Panolopus melanchrous ( Schwartz 1964 )

Schools, Molly & Hedges, Blair, 2024, A new forest lizard fauna from Caribbean islands (Squamata, Diploglossidae, Celestinae), Zootaxa 5554 (1), pp. 1-306 : 187-191

Panolopus melanchrous ( Schwartz 1964)

Hispaniolan Chevronate Forest Lizard

(Fig. 69)

Diploglossus costatus melanchrous Schwartz, 1964:34 . Holotype: MCZ R-77157, collected by Richard Thomas from 8 km E. Gaspar Hernandez, Espaillat province, Dominican Republic, on 18 June 1963 (19.631, -70.220; 17 m).

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

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

Celestus costatus melanchrous — Schools & Hedges, 2021:230.

Material examined (n=80). DOMINICAN REPUBLIC. AMNH 40945 , 40947–8 , 40950–4 , 40956–8 , 40960–1 , Gladwyn K. Noble, La Bracita [=Los Bracitos], 20 August 1922 ; AMNH 40967 , 40969–72 , Gladwyn K. Noble, La Bracita [=Los Bracitos], August 1922 . El Seibo. USNM 66678 , Guarabo, 24 November 1923 ; USNM 66679 , Jovero (= Miches), 30 November 1923 . Espaillat. KU 225232 , 10 mi N San Victor , 1971 ; MCZ R-77157, Richard Thomas, 8 km E. Gaspar Hernandez, 18 June 1963 . Hato Mayor. KU 225255 , 2.3 mi N El Valle , 1971 ; USNM 65780 , Las Canitas, 23 February 1923 . La Altagracia. KU 225261 , 225263 , 225266 , Playa El Coco, 46 km N Higuey , 1969. La Vega . AMNH 40975 , Gladwyn K. Noble, Paso Bajito , 3 September 1922 ; KU 225028 , 7 km E Paso Bajito , 10 July 1963 ; KU 225313–4 , 12 km NE Jarabacoa , 1964 ; KU 225315 , 4 km S La Vega, 1968 ; KU 225318 , 1.5 km W Jayaco , 1973. Puerto Plata . KU 225021 , 3 km NE Sosua , 15 October 1963 ; KU 225298–300 , 7.6 mi NE Sanchez , 1971 ; KU 225311 , 5.1 mi NW El Limon , 1971 ; KU 225321 , 0.25 km NW Sabaneta de Yasica , 1973. Samaná . AMNH 38378–85 , William G. Hassler, Samaná, 1929 ; AMNH 39361 , William G. Hassler, Roja Cabo, 18 November 1929 ; AMNH 39876 , William G. Hassler, Samaná, November–December 1929 ; AMNH 40231 , William G. Hassler, Laguna, November 1929 ; AMNH 40258 , 40260 , 40263 , 40265–6 , 40272 , 44745–52 , 44825 , 44827–8 , William G. Hassler, Samaná, October 1929 – December 1929 ; AMNH 40393–5 , 40397–01 , 40403 , 40405 , William G. Hassler, Samaná, October 1929 ; AMNH 40981 , Samaná, May 1923 ; USNM 62361 , Sanchez , 11 August 1919 . Santiago. KU 225348 , 0.5 mi SE Pedro Garcia , 1971 .

