Pseudogonatodes fuscofortunatus, MBLUZ, 1294

Schargel, Walter E., Hernández-Morales, Cristian, Daza, Juan D., Jowers, Michael J., Montes-Correa, Andrés Camilo, Freitas, Mayke De, Sullivan, Kathryn A., Gamble, Tony, Bauer, Aaron M. & Rivas, Gilson A., 2024, Morphology and molecular systematics support a new species of Pseudogonatodes (Squamata: Gekkota: Sphaerodactylidae) from Venezuela with a remarkable telescoped skull, Zoological Journal of the Linnean Society 202, pp. 1-19 : 6-13

Pseudogonatodes fuscofortunatus sp. nov.

( Figs 3A , 4–7 )

Pseudogonatodes manessi : Rivas et al. 2006: 107.

Pseudogonatodes sp : Rivas et al. 2021: supporting information, table S3.

Holotype: MBLUZ 1292 , an adult male, collected from a footpath between Macuro and Los Chorros ( Cerro El Olvido , 10°41 ʹ 33 ″ N, 61°57 ʹ 47 ″ W), at ~ 500 m elevation, Península de Paria, Sucre state, Venezuela; one of three specimens collected on 13 August 2014 by Gilson A. Rivas and Mayke De Freitas.

Paratypes: MBLUZ 1293–1294 ; two specimens with the same collection data as the holotype .

Referred specimen: MHNLS 16202 , a subadult specimen in poor condition (a piece of skin is missing on the body) from the same locality as the type series, but collected by Gilson Rivas and César Barrio-Amorós on 19 July 2002 .

Diagnosis: Pseudogonatodes fuscofortunatus can be distinguished from all its congeners by the following combination of characters: (1) maximum SVL of 39.2 mm; (2) dorsal scales granular, roughly homogeneous in size, subconical but somewhat flattened and inclined posteriorly, larger than scales on top of head; (3) 98–106 scales around midbody; (4) rostral with posterior median cless, bordered posteriorly by four postrostrals; (5) four supralabials; (6) three infralabials; (7) eight or nine loreals; (8) posterior edge of mental scale without conspicuous median clesss; (9) five or six postmentals, which are equal to subequal in size compared with subsequent scales; (10) 37–41 ventrals in a straight line between anterior level of forelimbs and border of cloaca, (11) 31–33 ventrals between anterior levels of forelimbs and hindlimbs; (12) long digits lacking expanded subdigital third lamella; (13) eight or nine subdigital lamellae under finger IV; (14) 10 subdigital lamellae under toe IV; (15) subcaudal scales with an inconspicuous medial row of larger scales in contact with three scales laterally alternating with smaller scales in contact with two scales laterally; (16) long snout, with an elongated ascending nasal process of the premaxilla separating the nasal bones; and (17) fused parietal bones in adults.

Comparisons: Pseudogonatodes fuscofortunatus is distinguished from P. barbouri , P. guianensis , and P. lunulatus by lacking an enlarged third subdigital lamella on the fourth toe (for a discussion of this character, see Huey and Dixon 1970). It also differs from those three species by its larger size, with adults of P. fuscofortunatus reaching a maximum SVL of 39.2 mm and the smallest specimen known (a juvenile) with an SVL of 32.2 mm, whereas the maximum SVL reported is 25.6 mm for P. barbouri , 30.0 mm for P. guianensis , and 29.9 mm for P. lunulatus . Pseudogonatodes fuscofortunatus further differs from P. guianensis and P. lunulatus by having a higher number of lamellae under the fourth finger (eight or nine vs. four to seven) and fourth toe (10 vs. five to seven), and from P. barbouri and by having dorsal scales that are granular and subconical as opposed to being flat and imbricated.

