Panolopus leionotus ( Schwartz 1964 )

Schools, Molly & Hedges, Blair, 2024, A new forest lizard fauna from Caribbean islands (Squamata, Diploglossidae, Celestinae), Zootaxa 5554 (1), pp. 1-306 : 178-182

Panolopus leionotus ( Schwartz 1964)

Pale Neiba Forest Lizard

(Fig. 65–66)

Diploglossus costatus leionotus Schwartz, 1964:28 . Holotype: MCZ R-77154, collected by Richard Thomas 15 km E. San Juan, San Juan province, Dominican Republic, on 14 August 1963 (18.732, -71.112; 345).

Celestus costatus leionotus — Schwartz & Henderson, 1988:95.

Celestus costatus leionotus — Schwartz & Henderson, 1991:367.

Celestus costatus leionotus — Hedges et al., 2019:16.

Panolopus costatus leionotus — Schools & Hedges, 2021:230.

Material examined (n=20). DOMINICAN REPUBLIC. Azua. Hispaniola . AMNH 92796 , D. C. Leber, 5 km S Padre las Casas , 13 August 1967 . Baoruco. ANSP 38562–5 , S. Blair Hedges, ca. 5 km N of Apolinar Perdomo , 25 May 1996 ; ANSP 38567–8 , S. Blair Hedges, Patrick Parker, Kristin Nastase, and Renee Sharp, Loma Monte Bonito , 24 May 1996 . San Juan. ANSP 38566 , Richard Thomas, 1.6 mi NNE of El Azul , 2 August 1999 ; KU 225018–9 , 15 km SE San Juan, 14 August 1963 ; MCZ R-77154, Richard Thomas, 15 km E. San Juan, 14 August 1963 ; SBH 266286 , Richard Thomas, 1.6 mi. NNE El Azul , 2 August 1999 . Elias Piña. ANSP 38573–7 , Jennifer B. Pramuk, Richard Thomas, and S. Blair Hedges, 0.6 km NE of Rosa de la Piedra , 2 August 1999 ; SBH 266313 , Jennifer B. Pramuk, Richard Thomas, S. Blair Hedges, 0.6 km NE Rosa de la Piedra , 3 August 1999 ; USNM 328752–3 , Richard Thomas, S. Blair Hedges, and locals, 17 km N Cacique Enriquillo (31 km N of Los Pinos), 3 July 1986 .

FIGURE 65. (A–F) Panolopus leionotus ( MCZ R-77154, holotype), SVL 100 mm.

FIGURE 66. Panolopus leionotus ( USNM 328752, SBH 161498), in life. From 17 km N Cacique Enriquillo (31 km N of Los Pinos), Elias Pina Province, Dominican Republic. Photo by SBH.

Diagnosis. Panolopus leionotus has (1) a dorsal pattern of absent/irregular dots/dots in series/dots in chevrons, (2) head markings absent, (3) markings in the longitudinal paramedian area absent/present, (4) dots arranged in bars in the lateral band present, (5) an adult SVL of 86.3–105 mm, (6) ventral scale rows, 84–101, (7) midbody scale rows, 35–40, (8) total lamellae on one hand, 43–48, (9) total strigae on ten scales, 191–266, (10) relative length of all digits on one hindlimb, 25.4–34.1 %, (11) relative distance between the angled subocular and mouth, 0.524– 1.17 %, (12) relative eye length, 2.36–3.75 %, (13) relative forelimb length, 18.6–23.5 %, (14) relative ear width, 1.06–2.24 %, (15) relative rostral height, 1.79–2.36 %, (16) relative head length, 14.6–19.7 %, (17) relative mental width, 1.67–2.02 %, (18) relative postmental width, 2.43–3.18 %, (19) relative cloacal width, 8.03–8.69 %, (20) relative prefrontal width, 4.06–5.21 %, (21) relative largest supraocular width, 1.94–2.50 %, (22) relative longest finger length, 4.58–6.10 %, (23) relative distance between the ear and eye, 6.78–8.80 %, (24) relative head width, 67.3–82.9 %, (25) relative frontal width, 68.7–81.2 %, (26) relative nasal height, 0.971–1.18 %, (27) relative angled subocular height, 0.750–1.33 %, (28) relative distance between the eye and naris, 4.46–5.61 %, (29) relative canthal iii length, 1.55–1.89 %, (30) relative angled subocular width, 2.48–2.95 %, and (31) relative nasal length, 1.59–2.01 %. The species stem time is 0.74 Ma and the species crown time is 0.07 Ma (Fig. 4).