Diagnosis. Panolopus melanchrous has (1) a dorsal pattern of absent/irregular flecks/irregular dots/dots in chevrons, (2) head markings absent/present, (3) markings in the longitudinal paramedian area present, (4) dots arranged in bars in the lateral band present, (5) an adult SVL of 93.2–124 mm, (6) ventral scale rows, 89–113, (7) midbody scale rows, 35–42, (8) total lamellae on one hand, 47–58, (9) total strigae on ten scales, 168–413, (10) relative length of all digits on one hindlimb, 30.7–41.3 %, (11) relative distance between the angled subocular and mouth, 0.442 –0.883 %, (12) relative eye length, 2.78–3.97 %, (13) relative forelimb length, 19.5–27.6 %, (14) relative ear width, 0.569–2.39 %, (15) relative rostral height, 1.40–2.75 %, (16) relative head length, 15.2–22.5 %, (17) relative mental width, 1.33–2.06 %, (18) relative postmental width, 2.71–3.38 %, (19) relative cloacal width, 7.61–9.20 %, (20) relative prefrontal width, 4.21–5.06 %, (21) relative largest supraocular width, 2.39–3.26 %, (22) relative longest finger length, 5.76–7.09 %, (23) relative distance between the ear and eye, 6.70–9.14 %, (24) relative head width, 68.3–83.6 %, (25) relative frontal width, 61.3–71.4 %, (26) relative nasal height, 0.897 –0.952 %, (27) relative angled subocular height, 0.680 –0.856 %, (28) relative distance between the eye and naris, 4.89–5.59 %, (29) relative canthal iii length, 1.67–1.94 %, (30) relative angled subocular width, 2.28–2.82 %, and (31) relative nasal length, 1.44–2.09 %. No genetic data are available to estimate the species stem or crown time.

We distinguish Panolopus melanchrous from the other species of Panolopus based on a complex of traits. From Panolopus aenetergum , we distinguish P. melanchrous by the longitudinal paramedian lines (present versus absent), the adult SVL (93.2–124 versus 83.0–92.0), the ventral scale rows (89–113 versus 80–86), the total lamellae on one hand (47–58 versus 40), the relative length of digits on one hindlimb (30.7–41.3 versus 26.8), the relative postmental width (2.71–3.38 versus 2.62), the relative cloacal width (7.61–9.20 versus 7.60), the relative prefrontal width (4.21–5.06 versus 4.15), the relative longest finger length (5.76–7.09 versus 4.83), the relative frontal width (61.3–71.4 versus 88.2), the relative nasal height (0.897 –0.952 versus 1.15), the relative angled subocular height (0.680 –0.856 versus 1.08), the relative distance between the eye and naris (4.89–5.59 versus 4.35), and the relative angled subocular width (2.28–2.82 versus 2.07). From P. aporus , we distinguish P. melanchrous by the relative longest finger length (5.76–7.09 versus 4.57–5.72) and the relative nasal height (0.897 –0.952 versus 1.08–1.23). From P. chalcorhabdus , we distinguish P. melanchrous by the relative width of canthal iii (1.67–1.94 versus 1.98– 2.05). From P. costatus , we distinguish P. melanchrous by the relative nasal height (0.897 –0.952 versus 1.02–1.28). From P. curtissi , we distinguish P. melanchrous by the dots arranged in bars in the lateral areas (present versus absent), the adult SVL (93.2–124 versus 64.1–85.5), the total lamellae on one hand (47–58 versus 32–39), the relative length of digits on one hindlimb (30.7–41.3 versus 20.8–28.1), the relative longest finger length (5.76–7.09 versus 3.59–4.54), and the relative nasal height (0.897 –0.952 versus 1.04–1.25). From P. diastatus , we distinguish P. melanchrous by the longitudinal paramedian lines (present versus absent), the adult SVL (93.2–124 versus 66.1– 83.7), the total lamellae