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Vesperopsis yanjiensis

Vesperopsis yanjiensis Mao Shaozhi et al., 1999, p.151–152, pl.2,figs.1–5; pl.3, figs.1–7; text-fig.3A–F.

Holotype: Mao Shaozhi et al., 1999, pl.2,fig.1; text-fig.3C.
Age: Valanginian–Hauterivian.

Original description (Mao Shaozhi et al., 1999):
Vesperopsis yanjiensis sp. nov. (Pl. II, Figs. 1—5; P1. III, Fig. 1—7; Text-Fig. 3). The name originated from a Latin- Chinese spelling “Yanjie” for the name of both city and basin where occurs the holotype.
Holotype. — PI. II, Fig. l, Hole Yan-DS of Yanji city, Yanji Basin, Sample 27, Tongfosi Formation.

Description. — Large cysts, the dorsal side is more projected than the ventral side, which may consists of two projected parts sandwiched with a narrow mid depression. The apical horn is long and broad-based, tapering and terminated bluntly. A solid stuff may fill the top part of the apical horn. The two precingular horns are about equal, as are the antapical and right postcingular horns. The distal end of two precingular horns point horizontally in almost opposite direction while the antapical and right postcingular horns are divergent each other. As a result, the whole shape of a cyst looks like a Chinese character “da” (means “big”). Indication of cingulum and sulcus is not always distinct, if any, by low ridges and an area reduced of ornamentation respectively. The archeopyle is apical, operculum usually in place and adnate ventrally, rarely free. Archeopyle suture usually angular, the accessory archeopyle suture may extend onto the precingular plates. Wall surface ornamented with granules and short fine strips partly connected to form incomplete reticulate pattern. The ornamentation is commonly reduced on surface of each horn.

Size (20 specimens measured):
Length of cyst 90.0-115.5 (holotype 105.0) µm
Width of cyst 65.0-105.0 (holotype 100.5) µm
Length of apical horn 33.5-91.5 (holotype 41.4) µm
Length of precingular horn 25.0-46.5 (holotype36.5) µm
Length of antapical horn 30.0-46.5 (holotype 38.5) µm
Length of postcingular horn 26.5-46.6 (holotype 36.5) µm

Comparison: the new species is characterized by being large in size and having a long apical horn and a unique shape resulting from the apical horn pointing up vertically, two precingular horns pointing horizontally, and the antapical horn and postcinular horn divergent to differ other species of the genus.
Location and horizon: Yanjie city of the Yanjie basin, the Tongfosi Formation, Valanginian to Hauterivian.
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