Pseudogonatodes fuscofortunatus shares with P. furvus , Pseudogonatodes gasconi Avila-Pires & Hoogmoed, 2000 , P. manessi , Pseudogonatodes peruvianus Huey & Dixon, 1970 , and P. quihuai the lack of an enlarged third lamella on the fourth toe. In comparison to P. fuscofortunatus , P. furvus seems to be a larger species, with adults exceeding 41 mm in SVL, differing in having fewer postrostrals (three vs. four) and postmentals (two to four vs. five or six), and more lamellae under the fourth finger (10 or 11 vs. eight or nine) and toe (11–15 vs. 10). Pseudogonatodes gasconi is a very small species; the only known specimen (holotype) is a gravid female 24 mm in SVL, much smaller than the only juvenile known of P. fuscofortunatus (SVL 32.2 mm). The single specimen of P. gasconi also has several other differences in comparison to P. fuscofortunatus , including more postrostrals (five vs. four), fewer lamellae under the fourth finger (seven vs. eight or nine) and toe (eight vs. 10), tall conical scales as opposed to short subconical scales dorsally, and lacking a medial cless on the rostral scale, which is present all specimens of P. fuscofortunatus . Pseudogonatodes fuscofortunatus differs from P. peruvianus in being a larger species (largest adult in P. peruvianus is 32 mm in SVL) and having more lamellae under the fourth finger (eight or nine vs. six or seven) and toe (10 vs. eight or nine). It differs from P. quihuai in having four postrostrals as opposed to three and having higher numbers of loreal scales (eight or nine vs. five or six) and scales around the midbody (98–106 vs. 85–91). Pseudogonatodes fuscofortunatus is both most phenotypically similar and most closely related to P. manessi , but it differs from this species in having four postrostrals as opposed to three and in aspects of cranial osteology, as discussed below. Among species of Pseudogonatodes for which cranial osteological data are available ( P. barbouri , P. furvus , P. fuscofortunatus , P. guianensis , P. lunulatus , P. manessi , and P. quihuai ), P. fuscofortunatus is unique in having fused parietals and a long ascending nasal process that completely separates the nasal bones.

Description of holotype: An adult male (SVL 39.2 mm) with fully regenerated tail (TL 27.8 mm) in a state of good preservation. Morphometric and meristic data are included in Table 4. Head cone-shaped, long, and pointed. Rostral large, visible from above, with a posterior medial cless extending anteriorly more than half the length of the rostral. Four postrostrals, the two medial ones indenting the rostral and about half of the size of the two laterals (= supranasals). Nostrils and surrounding scales slightly protruding from snout, each bordered by rostral, supranasal, one (less) or two (right) postnasals, and first supralabial. Postnasals about the same size as loreal scales. Scales on snout and loreal region gradually transitioning from flat, polygonal, and juxtaposed, anteriorly, to conical and subimbricate, posteriorly. Nine loreal scales counted in the shortest straight line between postnasals and eye socket. Scales on supraorbital region subconical and subimbricate, slightly larger than adjacent scales. Anterodorsal ocular scales form a supraciliary flap, with the two anteriormost in dorsal view significantly larger than adjacent scales. Four supralabials, first three subequal in length, but first and second significantly taller than third; fourth supralabial below middle of eye, much smaller than the first three and followed posteriorly by granular scales similar in size to scales on adjacent temporal region. Scales on the temporal and parietal region small, granular to subconical, juxtaposed. Ear opening small and oval, located at a distance from orbit about twice as long as the distance between orbit and nostril.

Mental large, without posterior clesss. Posterior border of mental resembles a half hexagon, with a transverse straight suture and two divergent oblique sutures. Six asymmetrically arranged postmentals, the first two in contact with right oblique suture, the second to fourth in contact with transverse suture, and fourth to sixth with less oblique suture of mental. Postmentals about same size as scales of chin, which are granular and subimbricate. Three infralabials, the first very long, almost reaching anterior level of orbit and more than twice as long as the second infralabial; third infralabial small, below midlevel of orbit, followed posteriorly by four or five small, elongated scales to rictus of mouth. Scales on upper part and sides of neck granular, like dorsals. Anterior scales of the throat granular, rounded, and juxtaposed, gradually transitioning posteriorly to larger, subimbricate granules, to flat, imbricated ventral scales.

