Plestiodon septentrionalis BAIRD, 1858
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Plestiodon septentrionalis
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| Higher Taxa | Scincidae, Scincinae, Scincoidea, Sauria, Squamata (lizards) |
| Subspecies | Plestiodon septentrionalis obtusirostris (BOCOURT 1879) Plestiodon septentrionalis pallidus (SMITH & SLATER 1949) Plestiodon septentrionalis septentrionalis (BAIRD 1858) |
| Common Names | Northern Prairie Skink obtusirostris: Southern Prairie Skink |
| Synonym | Plestiodon septentrionalis BAIRD 1858: 256 Eumeces septentrionalis — TAYLOR 1936: 394 Eumeces septentrionalis septentrionalis — CONANT & COLLINS 1991: 134 Eumeces septentrionalis — GRIFFITH, NGO & MURPHY 2000 Plestiodon septentrionalis — SCHMITZ et al. 2004 Plestiodon septentrionalis septentrionalis — CROTHER et al. 2012 Plestiodon septentrionalis obtusirostris (BOCOURT 1879: 423) Eumeces obtusirostris BOCOURT 1879: 423 Eumeces pachyurus COPE 1880: 19 (fide TAYLOR 1936: 405) Eumeces pachyurus — STRECKER 1910 Eumeces septentrionalis obtusirostris — STEJNEGER & BARBOUR 1917: 70 Eumeces septentrionalis obtusirostris — TAYLOR 1936: 405 Eumeces septentrionalis obtusirostris — CONANT & COLLINS 1991: 134 Eumeces septentrionalis obtusirostris — CROTHER 2000 Eumeces septentrionalis obtusirostris — DIXON 2000 Plestiodon obtusirostris — SCHMITZ et al. 2004 Plestiodon obtusirostris obtusirostris — COLLINS & TAGGART 2009 Plestiodon septentrionalis obtusirostris — CROTHER et al. 2012 Plestiodon septentrionalis pallidus (SMITH & SLATER 1949) Plestiodon obtusirostris pallidus — COLLINS & TAGGART 2009 Plestiodon septentrionalis pallidus — CROTHER et al. 2012 |
| Distribution | septentrionalis: USA (Wisconsin, Minnesota, SE North Dakota, E South Dakota, E Nebraska, C/E Kansas, Oklahoma, E Texas, Iowa), Canada (S Manitoba) pallidus: USA (Texas); Terra typica: USA: Palo Pinto, Palo Pinto, County, Texas; obtusirostris: USA (E Texas, Arkansas, Oklahoma) septentrionalis: USA (Minnesota, Nebraska, Kansas, Oklahoma); Type locality: Minnesota and Nebraska. |
| Reproduction | oviparous |
| Types | Lectotype: USNM 3156 (specimen of the three under this number with SVL 70mm), Fort Ripley, Minnesota, collected J.F. Head. Designation by Taylor (1936). Holotype: ZMB 8689, Dallas, Texas, USA, collected Boll. [obtusirostris] Holotype: INHS (= UIMNH) 1961, P. Harter; May 1, 1946 [pallidus] Holotype: lost, fide Strecker 1910: 119 [pachyurus] |
| Diagnosis | Diagnosis. “A medium-sized species (maximum size, about 75 millimeters) with (normally) two postmentals and no postnasal; frontonasal small, frequently fused with adjoining scales or absent, not in contact with the anterior loreal; limbs relatively short, not overlapping when adpressed in adult specimens; dorsolateral white line arising on the posterior part of the supraocular or superciliary region, and continuing some distance onl tail; lateral white line arising on snout, passing back above ear to some distance on tail; these lines bordered above and below by dark brown, and the entire space between them of the same color: ground color of back usually forming three light-brown lines, usually bordered by darker brown lines.” (Taylor 1936) Description of the species: “(from No. 6982 et seq. Kansas University Museum; collected June 10, 1928, near Onaga, Pottawatomie county, Kansas; E. H. Taylor, collector). The rostral large, the part visible above much larger (sometimes more than twice) than the frontonasal; supranasals normal, generally rectangular, forming a median suture and (usually) separating the frontonasal from the rostral, likewise forming a suture with the prefrontals, separating the frontonasal from the anterior loreal; prefrontals large, pentagonal, forming a broad median suture (usually) ; forming subequal sutures with the first supraocular. the two loreals (only one on right side) and the supranasals; frontal short, its length not equal to its distance from the end of the snout (occasionally as long as this distance), bordered laterally by two supraoculars (normally three) the second of which is very large; frontoparietals large, irregularly pentagonal, invariably forming a median suture; interparietal moderate, not enclosed by the parietals; parietals very large, broad, truncate behind; two pairs of nuchals (one pair more usually). Nasal scale large. nearly equal in area to the supranasal, its anterior elevation nearly equal to its length and not divided;* two loreals, the anterior somewhat higher, normally touching the prefrontal (failing to do so on the left side); second loreal nearly as high as long; four supraoculars, two or three touching frontal; seven super-ciliaries, the anterior about three times the size of the second; the last vertical, about size of second; two relatively large presuboculars; four postsuboculars; primary temporal moderately large, broadly in contact with the lower secondary temporal; upper secondary temporal largest; tertiary temporal vertical, narrow, separated from the auricular opening by a single tiny scale; seven upper labials. the first largest of the four anterior, and (usually) highest; the first loreal tends to make a wide notch between the first and second