RHYNCHONELLIDE BRACHIOPOD 1SOPOMA TORLEY 



157 



Figs 4, 5 hopoma brachyptyctum (Schnur). 4, section of a dorsal valve at the socket showing well defined, separated, outer hinge plates and crural bases; 

 Ahbach Formation, Lahr Member, mid-Eifelian, Im Lahr, NE of Niederehe, St. 949, Germany; BD 12782, x 9. Sa, b, sections through a shell near the 

 socket, where the valve is thickened, slightly posterior and dorsal to that of Fig. 4; Massenkalk, Kohlenstein Member, Upper Givetian, Iserlohn- 

 Bilveringsen, Germany; BD 12783, x 9. 



Maillieux (1941: 10) listed hopoma aptyctum (Schnur) and /. 

 brachyptyctum from Frasnien (F, beds) in the Devonian of Ardenne, 

 Belgium, but gave no description or illustrations, so the validity of 

 these occurrences cannot be verified. 



Havh'cek (1951, 1961) reported /. brachyptyctum (Schnur) from 

 the Middle Devonian (Givetian) limestones in the vicinity of 

 Celechovice (Moravia). Biernat (1966) described specimens of /. 

 brachyptyctum (Schnur) from the Skaly Beds and one from the 

 Pokrzywianka beds, Holy Cross Mountains, Poland. Although there 

 is some difficulty about the Eifelian/Givetian age for the Skaly Beds, 

 Biernat (1966) thought them to be Lower Givetian on the basis of her 

 brachiopod study. 



Bublichenko (1974: 72, 73, pi. 10, figs 8-10) described and 

 illustrated /. brachyptyctum (Schnur) from the Krjukovo Beds 

 (Lower? Emsian) of the Russian Rudnogo Altai region. However, 

 serial sections and precise information about the interior is lacking, 

 so the identification is doubtful. 



Sapel'nikov & Mizens (1984: 23-24, pi. 4, figs 10, 13, pi. 5, figs 

 4, 5) described and figured /. aff. brachyptyctum (Schnur) from beds 

 with Ivdelinia acutolobata of Lower Givetian age from the central 

 part of the Ufa Amphitheatre in the southwest Urals, Russia. 

 Mamedov (1985) reported the occurrence of hopoma brachyptycta 

 in a key section of the Middle Devonian of Transcaucasia, in the 

 upper Arpachaisk sub-suite of Givetian age. He claimed that this 

 interval corresponds with the Alchedatskii horizon of the Kuznetsk 

 Basin, the upper parts of the Starooskolskii (old Oskolskii) horizon 

 (Mulinskii/Moulins beds) on the Russian platform and possibly the 

 upper parts of the Aidarlinskii horizon of Kazakhstan. According to 

 Mamedov (1985: 159) the Mont-Aur Layers with Hexagonaria 

 guadrigemina in the Ardennes correspond to this interval and the 

 Bolsdorf layers in the Eifel are possibly synchronous. 



Sapel'nikov & Mizens (1985), while providing new data on the 

 biostratigraphy of the Ural Mountains, recorded hopoma aff. 

 brachyptyctum on both western and eastern slopes, at a stratigraphic 

 level which they correlated with the Eifelian-Givetian horizons of 

 the Ardennes-Rhine region of Western Europe. 



Xian Si-yan & Jiang Zong-long (1978: 289, pi. 106, fig. 14) 

 described and illustrated /. brachyptyctum (Schnur) from the lower 

 part of the Dushan Formation (Givetian), Dongyao, Xiasi, Dushan 

 County, Guizhou, China. Although no internal information was 

 given, the shape resembles that of the lectotype figured by Schmidt 

 (1941: 45, pi. 4, fig. 88). Xian & Jiang (1978) did not give detailed 



information on the stratigraphic levels from which their two species 

 (/. brachyptyctum and /. ovale) were found. 



hopoma alecto (Barrande, 1847) 



1847 Terebratula alecto Barrande: 42, pi. 20, fig. 2. 



1961 hopoma alecto (Barrande); Havh'cek: 40, pi. 6, fig. 5. 



Comment. This species was described from the Pragian of Bohe- 

 mia. Havh'cek's ( 1961 ) redescription showed that it is characterized 

 by a ventral sulcus starting just before half the valve length and 

 containing three ribs. Havh'cek (1961: 40, text-fig. 7) also gave a 

 section showing a thin divided hinge plate and crural bases, which 

 are directed dorsally, as in all known hopoma species. Havh'cek 

 (1992: 56, table 1) listed this species in the Suchomasty Limestones 

 (Dalejan). The species name was used by Perry (1984) for speci- 

 mens from the Upper Lochkovian of the Yukon Territory in Arctic 

 Canada. However, we think more critical studies are necessary 

 before accepting the Yukon forms as true hopoma. 



hopoma gryps Schmidt, 1965 



Fig. 6 



1965 hopoma gryps Schmidt: 13-16, text-figs 18, 19; pi. 1, figs 

 1-7. 



Material. From Greifenstein, Eifel region, Germany, 17 speci- 

 mens (SMF 19531 ) and two unregistered specimens, donated by the 

 late Dr Struve, from an exploration trench from the Greifensteinkalk 

 of the same area (BD 12786-87). 



Comment. This species was originally described from the Lower 

 Eifelian Greifensteiner Kalk of the Eifel region. It is characterized 

 by a prominent ventral sulcus, which originates close to the umbo. In 

 some specimens the sulcus contains a single median rib. Serial 

 sections (Fig. 6a-c) show characters typical of the genus, with a 

 thickened dorsal umbo and prominent teeth. 



hopoma hertae Mohanti, 1972 Figs 7, 8 



1972 hopoma hertae Mohanti: 170, pi. 6, fig. 4. pi. 7. figs 1-5. 



Comment. Specimens were originally described from the upper 

 Eifelian to Givetian transitional beds in the Cantabrian Mountains, 

 northern Spain, and these have been studied. This species is charac- 

 terized by a circular to subpentagonal outline, weakly developed 



