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Current understanding of sex chromosome evolution is largely dependent on species with highly degenerated, heteromorphic sex chromosomes, but by studying species with recently evolved or morphologically indistinct sex chromosomes we can greatly increase our understanding of sex chromosome origins, degeneration and turnover. Here, we examine sex chromosome evolution and stability in the gecko genus Aristelliger. We used RADseq to identify sex-specific markers and show that four Aristelliger species, spanning the phylogenetic breadth of the genus, share a conserved ZZ/ZW system syntenic with avian chromosome 2. These conserved sex chromosomes contrast with many other gecko sex chromosome systems by showing a degree of stability among a group known for its dynamic sex-determining mechanisms. Cytogenetic data from A. expectatus revealed homomorphic sex chromosomes with an accumulation of repetitive elements on the W chromosome. Taken together, the large number of female-specific A. praesignis RAD markers and the accumulation of repetitive DNA on the A. expectatus W karyotype suggest that the Z and W chromosomes are highly differentiated despite their overall morphological similarity. We discuss this paradoxical situation and suggest that it may, in fact, be common in many animal species.

Well-resolved phylogenetic hypotheses and ontogenetic data are often necessary for investigating the evolution of structural novelty. The Sphaerodactylidae comprises 12 genera of predominantly miniaturized geckos. The genera Aristelliger and Teratoscincus are exceptions, with taxa reaching snout-to-vent lengths far exceeding those of other sphaerodactylids. These two genera possess enigmatic, supraorbital ossifications-parafrontal bones-which are encountered nowhere else among squamates. At the time of their discovery, these structures were believed to be the result of evolutionary convergence. Although relationships between other sphaerodactylids remain unresolved, recent molecular and morphological data have supported a close relationship between Aristelliger and Teratoscincus. We investigated the ontogeny of parafrontal bones to better understand relationships between sphaerodactylid body size and the presence of parafrontals, and to evaluate whether ontogenetic data support the homology of parafrontals between Aristelliger and Teratoscincus. We hypothesize that the parafrontals of Aristelliger and Teratoscincus are homologous and that there is a threshold body size in sphaerodactylids below which parafrontals do not develop, thus explaining their absence from the miniaturized taxa. The presence of parafrontals was investigated in all sphaerodactylid genera using cleared-and-stained, radiographed, and skeletonized specimens. Total surface area of parafrontals was measured for seven species of Aristelliger and six species of Teratoscincus throughout their ontogeny. Histology was used to investigate the cellular composition of the parafrontals throughout their ontogeny. Our data suggest that parafrontals have evolved in parallel from a homologous, parafrontal precursor and that the onset of parafrontal development is not strictly dependent on a threshold body size. Anat Rec, 301:581-606, 2018. © 2017 Wiley Periodicals, Inc.

The genus Aristelliger comprises seven species of which six inhabit the West Indies, and one occurs in Central America and satellite islands. For the first time, the genus is reported from Cuba, and a new species (Aristelliger reyesi sp. n.) is described from that island. The new taxon has affinities with the smaller species of the genus (subgenus Aristelligella): A. expectatus, A. cochranae, and A. barbouri. It differs from them in color pattern and other morphological characters.

A new species of gecko of the genus Tarentola is described from a single specimen in the herpetological collection of the National Museums of Scotland. The gecko was part of a presentation made in 1884 by a resident of Jamaica, and is presumed to be a Jamaican endemic, possibly now extinct. Though clearly a member of the predominantly African genus Tarentola, the new species bears no specific affinity with the only other known New World species, and is very distinct in lepidosis from similar African taxa. A complete description is given for this new species, and it is named Tarentola albertschwartzi. Its possible relationship to the fossil Aristelliger titan Hecht, 1951, is discussed.