We distinguish Panolopus leionotus from the other species of Panolopus based on a complex of traits. From Panolopus aenetergum , we distinguish P. leionotus by the total lamellae on one hand (43–48 versus 40), the total strigae on ten scales (191–266 versus 267), the relative mental width (1.67–2.02 versus 1.63), the relative cloacal width (8.03–8.69 versus 7.60), the relative frontal width (68.7–81.2 versus 88.2), the relative distance between the eye and naris (4.46–5.61 versus 4.35), and the relative angled subocular width (2.48–2.95 versus 2.07). From P. aporus , we distinguish P. leionotus by the relative largest supraocular width (1.94–2.50 versus 2.74–3.62). From P. chalcorhabdus , we distinguish P. leionotus by the relative largest supraocular width (1.94–2.50 versus 2.52–2.86) and the relative width of canthal iii (1.55–1.89 versus 1.98–2.05). From P. costatus , we distinguish P. leionotus by the total lamellae on one hand (43–48 versus 49–58) and the relative frontal width (68.7–81.2 versus 56.2–67.4). From P. curtissi , we distinguish P. leionotus by the dots arranged in bars in the lateral areas (present versus absent), the adult SVL (86.3–105 versus 64.1–85.5), the total lamellae on one hand (43–48 versus 32–39), and the relative longest finger length (4.58–6.10 versus 3.59–4.54). From P. diastatus , we distinguish P. leionotus by the adult SVL (86.3–105 versus 66.1–83.7) and the total lamellae on one hand (43–48 versus 35–41). From P. emys , we distinguish P. leionotus by the relative angled subocular width (2.48–2.95 versus 2.12–2.20) and the relative nasal width (1.59–2.01 versus 1.23–1.58). From P. hylonomus , we distinguish P. leionotus by the dots arranged in bars in the lateral areas (present versus absent), the adult SVL (86.3–105 versus 59.3–76.5), the relative largest supraocular width (1.94–2.50 versus 2.65–2.90), and the relative width of canthal iii (1.55–1.89 versus 1.95–2.03). From P. lanceolatus sp. nov., we distinguish P. leionotus by the frontal width by the SVL (3.89–5.00 versus 3.48–3.84) (see Remarks). From P. lapierrae sp. nov., we distinguish P. leionotus by the relative longest finger length (4.58–6.10 versus 4.49–4.55). From P. marcanoi , we distinguish P. leionotus by the head markings (absent versus present) and the adult SVL (86.3–105 versus 64.6–85.8). From P. melanchrous , we distinguish P. leionotus by the relative nasal height (0.971–1.18 versus 0.897 –0.952). From P. neiba , we distinguish P. leionotus by the nasal height by the nasal width (1.47–1.80 versus 1.82–2.18) (see Remarks). From P. nesobous , we distinguish P. leionotus by the total lamellae on one hand (43–48 versus 50–59), the relative length of digits on one hindlimb (25.4–34.1 versus 35.1), the relative largest supraocular width (1.94–2.50 versus 2.85–3.11), the relative longest finger length (4.58–6.10 versus 6.19–6.33), the relative frontal width (68.7–81.2 versus 60.8–63.5), the relative distance between the eye and naris (4.46–5.61 versus 5.62–5.73), and the relative width of canthal iii (1.55–1.89 versus 2.01–2.12). From P. oreistes , we cannot distinguish P. leionotus based on our standard suite of characters (see Remarks). From P. psychonothes , we distinguish P. leionotus by the relative angled subocular width (2.48–2.95 versus 2.01–2.44). From P. saonae , we distinguish P. leionotus by the total lamellae on one hand (43–48 versus 40–42), the relative mental width (1.67–2.02 versus 1.52), the relative largest supraocular width (1.94–2.50 versus 2.77), the relative distance between the eye and naris (4.46–5.61 versus 6.43), the relative width of canthal iii (1.55–1.89 versus 1.99), and the relative angled subocular width (2.48–2.95 versus 2.31). From P. semitaeniatus sp. nov., we distinguish P. leionotus by the SVL (86.3–105 versus 77.4–84.1), the relative rostral height (1.79–2.36 versus 2.41–2.63), the relative largest supraocular width (1.94–2.50 versus 2.59–3.32), the relative head width (67.3–82.9 versus 58.8–63.8), the relative angled subocular height (0.750–1.33 versus 0.654), and the relative nasal width (1.59–2.01 versus 1.51). From P. unicolor sp. nov., we distinguish P. leionotus by the adult SVL (86.3–105 versus 67.6), the total strigae on ten scales (191–266 versus 144), the relative length of digits on one hindlimb (25.4–34.1 versus 36.8), the relative cloacal width (8.03–8.69 versus 7.61), the relative largest supraocular width (1.94–2.50 versus 3.12), the relative longest finger length (4.58–6.10 versus 6.65), and the relative frontal width (68.7–81.2 versus 58.2).

