Calyptommatus frontalis, Recoder & Marques-Souza & Silva-Soares & Ramiro & Castro & Rodrigues, 2022

Recoder, Renato Sousa, Marques-Souza, Sergio, Silva-Soares, Thiago, Ramiro, Carolina Nisa, Castro, Thiago Marcial & Rodrigues, Miguel Trefaut, 2022, Morphological variation and genealogical discordance in Caatinga sand lizards Calyptommatus Rodrigues 1991 (Squamata: Gymnophthalmidae) with the description of a new species, Zootaxa 5129 (3), pp. 374-398 : 383-388

Calyptommatus frontalis sp. nov.

( Figs. 3–4 )

Holotype: MZUSP 106738 , field number MTR 38950, an adult female from Lameirão (10°40'28"S, 43°34'52"W, datum WGS84, elevation 532 m a.s.l.), Buritirama, state of Bahia, northeast of Brazil, collected by M. T. Rodrigues, S. Marques-Souza, M. Teixeira Jr., T. Silva-Soares and T. M. Castro on 2 nd November 2016.

Paratopotypes: One adult male MZUSP 106739 (field number MTR 38949), one juvenile female MZUSP 106740 (field number MTR 38966), and one adult female MZUSP 106741 (field number MTR 38968), collected from the same locality and by the same collectors as the holotype, on 2 nd November 2016 .

Paratypes: One adult female MZUSP 106744 (field number MTR 38956) , one juvenile female MZUSP 106745 (field number MTR 38957) , two adult males MZUSP 106742-106743 (MTR 38951, 38952), and one juvenile male MZUSP 106746 (field number MTR 38958), collected from Lameirão (10°41'06"S, 43°35'26"W, 537 m a.s.l.), Buritirama , Bahia, Brazil, on 1 st November 2016 ; one adult male MZUSP 106747 (field number MTR 38989) and two adult females MZUSP 106748-106749 (field numbers MTR 38990, 38991) collected from Lameirão (10°41'29"S, 43°35'52"W, 527 m a.s.l.), Buritirama , Bahia, Brazil, on 3 rd November 2016 ; two juvenile females MZUSP 106755, 106758 (field numbers MTR 38953, 38972) and three adult males MZUSP 106756-106757, 106759 (field numbers MTR 38965, 38969, 38974 respectively) collected from Brejão (10°42'04"S, 43°36'59"W, 503 m a.s.l.), Buritirama , Bahia, Brazil, on 1 st November 2016 ; one adult female MZUSP 106753 (field number MTR 38962) , one juvenile male MZUSP 106751 (field number MTR 38955), and three males MZUSP 106750, 106752, 106754 (field numbers MTR 38954, 38961, 38967 respectively) collected from Brejo do Poção (10°40'14"S 43°34'36"W, 513 m a.s.l.), Buritirama, Bahia, Brazil, on 2 nd November 2016; all collected by M. T. Rodrigues, S. Marques-Souza, M. Teixeira Jr., T. Silva-Soares and T. M. Castro.

Etymology: The specific name refers to the presence of a frontal scale in the new species.

Diagnosis: A species of Calyptommatus characterized by a distinctive frontal scale; absence of supraocular scales; five supralabial scales, the third being the largest and located below the eye; 40–43 dorsals; dorsal scales smooth to slightly keeled posteriorly; five to seven scales covering the hind limbs, most frequently six; dorsal surface of body and tail cream with irregular brown spots; ventral part of body and tail immaculate, without spots.

