Nucras margaritae, Bauer & Childers & Burger, 2025

Bauer, Aaron M., Childers, Jackie L. & Burger, Marius, 2025, The Nucras (Squamata: Lacertidae) of the eastern Zambezi River Basin, with the description of a new species from Zambia, Zootaxa 5632 (3), pp. 480-500 : 488-494

Nucras margaritae sp. nov.

( Figs. 7–8 )

Holotype: NMB (National Museum, Bloemfontein) R11574 (field number MBUR [Marius Burger] 01427), adult female (confirmed by epiphyseal fusion in long bones in radiographs). Zambia, Northern Province, 5.3 km WSW of Senga Hill , -9.386°, 31.19683°, 1650 m elevation. (see Distribution below). Collected by Marius Burger, 27 November 2005.

Diagnosis: A moderately sized (SVL to at least 65 mm) Nucras distinguished from all congeners by having 46–48 dorsal scale rows across midbody, enlarged plates on the preaxial face of the forearm ( Fig. 7B ), two granules between the supraocular and supraciliary scales on each side ( Fig. 8B ), a tiny parietal window evident in interparietal scale ( Figs. 7C–D ), 26 subdigital lamellae under digit IV of the pes, 28 femoral pores (14 on each side with a diastema of two poreless scales medially), nape and forebody bearing three pale stripes, no stripes on flanks, distinct barring on lateral surface of head and neck ( Fig. 8B ), and flanks bearing more-or-less vertically oriented pale spots surrounded by thick black borders ( Figs. 7A , 8A ).

Nucras margaritae sp. nov. differs from N. lalandii in having enlarged plates on the preaxial face of the forearm, from N. boulengeri in having more (26 versus 24) subdigital lamellae under digit IV of the pes and granules present between the supraocular and supraciliary scale rows; from N. scalaris and N. aurantiaca in having a color pattern with longitudinal elements (versus crossbands only and a more-or-less uniform/patternless dorsum, respectively); and from N. intertexta in lacking pale dorsal spots or reticulations. In having three pale dorsal stripes on the nape, N. margaritae sp. nov. is distinguished from N. tessellata (usually two or four stripes on nape), N. livida (six stripes on nape), N. broadleyi (four stripes on nape), and N. taeniolata (four or five stripes on nape). It shares three stripes on the nape with N. caesicaudata , N. holubi , N. damarana , and N. ornata (although the vertebral stripe may be lacking in the last of these), but differs from N. caesicaudata in having fewer pale stripes on the body dorsum (three versus seven), lacking a bright blue tail, and in its larger body size (65 versus 57 mm maximum SVL). Nucras margaritae sp. nov. is most similar to N. ornata , N. damarana , and N. holubi . Nucras margaritae sp. nov. differs from N. holubi and N. damarana in possessing a distinct barring pattern on the temporal region and neck and having the pale markings of the anterior flank arranged vertically (versus lateral pattern of neck and trunk comprising pale spots in one or two more-or-less horizontal rows). It differs from N. ornata in possessing a visible parietal window ( Figs. 7C–D ) in the interparietal scale (usually absent in N. ornata , including northern specimens; D.G. Broadley, unpubl. data—the consistency of this character in N. margaritae sp. nov. can only be evaluated when more specimens are available), and in its smaller size (65 versus 95 mm maximum SVL). The head also appears to be more depressed, but due to variation in the position of fixation we were not able to confirm this impression. Broadley (1972) considered that variation in several scale characters, including the number of transverse rows of ventral scales, was uninformative in the N. tessellata group, but his comparisons were confounded by the fact that his taxonomy resulted in the lumping of some now-accepted species. It may or may not be of note that the holotype of N. margaritae sp. nov. has 29 transverse rows of ventral scales between the collar and groin. While this falls within the range of N. ornata from Zambia, Malawi and Mozambique (n = 39; range 28–35; mean 31.3), only three individuals had a count below 30, and among 107 specimens of “ N. ornata ” from Zimbabwe (Broadley’s concept of N. ornata included N. holubi as well), the mean was 31.1. Of course, the reliability of putative diagnostic features in N. margaritae sp. nov., as for all taxa known from a single individual, must be considered tentative until such time as variability in the species can be assessed.

