Taxonavigation

Familia: Asaphidae
Genus: Asaphus
Species: Asaphus broeggeri

Geological age

Middle Ordovician, Dapingian stage

Locality

St.Petersburg, Russia, Volkhov river in Volkhov horizone, Zheltyaki Member, B₂β

History of species descriptions and revisions

1. 1898 and 1901 - Schmidt, p. 20 (nom. nud.); (1901) p. 21, pl. 2, figs. 4-7; pl. 12, fig. 5; text-figs. 4 and 13 as Asaphus broeggeri;
2. 1905 - Lamanskii, p. 62 as Asaphus broeggeri;
3. 1949 - Lesnikova and Weber, p. 284, pl. 68, figs. 1 and 2 as Asaphus broeggeri;
4. 1953 - Balashova, p. 388, pl. 1, fig. 1, pl. 2, figs. 1 and 2 as Asaphus (Schizophorus) broeggeri;
5. 1953 - Jaanusson, 1953a, p. 397 as Asaphus (Asaphus) broeggeri;
6. 1976 - Balashova, p. 8 as Asaphus (Asaphus) broeggeri;
7. 2003 - Ivantsov A.Yu., p.s318-s319, pl. 16, figs. 1-3. (latest)

Diagnosis

Cephalon elongated, acuminate anteriorly, glabella not reaching anterior margin; basal lobes lenslike and almost not expressed on outer surface of carapace; rudiments of glabellar lobes absent; eyes low; weak list present at posterior margin of ocular area; genal corners acuminate and lacking of spines; occipital furrow absent; pygidium of medium proportions, rachis undivided; pleurae unsegmented.

Lectotype

PIN, no. 4248/92, unrolled, partially destroyed carapace, depicted by Schmidt (1901, pl. 2, fig. 4), designated by Balashova (1953); Volkhov River, village of Izvoz; substages B2a-b.

Asaphus broeggeri. Lectotype.

Worldwide occurrence

• Ladoga Glint: Lower Ordovician, Arenig. Volkhov Horizon, beds with A.? broeggeri; Volkhov Formation, Zheltyaki Member;
• Baltic Glint: Toila Formation, Kunnapohja Member;
• Moscow Syneclise, Valdai Monocline: Volkhov-Formation (Alikhova, 1960; Dmitrovskaya, 1991)
• Rock masses detached by a glacier in the Tver' Region (Balashova, 1953,1976).