Dorsal scales granular, rounded in lateral and dorsal view, slightly inclined posteriorly. Dorsal granules slightly larger than those on parietal region. Ventral scales distinctly larger than dorsals, flat, smooth, imbricate, more or less rhomboidal, with rounded corners; 33 scales in a midventral line between anterior levels of fore- and hindlimbs, 41 until vent. A single row of small irregular scales borders the vent anteriorly, two rows posteriorly. A narrow transitional zone between dorsals and ventrals. Longitudinal scale rows around midbody 100, of which ~15 are well-defined ventrals. Escutcheon absent.

On the base of tail, supracaudal scales are similar in size and shape to trunk dorsals, abruptly transitioning into large, flat, subimbricate scales on the second sixth of the tail. Tail regenerated at the beginning of the third sixth of tail. Original tail segment has an inconspicuous midventral row of larger scales in contact with three scales laterally alternating with smaller scales in contact with two scales laterally. Dorsal region of the regenerated portion of tail with flat, oval-shaped, imbricate scales, slightly smaller than scales on unregenerated portion. Subcaudal scales on regenerated portion of tail irregular in shape and size, but flat and imbricate.

Scales on anterior part of forelimbs flat, smooth, and imbricate; elsewhere on the forelimbs granular and subimbricate to juxtaposed. Scales on forelimbs flat, smooth, and imbricate except posteriorly, where they are granular and juxtaposed. Ventral surfaces of manus and pes with heterogeneous squamation in shape and size. Lamellae under fourth finger eight, under fourth toe 10. Lamellae under digits subequal in size. Claws enclosed by an ungual sheath comprising five scales, as is characteristic for the genus.

Holotype coloration: In life, the background dorsal coloration of the head, body, limbs, and tail is chocolate brown overlaid with irregular dark brown mottling. A longitudinal and nearly mid-dorsal series of nine small pale cream dots extends from the level of the forelimbs to the midbody level and continues with three additional dots immediately anterior to the level of the hindlimbs. These pale dots are small, encompassing two to four scales, and are separated by three to four scales. There are also slightly larger pale spots dorsolaterally, but much more interspersed, three on each side of the body. The top of the head has inconspicuous pale dots not forming a discernible pattern. The labial region also has inconspicuous pale markings, especially around the sutures between the supralabials and infralabials, respectively. The top of the tail has short irregular and broken cream and brown dorsolateral stripes that extend only from the level of the hindlimbs to the anterior sixth portion of the tail. The venter is pinkish brown. The gular area is cream coloured, with some brown suffusions around the postmentals and posteriorly, where there is the colour transition to the venter. Subcaudal coloration same as dorsum except anteriorly, where it is suffused with pinkish brown. The preserved specimen has not changed much in colour, with only the pink hue in the ventral area fading.

Variation: Morphometric and meristic data for the type series is presented in Table 4. Sexing of the holotype and the largest paratype (MBLUZ 1293) is tentative. These two specimens have differences in the subcaudal region adjacent to the vent. In the holotype, presumably a male, there are two inconspicuous bulges ventrolaterally that might correspond to the presence of hemipenes. In MBLUZ 1293, presumably a female, the tail is constricted and regenerated shortly behind the vent, and there does not seem to be enough space for hemipenes. This specimen also has a noticeable swollen and decoloured area on the less side of the neck (observable in Fig. 3A ), which might correspond to an extracranial endolymphatic sac, but computed tomography scans do not show extracranial calcium deposits in the endolymphatic sacs in any of the three type specimens. In geckos, it has been demonstrated that females have larger endolymphatic sacs than males, e.g. in Gonatodes antillensis (de Jeude, 1887) ( Lamb et al. 2017) and Gekko gecko (Linnaeus, 1758) ( Laver et al. 2019) , but unfortunately the lack of visible extracranial calcium deposits in MBLUZ 1293 precludes us from using this structure to help determine the sex of specimens.