Finally, N. margaritae sp. nov. can be excluded as the undescribed species illustrated by Broadley and Berry (2004), as the only photograph of the latter species reveals four pale stripes on the nape and on the sides of the neck, and a pale-yellow longitudinal stripe extending to the shoulder, where it breaks up into a series of spots. Moreover, the photographed individual lacks any trace of barring on the neck and temporal region.

Description: Measurements: SVL 65.2 mm, TrW 9.6 mm, TailL (regenerated) 77.4 mm, TailW 6.2 mm, AGL 34.7 mm, HumL 6.2 mm, ForeaL 13.8 mm, FemL 11.4 mm, CrusL 11.2 mm, PesL 16.2 mm, HeadL 16.4 mm, HeadW 9.2 mm, HeadD 8.0 mm, CSn 21.1 mm, OrbD 3.4 mm, NEye 4.8 mm, EyeE 5.5 mm, EarH 3.5 mm., EarW 1.5 mm.

The holotype is intact and in good condition except that the distal portion of the regenerated tail had been taken for tissue. Body moderately slender and elongate (AGL/SVL 0.53), trunk shorter than hind limbs (AGL/[FemL + CrusL + PesL] 0.89), regenerated tail longer than SVL (TailL/SVL 1.19), moderately slender and tapering. Limbs short, pes longer than shank or femur (PesL/FemL 1.42; PesL/CrusL 1.47). Head large (HeadL/SVL ratio 0.25), distinct from neck, slightly elongate (HeadW/HeadL 0.56), not strongly depressed (HeadD/HeadL 0.49). Snout blunt, short (NEye/HeadL 0.29), less than 1.5 times eye diameter (NEye/OrbD 1.41). Eye relatively large (OrbD/ HeadL ratio 0.21); lower eyelid scaly, with four large translucent/semi-opaque scales surrounded by a rim of small granules. Margin of eyelids pigmented dark brown. Eye to ear distance more than 1.5 times diameter of eye (EyeE/ OrbD 1.62).

Ear opening vertical, much higher than wide (EarH/EarW 2.33), without projecting lobules, bordered posteriorly by a series of tiny granules and anteriorly by a series of slightly larger, elongate scales and anterior to this a vertical row of enlarged juxtaposed scales; tympanic shield narrow, 2.5 times the size of cheek scales. Rostral approximately as wide as deep, strongly gabled, separating supranasals for most of their length; loreal region flat to very slightly concave. Supralabials 8/8, increasing in size posteriorly to the fifth, which is largest and in subocular position. Infralabials 7/7, all much longer than high.

Nostrils semicircular, surrounded by enlarged supranasal and bordered posteriorly by two postnasals, each approximately a quarter the size of supranasal. Two loreal scales, anterior trapezoidal, bordering posterior loreal, postnasals, second and third (point contact only) supralabials, and, narrowly, both prefrontal and frontonasal; posterior loreal seven-sided, posterior face much higher than anterior, 4–6 times larger than anterior loreal ( Fig. 8B ), and bordering the prefrontal, first supraciliary, three preocular scales, supralabials three and four (and in point contact with supralabial five on the left side). Supranasals in contact with one another posteriorly; frontonasal roughly hexagonal, wider than long, with lateral apices projecting posteriorly, gabled anteriorly; prefrontals in broad contact medially. Frontal scale approximately 1.5 times wider anteriorly than posteriorly, lateral terminus of frontalfrontoparietal suture lies posterior to border between second and third supraoculars. Four supraocular scales, second and third much larger than first and fourth; seven supraciliary scales, smallest at midorbit, where there are two small granules separating the supraoculars from the main row of supraciliaries. Parietals six-sided, much longer than wide, with slight forward projection wedging between frontoparietal and fourth supraciliary. Interparietal scale narrow and elongate, separating posterior-most portion of frontoparietals from one another and completely separating left and right parietals; parietal window present but tiny; occipital scale very small, pentagonal, narrower anteriorly than posteriorly, only about 4–5 times size of nuchal granules ( Fig. 7C ). 2/2 supratemporal scales, anterior narrow and elongate, posterior less than half the size of anterior, but much larger than scales of cheek region.

