Type Species. Wurmiella tuma (Murphy and Cebeçioglu 1986).

The systematics of Ozarkodina (Branson and Mehl 1933) was reviewed recently (Murphy et al. 2004) and the group of forms that have an apparatus similar to that of O. excavata (Branson and Mehl 1933) were classified in the genus Wurmiella. These authors envisioned four long-ranging lineages as constituting the main taxonomic units within the genus (Murphy et al. 2004). Here we use Murphy et al.'s (2004) conclusions as our working hypothesis as we consider the two lineages that occur in the middle Lochkovian, W. wurmi and W. tuma, and identify a third, W. n. sp., that was unrecognized by those authors (Figure 1).

The genus is characterized by the simple blade with rather even sized denticles and generally small expansion of the basal platform of the P1 element and the similarity of its apparatus, especially the Pb elements with their very high cusps, the even curvature of the M elements and the incrementally larger posterior denticles of the Sc element.

Wurmiella wurmi (Bischoff and Sannemann 1958)

Holotype by original designation = Spathognathodus wurmi Bischoff and Sannemann, 1958, pl. 14, fig. 5.

Diagnosis. A species of Wurmiella with a combination of the following characteristics in the P1 element: biconcave to convexo-concave lower profile in lateral view, moderate shoulder with or without a denticle on the shoulder on the inner side of the blade or without a shoulder; ledge at the base of the denticle row; 17-27 denticles depending on the size and stratigraphic level of the specimen.

Description. P1 element gently twisted, slightly more strongly near the extremities; basal cavity small, asymmetrical, with inner side more expanded; basal grooves appressed at their distal ends and with straight anterior segment in smaller specimens; lower profile in lateral view biconvex to convexo-concave; upper margin in lateral view biconvex; cross section of blade (below the denticles) low walled, thick at maturity; ledge normally developed on inner side at base of denticles; flanks of blade inflated below ledge and with a narrow pinch zone close to the lower margin; height of both parts (anterior and posterior) of blade about equal; thicker (wider) and higher denticles concentrated near the centers of anterior and posterior parts of blade; at the position of basal cavity ledge bulges laterally to form shoulder on inner side of some specimens and in some specimens on both inner and outer sides; denticle number varies from 17-27, counting all germ denticles and depending on the size of element; denticles straight, stout, with elliptical cross sections, and blunt to moderately sharp tips.

Comparison. Wurmiella wurmi differs from W. excavata in the greater number of denticles and the biconcave lower margin of the blade that is angulate in W. excavata; from W. n. sp. in having a biconcave lower margin as opposed to a uniformly arched one, and a basal platform with a well-developed inner lip and shoulder above it.

Discussion. We have recognized three common morphs in this taxon that may be of restricted stratigraphic distribution and, thus, broad diagnosis. They are 1) the type or tau morph () with a well-developed inner shoulder and strongly biconvex lower profile; 2) the alpha morph () with a denticle developed on the shoulder; and 3) the beta morph () without a shoulder and fewer denticles.

Diagnosis. A Wurmiella species based on P1 elements with the following combination of characters: arched lower profile; element bowed or twisted in upper view; basal cavity small, asymmetrical, only slightly or not at all expanded on the inner side.

Description. Element gently bowed in basal view, slightly more strongly near the extremities; basal cavity very small to small, asymmetrical with expansion at base on outer side of blade; basal grooves appressed or open to inverted in some morphs; lower profile moderately arched with somewhat stronger curvature in posterior portion of the element; flanks moderately inflated with narrow pinched zone at base; blade height short with posterior shorter than anterior half; upper profile biconvex with broader and higher denticles concentrated around the position of the cusp and in the anterior one third of element; a slight ledge may be developed at base of denticles; denticle number varies from 17-22 counting all germ denticles depending somewhat on size of element.

Comparison. Differs from W. excavata in the more strongly arched and bowed blade and greater number of denticles; from W. wurmi in having an arched as opposed to a biconcave lower profile, and in lacking a shoulder.