AMNH (American Museum of Natural History) R64160; adult male from Alamos (approximate location 27°02'N, 108°55'W, elevation 433 m), Sonora, Mexico, collected on 27 August–2 September 1942 by Charles M. Bogert and preserved in ethanol (Figs 6–14).

AMNH R64157, an adult male; AMNH R64158, an adult female; and ROM (Royal Ontario Museum) 53301 (formerly AMNH R64159), an adult female; all with same collecting data as the holotype and all preserved in ethanol.

ASU (Arizona State University, Tempe) 6427, ASU 6543–44, ASU 6605–06, ASU 6620–22, ASU 6702–03, ASU 6769, ASU 8534–39, CAS (California Academy of Sciences) 142243, CM (Carnegie Museum) Herps:62200, CNAR (Colección Nacional de Anfibios y Reptiles)-4002, LACM (Los Angeles County Museum) 105338, LSUMZ (Louisiana State University Museum of Zoology, Baton Rouge) 34925, MSB (Museum of Southwestern Biology) MSB 41497–99, MVZ (Museum of Vertebrate Zoology) 129943, SMNS (Staatliches Museum fuer Naturkunde, Stuttgart) 7367–68, SMNS 7515, TNHC (Texas Memorial Museum) 60607, UAZ (University of Arizona) 28105, UAZ 35405, UAZ 36875–76, UAZ 56589-PSV, UAZ 56607-PSV, and UIMNH (University of Illinois Museum of Natural History) 85836.

Molecular data can readily diagnose all species of Gopherus and their hybrids (Murphy et al. 2011; Edwards et al. 2016). Morphologically, Gopherus evgoodei, Gopherus agassizii and Gopherus morafkai (the agassizii group) can be separated generally from both Gopherus flavomarginatus Legler and Gopherus polyphemus (Daudin) in having relatively smaller front feet. Whereas the distance from the bases of the first to fourth claws is the same on all feet in the agassizii group, in the latter two species the distance from the bases of the first and third claws on the forelimb is about the same as the distance between the bases of the first and fourth claws on the hindlimb (Auffenberg and Franz 1978). Living captive specimens of the agassizii group and Gopherus berlandieri cannot all be distinguished morphologically because of extensive hybridization (Edwards et al. 2010) and developmental abnormalities in shell, head and limb integument from poor nutrition (Donoghue 2006). However, in native non-hybrid individuals, Gopherus berlandieri can be separated from the agassizii group in having a wedge-shaped snout when viewed from above in contrast to a rounded snout (Fig. 12) (Auffenberg and Franz 1978). Further, the gular projections of Gopherus berlandieri often diverge in large males and the species often exhibits paired axillary scales preceding each bridge. In contrast, the gular projections do not normally diverge in the agassizii group and there is a single axillary scale. Morphological characters among the agassizii group exhibit overlap (Germano 1993; McLuckie et al. 1999) and characters like coloration in desert tortoises can be highly variable (Legler and Vogt 2013). However, Gopherus evgoodei differs from Gopherus morafkai and Gopherus agassizii (Table 1). Gopherus evgoodei is flatter in shell profile (Fig. 2). It has rounded foot pads, multiple enlarged spurs on the radial-humeral joint (Fig. 3). The new species has short tails (Fig. 4), orange tones in the integument (skin) and shell (Fig. 5), and a distinctly shallower concavity on the plastron of males.

(parallels that of Gopherus morafkai by Murphy et al. 2011). An adult male, with

carapace length at the midline

Gopherus evgoodei may exhibit orange or yellow mottling or spotting on the shell and integument. Because color constitutes a diagnostic feature, these data are given above.

As with all species of Gopherus, substantial variability exists among individuals for most morphological features (Germano 1993; McLuckie et al. 1999). Bogert and Oliver (1945) first recognized the distinct morphology of tortoises at Alamos, but they were unable to quantify it due to small sample sizes. Shell profile is generally flat but may also appear domed in some individuals. Spikiness of scales on forelimbs can vary widely and the shape of the plantar surface of the rear feet, while generally rounded, can be difficult to classify in some cases.

