The American Eumeces laticeps and E. inexpectatus seem to be more specialized than E. fasciatus and might have been derived from it or from a common ancestor differing but little from the modern fasciatus. Both differ from fasciatus in having more scale rows. E. laticeps also differs in having eight instead of seven supralabials and in having the median subcaudal scales greatly widened, in having intercalated plates on the outer side of the fourth toe nearly to the ultimate phalanx, posterior supralabial low and elongate, young sometimes seven-lined instead of five-lined, and especially in much larger size, stocky build, and in early loss of striped pattern. E. inexpectatus differs in having the median subcaudals not at all enlarged, and in having the dorsolateral stripes a little more widely separated from the midline.
Eumeces fasciatus and its relatives present a curious exception to Jordan’s Rule, which states that the nearest relatives of any given species are to be found neither in the same area nor in a remote one, but in an adjacent region separated by a barrier. E. fasciatus is absent from almost all of Florida; otherwise its range overlaps most of the ranges of both laticeps and inexpectatus, the former including the southeastern United States south of about latitude 40°, and the latter being mainly in the Atlantic and Gulf states from Chesapeake Bay into eastern Louisiana. Presumably both of these species began their differentiation as southern populations of an ancestral fasciatus and later became isolated from it and continued their differentiation until they overlapped it again as distinct species. The differentiation of laticeps, being much greater, presumably took place at an earlier time than did that of inexpectatus, and at present it overlaps fasciatus more extensively. E. laticeps probably diverged to such an extent that competition with fasciatus is greatly reduced where the two species occur together.
Since Eumeces laticeps was recognized by Taylor as a species distinct from fasciatus, numerous authors have accumulated field observations that demonstrate ecological divergence between the two. Conant (1951:33) wrote that in Ohio laticeps prefers a dry habitat of bare rocks, cliffs, dry hillsides, and trees. He summed up the habitat difference as follows: “Fasciatus appears to be essentially terrestrial, to prefer a moist environment and to be at home in ravines in southern Ohio. Laticeps on the other hand, is largely arboreal (particularly adults), prefers dry cliffs, sunny hillsides and hilltops and lives in general above the habitat of fasciatus.” Netting (1939:127) likewise states that in Pennsylvania E. laticeps inhabits drier places than does fasciatus, and is largely arboreal. Other authors with few exceptions agree that laticeps is largely arboreal, but most describe it as at home in forest swamps and bottomlands. My own field experience with it is limited. In the Pigeon Lake area of Miami County, Kansas, the northwesternmost known locality of occurrence for laticeps, the habitat relations described by Conant for Ohio were almost reversed. Eumeces laticeps was relatively scarce, and confined to the vicinity of the swamp chiefly in areas that are flooded in time of high water. All those seen were on or near massive snags of dead trees still standing, but decayed and honeycombed with cavities. Slabs of bark clinging loosely to the tree trunks, with spaces beneath, provided shelter for the skinks and for the abundant arthropod fauna which probably constituted their chief food source. This is one of the few places in Kansas where a remnant of the original bottomland forest remains. In central Louisiana, in 1947 and 1948, persons living on the Kisatchie National Forest told me of large, red-headed skinks living in hollow trees, which must have been E. laticeps. In the literature E. laticeps is frequently referred to as red-headed, although the reddish suffusion on the head of the adult male is ephemeral in this species as it is in E. fasciatus and others. The heightened activity of the adult males in the breeding season seems to have drawn attention to this conspicuous temporary coloration while its absence at other seasons has scarcely been mentioned.
Mansueti (1948:213) describing the habits of laticeps in Maryland, Louisiana and elsewhere in the southern states, emphasizes its arboreal habits, referring to it as “‘scorpion’ of the treetops.” He describes it as dashing up and down tree trunks, along fences, and in abandoned buildings. However, he states that it also spends much time on the ground, and may take refuge in holes and cracks near ground level, and gravid females are less arboreal, making their nests in decayed logs of chestnut or oak. He mentions individuals having been found living far above ground in tall trees, in nests of birds of prey. One old male that was frequently seen by him always retreated far up a dead chestnut tree that towered above the surrounding forest of scrub pine. Mansueti also mentions arboreal combats between males and implies that they are territorial. Taylor (1936:59) described laticeps as typically an arboreal form, almost invariably found in trees, and he indicated that it has claws more curved than in other species—an obvious arboreal adaptation. Parker (1948:25), however, stated that “E. laticeps is reputed to be rather arboreal, but field work in western Tennessee has not borne out this belief. A few of the specimens have been found in tall, dead trees, as has E. fasciatus.” This statement evidently was based on a small number of observations.
