Robert G. Webb

“ These two characters, however, coupled with the distinctive juvenile pattern of spots, serve, in combination, to distinguish calvatus from muticus.
Discussion.—The two populations are recognized as subspecies because: (1) there is close resemblance, (2) the diagnostic characters pertaining to pattern are few and superficial, and (3) the geographic ranges are allopatric, but juxtaposed. It is probable that muticus and calvatus would be capable of interbreeding if they were not spatially isolated. ”

“ Diagnosis and definition.—A subspecies of softshell turtle most closely allied to Trionyx muticus muticus but differing from that subspecies in having: (1) a juvenal pattern of large, circular spots, (2) no stripes on dorsal surface of snout, and (3) postocular stripe with thick, black borders immediately behind eye in adult males. ”

“ Both subspecies have the following characteristics: (1) no enlarged tubercles on the anterior edge of the carapace, (2) no ridge projecting from the nasal septum, and (3) a smooth carapace in adult males. These characters distinguish these two subspecies from the several subspecies of T. spinifer, and, except for the smooth carapace in adult males, from T. ferox. ”