Gonatodes machelae, Rivero-Blanco & Schargel, 2020

Rivero-Blanco, Carlos & Schargel, Walter E., 2020, A new diurnal gecko in the genus Gonatodes (Squamata: Sphaerodactylidae) from Margarita Island, Venezuela, Zootaxa 4729 (3), pp. 429-439 : 430-437

Gonatodes machelae sp. nov.

( Figs. 1–4 )

Gonatodes fuscus ( Hallowell, 1855) : Marcuzzi 1950a:82 [misidentification]

Gonatodes cf. condifentatus [sic]: Marcuzzi 1950b:247 [unclear whether the author was referring to G. caudiscutatus ( Günther, 1859) or G. concinnatus ( O’Shaughnessy, 1881) ]

Gonatodes ocellatus? ( Gray, 1831) : Roze 1964:230 [tentative identification]

Gonatodes ocellatus ( Gray, 1831) : Donoso-Barros 1968:108 [misidentification]

Gonatodes sp.: Rivas et al. 2005:348; Ugueto & Rivas 2010:143.

Holotype. MHNLS 9164 ( Fig. 1 ), an adult male collected by M. Ristorto and M. Ameruoso, April 18, 1983, from road to the summit of Cerro El Copey (ca. 675 m), Parque Nacional Cerro El Copey , Margarita Island, Nueva Esparta, Venezuela (11 00’25’’N, 63 53’50’’W).

Paratypes. All from the road to the summit of Cerro El Copey, at altitudes between 450 and 900 m. EBRG 1583 (unsexed juvenile) collected ca. 750 m by Ramon Rivero on 21 July 1982 . EBRG 1584 (♂) collected ca. 770 m by Ramon Rivero on 9 October 1982 . EBRG 1585 (♂) collected ca. 550 m by Ramon Rivero on 12 October 1982 . MHNLS 9165 (♂) , MHNLS 9166 (♂) , MHNLS 9167 (♂) , MHNLS 9168 (♂) , MHNLS 9169 (♂) , MHNLS 9170 (♂) , MHNLS 9171 (♂), all collected ca. 675 m by M. Ristorto and M. Ameruoso on 18 April 1983 . MHNLS 16702 (♀) , MHNLS 16703 (♀) , MHNLS 16704 (♂) , MHNLS 16705 (♂) , MHNLS 16706 (♂) , MHNLS 16707 (♂) , MHNLS 16708 (♂), all collected 600–900 m by Gilson Rivas and Walter Schargel on 10 July 2004 . TCWC 54126 (♂) , TCWC 54127 (unsexed juvenile) , TCWC 54128 (unsexed juvenile) , TCWC 54129 (unsexed juvenile) , TCWC 54130 (♀) , TCWC 54131 (♀) , TCWC 54132 (♂) , TCWC 54133 (♂) , TCWC 514134 (♀) , TCWC 54135 (♀) , TCWC 54136 (♂) , TCWC 54137 (♀) , TCWC 54138 (♂) , TCWC 54139 (♂) , TCWC 54140 (♀) , TCWC 54141 (♀), all collected 450–900 m by Carlos Rivero-Blanco on 1 July 1976 .

Definition. A species of Gonatodes distinguished from all congeners by the combination of the following characters: (1) small size, adults not exceeding 34.0 mm in snout-vent length ( SVL); (2) supraciliary spine single, not elongated; (3) 78–100 scales around midbody; (4) 35–40 midventral scales along the trunk; (5) males with escutcheon area on lower belly and undersurface of thighs; (6) typically three (sometimes two or four) lateral scale rows on the distal portion of the fourth digit; (7) subcaudal pattern type C (1’1’’ sensu Avila-Pires 1995); (8) gular scales posterior to the postmentals gradually transitioning from larger, flat and polygonal scales to smaller granular/ subconical scales ( Fig. 1 ); (9) golden brown iris with a yellow ring around the pupil; and (10) males with a bright yellow head with or without black markings, and one or two white ocelli or a white bar contained in a black blotch on the sides of the neck ( Fig. 2 ).

