Norops arenal, Köhler & Vargas, 2019

Köhler, Gunther & Vargas, Joseph, 2019, A new species of anole from Parque Nacional Volcán Arenal, Costa Rica (Reptilia, Squamata, Dactyloidae: Norops), Zootaxa 4608 (2), pp. 261-278 : 264-267

Norops arenal sp. nov.

Figs. 1 , 4–8

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Holotype: SMF 103506 , adult male, from Costa Rica, Province Alajuela, Parque Nacional Volcán Arenal (10.46048°; -84.75434°, 585 m elevation above sea level); collected by Joseph Vargas Alvarez on 9 November 2016; original field number JV-0582.

Paratype. UCR 22949, adult female, from Costa Rica, Province Alajuela, Parque Nacional Volcán Arenal (10.45696°, -84.75661, 555 m elevation above sea level); collected by Gunther Köhler on 10 February 2018 .

Diagnosis and comparisons: In external morphology and genetic similarity of the 16S DNA barcode, Norops arenal is most similar to N. altae , N. fortunensis , N. fuscoauratus , N. gruuo , N. kemptoni , N. monteverde , N. pseudokemptoni , and N. tenorioensis . In morphology it shares with these species the following characteristics: (1) short hind limbs; (2) a single elongate prenasal scale; (3) tiny, smooth, often juxtaposed body scales; and (4) a slender habitus, often delicate. Norops arenal differs from these species, among several scalation details, by having a blackish central area in the male dewlap in life and in preservative (vs. no suffusion of black pigment on male dewlap in the other species), and a small red female dewlap in life (vs. dirty white, cream colored, or orange); extremely short hind legs with the tip of fourth toe of the adpressed hind leg reaching only to level of shoulder (vs. usually at least to level of ear in the other species); a short tail with a tail length/SVL ratio of 1.53 in single specimen with complete tail (vs. this ratio> 1.6 in the other species); and a tiny size with 41.5 mm in single known adult male and 38.5 mm in single known adult female (vs. SVL of adults usually>42.0 mm). It further differs from N. altae , N. fuscoauratus , N. gruuo , N. pseudokemptoni , and N. tenorioensis by having a unilobed hemipenis (vs. bilobed in these four species). Norops arenal differs further from N. fortunensis , N. kemptoni , and N. monteverde by the following characteristics (condition for N. arenal in parentheses): Norops fortunensis : 4–6 granular scales between enlarged supraoculars and posterior (smaller) superciliary (2–3 such scales); anterior superciliary more than twice the length of posterior one (anterior superciliary only slightly longer than posterior one); posterior portion of male dewlap greenish beige, anterior portion reddish orange (male dewlap red with a blackish central suffusion); dewlap in females white (red). Norops kemptoni : ventral scales faintly to moderately keeled and usually slightly imbricate (ventrals smooth and non-imbricate); dewlap in females white (red); male dewlap bicolored: posterior portion rose pink, anterior portion orange (male dewlap red with a blackish central suffusion); ratio tail length / SVL 1.78–2.25 (vs. 1.53 in single known individual with complete tail). Norops monteverde : hemipenis without a crest-like structure on upper asulcate side of apex (vs. such crest-like structure present on upper asulcate side of apex); dewlap in females white (red); 138–160 scales around midbody (vs. 130–136); total number of loreal scales 37–68 (vs. 29–36).

Description of the holotype ( Figs. 4–8 ). Adult male as indicated by presence of large dewlap and everted hemipenes; SVL 41.5 mm; tail length 33.0 mm, tail incomplete; tail slightly compressed in cross section, tail height 1.7 mm, tail width 1.4 mm; axilla to groin distance 18.1 mm; head length 10.2 mm, head length/SVL ratio 0.25; snout length 4.7 mm; head width 5.0 mm; longest toe of adpressed hind limb reaching to level of shoulder; shank length 8.2 mm, shank length/head length ratio 0.80; scales on snout weakly keeled, mostly unicarinate; 6 postrostrals; 8 scales between nasals; scales in distinct prefrontal depression smooth to rugose; supraorbital semicircles differentiated, separated by a minimum of one scale; supraorbital disc composed of 4 to 5 moderately enlarged weakly keeled scales, unicarinate; circumorbital series complete, separating enlarged supraorbital scale from supraorbital semicircles; two elongated, overlapping superciliaries of about the same length; interparietal plate distinctly enlarged, 1.4 x 0.9 mm (length x width), surrounded by moderate-sized scales; 2/3 scales present between interparietal plate and supraorbital semicircles; canthal ridge distinct, composed of 3 large (posterior) and 5 small (anterior) canthal scales; 8 scales present between second (anterior) canthals; 9 scales present between first (posterior) canthals; 29/30 keeled loreal scales in a maximum of 5/4 horizontal rows; subocular scales weakly keeled, in a single row, in broad contact with supralabials (5 subocular scales in contact with 6 supralabial scales); 7/6 supralabials to level below center of eye; ear opening 0.4 x 0.7 mm (length x height); mental distinctly wider than long, almost completely divided medially, bordered posteriorly by 6 postmentals; 7/7 infralabials to level below center of eye; sublabials undifferentiated; slightly keeled granular scales present on chin and throat; dewlap large, extending well onto chest, anterior insertion at level of anterior border of orbit, posterior insertion at a point 4 mm posterior to level of axilla (relative dewlap size 4.08; see Köhler 2014), with about five regular gorgetal-sternal rows of 14–23 scales per row; dorsum of body with smooth, juxtaposed scales, 2 medial rows of slightly enlarged scales, largest dorsal scales about 0.20 x 0.18 mm (length x width); about 58 medial dorsal scales in one head length; about 110 medial dorsal scales between axilla and groin; lateral scales granular, homogeneous, about 0.15 mm in diameter; ventrals at midbody smooth, juxtaposed to somewhat spaced, about 0.22 x 0.18 mm (length x width); about 56 ventral scales in one head length; about 84 ventral scales between axilla and groin; about 136 scales around midbody; dorsal and lateral caudal scales smooth to weakly keeled, without whorls of enlarged scales, although an indistinct division in segments is discernible; subcaudal scales strongly keeled; middorsal caudal scale row distinctly enlarged; no enlarged postcloacal scales; no tube-like axillary pocket; scales on dorsal surface of forelimb smooth to weakly keeled; digital pads dilated, dilated pad about 3 times width of non-dilated scales on distal phalanx; distal phalanx narrower than and raised from dilated pad; 23/22 lamellae under phalanges II–IV of fourth toe; 7 scales under distal phalanx of fourth toe.