The distribution of Gopherus evgoodei (Fig. 1) occupies roughly 24,000 km2 and corresponds to habitat. The species primarily occurs in

tropical deciduous forest

Gopherus agassizii, Gopherus morafkai and Gopherus evgoodei appear to have diverged roughly 5.7–5.9 Ma from a common ancestor that was potentially widespread throughout what is now the Mojave, Colorado and Sonoran desert regions (Edwards et al. 2016). Gopherus agassizii likely diverged first via allopatric speciation when the Bouse embayment extended northward between 8–4 Ma (Lamb et al. 1989). This waterway (now the Colorado River) created a barrier between the Sonoran and Mojave deserts. About the same time, Gopherus morafkai and Gopherus evgoodei began to segregate into tropical and arid ecosystems, possibly under a parapatric model of speciation (ecological isolation), although allopatric speciation owing to climatic change and ephemeral isolation can also explain the split. By the end of the Miocene (5.3 Ma) much of the Sonoran region was likely covered in tropical forests or desert thornscrub but orogenesis initiated the drying trend that lead to the formation of the current North American deserts. The changing environment would have created new arid niches in the northern portion of the ancestral range of the desert tortoise. This could have started the ecological divergence of the three species.

Ecologically, Gopherus evgoodei occupies hills and low mountains with at least some large boulders or rock outcrops in the TDF, and the TDF–STS ecotone. Its distribution differs from Gopherus morafkai by its strong association with TDF and STS, as well as its absence from SDS. Similar to Gopherus morafkai, Gopherus evgoodei often associates with slopes where rock outcrops and boulders are common. In TDF, the tortoise generally excavates burrows under already existing boulders or enters and modifies existing rock cavities. In flatter areas where boulders are not be available, it digs burrows in soil, although possibly not as extensively as its congeners. During 2012–2013 surveys in Sonora, only 9 of 44 tortoise burrows (20%) in TDF were in soil. In comparison, 56 of 87 burrows (64%) occurred in soil in STS and SDS. Local variation was not surprising. In northern Sinaloa, Vargas V (1994) reported Gopherus evgoodei used packrat middens, dry cacti and even burrows dug by other animals (e.g. nine-banded armadillo, Dasypus novemcinctus). Our observations of Gopherus evgoodei, as part of an ongoing radio-telemetry study near Alamos, Sonora, suggested that Goode’s Thornscrub Tortoise uses several burrows a year and exhibits strong site-tenacity, returning to familiar dens year after year (unpublished data), just like its sister-species.

Presumably, tortoise activity corresponds with monsoonal rains and vegetation growth (Bury et al. 2002). Goode’s Thornscrub Tortoise is active from at least June well into November; we lack data on activity during the dry season. In Sonora, the TDF hugs the western edge of the Sierra Madre Occidental and the biome hosts extremely lush vegetation during periods of summer rainfall (July–September). During dry periods, the TDF is almost entirely leafless, but with many spectacularly blooming trees and large columnar cacti (Krizman 1972; Van Devender et al. 2000).

Little is known about daily activity patterns, reproduction, movements or forage of Gopherus evgoodei. Like other species of Gopherus, their activity relates to forage availability and ambient temperatures. Van Devender et al. (2002) reported that scat from tortoises near Alamos, Sonora contained many species of plants not found in the Sonoran Desert, suggesting differences in foraging activity and selection, although species-availability might also account for this. We observed adults to begin seasonal activity shortly in advance of the growth of forage, usually in June at the leading edge of the monsoons, and enter winter dens by sometime in December and remain underground during the dry, cool winter season (unpublished data).

The new species is a patronym, a noun in the genitive case, in recognition of Eric V. Goode, a conservationist, naturalist, and founder of the Turtle Conservancy. He has contributed generously to the conservation of this species via the preservation of land in Mexico, and he actively pursues the conservation of turtles and tortoises on a global scale. Eric sets an important precedent by complementing this taxonomic description with a tangible action that contributes to the conservation of the new species in its native habitat.