Mental roughly semicircular, broader than deep, much wider than rostral, bordered posteriorly by a pair of small chin shields in midline contact with one another and bordering first and second infralabials ( Fig. 8C ). Second set of chin shields larger and also in contact with each other medially and second and third infralabials laterally; third pair larger still, in point contact with each other anteriorly but otherwise separated from one another by a narrow longitudinal row of throat scales. Fourth pair of chin shields 1.5 times as large as third and widely separated from one another, bordering infralabials four through six. A relatively indistinct gular fold present, scales anterior to this roughly hexagonal and becoming longitudinally elongate and angled medially at approximately the level of the angle of the jaws; scales between gular fold and collar enlarged and rectangular. Collar border comprising a series of enlarged scales, the largest in median position and rhomboidal in shape, decreasing in size laterally and anteriorly.

Dorsal pholidosis homogeneous, comprising 46–48 longitudinal rows of small granules ( Figs. 7A , 8A ), becoming slightly larger and more flattened on flanks. Six longitudinal rows of transversely widened ventral plates plus one ventrolateral row of smaller plates on each side (= 8 longitudinal ventral rows sensu Broadley 1972; Fig. 7B ), and 29 transverse rows of ventral plates between collar and groin.

Femoral pores extending to knee, 14 on each thigh, with left and right series separated by a diastema of two small poreless scales ( Fig. 7B ). Scales in row immediately posterior to femoral pore row oval, approximately one-half size of pore-bearing scales. Scales of rows anterior to pores much larger, two (distal) to four (middle and proximal) rows between pore-bearing scales and enlarged preaxial plates. Large, roughly semicircular patch of precloacal plates anterior to cloaca, constituent scales extremely large, largest bordering posterior margin medially, bordered laterally by one plate on each side, each half the size of the median plate, and anteriorly by two scales, each slightly larger than the lateral plates; a semi-circular series of much smaller scales bordering the precloacal plates laterally and anteriorly.

Preaxial surface of forelimb with a series of seven transversely enlarged scales; postaxial surface covered by smaller, flattened, juxtaposed scales ( Fig. 7B ). Scales on palms small, flattened, juxtaposed to subimbricate. Manual digits 4>3>5>2>1, all clawed. Preaxial aspect of thigh with large transverse plates, continuing on to shank and dorsum of pes; postaxial aspect with small, smooth, subimbricate scales, granular on shank. Scales on the sole small, smooth, granular to slightly elongate. Digits of pes 4>3>5>2>1, all clawed, bearing a series of smooth narrow subdigital lamellae 8-12-20-26-11/8-10-19-26-12.

Posterior 38.0 mm of tail regenerated. Original tail portion with approximately 35 elongate rectangular scales per whorl at level of knee of adpressed hindlimb. Basal portion of tail with two rows of dorsal scales for each ventral row, although becoming 1:1 at level of crus of adpressed limb. Basal portion of tail with most scales smooth and only scattered keeled scales, rapidly transitioning to keeled dorsal scales, and with most of the tail with all scales keeled. Scales of regenerated portion of tail similar, but more irregular in shape.

Coloration (in life) (based on life photographs; Figs. 7C–D ; 8A–C ). Dorsum mid-brown becoming increasingly orangey-brown towards the sacrum, with three pale dorsal stripes. A thicker (1.5–2 granules wide) vertebral stripe grades from light brown at occiput to orange-brown at level of shoulder and becomes brighter from mid-trunk posteriorly and is bordered by narrow (maximum one granule wide) black stripes from the occiput to mid-trunk and thereafter to tail base by scattered black flecks. A pair of thinner (one granule wide) cream-colored dorsolateral stripes bordered by thicker (1–1.5 granules wide) black stripes extend from occiput to mid-trunk, where they fade out, with only a single broken line of black granules extending towards the sacrum. Flanks below dorsolateral stripe bearing a series of irregular, fragmented, more-or-less vertically oriented yellowish-cream markings, each 1–2 scales in width and surrounded by a black border of 1–2 scales in width. These markings are largely confluent, but with small interstitial areas mid-brown, like dorsum; markings more fragmented posterior to the level of midbody.

