TYPE SPECIMENS OF MORPHOLOGICAL CHARACTERS: AN EXPERIMENTAL APPROACH IN PHYLOGENETIC ANALYSES

One practical difficulty often found by researchers working on phylogenies with morphological characters is when the morphologies approached in the character states are not clearly described, hindering a prompt or even a complete understanding of them. One approach that may help to diminish this problem is the use of specimens as "type specimens" of morphological phylogenetic characters as actual representatives of the morphology approached by the character state. The type specimen of the character state may be named by the researcher who proposed the character or by a later reasercher who uses it, if the researcher deems it necessary to make the character state more easy to understand to readers by allowing them to observe an actual specimen that "represents" the character stata, thus facilitating the understanding of it using a visual resource. This approach is proposed by this study experimentally using two examples of new characters proposed for the phylogeny of the crocodylian group Alligatoroidea. For a character that regards the shape of the maxillary bone, the proposed type specimens of each state are: _Crocodylus niloticus_, AMNH-R-10081 (0); _Paleosuchus palpebrosus_, FMNH-69869 (1); _Wannaganosuchus brachymanus_, SMM-P76.28.247 (2); _Purussaurus mirandai_, CIAAP-1369 (3); _Mourasuchus amazonensis_, DGM-526-R (4); _Gavialis gangeticus_, AMNH-R-88316 (4). And for a character that regards the size pattern of the maxillary alveoli, the proposed type specimens are: _Alligator mississippiensis_, AMNH-R-71621 (0); _Wannaganosuchus brachymanus_, SMM-P76.28.247 (1); _Purussaurus mirandai_, CIAAP-1369 (2); _Gavialis gangeticus_, AMNH-R-88316 (3); _Acynodon iberoccitanus_, ACAP-FX1 (4). The type specimens for state characters are not supposed to be mandatory, and they are neither "state-bearing" specimens, in the sense that holotypes, lectotypes etc. are name-bearing specimens of species, for example. As such, an eventual reconsideration that concludes that the type specimen does not represent the character state would not make the character state invalid; the type specimen is to be an auxiliary instrument only. Additionally, any other specimen must not have the strictly same morphology of the type specimen to be assigned to the state; the type specimen is supposed to serve first and foremost as a guide to aid in the assignment of other specimens to that particular state. [CNPq 140808/2016-7]