Aristelliger reyesi, new species Figure 1 Holotype. MNHNCu 4665, an adult male collected by Luis M. D��az, Ernesto Reyes, and Ariatna Linares along the trail Los Musulmanes (23 �� 11 ' 37 ''N, 81 ��09' 26 ''W), Reserva Ecol��gica Varahicacos, sea level, Pen��nsula de Hicacos, Matanzas Province, on 5 June 2007. Paratypes (N= 15). Males (8): MNHNCu 4666 ��� 67, from Cueva Ambrosio, Reserva Ecol��gica Varahicacos (23 �� 11 ' 34 ''N; 081��09' 47 ''W), Pen��nsula de Hicacos, Matanzas Province, on 4���5 June 2007, by same collectors; MNHNCu 4668 ��� 69, from wooden buildings at Estaci��n Ecol��gica de Varahicacos (23 �� 11 ' 39 ''N; 081��09' 11 ''W), collected by Luis M. D��az on 4 June 2007; MNHNCu 4670 ��� 73, same data as the holotype. Females (6): MNHNCu 4674���4676, from wooden buildings at Estaci��n Ecol��gica de Varahicacos, collected by Luis M. D��az on 4 June 2007; MNHNCu 4677 ��� 79, same data as the holotype. Embryo: MNHNCu 4680, from an egg laid in captivity. Diagnosis. A small species (maximum SVL: 63.6 mm) of the subgenus Aristelligella (Fig. 1) according to size, and by the arrangement of friction pads and lateral postmentals. Both sexes have a dark stripe (almost black) that extends laterally through the head and over shoulders, fading from there as dorsolateral bifurcated brown zones that reach the tail base. From Aristelliger barbouri it differs in having a conspicuous pattern of longitudinal zones (vs. a more faded coloration in A. barbouri, with lateral stripes only reaching shoulders), and a higher number of total fourth toe lamellae (21���29, vs. 18���19 in A. barbouri). In A. cochranae, dark lateral zones similar to those found in A. reyesi are conspicuous in juveniles and subadults, but less evident or absent in adults, where they are substituted by many pale dots and blotches (Fig. 1); the number of loreal scales is lower in A. reyesi than in A. cochranae (11���15 vs. 15���16, respectively), the snout-to-center of eye distance averages shorter with respect to SVL (13.0��� 14.4 %, x= 13.8; vs. 14.2���15.8 %, x= 15.2 %, in A. cochranae) and the ratio of the ear opening longest diameter/ SVL is smaller (1.7���2.9, x= 2.3; vs. 2.9���4.2, x= 3.4). Aristelliger reyesi requires closer comparison with A. expectatus. The new species is longer than A. expectatus (63.6 mm maximum SVL in A. reyesi, vs. 55 mm in A. expectatus), and has a more robust body. Typically, A. expectatus has a more distinctive dorsal ���ladder��� pattern than A. reyesi, because the lateral darker zones (if defined) are connected to each other by bridges, ���saddles��� or bands (only pairs of middorsal dots or small chevrons are present in A. reyesi) (Fig. 2); the hemipenes of A. reyesi have two prominent horn-like asulcal papillae, which are absent in A. expectatus (Fig. 3); the number of total fourth toe lamellae is 22���29 (x= 24) in A. reyesi, vs. 16���22 (x= 19) in A. expectatus; the dorsal scales of snout are smaller (and higher in number) in A. reyesi (16���19, x= 18) than in A. expectatus (14���16, x= 15); the ear opening is rounded in A. reyesi and narrow in A. expectatus (horizontal diameter 47.6���112.5 %, x= 76.5 %, of longest diameter in A. reyesi, vs. 18.7���39.3 %, x= 28.8 %, in A. expectatus) (Fig. 4). Description. Males, maximum SVL 63.6 mm; females, 55.1 mm. Head length 23���24 % of SVL. Ear opening rounded or oval, with the upper margin slightly folded; the columella is well visible. Fourth toe lamellae modally 10���15; fourth finger lamellae 9���15. Supralabials modally 7; infralabials modally 6. Two enlarged lateral postmentals in median contact behind the mental. Dorsal scales small, granular, and swollen. Ventral scales semicircular, smooth, and partially imbricated. One or two internasal scales (mode 1). Two postnasal scales. Subcaudal scales transversally enlarged. Males are more bulky-headed than females, appearing more robust. Metric and meristic data are shown in Table 1 (by sexes), compared with those of other species of the subgenus Aristelligella. Color in life: Overall coloration mostly olive-green with yellowish shades; grayish on legs and some dorsal areas. Females somewhat more grayish colored than males. Supralabial scales white colored in both sexes. Usually, lower body flanks more yellow in males than in females. Males and females with a dark brown (almost black) stripe that runs along head sides and neck, from which it becomes a less conspicuous and bifurcate dorsolateral zone that reach the tail base. Another brown stripe is on lower flanks. Middorsum almost plain colored, with either vertebral series of small, chevron