Fig. 2. Pseudemys scripta taylori new subspecies: anterior view of left antebrachium, female paratype (KU 46934), × 1.
Comparisons.—Of the five other subspecies of Mexican P. scripta mentioned above, three subspecies (gaigeae, hiltoni, and nebulosa) form a natural group herein referred to as the gaigeae group. Pseudemys s. taylori is distinguished from members of the gaigeae group by elongate, red postorbital mark (yellow or orange in the gaigeae group), extensive black plastral pattern (narrow—or if wide, brownish—in gaigeae group), and serrate lower jaw (nearly smooth in gaigeae group).
The subspecies P. scripta taylori differs from P. scripta elegans as indicated in the following comparative list of characteristics:
| P. s. taylori | P. s. elegans |
| 1. Extensive black plastral pattern, all parts of which are interconnected. Plastral pattern partly obliterated by melanism in old individuals of both sexes. | 1. Plastral pattern consisting of separate brown smudges (at least anteriorly). Plastral pattern obliterated by melanism only in adult males. |
| 2. Markings of carapace in form of indistinct ocelli. | 2. Markings of carapace having linear and vertical. |
| 3. Cutting edge of mandible serrate. | 3. Cutting edge of mandible smooth. |
| 4. Foreclaws of mature males unmodified. | 4. Foreclaws of mature males greatly elongated. |
| 5. Gular shorter than pectoral (91 per cent of specimens), gular and femoral subequal. | 5. Gular longer than pectoral (90 per cent of specimens) and longer than femoral (all specimens). |
| 6. Shell relatively higher, posterior lobe of plastron relatively narrower (Fig. 3). | 6. Shell relatively lower, posterior lobe of plastron relatively wider (Fig. 3). |
| 7. Lateral edges of posterior plastral lobe reflected downward. | 7. Lateral edges of posterior plastral lobe unmodified. |
Four specimens of P. s. ornata (MCZ 46392-3, 46397, 46400, two adult females and two adult males) from the Río Soto la Marina drainage of Tamaulipas differ from P. s. taylori as follows: plastral pattern diffuse and brownish, not black; gular longer than pectoral; cutting edge of lower jaw only slightly serrate; stripe on mandibular symphysis isolated, not joined with ventral neck stripes to form inverted Y; postorbital stripe (yellow in preservative) connected to eye by narrow isthmus and continuous with neck stripe to shoulder.
In P. s. taylori there is an obtuse ridge or prominence across the bridge, on a line joining the free lateral edges of the plastron; the area between the ridges is nearly flat. The bridge forms a distinct plane on each side between the mentioned ridge and the outer edges of the marginals. In cross section this plane forms an angle of 30 to 45 degrees with the horizontal plane of the plastron. The higher bridge and deeper shell of taylori result in a slightly higher center of gravity in this subspecies than in the specimens of elegans and ornata I have examined. In the two subspecies last named the longitudinal ridges on the plastron are indistinct or wanting and the bridge forms a lesser angle with the horizontal plane of the plastron.
The largest female of taylori (218 mm.) is shorter by some 30 mm. than the smaller female in the series of ornata from Tamaulipas whereas the largest male of taylori (179 mm.) is shorter by some 80 mm. than the smaller male from Tamaulipas. Pseudemys s. taylori probably is smaller, on the average, than either elegans or northern populations of ornata.
There seems to be no reliable published record of the color of the postorbital mark in living examples of P. s. ornata from Tamaulipas. Williams (1956:147, 154) indicated that this color may be red or yellow for Mexican and Central American populations of ornata in general and Günther (1885: Pl. 6 b) indicated that the color was yellow in Emys cataspila; however, both of the observations mentioned were presumably based on preserved rather than living specimens. The postorbital marks of a live specimen of ornata (KU 40131) from southern Veracruz were yellowish to buffy with a pinkish tinge anteriorly (fide notes of Robert G. Webb and a color photograph by him).