There is noteworthy colour variation in the type series. Both MBLUZ 1293 and 1294 lack a well-defined series of mid-dorsal pale dots as observed in the holotype. MBLUZ 1293 has many more pale markings than the other two types, as described in the next few lines. The dorsolateral pale dots are more conspicuous and frequent, five as opposed to three on each side, compared with the holotype. These dots seem to have dark markings suffused around them, forming poorly defined ocelli. There is an additional series of smaller (encompassing two scales) pale cream dots laterally, about eight on each side. The rest of the pale markings are small and do not seem to form any pattern. MBLUZ 1293 also has a creamish yellow, roughly W-shaped marking on the parietal area that is not observed in the two other types. MBLUZ 1294 has dark suffusions in the gular area that form three diffuse and incomplete slanted stripes on each side of the head that extend posteromedially from the infralabials and, except for the anteriormost, do not contact each other medially. It is possible that these stripes fade ontogenetically, because they are not observed in the two adult specimens.

Etymology: The specific epithet fuscofortunatus is a combination of the words fusco (from fuscus, a noun in Latin), referring to the general brown colour of this species of lizard, and fortunatus (Latin adjective meaning lucky or fortunate), and is formed as a compound noun in apposition. It is in reference to the lucky occasion of the discovery of this small brown gecko, which had gone unnoticed by other naturalists and explorers who visited these mountains over the previous century. The name was selected from a list of names proposed at the OroVerde office.

Cranial anatomy: Typically, the skull ( Figs 5–7 ) is lightly built, as in other sphaerodactyls (i.e. Chatogekko , Coleodactylus , Gonatodes , Lepidoblepharis , and Sphaerodactylus ); however, it is unique in being slender, having an elongated snout, and having a distinctive overlap of the premaxilla, nasals, and frontal. The nasals are completely separated from one another by the premaxilla; the frontal width is almost constant along most of the bone length and expands significantly and abruptly only in the posterior quarter. There is only a slight interorbital constriction of the frontal, which is unique among congeners. The frontal also has two long and well-defined anterolateral processes. Each eye has 14 scleral ossicles. The premaxilla has 11 tooth loci, the maxilla 25 tooth loci, and there are four supralabial foramina. The parietals are fused, and the frontoparietal suture is braced by the postorbitofrontal, which has a curved lateral margin. The braincase is not globular as in many other miniaturized sphaerodactyls. The vomer is fused; the palatine has a deep ventral choanal groove. The pterygoid braces the ectopterygoid as in other Pseudogonatodes .

The crista prootica extends to the base of the basipterygoid process; the posterior opening of the vidian canal is entirely ventral; the lateral aperture of the recessus scalae tympani is visible ventrally and the spheno-occipital tubercle is reduced. A stapedial foramen is present. The jaw is formed by the dentary, coronoid, splenial, and compound bone. The dentary extends laterally almost to the level of the posterior surangular foramen and bifurcates posteriorly into angular and surangular processes. There are three mental foramina and 30 tooth loci. The compound bone has a moderate retroarticular process, not expanded or excavated dorsally; the foramen for the chorda tympani opens medially.

Postcranial anatomy: The skeleton ( Fig. 7 ) of P. fuscofortunatus has 26 presacral vertebrae; the atlas has fused neural arches and bifurcated hypaphophyses. MBLUZ 1293 has a total of nine caudal vertebrae, five in the pygal series, and four with autotomy planes. It has a regenerated axial rod beginning at the level of the ninth caudal. The specimen has no clavicular fenestra; the interclavicle has no lateral processes; and there are four pairs of ribs attached to the presternum, one via the mesosternum.

There are four phalanges in the 4th digit of manus and pes.Four phalanges are also present in the manual digit IV in Coleodactylus and Chatogekko , but this character is unique in the pedal digit IV of Pseudogonatodes ( Kluge 1995, Gamble et al. 2011a, Bauer et al. 2018, Montes-Correa et al. 2021). Using a combination of X-rays and micro-computed tomography data, this character was confirmed in 28 specimens, belonging to six species (including P. fuscofortunatus ). Pedal digit IV looks long in P. quihuai , but no osteological data are available to corroborate the reduction in the number of phalanxes. Pseudogonatodes quihuai is also differentiated from all other Pseudogonatodes in having paired frontals, a character reported before only in Coleodactylus , Teratoscincus , and Saurodactylus ( Daza and Bauer, 2012) , but in recent analyses this species was confirmed as member of Pseudogonatodes (F.M.J. Rojas-Runjaic, personal communication to W.E. Schargel).

