Sinokontikia lianmuqinensis Wang, 1985

TENG, XIAO, 2022, A morphological re-study of three spinicaudatan species from the Middle-Upper Jurassic of Gansu Province, northwestern China, Palaeoentomology 5 (4), pp. 327-339 : 332

Sinokontikia lianmuqinensis Wang, 1985

( Fig. 4 )

1985 Sinokontikia lianmuqinensis Wang , p. 12–13, pl. 3, figs 3–5

2002 Sinokontikia lianmuqinensis Wang in Shen et al., pl. 2, fig. 8

2004 Sinokontikia lianmuqinensis Wang in Shen, pl. 19, fig. 2

Material. NIGP 130637 , external mould of a right valve. Middle–Upper Jurassic Yaojie Formation at Tanshanling Town of Bairi (Tianzhu) Tibetan Autonomous County, Gansu Province, northwestern China .

Diagnosis. Carapace of medium size (L = 9.4–14 mm, H = 6.2–7.4 mm), shape elongated oval; dorsal margin long; larval valve small; umbo in anterior and marginal position; growth lines stout, usually with central concave; growth bands wide and flat, 8–13 in number; growth bands ornamented with tubercles; tubercles are stretched or irregular.

Description. Carapace of medium size, shape elongated oval; dorsal margin long; larval valve small; umbo in anterior and marginal position; growth lines stout, usually with central concave; growth bands wide and flat, 12 in number; growth bands ornamented with tubercles, tubercles are stretched or irregular ( Fig. 4B–G ); on the growth bands in antero-ventral or postero-ventral part of the carapace, tubercles stretched vertically, appearing as radial lirae( Fig. 4C–E, G ); tubercles transversely stretched sporadically near the upper or lower margin of growth bands( Fig. 4D, F ); in the dorsal and middle part of the carapace, growth bands ornamented with irregularly arranged tubercles, forming irregular fine reticulation ( Fig. 4B–D ).

Measurements.

Number of

Specimen number Fig. L/mm H/mm H/L

growth lines

NIGP 130637 4A 12 9.7 5.9 0.61 Legend: H = height of carapace, L = length of carapace

Locality and horizon. Middle–Upper Jurassic Yaojie Formation at Tanshanling of Tianzhu, Gansu Province, P. R. China ; Middle– Upper Jurassic Qiketai Formation at Lianmuqin of Shanshan, Xinjiang Uygur Autonomous Region, China .

Remarks. According to Wang (1985), in the middle and dorsal part of the carapace, there are some remained fine reticulation, and in fact, the tubercles are changed from the bulge mesh wall. This feature indicates that this genus has an ancestor that is ornamented with fine reticulation.

Figures

FIGURE 4. Sinokontikia lianmuqinensis Wang, 1985. Type specimens (NIGP 130637) in Shen et al., 2002. A, Focus-stacked images. B–G, SEM images.A, External mould of a right valve. B, Growth bands in the anterior part of the carapace, ornamented by irregularly stretched tubercles, appearing as irregular reticulation on external mould. C and D, Growth bands in the antero-ventral part of the carapace, ornamented by irregularly stretched tubercles, tubercles stretched vertically on the lower part of each growth band, appearing as irregular reticulation with radial lirae on the lower part of each growth band in the external mould. E–G, Growth bands in the postero-ventral part of the carapace, ornamented by irregular tubercles, tubercles stretched transversely, appearing as irregular reticulation, some growth bands with transversely reticulation on external mould. Scale bars = 1 mm in A, 100 μm in B and D–G, 200 μm in C.