labials; subocular labial longer than high; the sixth and seventh labials with about the same elevation. but the seventh largest and longest (usually) ; two postlabials, upper largest, separated from the minute auricular lobules by three tiny scales; five (usually) lower labials anterior to the elongate posterior (sixth) labial; mental large, with a labial edge much larger than the rostral; two postmentals; three pairs of chinshields followed by the elongate postgenial, which is bordered on its anterior inner edge by a scale longer than wide. Eye moderate, its length equal to the distance from its anterior corner to the anterior edge of the nostril; the upper median palpebral scales join the superciliaries: lower eyelid with four or five enlarged opaque scales separated from the subocular by two rows of granular scales. The car opening of moderate size, surrounded by about 20 scales, the lobules minute, scarcely differentiated; the scales on the body are in parallel longitudinal rows except behind the arm, where the interpolated series back of the arm are diagonal (some specimens show some irregularity to the groin); pitting on the lateral seales evident, few on sides of neek (2 or 3), while pits may be more numerous on posterior sides of limbs and about insertion of limbs; in the narrow part of the neck there are 30 scale rows; behind arm, 35 rows; about middle of body. 28 rows; on base of tail behind anus, 21 rows; 60 scales in a row from the parietals to above anus; scales under the tail somewhat widened; two enlarged preanals (a median abnormal scale present), bordered laterally by a differentiated pre-anal, and this by a second smaller scale, the outer preanals overlapping the inner. Limbs small. widely separated when adpressed (a distance of about 10 scales) the terminal lamellae not tightly bound about claws. Lamellar formula of fingers: 5; 9; 11; 11; 7; of toes: 7; 9; 13; 15; 9. Palm bordered by enlarged scales; on sole of foot, the scales are imbricating, flat, irregular in size. The subeaudals are not greatly widened. (The regenerated tail, however, may show them very strongly widened. The same is true of the dorsal caudal series which in the regenerated tail is quite unlike the original dorsal squamation and is of a different shade.)” (Taylor 1936) Coloration. Above, the ground color is gray, or olive-gray, forming a slightly lighter putty-colored median line, terminating anteriorly at the interparietal, covering somewhat less than half of each of the two median scale rows; this line bordered laterally by two darker gray lines with brown spotting (frequently well-defined dark brown lines). each about as wide as the median; these darker lines bordered by lines of the gray-olive ground color, each covering approximately one and two thirds scale roWS; lying between these and the dorsolateral white (or cream) lines are narrow brown lines less than one whole scale rOW in width; these originate on the parietals and continue on the tail; the dorsolateral light line definitely originates on the last supraocular and continues as a narrow line to nearly a half the length of the tail, its width rarely more than half a scale, but occupying edges of two scale rows (fourth and fifth); lying between the dorsolateral and lateral lines is a deep brown band originating behind eye (although a few brown spots about and in front of eye suggests that the brown band began farther forward and has become obscured); it continues to some distance on the tail; the light lateral line begins below eye, runs diagonally upward to and above the upper edge of the ear, where after a slight break it passes back, bordering the brown lateral stripe to some distance on the tail; below the lateral white line there is 2 very narrow brown line (sometimes not a connected line) bordering it; upper labials generally light from rostral, somewhat edged with darker, gray or brown on their upper edges and with a tiny light spot in each corner of the eye; lower labials and chin, to a lesser extent the throat, breast. underside of limbs and anal plates, creamy white; the lateral and ventral sides of the abdomen and underside of tail a dull, light bluish-gray: limbs above generally like ground color of the body with some darker dots; a whitish black-bordered line on posterior side of femur; dorsal surface of tail colored like body, and after the definite dark lines cease, they may be evident as scattered brown dots.” (Taylor 1936) Variation. The material available for the study of septentrionalis septentrionalis consisted of 98 specimens. By far the larger number of these specimens are in the collection of the Kansas University Museum. The material, with few exceptions, was made up of small series from widely separated localitics. Material from the critical region in Oklahoma was meager, and more specimens, particularly large series from a few localities, will determine beyond peradventure the status of obtusirostris and septentrionalis, which are here treated as subspecies of the same species. The maximum size of the subspecies as shown by material studied is about 75 millimeters, four specimens reaching this size. Newly hatched young are 25 to 26 millimeters in length. The number of scales from parictals