Diagnosis. Gonatodes machelae differs from the medium (max SVL 42–49 mm) and large (max SVL> 49 mm) species in the genus (see Rivero-Blanco and Schargel 2012), namely G. alexandermendesi Cole & Kok, 2006 , G. annularis Boulenger, 1887 , G. astralis Schargel, Rivas, Makowsky, Señaris, Natera, Barros, Molina & Barrio- Amorós, 2010, G. ceciliae Donoso-Barros, 1966 , G. concinnatus , G. infernalis Rivas & Schargel, 2008 , G. falconensis Shreve, 1947 , G. hasemani Griffin, 1917 , G. lichenosus Rojas-Runjaic, Infante-Rivero, Cabello & Velozo, 2010 , G. nascimentoi Sturaro & Avila-Pires, 2011 , G. ocellatus , G. purpurogularis Esqueda, 2004 , G. riveroi Sturaro & Avila-Pires, 2011 , G. rozei Rivero-Blanco & Schargel, 2012 , G. seigliei Donoso-Barros, 1966 , G. superciliaris Barrio-Amorós & Brewer-Carías, 2008 , G. taniae, Roze, 1963 , G. tapajonicus Rodrigues, 1980 , and G. timidus Kok, 2011 , in having a small size, not exceeding 34.0 mm in SVL. Gonatodes machelae further differs from all these species, except G. alexandermendesi , G. infernalis , G. superciliaris and G. timidus , in having subcaudal pattern type C (see Rivero-Blanco and Schargel 2012). From G. alexandermendesi , G. infernalis , G. superciliaris and G. timidus , it further differs by having gular scales gradually transitioning posteriorly from larger polygonal scales to smaller granular/subconical ( Fig. 1 ) as opposed to gular scales sharply transitioning posteriorly into smaller granular scales (see Rivero-Blanco and Schargel 2012 for an illustration of this character). From the small species in the genus, G. machelae differs from G. albogularis ( Duméril & Bibron, 1836) , G. antillensis ( Lidth de Jeude, 1887) , G. atricucullaris, Noble, 1921 , G. caudiscutatus , G. daudini Powell & Henderson, 2005 , G. humeralis ( Guichenot, 1855) , G. ligiae Donoso-Barros, 1967 , G. petersi Donoso-Barros, 1967 , and G. vittatus ( Lichtenstein & Martens, 1856) in having subcaudal pattern type C. From G. naufragus Rivas, Ugueto, Schargel, Barros, Velozo, & Sánchez, 2013 , it differs by having a much higher number of scales around midbody (78–100 vs. 52–53), and a round pupil as opposed to elliptical, and more lamellae under the fourth finger (17–21 vs. 10–11) and fourth toe (21–25 vs. 12–14). From G. eladioi Do Nascimento, Avila-Pires & Da Cunha, 1987 , the new species differs in having more lamellae under the fourth finger (17–21 vs. 12–14) and fourth toe (21–25 vs. 14–16), and having in males an inconspicuous vertebral stripe that extends posteriorly from the parietal area as opposed to a distinct vertebral stripe that extends posteriorly from the rostral scale. Finally, males of G. machelae have a bright yellow hood in life that is not present in G. naufragus or G. eladioi , but this color fades quickly in preservative limiting the value of this character when examining preserved specimens.

Description of holotype. An adult male, with snout-vent length of 33.6 mm. Tail length 30.0 mm, complete but regenerated. Head about 1.59 times longer than wide (head length: 9.2 mm; head width: 5.8 mm). Snout short (eye-nostril distance is 3.2 mm), 0.35 times head length, acutely rounded in dorsal view, sloping toward top of head with an approximate 45º angle in lateral view. Neck 4.4 mm wide (shortest distance), distinctly narrower than head and body. Body subcylindrical, wider than high; axilla-groin distance 15.0. Limbs well developed with digits of moderate length, fourth toe length 3.6 mm, 0.65 times shank length (5.5 mm, from base of palm to knee). Tail round in cross section, tapering towards tip.

Tongue relatively wide, bluntly rounded anteriorly but with very short median cleft on tip; covered by small, scale-like papillae. Tongue white, gently suffused with gray anteriorly except along the edges. Teeth tiny, subequal, conical, closely spaced.