like patterns, pairs of brown spots, or small papilionaceus figures. Parietal area of head with a chevron like or an X-shaped brown pattern weakly evident, followed by a pair of dark spots near the occiput. Legs with small brown spots or reticulations. The belly is gray or tan. Tail dorsally unpatterned, or with a pale series of rhombs slightly evident. Adult males tend to have a dark brown tail on the ventral surface, with some pinkish patches. Frequently, males also exhibit regenerated areas of skin on body (probably from territorial encounters), which appear as grey patches (see the head of male in Fig. 1). These geckoes may turn into a dark brown color. N (males/females): 1 10 / 10; 2 5 / 4; 3 3 / 2. Color in alcohol: General pattern remains essentially intact, but coloration becomes gradually gray or grayish brown. Discriminant function analysis (DFA). The analysis of nine variables (SVL, total fourth toe lamellae, number of dorsal scales, number of ventral scales, number of loreal scales, supralabials scales, infralabials scales, snout to eye distance/SVL, and ear longest diameter/SVL) provided a 97.9 % of total correct classification (Wilks��� Lambda 0.013, approx. F (27, 105) = 14.23, pAristelliger expectatus was not discriminated from A. cochranae, for a 91.7 % of classification success (see Table 2). The remaining species were 100 % correctly assigned. The model suggests that the combination of those characters has a strong diagnostic value as expressed by the representation of the two first canonical functions (Fig. 5). The four characters with the highest discriminant value were (in the following order): SVL, loreal scales, total fourth toe lamellae, and number of dorsal scales. Etymology. We are pleased to name this new gecko after Ernesto Reyes, who provided the first evidence of its existence. A. reyesi sp. n. 100 0 0 0 11 Total 97.91 5 11 21 11 Distribution. Only known from the Pen��nsula de Hicacos (Fig. 6), Matanzas Province, Western Cuba. The type series was collected between Cueva de Ambrosio and the Estaci��n Ecol��gica de Varahicacos, which are separated by approximately 800 m; however, a single male was seen (not collected) during the day climbing the rustic roof of a restaurant in a populated village about 20 km SW from the type locality. Ecological notes. Individuals of Aristelliger reyesi were relatively easy to find in several habitats, both during the day and at night, suggesting the existence of a large population. Lizards were detected on limestone outcrops, cliffs, caves entrances, rocky shelters, sinkholes, rustic wooden houses roofed with ��� guano ��� (palm fronds), tree cactus (Dendrocereus nudiflorus), and on fig (Ficus sp.) root tangles (Fig. 7). At some places, we collected or observed 4���5 of these geckoes within an area of less than five meters. The limestone rock at the type locality was mostly covered by a microphyll evergreen forest. Two males were seen fighting during the midday on fig roots at Cueva Ambrosio. One of these males (MNHNCu 4666) easily lost pieces of head skin when handled during the collection. Most of the individuals exposed on limestone surfaces were always very close to small holes that serve as refuge, or were partially hidden within them. When collected, some males produced croaking distress calls. Many females were gravid, with a single egg easily seen trough the ventral skin. Three of them laid white, oval eggs in isolated terraria, all firmly attached to the inner surfaces of bamboo tubes offered as shelters (Fig. 8). Two of those eggs measured 10.6 x 8.4 mm and 10.8 x 9.1 mm, respectively. The absence of juveniles during the field work suggested us that the breeding season was probably starting. Geckos were detected at heights of one to three meters above the ground. The following ingested items were found in lizard feces: ants (including several winged females of Camponotus sp.), adult neuropterans, beetles, shed skin, and small stones. Other reptiles observed at the surroundings of the type locality were: Sphaerodactylus intermedius, S. e. elegans (Sphaerodactylidae), Tarentola a. americana (Gekkonidae), Anolis allisoni, A. a. angusticeps, A. equestris buidei, A. p. porcatus, A. pumilus, A. s. sagrei, A. h. homolechis, Leiocephalus c. carinatus, L. c. cubensis, L. raviceps klinikowskii (Iguanidae), Ameiva auberi abducta (Teiidae), Tropidophis m. melanurus (Tropidophiidae), Arrhyton dolichurus (new locality record), Antillophis a. andreai, and Alsophis c. cantherigerus (Dipsadidae)., Published as part of D��az, Luis M. & Hedges, Blair, 2009, First record of the genus Aristelliger (Squamata: Sphaerodactylidae) in Cuba, with the description of a new species, pp. 31-40 in Zootaxa 2028 on pages 32-37, DOI: 10.5281/zenodo.186219