Description of the holotype ( Figs. 3–4 ): 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 head; the last third extends straight ventrally, on the same plane with the symphyseal, broadly projecting anteriorly to the latter. Frontonasal polygonal, 1.5 times wider than long, in broad contact with rostral, nasal, superciliaries, and frontal. Rostral-frontonasal contact straight; frontonasal-frontal contact slightly rounded anteriorly; 1.4 times wider than rostral-frontonasal contact. Frontal three times wider than long, contacting supraciliaries, parietals, and interparietal. Interparietal broad, about 1.5 longer than wide; as long as parietals and about two times longer than frontonasal; straight anteriorly, angulose and contacting three dorsals posteriorly, with straight lateral margins. Parietals irregularly hexagonal, longer than wide, contacting superciliar, ocular, subocular, temporal, two dorsals, frontal and interparietal; narrower than interparietal, and not reaching the level of its posterior margin. Prefrontals, supraocular, and frontoparietals absent. A diagonally directed, postero-anteriorly oriented polygonal superciliar contacts nasal, second and third supralabial, subocular, ocular, parietal, frontal and frontonasal; wider anteriorly, its largest suture with frontonasal. Subocular above third and fourth supralabial, longer than wide, contacting superciliar anteriorly, and temporal and parietal posteriorly. Eyelid absent, eye covered by an ocular scale, slightly longer than large, 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 the suture between first and second supralabials. Nostril located on the anterior half of nasal. Loreal and frenocular absent. Five supralabials in the following order of increasing size (base): second, first, fourth, third and fifth; third below eye, fourth highest, fifth longest and narrower. A greatly enlarged temporal, slightly longer than wide, above fourth and fifth supralabials, contacting subocular, parietal, one dorsal and a tympanic scale. Tympanic large, about two times higher than long. The tympanic scale covers the external ear opening (therefore absent in the species) and reaches the fifth infralabial. A tympanic recess can be visualized at the level of the contact between tympanic scale and fifth 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 infralabial and post-mental, and situated clearly posterior to ventral edge of rostral. Post-mental single, pentagonal, slightly wider than long, contacting first, second and third infralabials, and first pair of genials. Two pairs of genials in broad and straight contact at midline, the first pair with the longest midline suture; second pair of genials widest; both pairs wider at the suture and in contact with third, fourth and fifth infralabials. Five infralabials on the left side following order of increasing size: first, second, fifth, third, and fourth. Two longitudinal series of transversally enlarged gular scales, smooth, imbricate, disposed in seven rows extending from genials to the interbrachial region and increasing in width posteriorly. 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 pentagonal one, the narrowest, marginated by two enlarged quadrangular scales, and by two paraventrals longer than wide. All head scales with several and irregularly distributed small sensorial organs.

Dorsal scales cycloid, smooth and imbricate, mostly wider than long anteriorly, sometimes irregular in size, gradually changing to a longer shape until the interbachial level and toward subhexagonal dorsals; 43 slightly oblique rows between interparietal and posterior level of leg insertion; 18 scales around midbody. Ventrals in four longitudinal rows, the external one larger, quadrangular; the internal pair shorter, rectangular to trapezoid, about 1.5 times longer than wide; ventral scales slightly imbricated, smooth; 36 transverse rows between gulars and preanal region. 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 recognizable longitudinal rows. Flanks with a ventrolateral row of smooth, imbricate, and elongate scales just slightly wider than dorsals, forming a longitudinal keel bordering the ventral surfaces from interbrachials through the unregenerated part of the tail. Above the latero-ventral keel, two irregularly longitudinal rows of subrectangular and larger scales, until dorsals.

Precloacal region with three scales, two lateral enlarged ones separated anteriorly by a straight suture, and posteriorly by a central scale, about half the size of the others. Precloacal pores absent. Dorsal part of tail with scales smaller, wider than posterior dorsals. Ventral and lateral squamation of the tail mostly similar to their corresponding parts of the body. Differences between dorsal, lateral and ventral scales fade away towards the tip of the tail. Regenerated posterior-most part of tail with scales narrower than normal tail, and keeled.

Forelimbs absent. Forelimb level distinctively marked by an elongated scale present at the contact area between interbrachial region and flank. Hind limbs reduced to a needle-shaped vestigial leg bud covered by six scales from the base to the tip; nails absent. When stretched, leg bud reaches the level of second ventral scale row of tail. Tail broken and regenerated, about half the snout-vent length.

Color pattern ( Figs 4–5 ): Dorsal surface of body and tail cream with irregular darker brown spots. Ventral part of body and tail immaculate, without spots. Hindlimb buds darker dorsally; immaculate ventrally. In preservative, color pattern is similar but spots are faded to light brown.

Measurements of the holotype (mm): snout-vent length 54.7 mm; body width 4.1 mm; tail length (regenerated) 29.3 mm; right leg bud 3.5 mm.