Description of holotype. MCZ R-77154. An adult male; SVL 100 mm; tail nearly cylindrical, broken in life midway, regenerated, 80.8 mm (80.8% SVL); axilla-to-groin distance 62.6 mm (62.6% SVL); forelimb length 17.9 mm (17.9% SVL); hindlimb length 27.1 mm (27.1% SVL); head length 16.3 mm (16.3% SVL); head width 12.0 mm (12.0% SVL); head width 73.6% head length; diameter of orbit 3.11 mm (3.11% SVL); horizontal diameter of ear opening 1.06 mm (1.06% SVL); vertical diameter of ear opening 1.48 mm (1.48% SVL); length of all toes on one foot 25.5 mm (25.5% SVL); shortest distance between angled subocular and lip 0.56 mm (0.560% SVL); shortest distance between the ocular and auricular openings 7.96 mm (7.96% SVL); longest finger length 5.00 mm (5.00% SVL); largest supraocular width 1.95 mm (1.95% SVL); cloacal width 8.45 mm (8.45% SVL); mental width 1.69 mm (1.69% SVL); postmental width 2.76 mm (2.76% SVL); prefrontal width 4.65 mm (4.65% SVL); frontal width 72.8% frontal length; nasal height 1.10 mm (1.10% SVL); angled subocular height 0.99 mm (0.990% SVL); shortest distance between the eye and naris 4.46 mm (4.46% SVL); canthal iii width 1.79 mm (1.79% SVL); angled subocular width 2.77 mm (2.77% SVL); nasal width 1.81 mm (1.81% SVL); rostral 1.79X as wide as high, barely visible from above, not in contact with nasals, in contact with 1 st supralabial and anterior internasal (left)/(right); anterior internasals are narrower than posterior ones; frontonasals and prefrontal fused into a single large plate with an irregular posterior margin, much wider than long, bordered by posterior internasals, 1 st loreals, canthal iii, 1 st median oculars, and the frontal; frontal longer than wide; a pair of frontoparietals, separated by the posterior prolongation of the frontal and the interparietal plate; interparietal plate smaller than parietals and separating them, posteriorly touching the interoccipital, which is wider than long; parietal separated from supraoculars by 1 st and 2 nd temporals and frontoparietal (left)/(right); nasal single; nostril above suture between 1 st and 2 nd supralabials (left)/just posterior to suture between 1 st and 2 nd supralabials (right); 1 postnasal (left)/(right); 2 loreals (left)/(right); 1 st loreal higher than wide (left)/(right), in contact with postnasal, posterior internasal, prefrontal/frontonasal complex, canthal iii, 2 nd loreal, and 3 rd –4 th supralabials (left)/(right); 2 nd loreal shorter than 1 st, wider than high (left)/(right), excluded from contact with supraocular by canthal iii (left)/(right); final loreal posteriorly bordering the upper and lower preoculars (left)/(right); canthal iii wider than high (left)/(right), contacting 1 st median ocular, anterior supraciliary, upper preocular, prefrontal/frontonasal complex, and 1 st and 2 nd loreals (left)/(right); 8 (left)/9 (right) median oculars, 1 st contacting the prefrontal (left)/(right); 1 upper preocular (left)/(right); an irregular anterior supraciliary (left)/(right); 6 (left)/5 (right) lateral oculars; 5 temporals (left)/(right); 2 suboculars (left)/(right); posterior subocular large and elongate (left)/(right); anterior subocular small (left)/(right); 9 supralabials (left)/(right), 6 to level below center of eye (left)/(right); 9 infralabials (left)/(right), 5 to level below center of eye (left)/(right); mental small, followed by a single, larger postmental; 4 pairs of enlarged chin shields; 1 st pair in contact with one another; 2 nd –4 th pairs separated by 1–2 scales; 86 transverse rows of dorsal scales from interoccipital to base of tail; 91 transverse rows of ventral scales from mental to vent; 36 scales around midbody; 5 digits; finger lengths 3>4>2>5>1; 11 (left)/12 (right) lamellae under longest finger; 45 total lamellae on one hand; toe lengths 4>3>5>2>1; 17 (left)/16 (right) lamellae under longest toe; striate and keelless dorsal body and caudal scales; smooth to faintly striated ventral scales; 204 total strigae counted on ten scales.