on one hand (47–58 versus 35–41), the relative length of digits on one hindlimb (30.7–41.3 versus 21.5–27.4), and the relative longest finger length (5.76–7.09 versus 3.48–4.87). From P. emys , we distinguish P. melanchrous by the relative nasal height (0.897 –0.952 versus 0.963–1.10) and the relative angled subocular width (2.28–2.82 versus 2.12–2.20). From P. hylonomus , we distinguish P. melanchrous by the dots arranged in bars in the lateral areas (present versus absent), the adult SVL (93.2–124 versus 59.3–76.5), the relative length of digits on one hindlimb (30.7–41.3 versus 22.8–28.2), the relative longest finger length (5.76–7.09 versus 4.47–5.27), the relative nasal height (0.897 –0.952 versus 0.961–1.37), and the relative width of canthal iii (1.67–1.94 versus 1.95–2.03). From P. lanceolatus sp. nov., we distinguish P. melanchrous by the relative postmental width (2.71–3.38 versus 2.36– 2.66). From P. lapierrae sp. nov., we distinguish P. melanchrous by the adult SVL (93.2–124 versus 72.6–88.3), the relative longest finger length (5.76–7.09 versus 4.49–4.55), the relative frontal width (61.3–71.4 versus 77.6–79.0), and the relative nasal height (0.897 –0.952 versus 1.06–1.09). From P. leionotus , we distinguish P. melanchrous by the relative nasal height (0.897 –0.952 versus 0.971–1.18). From P. marcanoi , we distinguish P. melanchrous by the adult SVL (93.2–124 versus 64.6–85.8), the total lamellae on one hand (47–58 versus 36–44), and the relative nasal height (0.897 –0.952 versus 1.07–1.28). From P. neiba , we distinguish P. melanchrous by the relative nasal height (0.897 –0.952 versus 0.963–1.08). From P. nesobous , we distinguish P. melanchrous by the relative nasal height (0.897 –0.952 versus 1.12–1.14), the relative distance between the eye and naris (4.89–5.59 versus 5.62–5.73), and the relative width of canthal iii (1.67–1.94 versus 2.01–2.12). From P. oreistes , we cannot distinguish P. melanchrous based on our standard suite of characters (see Remarks). From P. psychonothes , we distinguish P. melanchrous by the total lamellae on one hand (47–58 versus 37–44) and the relative nasal height (0.897 –0.952 versus 1.12–1.32). From P. saonae , we distinguish P. melanchrous the longitudinal paramedian lines (present versus absent), the total lamellae on one hand (47–58 versus 40–42), the relative length of digits on one hindlimb (30.7–41.3 versus 26.5– 29.8), the relative postmental width (2.71–3.38 versus 2.43), the relative prefrontal width (4.21–5.06 versus 4.14), the relative longest finger length (5.76–7.09 versus 5.01), the relative frontal width (61.3–71.4 versus 72.5), the relative nasal height (0.897 –0.952 versus 1.01), the relative distance between the eye and naris (4.89–5.59 versus 6.43), and the relative width of canthal iii (1.67–1.94 versus 1.99). From P. semitaeniatus sp. nov., we distinguish P. melanchrous by the SVL (93.2–124 versus 77.4–84.1), the total lamellae on one hand (47–58 versus 34–46), the relative head width (68.3–83.6 versus 58.8–63.8), the relative nasal height (0.897 –0.952 versus 1.08), the relative angled subocular height (0.680 –0.856 versus 0.654), and the relative distance between the eye and naris (4.89–5.59 versus 4.61). From P. unicolor sp. nov., we distinguish P. melanchrous by the adult SVL (93.2–124 versus 67.6), the total strigae on ten scales (168–413 versus 144), the relative frontal width (61.3–71.4 versus 58.2), the relative nasal height (0.897 –0.952 versus 1.15), and the relative angled subocular width (2.28–2.82 versus 2.90).

