Comptus arboreus, Schools & Hedges, 2024

Schools, Molly & Hedges, Blair, 2024, A new forest lizard fauna from Caribbean islands (Squamata, Diploglossidae, Celestinae), Zootaxa 5554 (1), pp. 1-306 : 110-114

Comptus arboreus sp. nov.

Tiburon Keeled Forest Lizard

(Fig. 37–38)

Celestus stenurus — Schwartz & Henderson, 1991:378 (part, from ca. 5 km S Dame Marie).

Holotype. ANSP 38540 , an adult from Belandier (5.0 km N Dame Marie), collected by S. Blair Hedges and Richard Thomas on 26 July 2010 (18.58568, -74.40762; 24 m).

Paratypes (n=8). HAITI. Grand’Anse. ANSP 38538–39 , an adult, S. Blair Hedges and Richard Thomas, Belandier (5.0 km N Dame Marie [turn back locality]), 26 July 2010 ; ANSP 38543 , S. Blair Hedges and Richard Thomas, 1.5 km N Carcasse , 26 July 2010 ; KU 227117–8 , ca 5 km (airline) S Dame Marie , 13 March 1966 ; SBH 191945–6 , 0.8 km E of Dame Marie , 29 May 1991 ; SBH 269065 , juvenile, Bourdon ( 9.2 km E Ause D’Hainalt ) .

Diagnosis. Comptus arboreus sp. nov. has (1) a dorsal pattern of dots in series/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 93.2–123 mm, (6) ventral scale rows, 102–110, (7) midbody scale rows, 41–44, (8) total lamellae on one hand, 48–54, (9) total strigae on ten scales, 143–207, (10) relative length of all digits on one hindlimb, 37.4–39.7 %, (11) relative distance between the angled subocular and mouth, 0.723 – 0.923 %, (12) relative eye length, 3.46–4.18 %, (13) relative forelimb length, 24.1–25.3 %, (14) relative ear width, 1.22–1.60 %, (15) relative rostral height, 1.53–1.85 %, (16) relative head length, 15.5–18.0 %, (17) relative mental width, 1.54–1.74 %, (18) relative postmental width, 2.95–3.01 %, (19) relative cloacal width, 9.05–9.51 %, (20) relative prefrontal width, 4.50–4.82 %, (21) relative largest supraocular width, 2.61–3.05 %, (22) relative longest finger length, 6.01–6.37 %, (23) relative distance between the ear and eye, 6.45–7.03 %, (24) relative head width, 71.7–80.3 %, (25) relative frontal width, 62.6–71.4 %, (26) relative nasal height, 1.03–1.20 %, (27) relative angled subocular height, 0.929 –0.992 %, (28) relative distance between the eye and naris, 5.11–5.52 %, (29) relative canthal iii length, 1.86–1.94 %, (30) relative angled subocular width, 2.82–3.28 %, and (31) relative nasal length, 1.47–1.99 %. The species stem time is 2.38 Ma and the species crown time is 0.02 Ma (Fig. 4).

FIGURE 37. (A–F) Comptus arboreus sp. nov. (ANSP 38540, holotype), SVL 116 mm.

FIGURE 38. Comptus arboreus sp. nov. (ANSP 38538, SBH 269043), SVL 123 mm, in life. From Belandier, Grand’Anse Department, Haiti. Photo by SBH.

Comptus arboreus differs from all other species of the genus in having the largest relative length of digits on one hindlimb (37.4–39.7).

From Comptus alloeides , we distinguish C. arboreus sp. nov. by the adult SVL (93.2–123 versus 124–161), the total strigae on ten scales (143–207 versus 237–323), the relative length of digits on one hindlimb (37.4– 39.7 versus 23.8–35.2), and the relative longest finger length (6.01–6.37 versus 5.32–5.95). From C. badius , we distinguish C. arboreus sp. nov. by the dorsal pattern (dots in series/dots in chevrons versus irregular dots/mottled), the total lamellae on one hand (48–54 versus 40–45), the relative length of digits on one hindlimb (37.4–39.7 versus 23.4–33.9), the relative forelimb length (24.1–25.3 versus 19.6–23.0), the relative mental width (1.54–1.74 versus 1.38), the relative postmental width (2.95–3.01 versus 2.39), the relative longest finger length (6.01–6.37 versus 4.38–5.04), the relative head width (71.7–80.3 versus 62.8–69.3), and the relative angled subocular width (2.82–3.28 versus 1.91–2.31). From C. maculatus , we distinguish C. arboreus sp. nov. by the dorsal pattern (dots in series/dots in chevrons versus absent/chevrons), the adult SVL (93.2–123 versus 60.1–81.3), the total lamellae on one hand (48–54 versus 32–37), the relative length of digits on one hindlimb (37.4–39.7 versus 24.8–27.0), the relative forelimb length (24.1–25.3 versus 19.3–21.6), the relative postmental width (2.95–3.01 versus 2.32–2.86), the relative longest finger length (6.01–6.37 versus 4.14–5.01), the relative width of canthal iii (1.86–1.94 versus 1.73–1.85), and the relative angled subocular width (2.82–3.28 versus 2.25–2.52). From C. stenurus , we distinguish C. arboreus sp. nov. by the relative length of digits on one hindlimb (37.4–39.7 versus 29.2–37.1) and the relative angled subocular height (0.929 –0.992 versus 0.697 –0.893). From C. weinlandi , we distinguish C. arboreus sp. nov. by the relative length of digits on one hindlimb (37.4–39.7 versus 24.5–36.5) and the relative postmental width (2.95–3.01 versus 2.57–2.91).

