Calyptommatus confusionibus RODRIGUES, ZAHER & CURCIO, 2001
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|Higher Taxa||Gymnophthalmidae (Gymnophthalminae), Gymnophthalmini, Sauria, Gymnophthalmoidea, Squamata (lizards)|
|Common Names||Portuguese: Lagarto-Escrivão|
|Synonym||Calyptommatus confusionibus RODRIGUES, ZAHER & CURCIO 2001|
Calyptommatus confusionibus — DELFIM et al. 2011
|Distribution||NE Brazil (Piaui: western margin of São Francisco River)|
Type locality: Toca da Cabocla (Serra Grande), Parque Nacional da Serra das Confusões: State of Piaui: Brazil (08°55' 28"S, 43°26'58"W)
|Types||Holotype: MZUSP 88077|
|Diagnosis||Diagnosis. A Calyptommatus characterized by keeled dorsals, a distinctive supraocular between frontonasal and parietal scales, a frontonasal wider than long, and four supralabials, the third being the largest and located below the eye.|
Description (holotype): (Figs. 1-3). Body long, snout prominent, without pronounced constrictions on the neck or base of tail; no evidence of collar fold. Rostral broad, wider than high, contacting first supralabial, nasal and frontonasal. On lateral view, the rostral forms a straight angle, with about two thirds of its total length visible on dorsal view of the head, the other one third extends straight ventrally, on the same plane with the simphysal, broadly projecting anteriorly to the latter. Frontonasal polygonal, wider than long, in broad contact with rostral, nasal, loreal, supraocular and interparietal; reaching the level of the ocular. Rostral-frontonasal contact straight, as wide as interparietal-internasal contact. Interparietal about twice as long as wide and longer than parietals and frontonasal; slightly wider and straight anteriorly; angulose or rounded posteriorly, with almost straight and slightly posteriorly converging lateral margins. Parietals irregularly hexagonal, longer than wide, contacting supraocular, superciliar,ocular, subocular, temporal and interparietal; smaller and narrower than interparietal, never reaching the level o f its posterior margin. Prefrontals, frontal, and frontoparietals absent. A small but distinctive pentagonal supraocular, contacting frontonasal, interparietal, superciliar and ocular and indenting sutures between interparietal-parietal and superciliar- parietal. The supraocular is smaller than first supralabial, and about the same size as the ocular. A diagonally directed, postero-anteriorly oriented polygonal superciliar contacts nasal, second supralabial, subocular, ocular, parietal, supraocular and frontonasal. Superciliar larger than wide, wider anteriorly, its largest suture with frontonasal. Subocular above third supralabial, longer than wide, smaller than superciliar, contacting superciliar anteriorly, and temporal and parietal posteriorly. Eyelid absent, covered by an ocular scale, slightly longer than large and smaller than first supralabial, totally inserted between subocular, superciliar and parietal. Ocular semitransparent anteriorly,opaque and pigmented near posterior border. Nasal pentagonal, contacting first and second supralabials, rostral, frontonasal and superciliar; longer than wide, wider at the level of suture between referred supralabials, Nostril located on the anterior half of nasal. Loreal
and frenocular absent (eventually fused with superciliar). Four supralabials in the following order of increazing size: first, second, third, and fourth; fourth below eye, third and fourth wider, fourth longest and larger ventrally. The first three angulose, expanding straigth and horizontally on the ventral surface of head. A greatly enlarged temporal, slightly longer than wide above third and fourth supralabials, and contacting subocular, parietal, a small cycloid scale and a lateral scale. The latter (named tympanic from now on), much higher than long, about as large as posterior margin of temporal and imbricating slightly posteriorly with the latter. This tympanic scale covers the external ear opening (which is thus absent in the species) and reaches the fifth infralabial.A tympanic recesss can be visualized at the level ofthe contact between tympanic scale and last supralabial, when viewed ventrally and after raising the ventral edge of the tympanic scale.
Mental broad with convex anterior border and straight posterior margin, wider than long, contacting first supralabial, and situated clearly posterior to ventral edge ofrostral. Postmental single, wider than long, contacting first and second infralabials. Two pairs of genials in broad contact at midline, the first pair with the longest midline suture; second pair of genials largest; both pairs wider at the suture and in contact with infralabials. Five infralabials in the following order of increasing size: first, second/fifth, third, and fourth. All head scales with several and irregularly distributed small sensorial organs, best visible on dry skin . Two longitudinal series of transversally enlarged gular scales, smooth, imbricate, disposed in 7 rows, and extending from genials to the interbrachial region. Gular scales separated from lateral neck scales by a series of much smaller and longitudinally elongated scales. Interbrachial region with five transversally disposed scales: a central one, the longest and narrowest, marginated by two quadrangular scales almost identical in size and shape to ventra Is, and by one paraventral longer than wide. VentraIs in four longitudinal rows, the external one larger and the others slightly longer than wide; slightly imbricated, smooth, quadrangular; 39 transverse rows between gulars and preanal region.
Anterior dorsal scales cycloid, smooth and imbricate, mostly wider than long, sometimes irregular in size, gradually changing to a longer shape until the level of row 7 and toward hexagonal and keeled scales from this point to the level of leg insertion; 48 regularly transverse rows between interparietal and posterior level of leg insertion; 19 scales around midbody. Lateral neck scales smooth, cycloid, imbricate; the uppermost scale row being larger and higher than long, similar to the tympanic scale; other lateral neck scales smaller, irregular in size and shape and disposed in two more or less recognisable longitudinal rows. Flanks with a ventrolateral row of smooth, imbricate, and elongate scales with approximately the same size as dorsals. Above it, two irregularly longitudinal rows of subrectangular and much larger scales.