Aristelliger reyesi, new species Figure 1 Holotype. MNHNCu 4665, an adult male collected by Luis M. Díaz, Ernesto Reyes, and Ariatna Linares along the trail Los Musulmanes (23 ° 11 ' 37 ''N, 81 °09' 26 ''W), Reserva Ecológica Varahicacos, sea level, Península de Hicacos, Matanzas Province, on 5 June 2007. Paratypes (N= 15). Males (8): MNHNCu 4666 − 67, from Cueva Ambrosio, Reserva Ecológica Varahicacos (23 ° 11 ' 34 ''N; 081°09' 47 ''W), Península de Hicacos, Matanzas Province, on 4−5 June 2007, by same collectors; MNHNCu 4668 − 69, from wooden buildings at Estación Ecológica de Varahicacos (23 ° 11 ' 39 ''N; 081°09' 11 ''W), collected by Luis M. Díaz on 4 June 2007; MNHNCu 4670 − 73, same data as the holotype. Females (6): MNHNCu 4674−4676, from wooden buildings at Estación Ecológica de Varahicacos, collected by Luis M. Díaz on 4 June 2007; MNHNCu 4677 − 79, same data as the holotype. Embryo: MNHNCu 4680, from an egg laid in captivity. Diagnosis. A small species (maximum SVL: 63.6 mm) of the subgenus Aristelligella (Fig. 1) according to size, and by the arrangement of friction pads and lateral postmentals. Both sexes have a dark stripe (almost black) that extends laterally through the head and over shoulders, fading from there as dorsolateral bifurcated brown zones that reach the tail base. From Aristelliger barbouri it differs in having a conspicuous pattern of longitudinal zones (vs. a more faded coloration in A. barbouri, with lateral stripes only reaching shoulders), and a higher number of total fourth toe lamellae (21–29, vs. 18–19 in A. barbouri). In A. cochranae, dark lateral zones similar to those found in A. reyesi are conspicuous in juveniles and subadults, but less evident or absent in adults, where they are substituted by many pale dots and blotches (Fig. 1); the number of loreal scales is lower in A. reyesi than in A. cochranae (11–15 vs. 15–16, respectively), the snout-to-center of eye distance averages shorter with respect to SVL (13.0– 14.4 %, x= 13.8; vs. 14.2–15.8 %, x= 15.2 %, in A. cochranae) and the ratio of the ear opening longest diameter/ SVL is smaller (1.7–2.9, x= 2.3; vs. 2.9–4.2, x= 3.4). Aristelliger reyesi requires closer comparison with A. expectatus. The new species is longer than A. expectatus (63.6 mm maximum SVL in A. reyesi, vs. 55 mm in A. expectatus), and has a more robust body. Typically, A. expectatus has a more distinctive dorsal “ladder” pattern than A. reyesi, because the lateral darker zones (if defined) are connected to each other by bridges, “saddles” or bands (only pairs of middorsal dots or small chevrons are present in A. reyesi) (Fig. 2); the hemipenes of A. reyesi have two prominent horn-like asulcal papillae, which are absent in A. expectatus (Fig. 3); the number of total fourth toe lamellae is 22–29 (x= 24) in A. reyesi, vs. 16–22 (x= 19) in A. expectatus; the dorsal scales of snout are smaller (and higher in number) in A. reyesi (16–19, x= 18) than in A. expectatus (14–16, x= 15); the ear opening is rounded in A. reyesi and narrow in A. expectatus (horizontal diameter 47.6–112.5 %, x= 76.5 %, of longest diameter in A. reyesi, vs. 18.7–39.3 %, x= 28.8 %, in A. expectatus) (Fig. 4). Description. Males, maximum SVL 63.6 mm; females, 55.1 mm. Head length 23−24 % of SVL. Ear opening rounded or oval, with the upper margin slightly folded; the columella is well visible. Fourth toe lamellae modally 10−15; fourth finger lamellae 9−15. Supralabials modally 7; infralabials modally 6. Two enlarged lateral postmentals in median contact behind the mental. Dorsal scales small, granular, and swollen. Ventral scales semicircular, smooth, and partially imbricated. One or two internasal scales (mode 1). Two postnasal scales. Subcaudal scales transversally enlarged. Males are more bulky-headed than females, appearing more robust. Metric and meristic data are shown in Table 1 (by sexes), compared with those of other species of the subgenus Aristelligella. Color in life: Overall coloration mostly olive-green with yellowish shades; grayish on legs and some dorsal areas. Females somewhat more grayish colored than males. Supralabial scales white colored in both sexes. Usually, lower body flanks more yellow in males than in females. Males and females with a dark brown (almost black) stripe that runs along head sides and neck, from which it becomes a less conspicuous and bifurcate dorsolateral zone that reach the tail base. Another brown stripe is