FIGURE 69. (A–F) Panolopus melanchrous (MCZ R-77157, holotype), SVL 95.9 mm.

Description of holotype. MCZ R-77157. An adult; SVL 95.9 mm; tail slightly laterally compressed, 136 mm (142% SVL); axilla-to-groin distance 53.7 mm (56.0% SVL); forelimb length 23.4 mm (24.4% SVL); hindlimb length 34.3 mm (35.8% SVL); head length 18.0 mm (18.8% SVL); head width 12.3 mm (12.8% SVL); head width 68.3% head length; diameter of orbit 3.34 mm (3.48% SVL); horizontal diameter of ear opening 1.15 mm (1.20% SVL); vertical diameter of ear opening 1.40 mm (1.46% SVL); length of all toes on one foot 35.5 mm (37.0% SVL); shortest distance between angled subocular and lip 0.69 mm (0.719% SVL); shortest distance between the ocular and auricular openings 8.41 mm (8.77% SVL); longest finger length 6.80 mm (7.09% SVL); largest supraocular width 2.44 mm (2.54% SVL); cloacal width 8.82 mm (9.20% SVL); mental width 1.90 mm (1.98% SVL); postmental width 2.68 mm (2.79% SVL); prefrontal width 4.48 mm (4.67% SVL); frontal width 64.3% frontal length; nasal height 0.90 mm (0.938% SVL); angled subocular height 0.70 mm (0.730% SVL); shortest distance between the eye and naris 5.36 mm (5.59% SVL); canthal iii width 1.77 mm (1.85% SVL); angled subocular width 2.36 mm (2.46% SVL); nasal width 2.00 mm (2.09% SVL); rostral 2.10X as wide as high, 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 a concave posterior margin, much wider than long, bordered by posterior internasals, 1 st loreals, 1 st (and 2 nd on the left) 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)/(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, 1 st median ocular, canthal iii, 2 nd loreal, and 3 rd –4 th supralabial (left)/(right); 2 nd loreal shorter than 1 st, approximately as high as wide (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, and 1 st and 2 nd loreals (left)/(right); 9 (left)/10 (right) median oculars, 1 st and 2 nd contacting the prefrontal (left)/1 st (right); 1 upper preocular (left)/(right); an irregular anterior supraciliary (left)/(right); 6 lateral oculars (left)/(right); 5 temporals (left)/(right); 2 suboculars (left)/(right); posterior subocular large and elongate (left)/(right); anterior subocular small (left)/(right); 10 supralabials (left)/(right), 6 to level below center of eye (left)/(right); 11 (left)/10 (right) infralabials, 6 to level below center of eye (left)/(right); mental small, followed by a single, larger postmental; 4 pairs of enlarged chin shields, followed by 1 pair of reduced chin shields; 1 st pair in contact with one another; 2 nd –5 th pairs separated by 1–5 scales; 90 transverse rows of dorsal scales from interoccipital to base of tail; 97 transverse rows of ventral scales from mental to vent; 38 scales around midbody; 5 digits; finger lengths 3>4>2>5>1; 13 lamellae under longest finger (left)/(right); 51 total lamellae on one hand; toe lengths 4>3>2>5>1; 18 lamellae under longest toe (left)/(right); dorsal body and caudal scales striate with a faint median keel; striate ventral scales; 216 total strigae counted on ten scales.

Color (in alcohol): dorsal surface of head medium brown with several darker brown spots; lateral surfaces of head grading from medium brown to cream with darker brown eye masks; dorsal surfaces of the body are medium brown with darker brown dots in longitudinal paramedian series and smalls dots continuing down the back in broken chevrons; dorsal surface of tail same as the body; lateral areas grade from dark brown to cream with rows of darker brown and off-white dots in bars; dorsal surfaces of the limbs are medium brown with darker brown mottling; lateral and ventral areas of the limbs grading from medium brown to cream, patternless; ventral surfaces of the head, body, and tail are cream, patternless.

Variation. Measurements and other morphological data for the holotype and other examined material are presented in Table 1.

Distribution. Panolopus melanchrous is distributed in the northeastern portion of Hispaniola at elevations of 0–690 m (Fig. 49).

Ecology and conservation. No ecological data are associated with this species. We consider the conservation status of Panolopus melanchrous 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. Schwartz (1964) did not give the etymology of the species name ( melanchrous ), but it likely refers to the unique dark dorsal chevron-shaped crossbands of this species.

Remarks. Panolopus melanchrous and P. oreistes cannot be distinguished based on our suite of morphological characters and future studies should examine additional characters to morphologically diagnose P. melanchrous and P. oreistes .

Prior to this work, Panolopus melanchrous was regarded to be a widely distributed subspecies of P. costatus . Several museum specimens that were identified as P. melanchrous , including MCZ R-126743 and MCZ R-186653 (both members of the genus Comptus ), were misidentified. Further studies should examine additional museum material that has been identified as P. melanchrous to confirm its correct designation. Panolopus melanchrous is not included in our genetic dataset and future studies should be conducted using genetic or genomic data from this species.