Rostral moderately large, visible from above, much wider than high, round anteriorly, relatively straight posteriorly but with small cleft in which medial postrostral scale intrudes. A small, slightly curved, longitudinal groove extends anteriorly from cleft to about middle of rostral. Five postrostrals, lateral ones (supranasals) distinctly larger than the three, subequal, medial postrostral scales; the latter are about same size as scales on snout. Nostrils bordered by rostral, three postnasals, and lateral postrostral (= supranasal). Postnasals on average slightly larger than scales on the loreal region. Scales on top of snout and loreal region basally round to elliptical, granular to subconical, juxtaposed. Loreal scales number about ten in a line between postnasals and anterior margin of eye socket. Scales decrease slightly in size from the postrostrals toward posterior part of head. Scales on supraorbital region slightly smaller than those on the top of head. A poorly developed supraciliary flap bears two small spines on the right, one on the left, located anterior to the center of the eye. The supraciliary scales anterior to these spines are flat and larger than those on the supraorbital region; posterior to the spines the supraciliary scales are small and granular, about the same size and shape as the scales on the supraorbital region. Pupil subround, slightly higher than long. Supralabials 6/6 to level of center of eye of which the first is the largest, bearing minute tubercles; sixth supralabial followed by one small (about size of loreal scale) scale, followed by about nine tiny, granular scales along the lip to rictus of mouth; these tiny scales about same size as those on supraorbital region. Scales on temporal region similar to those on posterior top of head. Ear opening (0.5 mm long, 0.7 mm high), much smaller than eye (1.8 mm), obliquely oval.

Mental large, with bluntly rounded anterior margin and roughly trapezoidal posterior margin. Postmentals two, distinctly larger than adjacent posterior scales. Scales on the gular region with a gradual transition from larger, juxtaposed, polygonal scales near the chin; to smaller, slightly imbricated, somewhat granular scales towards the neck. The scales adjacent to the infralabials are juxtaposed, roughly elliptical, larger than scales in the middle of the gular region. Infralabials 4/4 to level of center of eye, decreasing in size posteriorly, first two large and projecting onto ventral plane.

Scales on nape and on sides of neck granular to subconical. Scales on throat are transitional between the somewhat granular scales on the posterior margin of the gular region, and the smooth, imbricate, with round posterior margin, scales in the pectoral area.

Dorsals mostly granular but some somewhat conical, fairly round at base, mostly homogeneous in size, subequal to those on top of head. Transition between scales on flanks and ventrals abrupt but with a couple scale rows of intermediate morphology. Ventral scales distinctly larger than dorsals, slightly smaller on chest than on belly, smooth, imbricate (each scale overlapping anterior portion of scale lying posteriorly), with round posterior margin, arranged for the most part in oblique rows. There are 35 scales along the midventral line between the level of anterior margin of forelimbs and the small scales anterior to vent. Scales around midbody about 91, of which about 18 are ventrals. Scales on precloacal region similar to ventrals but larger and more bluntly rounded or with trapezoidal posterior margins, except proximally to vent, which has minute irregular scales arranged in three rows. Escutcheon distinct, divided into three patches. Midventrally it extends from about 3 mm anterior to the level of the groin to nearly the vent. On ventral surfaces of posterior limbs, escutcheon is 2–3 scales wide and extends medially for almost full extent of thighs.

Scales dorsally on tail slightly larger than on body, flat, imbricate, with round posterior margin; a short transition area between the granular body scales and the caudal scales just described extends posteriorly about 3 mm from base of tail. Underside of regenerated part of tail covered anteriorly with flat, wide, short, roughly rectangular plates; posteriorly the plates become irregular and almost as long as wide. Underside of unregenerated part of tail extends about 4 mm from vent, with scales like those on venter increasing in size posteriorly. Unregenerated part of tail too short to observe subcaudal pattern condition (see Rivero and Schargel, 2012).

Scales on anterior limbs small (about same size as in dorsum), granular and juxtaposed to slightly conical and imbricate, except on anterior margin of the limb, on which scales are bigger, flat and clearly imbricated. Scales on posterior limbs small granular and juxtaposed to somewhat conical and slightly imbricate, dorsally, posteriorly, and on posterior half ventrally; flat, imbricate, much larger (about same size as scales on venter), anteriorly and on anterior half ventrally; on ventral surface of posterior limbs there is a sharp transition between the two types of scales that coincides with posterior margin of escutcheon. Lamellae under first (I) through fifth (V) finger (infraproximals in parentheses; right/left): I: 10/9 (2/2), II: 13/13 (4/4), III: 15 /16 (4/4), IV: 17/17 (6/6), and V: 14/14 (4/5), respectively. Lamellae under first through fifth toe (infraproximals in parentheses): I: 8/8 (not distinct), II: 13/13 (4/4), III: 17/17 (4/5), IV: 22/22 (9/9), and V: 18/18 (6/6), respectively. Fingers and toes with three (observed only on the distal portion) lateral rows. Claws exposed, non-retractile, between two basal scales.