Color (in alcohol): dorsal surface of head pale tan, patternless; lateral surfaces of head grading from pale tan to cream with darker brown eye masks; dorsal surfaces of the body are red-brown, patternless; dorsal surface of tail red-brown to yellow (on regenerated section), patternless; lateral areas slightly darker than body with some darker brown lines near the forelimb grading to yellow-cream; dorsal surfaces of the limbs are golden tan with darker brown mottling; lateral and ventral areas of the limbs fade to yellow-cream, patternless; ventral surfaces of the head, body, and tail are pale cream, patternless.

Variation. Several other specimens resemble the holotype in lacking a dorsal pattern. The majority of other specimens have irregular flecks or dots, dots arranged in chevrons, or dots occurring in series. All specimens have patternless head scales. The majority of specimens have markings in the longitudinal paramedian series, with only AMNH 92796 completely lacking any pattern in the longitudinal paramedian area. All specimens possess dots arranged in bars in the lateral band. Measurements and other morphological data for the holotype and other examined material are presented in Table 1.

Distribution. Panolopus leionotus occurs primarily in the Sierra de Neiba of central Hispaniola and adjacent areas at elevations of 320–1700 m (Fig. 49). Currently, it is known only from the Dominican Republic, but is found next to the border with Haiti and therefore is expected to occur in adjacent areas of that country.

Ecology and conservation. Many animals of this species were collected from under rocks during the day.

We consider the conservation status of Panolopus leionotus to be Least Concern, based on IUCN Redlist criteria ( IUCN 2023). It is likely a common species tolerant of some habitat disturbance, based on what is known of most species of Panolopus . However, it faces a primary threat of habitat destruction resulting from deforestation. A secondary threat is predation from introduced mammals, including the mongoose and black rats. Studies are needed to determine the health and extent of remaining populations and better understand the threats to the survival of the species.

Reproduction. No data on reproduction are available for this species.

Etymology. The species name leionotus is derived from the Greek words leios, meaning “bald”, and notos, meaning “back,” referring to the distinctive patternless dorsum of this species.

Remarks. Previously a subspecies of Panolopus costatus , herein we elevate P. leionotus to a full species based on genetic and morphological differences. Additional museum specimens identified as P. costatus and P. curtissi , from this region of the island, should be examined to determine if they are additional members of P. leionotus .

Panolopus leionotus and P. lanceolatus sp. nov. cannot be morphologically separated based on our standard suite of characters; however, they can be separated by the frontal width divided by the SVL (3.89–5.00 [n=5] versus 3.48–3.84 [n=8]). Panolopus leionotus and P. neiba cannot be morphologically separated based on our standard suite of characters; however, they can be separated by the nasal height by the nasal width (1.47–1.80 [n=7] versus 1.82–2.18 [n=5]). Panolopus leionotus and P. oreistes cannot be distinguished based on our suite of morphological characters; however, both of these species are morphologically distinct from their respective closest relative ( P. semitaeniatus sp. nov. and P. costatus , respectively).Additionally, P. leionotus and P. oreistes are genetically distinct (Fig. 3) and diverged 3.81 Ma (Fig. 4). Future studies should examine additional characters to morphologically diagnose P. leionotus and P. oreistes .

Panolopus leionotus is included in our genetic dataset and has significant support in both Bayesian and ML likelihood analyses at the crown node of the species and the stem node that places it as the closest relative to P. semitaeniatus sp. nov. Based on our timetree (Fig. 4), P. leionotus is separated from that species by 0.74 Ma, consistent with typical species of vertebrates (> 0.7 Ma; Hedges et al. 2015). We recognize P. leionotus as a distinct species based on the multiple morphological characters that separate it from P. semitaeniatus sp. nov. Panolopus leionotus also occurs in sympatry with P. neiba , with the two species being separated by 1.23 Ma. Panolopus leionotus was recovered as conspecific with Panolopus neiba and Panolopus semitaeniatus sp. nov. in our ASAP analysis.