Dorsum of head mid- to light brown with darker brown markings on all head shields posterior to prefrontals; suture zones of shields generally lighter. Side of head and neck dominated by alternating white to cream (ventral to dorsal) colored vertical bars and much wider dark brown markings. Anterior-most white bar just anterior to eye, second just behind eye, another in temporal region and one bordering anterior margin of ear. Three additional bars between posterior border of ear and level of collar. Ventral portions of anterior white bars confluent with predominantly white coloration of supralabials and jaw joint region. More posterior bars confluent with white of venter. Dark brown spaces between bars with irregular central cream centers, except anterior-most, which runs through eye. Iris black. Venter white with some irregular brown markings on lateral-most ventral plates and adjacent ventrolateral granules. Chin and throat immaculate white except for several faded gray markings on chin shields.

Forelimbs mottled mid- and dark brown with scattered irregular cream markings on dorsal and preaxial surfaces, white below. Dorsum of manual digits whitish. Hindlimbs mottled orangey-brown with small, scattered cream and dark brown markings, some just a single scale in extent although larger proximally, on dorsal and preaxial surfaces; venter white.

Tail dorsum orangey brown basally with narrow, transverse, brown paravertebral markings becoming more prominent posteriorly to form distinct rings alternating with straw-colored inter-spaces. Tail base bearing a narrow ventrolateral pattern of cream to pale-yellowish spots with dark brown margins, confluent with similar flank markings. Regenerated portion of tail grayish-brown with indistinct darker markings on dorsum.

Coloration (in preservative). Coppery above, with cream areas in life a pearl gray and white areas with a brownish tint, especially on venter ( Figs. 7A–B ).

Etymology: The specific epithet is a matronym honoring our friend and colleague Margarita Metallinou (1985– 2015), whose untimely passing during fieldwork in Zambia was a great loss to systematic herpetology and to all who knew her ( Carranza & Bauer 2016).

Distribution and Natural History: Nucras margaritae sp. nov. is presently only known from the type locality near Senga Hill in northeastern Zambia ( Fig. 5 ). The distribution map for Nucras ornata in Alexander & Tolley (2021b) shows the distribution for that species to extend to Chama in northeastern Zambia.As noted above, however, the Chama record is based on a photograph that cannot be identified to species. It may be another record of N. margaritae , sp. nov. or, as treated by Alexander & Tolley (2021b), a northern extension of N. ornata . Alternatively, it could represent yet another unnamed lineage.

The holotype of N. margaritae sp. nov. was found under a stone on sand in degraded Miombo Woodland ( Fig. 9 ) with scattered stones and rocky protrusions. Other lizards found at the same locality include Mochlus sundevallii ( Smith, 1849) and Lygodactylus cf. angularis Günther, 1893 .

Conservation: The status of Nucras margaritae sp. nov. must be considered as Data Deficient. Senga Hill does not fall within Zambia’s protected area network but is close to Nsumbu National Park and it is likely that this species may occur there. If the unidentified Nucras from Chama is referrable to N. margaritae sp. nov., then this species would likely occur in the adjacent North Luangwa and Luambe National Parks as well.

Figures

FIGURE 5. Map of Zambia, Malawi and Mozambique showing the known localities for Nucras spp. The red star indicates the type locality of Nucras margaritae sp. nov. The overlapping pink and gray dots mark Tete, the type locality of Lacerta cameranoi and L. tessellata pseudotessellata. Cartography by Jonathan DeBoer.

FIGURE 7. Holotype (NMB R11574) of Nucras margaritae sp. nov. A. Dorsal view of preserved specimen. B. Ventral view of preserved specimen. C. Dorsum of head of holotype in life, red rectangle corresponds to magnified image in D. D. Close-up of interparietal scale of holotype. The minute parietal window is the “dimple” visible in the center of the red circle. Photos A–B by Justin Bernstein, photos C–D by M. Burger.

FIGURE 8. Holotype of Nucras margaritae sp. nov. in life. A. Whole body showing color pattern. B. Oblique view of head illustrating dorsal and lateral head scalation. C. Ventral view of head and throat. Photos by M. Burger.

FIGURE 9. Degraded miombo woodland habitat at type locality of Nucras margaritae sp. nov. near Senga Hill, Northern Province, Zambia. Photo by M. Burger.