to above anus varies from 57 to 62, 60 being more than twice as frequent as any other number. The variation in scale rows about the middle of the body is rather considerable, varying as they do from 24 to 29, the usual numbers being 26, 27, or 28, the last appearing the greatest number of times. The northern specimens from Iowa, Minnesota, and Wisconsin have a lower number on the average, 26 being the most usual number. Four of the northern specimens have 25, while in three, the count is 24. The number of upper labials is 7. uniform in all save six specimens, of which there are five having two labials fused on one side of the head. No specimen showed a larger number. The number of nuchals is usually one pair, but in 18 specimens (out of 86) an extra nuchal is present on one side; in 14 two complete pairs are present; in one three pairs, and in one all of the nuchals are broken, resembling body scales. The supraoculars are invariably four, three usually contacting the frontal, but in eight cases, on one side only, two are in contact, while in three cases there are only two on each side. Three specimens only have a single postmental. The postnasal is absent in all cases, but in 12 specimens the anterior loreal is broken transversely, leaving an extra scale simulating a very large postnasal. The frontonasal is normally small, surrounded by the supranasal and the prefrontals. In four cases, however, the scale is in contact with the anterior loreal. In 19 cases the scale is in contact with the rostral; in 18 cases it 1s fused with either the right or left prefrontal or equally fused to the two prefrontals and apparently absent. The superciliaries are six, seven, or eight. seven being the normal number for Kansas specimens, with eight rarely, while in the Minnesota and Wisconsin specimens seven is most frequent, with six appearing occasionally. The number of lamellae on the fourth toe varies from 12 to 17. In seventy specimens, counting both sides, the following numbers appeared: 12. four times; 13. twenty-four times; 14, sixty-one times; 15, thirty-one times; 16, eleven times; and 17, three times. The limbs when adpressed on the sides of the body fail to touch in specimens over 50 mm. snout to vent measurement; while under this size they usually touch or overlap, and in newly hatched speeimens may overlap 4 millimeters. In general, the temporals are as described, the primary moderately large, forming a definite suture with the lower secondary. In two eases only are there exceptions which allow the seventh labial to form a definite suture with the upper secondary temporal. There are usually two postlabials. The postsuboculars are three or four (about equally), rarely five. In large adults the tail is 1.5 times head-body length; snout to forelimb in head-body length. 3.3 times: foreleg into head-body length, 4.54; hind leg into head-body length, 3.59 times; axilla to groin in head-body length, 1.61 times (average male and female). (Females have a longer axilla to groin measurement than males.) In younger specimens the proportions are quite different. In newly hatched young the proportions are as follows: the tail, 1.17 times head-body length the snout to forelimb in head-body length, 2.4: foreleg into head-body length, 3.67 times: hind leg into headbody length. 2.85 times: the axilla to groin in head-body length, 2.14 times. From these comparative figures it will be observed that the limbs are proportionally longer in the young than in the older specimens, 2 condition that obtains in all species have examined. The head length always exceeds the width. even in the oldest males. The head never assumes the strongly inflated condition found in males of the Fasciatus group.” (Taylor 1936) Color variation. “The variation in color and markings in Eumeccs septentrionalis septentrionalis is not great save that the brown pigment forming dorsal stripes may be sparse, so that instead of lines the stripes of the ground color may be bordered by dots or merely a line of deeper olive color. The median line usually shows as a lighter (sometimes approaching white) line. a difference that is evident in some newly hatched young. The brown stripes likewise vary in width and IN consequence the lighter. ground color lines are somewhat narrower. In the young the dark stripes occupy more area than the lighter ground color and the markings on the head are moderately distinct. These lighter marks are of about the same color intensity as the median dorsal line and are arranged somewhat concentrically in the parietal region. Occasionally the general olive ground color of the back tends toward a light brown; occasionally toward a somewhat greenish coloration. The tails of the young are blue and this color may be retained until the third year. Occasional older specimens may show some bluish reflections.” (Taylor 1936) Description (Eumeces pachyurus): Strecker 1910: 118 |
| Comment | Subspecies: Plestiodon septentrionalis pallidus has been treated as a subspecies of P. obtusirostris. |
| Etymology | The specific epithet is an adjective in the nominative case derived from the Latin for ‘northern’, referring to the distribution of this species. |
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