Natural history and conservation: All type specimens were collected on a trail that goes from Macuro to Los Chorros, along the eastern flank of Cerro El Olvido, at an elevation of ~ 500 m a.s.l. The individuals were active on the ground when captured at ~11.00 h. The species appeared to be common at that time, because eight individuals in addition to those collected were observed in 2 h. The first individual of this species was captured on 19 July 2002 ( Rivas et al. 2006). It was active at the base of a large tree located along the same trail where the type series was collected, but at ~15.00 h. It is important to note that at this elevation (500 m a.s.l.), there is a noticeable and abrupt transition in temperature and vegetation, changing from a warm lower level of deciduous vegetation to a cooler evergreen forest with mediumsized and larger trees. The soil is more humid, with abundant organic matter and rocky outcrops, producing a substrate with many suitable hiding places for these tiny lizards.

A particular feature of the Peninsula de Paria is that, owing to the Massenerhebung effect, Tropical Montane Humid Forest and Tropical Montane Cloud Forests are encountered at lower elevation than in the rest of Northern Venezuela. This phenomenon is particularly pronounced at the very end of the Peninsula, because the Trade Winds or Easterlies are prevalent and strong and carry seasonally high levels of moisture that are then pushed up by the mountain mass. The trade winds, moving from east to west, will encounter land at the easternmost side of the peninsula, offloading a higher amount of humidity at lower elevation. As they move westwards, the remaining humidity will be available at higher elevations, such as the surroundings of Cerro Humo, the highest peak of the Paria Range.

The Paria Range is composed of two geographically distinct sections (western and eastern) demarcated by a low pass (<200 m in elevation) at Mejillones Cove. This lowland region is reputed to break up the continuity of the evergreen forest, and it might represent a significant barrier to the dispersal of animal populations in recent times between both sections, although the barrier might have become established too recently to have allowed speciation to occur. However, there seem to be some differences in species composition between eastern and western Paria based on the significant fieldwork conducted by G.A.R. and M.D.F. in the region. Pseudogonatodes fuscofortunatus has been collected only in the eastern section of Paria, despite considerable field effort in the western section. Another example is Oreosaurus rhodogaster ( Rivas, Schargel & Meik, 2005; Gymnophthalmidae ), which appears to be common in the forest understorey of the western section, mainly in the surroundings of Cerro Humo and the village of Las Melenas, whereas it has not been observed in similar habitats in the eastern mountains around Macuro. This does not necessarily mean non-existence, but potentially that local conditions vary and significantly affect the abundances of these two species. It is well known that many amphibians have been observed at much lower elevations in the eastern section, around Macuro, than in the western ridges of Cerro Humo. Some amphibians and reptiles observed in Macuro and its surrounding mountains, El Olvido and Cerro Azul, are Mannophryne riveroi (Donoso-Barros, 1956) , Mannophryne venezuelensis Manzanilla, Jowers, La Marca, & García-Paris, 2007 , Hyalinobatrachium orientale (Rivero, 1968) , Vitreorana castroviejoi (Ayarzaguena & Señaris 1997) , Phyllomedusa trinitatis Mertens, 1926 , Scinao ruber (Laurenti, 1768), Flectonotus fitzgeraldi (Parker, 1934) , Leptodactylus turimiquensis Heyer, 2005 , Gonatodes ceciliae Donoso-Barros, 1966 , Hemidactylus palaichthus Kluge, 1969 , Phyllodactylus ventralis O'Shaughnessy, 1875 , Thecadactylus rapicauda (Houttuyn, 1782) , Ninia atrata (Hallowell, 1845) , Tantilla melanocephala (Linnaeus, 1758) , and Bothrops aff. venezuelensis Sandner-Montilla, 1952 . Ramón Urbano, as cited by Phelps and Phelps (1948), additionally mentioned the presence of the bushmaster ( Lachesis muta ) as very abundant in the upper slopes of the mountains surrounding Macuro.

