UPPER ORDOVICIAN BRACHIOPODS FROM KAZAKHSTAN 



31 



unequally parvicostellate in posterior half of mature valves with 2- 

 4 parvicostellae between accentuated ribs, becoming near equally 

 parvicostellate anteriorly with 5-8 ribs along the anterior margin. 

 Ventral interior with strong teeth and low, diverging dental plates 

 continuing anteriorly as straight muscle bounding ridges bordering 

 posteriorly the open subtriangular muscle field which is about 30% 

 as long as the valve. Adductor scars narrow, weakly impressed, 

 flanked laterally by slightly longer diductor scars. Dorsal interior 

 with cardinal process, low, widely diverging, oblique socket ridges 

 and a short median ridge up to 40% valve length. Adductor field 

 weakly impressed. 



Measurements. CNIGR 29/11989, conjoined valves, L=22.5, 

 W=26.4, Iw=23.6, T=5. 1 ; CNIGR 30/1 1989, ventral internal mould, 

 holotype, L=26.8, W=28.3, Ml=8.8, Mw=9.6; CNIGR 35/11989, 

 dorsal internal mould, L=16.7, W=18.5, T=3.5, Sl=7.8. 



Discussion. This species was originally referred to Strophomena, 

 but it is characterised by an open ventral muscle field bounded 

 posterolaterally by dental plates and short, diverging bounding ridges, 

 a short dorsal median ridge and the absence of side septa, all 

 suggesting attribution to Longvillia. It differs from the type species 

 Longvillia grandis in its less transverse outline, with the maximum 

 width slightly anterior to the hinge line, the radial ornament becom- 

 ing nearly regular in the anterior half of the shell, and in possessing 

 a somewhat stronger median ridge. 



Subfamily FURCITELLINAE Williams, 1965 

 Genus BELLIMURINA (BELLIMURINA) Cooper, 1956 



TYPE SPECIES. Leptaena charlottae Winchell & Schuchert, from 

 the Caradoc of Minnesota, U.S.A. 



Bellimurina (Bellimurina) sarytumensis sp.nov. PL 1 , figs. 



22-28. 



1986 Bellimurina rudis [sic] Lu; Kolobova & Popov: pi. 1, fig. 

 10. 



ETYMOLOGY. After Sarytuma Well in the Betpak-Dala Desert. 



Holotype. BC 57379, PL 1, figs 22, 23, a ventral valve from 

 Sample 8214, Anderkenyn-Akchoku section. 



MATERIAL. Two pairs of conjoined valves, ten ventral and four 

 dorsal valves from Samples 100 (BC 56826, BC 57380), 620 (BC 

 56827-28) and 626 (BC 56829-3 1 ), Anderkenyn-Akchoku section; 

 Sample 8214 (BC 56839-40, BC 57379), west side of Ashchisu 

 River; Samples 628 (BC 56837), 2538 (BC 56838, BC 57378) and 

 8256 (BC 56841), Kujandysai section; Sample 948 (BC 56832-36), 

 Tesik River; Samples 390 (BC 57365), 1041a (BC 57364), Burultas 

 Valley. 



Description. Shell concavoconvex, slightly transverse, sub- 

 rectangular in outline, about 70% as long as wide with maximum 

 width at mid-length with rounded cardinal extremities and 

 rectimarginate anterior commissure. Ventral valve convex with maxi- 

 mum height at geniculation (about three-quarters valve length). 

 Ventral interarea apsacline with well developed pseudodeltidium 

 perforated apically by a minute foramen. Dorsal valve flattened with 

 geniculation near the anterior margin. Dorsal interarea low, linear, 

 anacline with a well-developed chilidium. Radial ornament un- 

 equally parvicostellate with 6-7 accentuated ribs originating at the 

 umbo and up to 7 strong ribs in interspaces. About 4-7 fine 

 parvicostellae per mm along the anterior margin. Concentric ornament 



Table 8 Measurements of ventral valves of Beillimurina sarytumensis sp. 

 nov from samples 100, 626 and 8214 from Anderkenyn-Akchoku 

 section. Sample 2538 from Kujandysai section and Sample F- 1041a 

 from Burultas valley. 



Lv 



W 



LAV 



N 



6 



X 



7.8 



S 



3.62 



MIN 



5.2 



MAX 



14.8 



6 



6 



1.1 



69.4% 



4.35 



6.8 



8 



56.5% 



9.5 



75.9% 



of fine, slightly uneven rugellae about 2 per mm, covering all the 

 posterior half of the shell. 



Ventral interior with small teeth supported by low, divergent 

 dental plates and small, weakly impressed subtriangular muscle 

 field. Dorsal interior with bilobed cardinal process, widely flaring 

 socket plates, poorly impressed median septum extending about 

 one-third valve length, poorly impressed pair of side septa subparallel 

 to the median septum and not extending beyond it. 



Measurements. (435/12375) conjoined valves, L=6.4, W=8.3, 

 T=3.0; (436/12375) ventral valve, L=15.4, W=21.3, T=5.4. 



Discussion. These shells are most similar to, and possibly 

 conspecific with, the specimens described by Nikitin & Popov 

 (1996: 16, figs 6J-N) as Bellimurina? sp. from the Dulankara 

 Regional Stage of north Betpak-Dala in general shell shape and 

 radial ornament with 6-7 accentuated primary ribs, but the dorsal 

 interior in specimens from the Dulankara Stage remains unknown. 

 The Kazakh shells are similar to the specimens described as 

 Kiaeromena longxianensis Fu, 1982 from the Pinling Formation of 

 northwest China in size, ornament and weakly geniculated lateral 

 profile, but further comparison is difficult because of poor descrip- 

 tion and insufficient illustrations of that species, although it is 

 unlikely to belong to Kiaeromena, which is known only from the 

 Baltic. Cooper (1956) described eight species of B. (Bellimurina) 

 from the Caradoc of Laurentia, of which he named six, but the dorsal 

 interiors do not match B. (B.) sarytumensis, nor do those of B. (B.) 

 rudis Xu, Rong & Liu (1974) from the early Caradoc Shitzupu 

 Formation of South China. B. (B.) quadrata Fu (1982) appears more 

 quadrate in outline and its interior is not illustrated (see also under 

 Limbimurina? sp. below). 



Genus TERATELASMELLA Laurie, 1991 



Type SPECIES. Teratelasmella plicata Laurie, 1 99 1 , from the Up- 

 per Cashions Creek Limestone (Lower Caradoc ), Tasmania, Australia. 



Teratelasmella chugaevae sp. nov. 

 10, 11. 



PL 2, figs 10-20; Figs 



ETYMOLOGY. In memory of the late Marina Chugaeva to honour 

 her outstanding trilobite work. 



Holotype. BC 57392, PL 2, figs 14-18, conjoined valves, from 

 the Anderken Formation, Sample 626, Anderkenyn-Akchoku section. 



Material. 1 6 pairs of conjoined valves and 3 dorsal valves from 

 the Anderkenyn-Akchoku section, Samples 100 (BC 56842-5 1 , BC 

 57390-91) and 626 (BC 56853-57, 57392); Kujandysai section. 

 Samples 628 (BC 56858) and 85258 (BC 56852). 



Description. Shell strongly dorsibiconvex, transverse, suboval, 

 about 70% as long as wide, with maximum width at mid-length, and 