Preanal region with four scales, the two lateral ones larger than and separated on the midline by centrals that contact longitudinally. Four preanal pores present. Dorsal part oftail with scales smaller, wider and less keeled than posterior dorsals; some being only slightly keeled. Except for the dorsal region described above, tail with a squamation mostly identical to their corresponding parts ofthe body. Regenerated posteriormost part of tail with scales identical to normal tail, except dorsally where scales are smooth or keeled. Differences between dorsal, lateral and ventral scales fade away towards the tip of the tail.
Forelimbs absent. Forelimb level distinctively marked by an elongated scale present at the contact area between interbrachial region and flank. Hindlimbs reduced to a needle-shaped vestigial leg bud covered by 5 scales from the base to the tip; nail absent. When stretched, leg bud never exceeds in length the level ofsecond ventral scale row of tail. Tail shorter than body.
Coloration: Dorsal surface of body and tail light-brown with irregular darker brown spots. A wide lateral dark-brown stripe, formed by a highly irregul ar reticulate pattern, extends from nasal to tip of tail. Ventral portion of the lateral stripe lighter and less conspicuous than the dorsal portion. Ventral part of body and tail immaculate, with only some occasional dark spots on the tail. Hindlimb buds light-brown dorsally with a reticulate pattern identical to that of lateral stripe; ventrally immaculate.
Measurements (holotype, in mm): snout-vent length 64 mm; body diameter 4.7 mm; tail broken and regenerated; right leg bud 4.0 mm, left leg bud 3.7 mm.
Comparisons. Only three species of Calyptommatus have been described until now: C. leiolepis, C. nicterus and C. sinebrachiatus (Rodrigues, 1991).They are small limb-reduced, and elongated lizards. Apparently as a result of adaptation to a fossoriallife, females have a longer SVL but a shorter tail length than males, a condition also found in snakes. The larger body size is also expressed in slightly higher counts of transverse rows of dorsal and ventral scales (Rodrigues, 1991). Calyptommatus confusionibus fits this description perfectly, being morphologically similar to its three congeneric species. Tables 2 and 3 show the frequen cy distributi on of dorsal scales and scales around midbody, for all species of Calyptommatus, separated by sex . Although our sample is small when compared to the data available for other species (Rodrigues, 1991 a), the same sexual dimorphism pattern in scale counts is evident, espe cially for dorsal scales (Table 2). Tables 2 and 3 also show that dorsal scales and scales around midbody fail to completely separate all four species of Calyptommatus from each other. However, C. confusionibus differs most strongly from the geographically closest species C. leiolepis.
Calyptommatus confusionibus is the only species with a distinctive supraocular which prevents a parietal-frontonasal contact. Calyptommatus sinebrachiatus, C. nicterus, and C. leiolepis, which lack the supraocular, show a broad contact between frontonasal and parietal. Calyptommatus confusionibus is also unique in having only four supralabials (all others have five), the third one being equal in size and position to the third and fourth supralabials of other three species. It must be emphasized that both conditions, which are here viewed as diagnostic of C. confusionibus, have been previously reported as being part of the variation found in large samples representing the other three species of Calyptommatus. In the earlier study, Rodrigues (1991) examined 117 specimens of C. leiolepis from Ibiraba and 79 from Alagoado, 47 specimens of C. sinebrachiatus from Santo Inacio, and 95 specimens of C. nicterus from Vacaria, all localities from the sand dune area ofthe State of Bahia. Only one specimen of C. leiolepis from Ibiraba showed fusion of third and fourth supralabials. Two specimens ofC. leiolepis from Alagoado also presented a small supraocular; in one specimen, the character was symmetric, whereas the other retains it only on the right side . Other anomalies o f C. leiolepis also present in C. confusionibus are: a symmetric division ofthe posterior part ofthe superciliar in one specimen from Ibiraba (only at the left side in one individual of C. confusionibuss and a symmetric divi sion of the higher portion of the ocul ar, forming a "post-ocular" in one specimen from Alagoado (symmetrically represented also in one specimen of C. confusionibus).
Calyptommatus leiolepis is geographically closest to C. confusionibus. As far as we know, both are distributed only on the left bank of the Rio Sao Francisco; the linear distance from the type locality of C. confisionibus to the closest locality where C. leiolepis occurs is less than 100 kilometers. Calyptommatus leiolepis can be clearly recognized from C. confusionibus by its completely smooth and rounded dorsal scales.Among the two other species, only one specimen of C. nicterus shows symmetric presence of "post-oculars". In sum, despite the large number of specimens examined, none of these variations were common and no individual possessed more than one of the diagnostic characters. A more detailed examination will possibly confirm that some of the similar variations are probably the result of convergences. Evidence for that comes the fact that the "supraoculars" of C. confusionibus and those present in the specimens of C. leiolepis are probably not homologous. In fact , the supraocular of C. confusionibus most likely derives from the frontonasal, whereas the "supraocular" of C. leiolepis derives from a subdivision of the anteriormost part ofthe parietal. Table 4 summarizes the morphological variation present among the species of Calyptommatus.
All text above from Rodrigues et al. 2001.
|Etymology||Named after the type locality.|
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