Abstract
This study reports the results of a re-analysis of the number of lateral eyes in extant buthids. Specimens studied were confined mostly to those from China and the adjacent areas. 353 specimens belonging to 20 species (subspecies) and 8 genera were rechecked and found to have 5 pairs of lateral eyes contrary to earlier published works which reported the presence of 3 pairs of lateral eyes only. Combined with reported examples collected through reference investigation including 63 species from 16 genera, our study here shows a total of 79 species from 21 genera of scorpions spanning Asia and Africa had 5 pairs of lateral eyes. Reasons for not observing the presence of the extra lateral eyes are discussed and new protocols for examining specimens including using UV light are proposed to aid lateral eye recognition. Besides, a majority of genera in Buthidae are suggested to be in “Five-eye” model and a re-examination of all previously published taxonomic studies of buthid species is highly recommended.
Highlights
Eye features are widely known to be important characters in the study of taxonomy in most arthropod groups
In the widespread Chinese subspecies, M. martensii martensii, we found 2 extra pairs of lateral eyes here labeled as No 4 and No 5 when examined under the UV light
To confirm the existence of these extra pairs of lateral eyes and to discount confusion with tubercle structures on the carapace, we performed a dissection on the carapace to prepare histological sections for examination, which resulted in affirmation of eyes No 4 and No 5
Summary
Eye features are widely known to be important characters in the study of taxonomy in most arthropod groups. The number of lateral eyes varies among different major groups of extant scorpions. Koch [1] was the first to think highly of the number of lateral eyes in scorpion taxonomy. Stockwell [3] affirmed Kjellesvig-Waering’s opinion in fossil scorpions in his unpublished PhD thesis, but he did not emphasize on the importance of lateral eyes in the extant groups. Soleglad and Fet [5] re-analyzed the higher taxonomic system with 105 characters selected from all extant families which included the lateral eyes counts. They denoted the numbers from Buthidae and Pseudochactidae as ‘‘uninformative data’’
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