on lower flanks. Middorsum almost plain colored, with either vertebral series of small, chevron like patterns, pairs of brown spots, or small papilionaceus figures. Parietal area of head with a chevron like or an X-shaped brown pattern weakly evident, followed by a pair of dark spots near the occiput. Legs with small brown spots or reticulations. The belly is gray or tan. Tail dorsally unpatterned, or with a pale series of rhombs slightly evident. Adult males tend to have a dark brown tail on the ventral surface, with some pinkish patches. Frequently, males also exhibit regenerated areas of skin on body (probably from territorial encounters), which appear as grey patches (see the head of male in Fig. 1). These geckoes may turn into a dark brown color. N (males/females): 1 10 / 10; 2 5 / 4; 3 3 / 2. Color in alcohol: General pattern remains essentially intact, but coloration becomes gradually gray or grayish brown. Discriminant function analysis (DFA). The analysis of nine variables (SVL, total fourth toe lamellae, number of dorsal scales, number of ventral scales, number of loreal scales, supralabials scales, infralabials scales, snout to eye distance/SVL, and ear longest diameter/SVL) provided a 97.9 % of total correct classification (Wilks’ Lambda 0.013, approx. F (27, 105) = 14.23, pAristelliger expectatus was not discriminated from A. cochranae, for a 91.7 % of classification success (see Table 2). The remaining species were 100 % correctly assigned. The model suggests that the combination of those characters has a strong diagnostic value as expressed by the representation of the two first canonical functions (Fig. 5). The four characters with the highest discriminant value were (in the following order): SVL, loreal scales, total fourth toe lamellae, and number of dorsal scales. Etymology. We are pleased to name this new gecko after Ernesto Reyes, who provided the first evidence of its existence. A. reyesi sp. n. 100 0 0 0 11 Total 97.91 5 11 21 11 Distribution. Only known from the Península de Hicacos (Fig. 6), Matanzas Province, Western Cuba. The type series was collected between Cueva de Ambrosio and the Estación Ecológica de Varahicacos, which are separated by approximately 800 m; however, a single male was seen (not collected) during the day climbing the rustic roof of a restaurant in a populated village about 20 km SW from the type locality. Ecological notes. Individuals of Aristelliger reyesi were relatively easy to find in several habitats, both during the day and at night, suggesting the existence of a large population. Lizards were detected on limestone outcrops, cliffs, caves entrances, rocky shelters, sinkholes, rustic wooden houses roofed with “ guano ” (palm fronds), tree cactus (Dendrocereus nudiflorus), and on fig (Ficus sp.) root tangles (Fig. 7). At some places, we collected or observed 4–5 of these geckoes within an area of less than five meters. The limestone rock at the type locality was mostly covered by a microphyll evergreen forest. Two males were seen fighting during the midday on fig roots at Cueva Ambrosio. One of these males (MNHNCu 4666) easily lost pieces of head skin when handled during the collection. Most of the individuals exposed on limestone surfaces were always very close to small holes that serve as refuge, or were partially hidden within them. When collected, some males produced croaking distress calls. Many females were gravid, with a single egg easily seen trough the ventral skin. Three of them laid white, oval eggs in isolated terraria, all firmly attached to the inner surfaces of bamboo tubes offered as shelters (Fig. 8). Two of those eggs measured 10.6 x 8.4 mm and 10.8 x 9.1 mm, respectively. The absence of juveniles during the field work suggested us that the breeding season was probably starting. Geckos were detected at heights of one to three meters above the ground. The following ingested items were found in lizard feces: ants (including several winged females of Camponotus sp.), adult neuropterans, beetles, shed skin, and small stones. Other reptiles observed at the surroundings of the type locality were: Sphaerodactylus intermedius, S. e. elegans (Sphaerodactylidae), Tarentola a. americana (Gekkonidae), Anolis allisoni, A. a. angusticeps, A. equestris buidei, A. p. porcatus, A. pumilus, A. s. sagrei, A. h. homolechis, Leiocephalus c. carinatus, L. c. cubensis, L. raviceps klinikowskii (Iguanidae), Ameiva auberi abducta (Teiidae), Tropidophis m. melanurus (Tropidophiidae), Arrhyton dolichurus (new locality record), Antillophis a. andreai, and Alsophis c. cantherigerus (Dipsadidae).

