fila. 



Ventral interior with strong teeth and long, diverging, widely 

 spaced dental plates. Ventral muscle field large, about two-fifths 

 valve length, slightly raised anteriorly with wide, subtriangular 

 adductor track dividing narrow, strip-like diductor scars. Dorsal 

 interior with forked cardinal process on strong short shaft joined to 

 low and short socket plates. Adductor field quadripartite with ante- 

 rior and posterior pairs separated by strong, transverse ridges. Low 



PLATE 9 



Figs \-<\ Gacella institata sp. nov.. Sample 100, Anderkenyn-Akchoku section. 1, BC 57498, ventral valve, umbonal area, x 5. 2, Sample 100, BC 57502. 



enlargement of interarea of conjoined valves, x 3. 3, 4, BC 57499, dorsal valve exterior, x 2, and umbonal area showing radial ornament, x 6. 

 Figs 5-13 Bicuspina rukavishnikovae Klenina, 1984. 5-9. Sample 100, Anderkenyn-Akchoku section, BC 57505, conjoined valves, dorsal, lateral, ventral 



anterior and posterior views, x 2. 10-13, Sample 1018, area 7 km southwest of Karpkuduk well, Kotnak Mountains; 10, CNIGR 31/1 1989. ventral 



internal mould showing internal pedicle tube, x 5; 11, CNIGR 32/1 1989, dorsal exterior, x 2: 12, 13, CNIGR 33/1 1989, conjoined valves, ventral view, x 



2, posterior view, x 5. 

 Figs 14-21 Grammoplecia wrighti sp. nov. Anderkenyn-Akchoku section. 14, 15, 19-21, Sample 620; 14, BC 57506. ventral internal mould, x 2; 15. BC 



57507, conjoined valves, oblique posterior view of internal mould showing cardinal process, x 2; 19,20, BC 57510, dorsal and lateral views of exterior, x 



2; 21, BC 5751 1 , dorsal internal mould, x 2. 16-18, Sample 8214; 16, BC 57508, dorsal exterior, x 2; 17, 18. BC 57509. holotype, dorsal exterior and 



lateral views, x 2 

 Figs 22-26 Triplesia sp. Sample 8228, east side of Kopalysai. 22, 23, 25. dorsal internal mould, lateral and dorsal views, x 2. posterior view showing 



cardinal process, x 3. 24, BC 57512. latex cast of dorsal exterior, x 2. 26. ventral internal mould, x 2. 



