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Acanthodactylus is reassessed, supplementing the external features previously used with new data from the skeleton and hemipenis. The genus appears to be closely related to Eremias and Mesalina rather than to Latastia as was previously thought, and ‘Eremias’ guineensis is confirmed as an Acanthodactylus.
It is suggested that genitalia have an enhanced propensity to ‘store’ evidence of shared evolutionary experience in the form of common characters among descendants, when compared with other organ systems. Such characters deserve relatively high weight in assessing relationships. However, not all genital characters can be interpreted in this way for some seem likely to have evolved as physical isolating mechanisms between similar species and, in such cases, closely related forms may have radically different genitalia. Differences of this kind, together with some osteological features, have proved important in establishing the species status of several forms usually regarded as subspecies or varieties. Thus the four subspecies of A. cantoris are now accorded full species status as A. cantoris, A.blanfordii, A. schmidti and A. arabicus and a similar upgrading may well be appropriate for two taxa usually subsumed in A. tristrami: A. (t.) tristrami and A. (t.) orientalis. Within the A. pardalis complex, A. pardalis, A. maculatus and A. spinicauda are regarded as separate species and the form listed by Boulenger (1921) as var. bedriagai is treated as a subspecies of A. pardalis; a similar un-named West Moroccan population is also assigned to this species. Recently available material makes it probable that A. grandis and A. fraseri are closely related and perhaps allocatable to the same highly variable species. Within the A. scutellatus group the following taxa recognized by Bons and Girot (1962) are assigned to A. scutellatus itself: A. s. scutellatus, A. s. audouini, A. s. hardyi, A. i. inornatus and A. dumerilii. A. Iongipes is retained as a separate species and the same status is given to A. aureus which Bons and Girot regarded as a subspecies of A. inornatus. Geographical variation requires considerable further study in a number of taxa including the A. grandis complex, A. boskianus and the A. scutellatus group but a number of currently recognized subspecies are invalid such as A. tristrami iracensis Schmidt, 1939 (= A. (t.) orientalis), A. pardalis latastii (= A. maculatus) and probably several of the forms in the A. scutellatus group.
An attempt has been made to estimate a phylogeny for the species of Acanthodactylus, although considerable character conflict exists.