A decade ago, the Venezuelan state-owned oil company Petróleos de Venezuela, S. A (PDVSA) commissioned the reopening of the Güiria–Macuro road to facilitate access to the easternmost areas that were going to be developed as part of oil prospecting on the continental platform a few miles off-shore, but only the first phase of ground levelling was carried out. Finishing it could have spelled disaster for the Peninsula, because the road would have allowed easy access to otherwise isolated areas of the Peninsula, such as Patao and Macuro. Immigration would have been another negative aspect of the development of the liquified gas plant in Güiria and other related projects in or near Macuro (such as the underwater pipeline). Such development would have increased the pressure on a town already lacking basic government assistance for decades. However, for various reasons, the Paria liquified gas project collapsed, and a visit carried out by us in 2014 seemed to indicate that people have migrated from the village, abandoning the local crops. Also, most of the villagers are very happy buying food from grocery stores, rather than taking the risk of being bitten by snakes while looking for food on their small farms near forested areas. Most inhabitants in Paria have an almost supernatural fear of snakes, and most of them prefer not to wander in heavily vegetated areas, in order to avoid the risk of snake bites.

The locality where the type series of P. fuscofortunatus comes from is protected within the limits of the Paria Peninsula National Park, thanks to a recent presidential decree (Official Gazette 42.182, Decree No. 4547, dated 3 August 2021) that expanded the mountainous area and marine-coastal area of the Paria Peninsula National Park from 37 500 ha at its creation in 1978 to 89 244 ha. In this sense, the lands above 400 m a.s.l. in the extreme east and south of the Peninsula are now protected within the limits of the National Park.This is the product of a wise decision supported by a series of scientific discoveries in recent decades, which have shown that the local biodiversity is greater than had been estimated until a few years ago. Many of the recent findings deal with new species of plants, amphibians, and reptiles, most of which are endemic to the region. This opens more and broader questions about the distribution of plants and animals in northeastern Venezuela.

Figures

Figure 3. Specimens of Pseudogonatodes from northern South America in life.A, Pseudogonatodes fuscofortunatus female (presumably) paratype (MBLUZ 1293), Cerro El Olvido, Venezuela.B, Pseudogonatodes manessi, female, Rancho Grande, Parque Nacional Henri Pittier, Venezuela (MHNLS 17984). C, Pseudogonatodes furvus, male topotype, Sierra Nevada de Santa Marta, Colombia (CBUMAG:REP:00767). D,Pseudogonatodes manessi, young specimen, from La Cumbre, Municipio Bruzual, Sierra de Aroa, Venezuela; this individual would represent the westernmost limit of the species. E, view of Cerro Azul from Cerro El Olvido, two of the highest mountains with humid forests at the eastern end of the Paria Peninsula, Venezuela. F, undergrowth with abundant decomposing organic matter and rocks, an environment where P. fuscofortunatus lives.Photographs: Luis A.Rodríguez J. (A), Eric N. Smith (B), Andrés C. Montes-Correa (C), Alberto Navas and Edward Camargo (D), and Gilson Rivas (E, F).

Figure 4. Laser scanning images from the preserved holotype of Pseudogonatodes fuscofortunatus (MBLUZ 1292) in dorsal and ventral views.Images were obtained using a VR-6000 series KEYENCE 3D Optical Profilometer.

Figure 5. Three-dimensional rendering of the skull of the holotype of Pseudogonatodes fuscofortunatus (MBLUZ 1292). Cranium in dorsal (A), ventral (B), and lateral (C) view, and jaw in lateral (D), medial (E), dorsal (F) and ventral (G) views.

Figure 6. Telescoped pattern of the skull of Pseudogonatodes fuscofortunatus (MBLUZ 1292, top), compared with Pseudogonatodes manessi (KU 182740, bottom). Arrows indicate the facets that support each dorsal bone. Colours are as follows: purple, premaxilla; cobalt blue, nasal; light blue, frontal; green, parietal.

Figure 7. Complete skeleton of Pseudogonatodes fuscofortunatus (MBLUZ 1292) in dorsal and ventral view, and insets with close-up for the right manus and pes.