Variation. The paratypes show little variation in scale counts ( Table 2 ). Males have four precloacal pores, and pores are absent in females. No significant sexual dimorphism was observed in DOR, VEN, GUL and SAM (p> 0.05). Calyptommatus frontalis did not show sexual dimorphism in size (ANOVA, F 2,15 = 1.06, p = 0.32), with maximum SVL 54.7 mm in females and 53.1 mm in males. Relative tail length varied between 0.73 to 0.84 times the SVL. The margins of the interparietal scale are straight in most individuals (n = 21) but slightly concave laterally in one individual (MTR 38969). One individual (MTR 38972) had only four interbrachials, lacking the median scale. Dorsal scales are completely smooth (n = 9) or smooth anteriorly progressively changing to slightly keeled posteriorly (n = 13). Most individuals present four scales on the precloacal region (n = 19) while three individuals presented three precloacal scales (including the holotype). Most individuals presented six scales covering the hind limb bud (n = 17, left leg absent in one individual), two presented five scales on both legs, two presented seven scales on both legs, and one presented five scales on one leg bud and six on the other. Five individuals presented tiny nails on the tip of the leg bud. Color in life was similar among individuals ( Fig. 5 ), but smaller individuals presented the dorso-lateral region more pigmented.

Distribution and natural history. The new species is currently known only from its type locality in Buritirama, Bahia. The area consists of a low elevation (~ 500–600 m a.s.l.) sandstone plateau. The habitat where the new species was found is characterized by white sandy soils, at the eastern side of Serra do Estreito. The vegetation is represented by a short xeromorphic caatinga vegetation with sparse trees, shrubs, cacti, and clumps of bromeliaceae with scattered spaces of bare sand ( Fig. 6 ). Individuals were found buried in the sand under leaf-litter in shaded microhabitats. Like all other Calyptommatus , this species is nocturnal and moves under the sand, buried just below the surface ( Rodrigues 1991). Tracks in the sand were conspicuous in the area ( Fig. 7 ), especially at early morning, fading progressively latter due to the wind.

Comparisons. Calyptommatus frontalis is readily distinguished from all described species of Calyptommatus (comparative states in brackets) by the presence of a frontal scale (absent in the remaining species) ( Fig. 8 ). Furthermore, C. frontalis is distinguished from C. sinebrachiatus and C. confusionibus by having smooth to weakly keeled subhexagonal dorsals arranged in slightly oblique rows (strongly keeled hexagonal dorsals arranged in regular transverse rows) ( Fig. 9 ). Calyptommatus frontalis also differs from C. confusionibus by the absence of supraoculars (a pair of supraoculars present) and by having five supralabials (four supralabials) ( Fig. 8 ); from C. nicterus by a creamish dorsal coloration without stripes (brownish dorsal color with a dark lateral stripe) and having mostly six SHL (seven SHL); and from C. leiolepis by smooth to weakly keeled dorsal scales in adults (smooth dorsal scales in adults) and having mostly six SHL (five SHL most frequently). Table 2 summarizes the morphological variation present among the described and the two candidate species of Calyptommatus .

Figures

FIGURE 3. Calyptommatus frontalis sp. nov., adult female holotype: Dorsal, lateral and ventral views of head (MZUSP 106738, field number MTR 38950).

FIGURE 4. Details of body scalation of the holotype of Calyptommatus frontalis sp. nov. (MZUSP 106738, field number MTR 38950): A) dorsal view at midbody; B) ventral view at midbody; C) lateral view at midbody; D) precloacal region and hindlimbs. Scale bars correspond to 2 mm.

FIGURE 5. Paratype of Calyptommatus frontalis sp. nov. in life from Brejo do Poção, Buritirama, state of Bahia, northeast Brazil.

FIGURE 6. Habitat where Calyptommatus frontalis sp. nov. was collected, showing the typical deciduous caatinga vegetation over sandy soils present in the region during A) wet season and B) dry season.

FIGURE 7. Tracks of Calyptommatus frontalis sp. nov. on the sandy soil in Buritirama, Bahia.

FIGURE 8. Comparative of head scales of Calyptommatus species from dorsal view (left) and lateral view (right). (A) C. sinebrachiatus (MTR39001); (B) C. confusionibus (MTR24343); (C) C. frontalis sp. nov. (MZUSP 106738); (D) C. leiolepis (MTR39096); (E) C. nicterus (ACG44). Scale bars correspond to 2 mm.

FIGURE 9. Comparative of dorsal scales in Calyptommatus. (A) C. sinebrachiatus (MTR39001); (B) C. confusionibus (MTR24343); (C) C. frontalis sp. nov. (MZUSP 106753; MTR38962); (D) C. sp.2 (MTR18055); (E) C. leiolepis (MTR39096); (F) C. nicterus (ACG44). Scale bar corresponds to 2 mm.