Color in preservative. The dorsal and lateral background color of the body and the limbs is grayish brown. Small, black mottles scarcely suffuse the background color. A narrow, vaguely distinct, irregular, pale brown, vertebral stripe extends posteriorly from the neck and fades away at about midbody. The background color of the head and the neck is pale cream and it is overlaid with black markings that appear mostly as oblique and recurved longitudinal stripes that connect with each other forming a somewhat reticulated pattern. In dorsal view the pale cream and black colors of the head cover about the same amount of surface; in ventral view the pale cream color covers more surface than the black stripes, which are less recurved and hardly reticulated but still obliquely longitudinal. On each side of the specimen two small (smaller than the eye), white ocelli, are contained within a single black blotch located just posterior to the neck; this black blotch connects anteriorly with the black and cream cephalic hood. The smaller of the two ocelli is located in the prehumeral area and the larger one is located on the suprascapular area. Dorsally, the tail is slightly paler than the body. The ventral surface of the body, limbs and tail, except the escutcheon area, appears macroscopically as a mottled pale grayish brown pattern on a cream background; under magnification, the mottled appearance is conferred by the arrangement of melanophores, which tend to be concentrated on the posterior portion of the ventral scales. Palms and soles are slightly darker than the general ventral color. The escutcheon is cream with much less grayish brown mottling.

Variation. The largest male is EBRG 1585 measuring 33.8 mm in SVL. TCWC 54130 is the largest female measuring 33.3 in SVL. There are typically five, less frequently six, and rarely four supralabials to the level of the center of the eye, followed posteriorly by one or two small polygonal scales and subsequently by several tiny granular scales to the rictus of the mouth. There are typically three or four, infralabials to the level of the center of eye, followed posteriorly by one or two small polygonal scales and subsequently by several tiny granular scales. Postrostrals typically three, rarely four or five. Postmentals typically two, rarely one. Loreal scales 8–11. Scales around the midbody are 78–100 of which about 15–19 are ventrals. There are 35–40 midventral scales between the posterior margins of forelimbs to anterior margin of hind limbs. Lamellae (infraproximals in parentheses) under the fingers are: I: 9–11, II: 13–16 (3–5), III: 15–19 (3–5), IV: 17–21 (5–7), and V: 14–16 (4–5). Lamellae (infraproximals in parentheses) under the toes are: I: 8–10, II: 13–14 (3–4), III: 17–20 (4–6), IV: 21–25 (8–11), and V: 17–21 (5–7). Fingers and toes typically with three lateral scale rows distally, rarely two or four.

There are two color morphs found in males of this species ( Fig. 2 ). The holotype is a representative of the most common (17 out of 21 adult males) color morph. The coloration in life of the most common male morph is described as follows: the dorsal and lateral color of the body, the limbs and the tail, is dark smoke gray to gray. Dorsally the head is densely covered with bright yellow, irregular markings edged by black, which extend posteriorly to the neck. These yellow markings are roughly circular, irregular or elongated and crooked; and this variation occurs both within (markings differ in shape depending on the position on the head) and between individuals. A white ocellus with black edges is located posteriorly on the sides of the neck, extending obliquely from the prehumeral area to the suprascapular area. The ocellus may be single or divided (two white spots contained within a single black marking) and it is always in contact anteriorly with the posterior margin of the cephalic hood. A light gray, vertebral stripe with undulating edges extends posteriorly from the neck and fades, depending on the individual, somewhere between midbody and the anterior half of the tail. The vertebral stripe typically has narrow and vaguely defined black edges that accentuate the stripe. In one specimen (MHNLS 9171) the edges are thick and conspicuous. The sides of the body and the limbs have small, poorly defined, black and pale gray spots and suffusions. Pale, suffused markings may sometimes form poorly defined, incomplete, irregular bands across the limbs. Thighs are typically covered posteriorly with fine black reticulations. Some specimens have poorly defined, narrow, transverse, and widely interspaced, dark bands with creamish white posterior edges, dorsally on the tail, which sometimes form full rings towards the tip of the tail.

In the other, less frequent (four out of 21 adult males), male color morph, the coloration in life is as follows: the background color of the body and tail is dull grayish brown. The head is bright yellow and lacks the black markings of the common morph. The ocellus on the neck may be single or divided and only appears to be smaller than in the common morph. The light vertebral stripe is present but sometimes in this morph it is barely discernible.

