Haplorygma dorsalis

Baliński, Andrzej & Yuanlin, Sun, 2010, Tubular shell infestations in some Mississippian spirilophous brachiopods, Acta Palaeontologica Polonica 55 (4), pp. 689-694 : 693

Haplorygma dorsalis ichnosp. nov.

Fig. 1A, B.

Etymology: After the occurrence of the trace fossil in the dorsal valve of a brachiopod host.

Holotype: Trace fossil in the dorsal valve of spiriferide Tylothyris laminosa PKUM 02−0389 figured in Fig. 1B.

Type locality: Muhua section, between villages of Muhua and Gedoungguan (Guizhou province, South China).

Type horizon: Muhua Formation, correlated with the middle Tournaisian Siphonodella crenulata Zone.

Diagnosis.—Microscopic tubular outgrowth of the dorsal valve of spiriferide and spiriferinide brachiopods, attaining 600–750 µm in length and 160–240 µm in thickness, with a single subcircular to elliptical aperture measuring about 90 µm in diameter.

Material.— One specimen of this trace fossil was found in dorsal valve of Tylothyris laminosa collected from sample MH1, the other specimen was revealed in dorsal valve of Spiriferellina cf. insculpta from sample GB.

Description.—The tubular outgrowth simple, small (see Diagnosis for detailed dimensions), posteromedianly inclined, with its distal tip upturned sub−ventrally; subcircular to elliptical in cross section.

Remarks.—As for genus.

Stratigraphic and geographic range.— Known only from the type locality, i.e., Muhua village (Guizhou Province, Southern China), Muhua Formation, Tournaisian, early Mississippian. For details on location, geology, and stratigraphy of the occurrence, see Sun and Baliński (2008) .