Sunday 20 March 2016

Cobitis nanningensis: A fossil Loach from the Middle Oligocene of Guangxi Province, China.

Loaches, Corbitidae, are freshwater Cypriniform Fish related to Carp and Minnows, found across Eurasia and in parts of North Africa. They lack scales and are often vermiform (worm) shaped, and are inteligent and highly succesful omnivores, capable of feeding on plants, detritus, and a wide range animal prey. The oldest fossil Loach are known from the late Early Oligocene of Shandong Province in China, with Late Oligocene Loach known from Öhningen in Baden-Württemberg, Germany.

In a paper published in the journal Vertebrata PalAsiatica in 2015, Chen Geng-Jiao of the Natural History Museum of Guangxi Zhuang Autonomous Region and the State Key Laboratory of Palaeobiology and Stratigraphy  at the Nanjing Institute of Geology and Palaeontology, and Liao Wei and Lei Xue-Qiang, also of the Natural History Museum of Guangxi Zhuang Autonomous Region describe a new species of Loach from the Middle Oligocene Yongning Formation of Guangxi Province in South China.

The species is placed in the extant genus Cobitis, which is found across much of Eurasia (including China) today, and given the specific name nanningensis, meaning 'from Nanning'; it is described from samples recovered from an exposure of the Yongning Formation exposed at the Liluo Coal Mine in Nanning City. Only the suborbital spines (spines beneath the eyes which can be expanded as a defence mechanism) are preserved, however these are structures found only in Loaches, and the closely related Botiids (False Loaches); the spines of the two groups are easily distinguishable, and can usually be used to identify a specimens to species level. The Yongning specimens appear distinct from any known species, which combined with its significantly earlier age leads Chen et al. to conclude the specimens can confidently be assigned to a new species.

Suborbital spines of Cobitis nanningensis. (A-B) First specimen in  (A) lateral view and (B) dorsal view; (C-D) Second specimen in (C) lateroventral view and (D) laterodorsal view. Chen et al. (2015).

See also... new species of River Loach from Rakhine State, Myanmar.                                         River Loaches (Nemacheilidae) are ubiquitous members of the Eurasian freshwater fauna, with at least 704 species in 46 genera... new species of Minnow from southeast Turkey.                                                new species of Spotted Barb from the southern Western Ghats, India.                Spotted Barbs of the genus Puntius are small Cyprinid Fish (freshwater Fish related to Carp) from India and Southeast Asia...
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