The completely everted hemipenis ( Fig. 8 ) is a small unilobate organ; sulcus spermaticus bifurcates at base of apex into two diverging branches; a crest-like structure present on upper asulcate side of apex; no surface ornamentation discernable.

Coloration of the dewlap in life was recorded as “Centrally Dark Carmine (61), Geranium (66) along margin”.

Coloration after about 18 months in 70% ethanol was recorded as follows: Dorsal surfaces of head, body, and limbs Raw Umber (280) suffused with Raw Umber (23) on middorsum and dorsal head; an indistinct Amber (51) lyreform marking in occipital region; two Sepia (279) blotches in nuchal region and two Hair Brown (277) blotches in suprascapular region; dorsal surfaces of limbs True Cinnamon (260) with indistinct Brownish Olive (276) broken cross-bands; ventral surface of head Tawny Olive (17) with Pale Buff (1) flecks; dewlap Light Russet Vinaceous (246); venter Smoky White (261) with a suffusion of Light Neutral Gray (297); ventral surfaces of limbs and tail Light Buff (2).

Variation. The paratype agrees well with the holotype in general appearance, morphometrics and scalation ( Table 2 ). It has a single prenasal scale and three suboculars in broad contact with three supralabials. The longest toe of the adpressed hind leg reaches to shoulder. The coloration in life was recorded as follows: Dorsal ground color of head, body, limbs, and anterior portion of tail Raw Umber (22) with Sepia (286) flecks; posterior portion of tail Chamois (84); labial region Light Buff (2); iris Ferruginous (35); dewlap Flame Scarlet (73) with Cream White (52) gorgetals; ventral surfaces of body and limbs Cream White (52) with Sepia (279) suffusions.

Etymology. The name arenal is used in reference to the type locality and National Park where the type series of the species was collected.

Geographic distribution. Norops arenal is presently only known from two nearby localities at Parque Nacional Volcán Arenal, Province Alajuela, Costa Rica, at elevations between 555 and 585 m asl.

Natural history notes. The type specimens of Norops arenal were collected at night in the vegetation at 4 m, respectively 8 m above ground level. The individuals were clinging to small leafless twigs in the periphery of the canopy of large trees along a paved road ( Fig. 9 ). Along with the two specimens of N. arenal , we encountered several individuals of N. carpenteri that were also sleeping on twigs in the canopy of large trees. In the lower vegetation at this site we found N. biporcatus ( Wiegmann 1834) , N. capito ( Peters 1863) , and N. limifrons ( Cope 1862) . According to our datalogger readings (8–11 February 2018), the minimum night temperature was 18.9–19.9°C at both 1 m and 5 m above ground, whereas the daytime maximum was 25.2–25.3°C 1 m above ground and 27.6–28.4°C 5 m above ground. The vegetation at the type locality is a broad-leaf forest, mostly secondary but with some old patches.

Figures

FIGURE 1. Norops arenal in life. (A,B) SMF 103506 (holotype, male); (C,D) UCR 22949 (paratype, female). Photographs by J.V. (A,B) and G.K (C,D).

FIGURE 4. Holotype (SMF 103506: A–C) and paratype (UCR 22949: D–F) of Norops arenal in dorsal, lateral and ventral views. Scale bars equal 5.0 mm. Photographs by G.K.

FIGURE 5. Holotype (SMF 103506: A–D) and paratype (UCR 22949: E–H) of Norops arenal: right lateral head, left lateral head, dorsal head, and ventral head. Scale bars equal 1.0 mm. Photographs by G.K.

FIGURE 6. Holotype (SMF 103506: A–D) and paratype (UCR 22949: E–H) of Norops arenal: dorsal region, flank region, midventer, and lateral tail. Scale bars equal 1.0 mm. Photographs by G.K.

FIGURE 7. Holotype (SMF 103506: A–C) and paratype (UCR 22949: D–F) of Norops arenal: lateral snout, ventral snout, and cloacal region. Scale bars equal 1.0 mm. Photographs by G.K.

FIGURE 8. Hemipenes of Norops arenal (SMF 99150): sulcate view, asulcate view, and lateral view. Scale bar equals 1.0 mm. Photographs by G.K.

FIGURE 9. Habitat of Norops arenal at the type locality. Photograph by G.K.