Description of holotype. ANSP 38540. An adult; SVL 116 mm; tail nearly cylindrical, tip regenerated, 54.4 mm (46.9% SVL); axilla-to-groin distance 65.0 mm (56.0% SVL); forelimb length 28.0 mm (24.1% SVL); hindlimb length 38.6 mm (33.3% SVL); head length 19.9 mm (17.2% SVL); head width 14.5 mm (12.5% SVL); head width 72.9% head length; diameter of orbit 4.37 mm (3.77% SVL); horizontal diameter of ear opening 1.78 mm (1.53% SVL); vertical diameter of ear opening 1.33 mm (1.15% SVL); length of all toes on one foot 46.0 mm (39.7% SVL); shortest distance between angled subocular and lip 0.90 mm (0.776% SVL); shortest distance between the ocular and auricular openings 7.48 mm (6.45% SVL); longest finger length 6.97 mm (6.01% SVL); largest supraocular width 3.03 mm (2.61% SVL); cloacal width 10.5 mm (9.05% SVL); mental width 1.89 mm (1.63% SVL); postmental width 3.49 mm (3.01% SVL); prefrontal width 5.22 mm (4.50% SVL); frontal width 66.5% SVL; nasal height 1.20 mm (1.03% SVL); angled subocular height 1.09 mm (0.940% SVL); shortest distance between the eye and naris 6.29 mm (5.42% SVL); canthal iii width 2.18 mm (1.88% SVL); angled subocular width 3.38 mm (2.91% SVL); nasal width 1.71 mm (1.47% SVL); rostral 1.74X 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, wider than long, bordered by posterior internasals, 1 st loreals, 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)/(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 supralabials (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); 2 nd 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); 10 (left)/9 (right) median oculars, 1 st contacting the prefrontal (left)/(right); 2 upper preoculars (left)/(right); an irregular anterior supraciliary (left)/ (right); 8 (left)/7 (right) lateral oculars; 5 temporals (left)/(right); 2 (left)/(right) 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); 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 anteriorly, posteriorly separated by one scale; 2 nd –5 th pairs separated by 1–5 scales; 103 transverse rows of dorsal scales from interoccipital to base of tail; 105 transverse rows of ventral scales from mental to vent; 42 scales around midbody; 5 digits; finger lengths 3>4>5>2>1; 12 lamellae under longest finger (left)/(right); 49 total lamellae on one hand; toe lengths 4>3>5>2>1; 19 (left)/20 (right) lamellae under longest toe; dorsal body and caudal scales striate with a median keel; 207 total strigae counted on ten scales.

Color (in alcohol): dorsal surface of head dark tan, patternless; lateral surfaces of head grading from dark tan to yellow-cream, some darker spotting behind the eye and on the supralabial scales; dorsal surfaces of the body are medium brown with six lines of broken spots that extend down the length of the body, the median two lines made of large dark brown spots, outside of those are lines of small dark brown spots, outside of those are two lines of small gray spots; dorsal surface of tail the same as the body, with outer lines of dark brown dots joining to form thin, dark brown lines across the width of the tail; lateral areas grade from medium brown to yellow-cream with lines of dark brown and gray-white dots that extend down the sides and fade before the venter; dorsal surfaces of the limbs are dark brown with small off-white spots; lateral and ventral areas of the limbs fade to yellow-cream, patternless; ventral surfaces of the head, body, and tail are yellow-white with gray mottling on the chin shields.

Variation. The examined material resembles the dorsal pattern of the holotype with most specimens showing large dots that are continuations of the longitudinal paramedian series. In some specimens, the large dorsal dots are arranged in broken chevrons. Most specimens have patternless heads except for ANSP 38543, which has several irregular, darker areas on the head scales. The dorsal color of all is pale tan with markings in a longitudinal paramedian series that extend down the body. No darker lateral band is present; however, rows of dark brown and pale cream dots extend down the sides. In the majority of specimens, the dots in the lateral band are arranged in bars. Measurements and other morphological data for the holotype and other examined material are presented in Table 1.

Distribution. Comptus arboreus sp. nov. is known only from the western tip of the Tiburon Peninsula of Haiti, where it has been collected at elevations of 20–1100 m in the Grand’Anse and Sud departments (Fig. 35).

Ecology and conservation. Little is known of the ecology of this species except that two individuals were found in a cacao grove among rotting cacao and palm husks and fronds. As with other species confused in the past with Comptus stenurus , this species appears to be tolerant of some habitat disturbance.

We consider the conservation status of Comptus arboreus sp. nov. to be Least Concern, primarily because it has been encountered frequently in the past, based on IUCN Redlist criteria ( IUCN 2023). However, it has a relatively small range, which is of concern. Conversion of forests to agricultural and urban areas will reduce available habitat, and forests in general are under severe threat in Haiti ( Hedges et al. 2018). Also, introduced predators, including the mongoose and black rats, likely prey on it. Therefore, studies are needed to determine the health and extent of the populations, and threats to the survival of the species.

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

Etymology. The species name ( arboreus ) is a masculine adjective meaning “of trees,” in reference to the speculative arboreal habits of this species, given its long digits.

Remarks. Comptus arboreus sp. nov. 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 C. stenurus . Based on our timetree (Fig. 4), C. arboreus sp. nov. diverged from its closest relative 2.38 Ma, consistent with typical species of vertebrates (> 0.7 Ma; Hedges et al. 2015). Comptus arboreus sp. nov. was recognized as a distinct species by our ASAP analysis.