The adult morphological features of Aracajuia benderi are herein re-described, with the objective of making it simpler to identify. Some of the original features were removed from the diagnosis (shape of lateral and marginal pore canals), while others were incorporated (detailing of the central muscle scar pattern, selvage and eye tubercle and description of A-1, A-2, A-3 and possibly A-5 juvenile instars). The ontogenic development of the species is also presented (Fig. 7). Aracajuia distincta Gerry and Rosenfeld and Aracajuia benderi differ in
the size of the carapace, the shape of the central ridge and the overall thickness of the longitudinal ridges. However, the two species are highly similar, and Aracajuia distincta could represent an A-1 individual of Aracajuia benderi; thus, these two species may be synonyms. Aracajuia yakhininensis Rosenfeld and Raab is also a possible synonym; it differs from Aracajuia benderi only in having more developed ornamentation and the carina-like process on the ventral margin, which is actually a much-enlarged ventral ridge. Aracajuia benderi and Aracajuia gigantodistincta Andreu-Boussut can be separated by the orientation of the longitudinal central ridge (more zigzag-like in Aracajuia gigantodistincta than in Aracajuia benderi) and by the orientation of the dorsal margin (which is more strongly sloped toward the posterior end in Aracajuia gigantodistincta than in Aracajuia benderi). Aracajuia zemzenensis Andreu-Boussut differs from Aracajuia benderi in the development of the ventro-lateral carina-like process (which is stronger in Aracajuia zemzenensis). Aracajuia benderi is distinguished from Aracajuia theloides by the shape of the upper branch of the central ridge (which is highly developed in Aracajuia theloides) and the caudal process (less apparent in Aracajuia theloides). Compared to Aracajuia colchesterensis, Aracajuia valanginiana and Aracajuia acuta, Aracajuia benderi can be separated by its more rectangular overall shape and by its well-developed caudal process. Aracajuia benderi also has an ornamentation pattern more similar to that of Aracajuia valanginiana than to that of Aracajuia colchesterensis. Aracajuia benderi differs from Aracajuia lestai by the highly characteristic general outline of the latter species. Aracajuia ashqelonensis Rosenfeld and Raab is clearly distinguished by its strongly zigzag-like central ridge, where the ramifying branch appears to be the lower one instead of the upper. Females of Aracajuia benderi and Aracajuia antiqua Rosenfeld and Raab are nearly identical, but the males of Aracajuia antiqua have a more developed ventro-central carina-like process. In relation to Aracajuia sexta Bold, both can be differentiated by the shape in dorsal view (more slender than in Aracajuia benderi, with a larger anterior region). Aracajuia benderi can be separated fromAracajuia subbaramani Jain by the inclination of the slender central rib, which is steeply pointed in the anteroventral and postero-dorsal regions in Aracajuia subbaramani but much less oblique in Aracajuia benderi, running more parallel to the ventral and dorsal margins. Aracajuia decussata Grndel has a much thicker central ridge than Aracajuia benderi, resembling the central ridge of Amphicytherura species, although anteriorly bifurcate. Specimens of Aracajuia theesensis Grndel possess a similar but highly nodulated central ridge and a carina-like ventral ridge. These species are the earliest representatives of Aracajuia, and with their similarities to Amphicytherura, they could indicate a possible evolutionary trend between these genera.
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