Cook (1943:15) mentions a female laticeps found in a nest with a clutch of 27 eggs (hence certainly a communal nest of two or more females) in a burrow under a log, on July 8, 1941, in Lee County, Mississippi. This account is under the name Eumeces fasciatus but the large size of the female precludes the possibility of it being either fasciatus or inexpectatus. The remainder of Cook’s account is evidently based on a composite of observations on all three species.
Goin and Goin (1951:29-33) have given an excellent brief account of behavior and seasonal schedule in a small colony of E. laticeps near Gainesville, Florida, based on almost daily observations over a period of years. In view of the greatly different climatic conditions, the seasonal schedule is remarkably similar to that of E. fasciatus in Kansas, and it seems that the minimum threshold temperatures required for activity are much higher in laticeps. Temperatures of 80° F. or above for several consecutive days seemed to be a necessary stimulus for emergence from hibernation; emergence was in the last week in March or the first week in April in Florida. Hatching was found to take place in late June or early July. Adults were last seen before retiring into dormancy in the latter half of September and young of the year remained active into October some two or three weeks later. The skinks observed all lived in hollow water-oaks. When the population was at an especially high level, in the late summer of 1949, each hollow oak was inhabited by one young and one adult. Territoriality and mutual exclusiveness of adults and even of young seems to be implied. The skinks were seen eating spiders, ants, and cockroaches.
Neill (1950:115) mentions one sizable colony of E. laticeps living in a treeless urban area, in Georgia and depending for shelter on piles of metal drums and other industrial equipment. Evidently, however, this was an exceptional situation. In another paper, Neill (1948b:109) described the specialized hibernation site requirements of laticeps in Georgia; the skink retires inside large, rotting pine stumps, especially those that are leaning. He states (1948a:157) that in Georgia, laticeps is most common in the Coastal Plain and is much less numerous above the Fall Line (the line between the Coastal Plain and the Piedmont). Deckert (1918:31) wrote of “Plestiodon fasciatus” in the vicinity of Jacksonville, Florida, where only E. laticeps and E. inexpectatus occur: “Inhabits hollow trees, always near water. Blue-tailed ones often live around human habitations.”
With regard to the ecological traits of E. inexpectatus that distinguish it from fasciatus, authors are much less definite, and evidence is somewhat conflicting as the differences are relatively minor. Engels (1949:269) noted the occurrence of E. inexpectatus on two low islands of submarine origin, off the North Carolina Coast, Harkers Island and Shackelford Banks, and he surmised that the absence from them of E. fasciatus and E. laticeps must have some ecological significance, since all three species occur on the adjacent mainland. Most of the island inexpectatus were taken from beneath loose bark of standing trees, while mainland fasciatus was taken from beneath loose bark of fallen trees.
Barbour and Carr (1940:129) wrote of inexpectatus in the vicinity of Miami, Florida: “… it seems to be the only one [of the five-lined skinks] which has adapted itself to life under the rather specialized environmental conditions existing in its rocky and decidedly tropical habitat. It is one of the very few forms which have established themselves on some of the waterless and poorly vegetated islands on both coasts of the peninsula. E. inexpectatus is much less arboreal than either laticeps or fasciatus. Although it climbs trees when pressed, it is usually found on the ground among leaves or about fallen logs, and particularly about stone walls or old buildings made of cut rock.”
On the other hand, Neill (1948a:157) states that in Georgia, inexpectatus is often observed basking on tree trunks, and though adults often forage on the ground, they dash for the nearest tree when disturbed, usually climbing to a considerable height before halting. The juveniles, however, are said to climb only rarely; they hide beneath objects on the ground when they are pursued. Neill stated that E. inexpectatus occurs in dry pine forests where laticeps and fasciatus are lacking, as well as in moist or even swampy woods. E. inexpectatus often forages on the sides of old buildings.