In females the dorsal and lateral background color of the head, body and limbs, is gray to pale grayish brown. Dorsally the head has black, irregular, broken, diffuse lines, typically arranged in a longitudinal loreal line that extends into the orbit, an obliquely longitudinal or transverse line on the top of the snout, a transverse interorbital line, two postocular lines that recurve posteriorly into the parietal area. Other small white and black markings might be present on the head in a less stereotypical fashion. A distinct pale creamish gray to creamish white, vertebral stripe with undulating edges extends from the parietal region to the tail, where it blends into the background color. This vertebral stripe typically has black edges that may appear as solid or diffused. When the black edges are diffused, they may be overlaid with a series of paired, solid black spots; about five or six pairs of such spots from the neck to the level of the base of the tail. An irregular, broken, black, lateral line is typically present and extends from near the axillary region to close to the groin. Small irregular black and creamish white markings are scattered on the sides of the body. Most specimens have poorly defined, narrow, transverse, and widely interspaced, dark bands with creamish white posterior edges, dorsally on the tail, which sometimes form full rings towards the tip of the tail. In all specimens, both male and female, the iris in life is golden brown with a narrow yellow ring around the black pupil.

Distribution and natural history. Gonatodes machelae is only known from Cerro El Copey National Park (but see Discussion), Margarita Island, at elevations above 450 m. Margarita Island is the largest and most populated Venezuelan Island and is located in the Caribbean Sea, little more than 20 km off mainland northeastern Venezuela, between latitudes 10°51’ N and 11°11’ N, and longitudes 63°46’ W and 64°25’ W. The habitat in the altitudinal range of G. machelae consists of different types of cloud forest up to 700 m of elevation that are replaced by a mosaic of humid grasslands and shrublands near the summit ( González 2007). The new species may not be endemic to Cerro El Copey as it might also be found in other nearby mountainous areas (e.g. Cerro Matasiete, Cerro Tragaplata) of Margarita Island that harbor similar humid habitat. Individuals were observed active during the day on large rock outcrops and occasionally on tree trunks (see also Ugueto and Rivas 2010). However, most specimens collected by us were obtained by flipping rocks on the side of road. A few individuals were observed or collected associated to tank bromeliads of the species Glomeropitcarnia erectiflora ( Fig. 4 ). Gonatodes machelae is parapatric with the similar sized G. vittatus , which occurs at lower elevations throughout Margarita Island. The altitudinal replacement of the two species is strikingly noticeable with no areas of wide sympatry observed. When walking up the road to the summit of Cerro El Copey the complete replacement of the two species was observed in a short transect of about 100 m. It seems G. machelae competitively excludes G. vittatus from the higher elevations of Cerro El Copey given that G. vittatus is known to occur at higher elevations in other localities (e.g. Caracas) and in similarly open habitats ( Rivero-Blanco 1979). The holotype of G. machelae contained a 6 mm nymph of a roach (Order Blattodea) in the mouth. Another specimen contained a fruit fly of the family Tephritidae in the mouth. Large communal nests have been found on two occasions. On July 1, 1976, a communal nest containing nine viable eggs and 25 eggshells was found by CRB under a rock on the side of the road. Some eggs were half-buried in mud. On July 10, 2004, WES found another communal nest under a rock. The number of eggs in this nest was not counted but it was estimated to be more than 20. In addition to the eggs, a juvenile and a female of G. machelae , as well as a specimen of Bachia heteropa were found in the nest.

Etymology. The new species is dedicated by one of us (CRB) to Machela, wife for 53 years and counting, in recognition to her support while studying different species of Gonatodes in the field, including the new species in Cerro El Copey.

Figures

FIGURE 1. Photos of the head in dorsal (top left) and ventral (top right) views and of the left hand (bottom left) and left foot (bottom right) of the holotype of Gonatodes machelae sp. nov. The scale sutures on the anterior portion of the ventral view of the head were accentuated with black lines.

FIGURE 2. Individuals in life of Gonatodes machelae sp. nov. from Cerro El Copey, Margarita Island, Venezuela. An adult male with dark markings on the head (top), an adult male without dark markings on the head (middle), and an adult female (bottom). Photos by W. Schargel.

FIGURE 3. Map of eastern Margarita Island, Venezuela, showing the type locality of Gonatodes machelae sp. nov.

FIGURE 4. Habitat of Gonatodes machelae sp. nov. in Cerro El Copey, Margarita Island, Venezuela (top). Juvenile specimen of G. machelae found inside the tank bromeliad Glomeropitcarnia erectiflora. Photos by G. Rivas.