Aim Geckos (Reptilia: Squamata), due to their great age and global distribution, are excellent candidates to test hypotheses of Gondwanan vicariance against post-Gondwanan dispersal. Our aims are: to generate a phylogeny of the sphaerodactyl geckos and their closest relatives; evaluate previous phylogenetic hypotheses of the sphaerodactyl geckos with regard to the other major gecko lineages; and to use divergence date estimates to inform a biogeographical scenario regarding Gondwanan relationships and assess the roles of vicariance and dispersal in shaping the current distributions of the New World sphaerodactyl geckos and their closest Old World relatives. Location Africa, Asia, Europe, South America, Atlantic Ocean. Methods We used parsimony and partitioned Bayesian methods to analyse data from five nuclear genes to generate a phylogeny for the New World sphaerodactyl geckos and their close Old World relatives. We used dispersal-vicariance analysis to determine ancestral area relationships among clades, and divergence times were estimated from the phylogeny using nonparametric rate smoothing. Results We recovered a monophyletic group containing the New World sphaerodactyl genera, Coleodactylus, Gonatodes, Lepidoblepharis, Pseudogonatodes and Sphaerodactylus, and the Old World Gekkotan genera Aristelliger, Euleptes, Quedenfeldtia, Pristurus, Saurodactylus and Teratoscincus. The dispersal-vicariance analysis indicated that the ancestral area for this clade was North Africa and surrounding regions. The divergence between the New World spaherodactyl geckos and their closest Old World relative was estimated to have occurred c. 96 Myr BP. Main conclusions Here we provide the first molecular genetic phylogenetic hypothesis of the New World sphaerodactyl geckos and their closest Old World relatives. A combination of divergence date estimates and dispersal-vicariance analysis informed a biogeographical scenario indicating that the split between the sphaerodactyl geckos and their African relatives coincided with the Africa/South America split and the opening of the Atlantic Ocean. We resurrect the family name Sphaerodactylidae to represent the expanded sphaerodactyl clade.

Two types of supraorbital ossifications occur in members of the family Gekkonidae. True osteoderms, embedded within the dermis, overlie the orbital region in Tarentola and Geckonia. In Teratoscincus and Aristelliger, small bones in a supraorbital position, for which the term parafrontal bones or ossa parafrontalia is suggested, are found within the brillar fringe. These elements lie beneath the dermis in the plane of the frontal bone, and differ from osteoderms in their irregular shape and lack of correspondence with overlying epidermal scales. Parafrontal bones have been derived independently in the lineages in which they occur and their homologies to supraorbital ossifications in other lizards, if any, remain unclear.

Light and electron microscope studies of the digital lamellar setae of geckos and anoline lizards demonstrate that the free ends of the setae consist of flattened spatulas of less than 1 μ in width. The anoline setae are simple structures usually less than 30 μ in length and with a single terminal spatula to each seta. In contrast the setae of geckos are complex structures of about 100 μ in length, with numerous branchings, and having many spatulas per seta. The spatulas of Gekko and Aristelliger were smaller (0.2-0.4 μ in width) than the spatulas of Anolis (0.8 μ in width). The electron microscope studies indicate that the scales of lizards appear to be covered with small epidermal spines (1.5 μ long). The setae of anoles and geckos are considered to have evolved independently from these more primitive epidermal spines. It is further suggested that the mechanism that allows the lamellae to adhere to the substratum is a surface phenomenon. The spatulas provide a large surface that is in contact with the substratum and thus produces a large total frictional force. The α layer of the lizard stratum corneum can be readily identified in the lamellae. However, the structure of the β layer is not easily interpreted and there is evidence of a fibrous layer between the Oberhautchen and the α layer in the skin of the outer lamellar surface.

Resumen en inglés.