Devonozyga diversicostata Horný, 1955

Holotype. NMP 34890 (Horný 1955: pl. V, fig. 1).

Type locality. Section in small quarry NE of the village of Holynĕ and W of the Prastav quarry (50°1'57.627"N, 14°21'5.471"E).

Type horizon. Uppermost part of Třebotov Limestone (Daleje-Třebotov Formation); the latest Emsian to early Eifelian, Middle Devonian.

Remarks. This species is based on single shell collected by Dr. F. Prantl at the same locality and stratigraphic level as the type species D. perneri. It differs from the latter species only by an absence of collabral ribs on the lower part of its last whorl (probably caused by abrasion or by subsequent fossilization). Small differences of both Bohemian species of Devonozyga probably only represent intraspecific variability. However, very limited material was available for study (six, mostly poorly preserved specimens in the case of D. perneri; one in the case of D. diversicostata), making an analysis of shell variability difficult. Future analysis based on new fossil material from the Holynĕ locality, which will be newly collected during on-going project of the Grant Agency of the Czech Republic (P210/12/2018), probably will solve that problem.

Stratigraphic and geographic distributions. This rare species is only known from its type horizon and locality.