Potamites flavogularis, Altamirano-Benavides & Zaher & Lobo & Grazziotin & Nunes & Rodrigues, 2013

Altamirano-Benavides, Marco, Zaher, Hussam, Lobo, Luciana, Grazziotin, Felipe Gobbi, Nunes, Pedro Murilo Sales & Rodrigues, Miguel Trefaut, 2013, A new species of lizard genus Potamites from Ecuador (Squamata, Gymnophthalmidae), Zootaxa 3717 (3), pp. 345-358 : 347-357

Potamites flavogularis sp. nov.

Holotype. DHMECN 4581, an adult male from Reserva Biológica Narupa (0° 45’ 30.0”S, 77° 54’ 37.1”W), 1800 m elevation, Província de Napo, canton Loreto: Ecuador; collected by P. Meza-Ramos, S. Cáceres S., M. A. Urgilés, and L. Oyagata C., on November 29 th 2006, field number PMR409 .

Paratypes. DHMECN 4583, male, collected together with the holotype, field number PMR 412 ; DHMECN 10050–10051, females, DHMECN 10052, male, from Reserva Rio Zuñac (1° 24’ 03.6”S, 78° 11’ 12.4” W) 1440 m elevation, Província Tungurahua: Baños: Rio Negro : Ecuador, collected by M. Yánez-Muñoz, M. A. Urgilés y A. Laguna C., on May 8th 2008, field numbers MYM 1628, MYM1649, and MYM 1718, respectively; DHMECN 10054–10056, females, Rio Negro, Montana (1° 24’ 57.6”S, 78° 12’ 28.8”W) , 1440 m elevation, Provincia Tungurahua: Baños: Rio Negro : Ecuador, collected by Eric N. Smith, M. Yánez-Muñoz, B.Purtschert C., J. Stricher, y L. Oyagata C., on January 7th 2008, field numbers ENS 12220 -12225.

Diagnosis. a species of Potamites with a single frontonasal; regular longitudinal rows of dorsal tubercules in series of single enlarged and strongly keeled tubercles; absence of enlarged tubercules on sides of body, neck and gular region; tail slightly compressed with no intercalated scales along sides, and a brown spot around nostril. Potamites flavogularis sp. nov. differs from all species of Neusticurus (characteristics in brackets) by presenting a short and slightly compressed tail (long and highly compressed), tympanum slightly recessed (highly), presence of calcareous spinules on flounces of the hemipenis (absent) and sub-imbricate ventral scales (imbricate). From all other species of Potamites except for P. cochranae , it differs by presenting a single frontonasal, lateral body scales lacking conspicuous enlarged tubercles, four longitudinal rows of dorsal tubercles, six transverse series of ventral scales, absence of intercalated scales along sides of tail, and absence of tubercles on sides of neck and gular regions. Like P. cochranae the new species has a conspicuous black or brown spot surrounding nostril but differs from it by presenting a slightly shorter tail (1,34–1,41 times SVL vs 1,53–1,58), by having distinctive and homogeneous dorsolateral and paravertebral longitudinal rows of tubercles formed by a sequential series of unique enlarged and strongly keeled tubercles [irregular and heterogeneous, containing irregularly one or more than one (mostly two) enlarged tubercles more rounded and with keels never so conspicuous], dorsolateral and paravertebral rows of tubercles distinct anteriorly and closely approaching scales from posterior part of head (indistinct anteriorly and not so close from scales on the posterior part of head), a short loreal with its suture with nasal corresponding to less than half to the posterior part of nasal (large loreal, its suture with nasal corresponding to the major part of nasal scale), enlarged scales on posterior part of tight (mostly granular scales), basal flounces of the hemipenial body circulating the assulcate face of the base of the organ (basal flounces of the hemipenial body restricted to the center of asulcate face), and in color pattern where a strong sexual dichromatism is present (absent).

Etymology. From the Latin flavus (=yellowish) and gularis (=throat)

Description of the holotype. ( Figs 1A–C , 2A and 3A ). Rostral well visible from above, wider than high, anteriorly rounded, contacting first supralabial, nasal and frontonasal. Frontonasal single, as long as wide, wider posteriorly, contacting rostral, nasal, loreal and prefrontals. Prefrontals irregularly pentagonal, in broad midline contact, contacting frontonasal, first superciliary, first supraocular, and frontal, their midline suture as large as suture between rostral and frontonasal. Frontal large, as wide as long, wider anteriorly, its posterior part irregular, with asymmetric incomplete sutures. An irregular pair of wider than long small accessory frontal scales resulting from fission of posterior part of frontal, the left one smaller. A pair of irregularly pentagonal and slightly asymmetric frontoparietals contacting anteriorly accessory frontals, and third to fourth (left) or third to fifth (right) supraoculars. Suture between frontoparietals deeply indented by interparietal, twice as long as suture between prefrontals. Interparietal as wide as long contacting laterally a pair of wider than long parietals. Posterior border of parietals plus interparietal U-shaped. A series of juxtaposed, smooth occipitals of variable size, most enlarged, following parietals and interparietal; a small pair just behind interparietal followed posteriorly by two much longer scales. Laterally to them an enlarged occipital on each side, the left one smaller, divided. Other occipital scales smaller, irregular, almost identical to but smaller than temporals. Four supraoculars, first the smallest, second the largest. First and second supraoculars contacting frontal, third contacting the accessory frontal, and third and fourth contacting frontoparietals. Five superciliaries, first and second the largest. Canthus rostralis well defined, slightly rounded. Nasal undivided with nostril near the center, pentagonal, contacting rostral, first and second supralabials, loreal, frenocular and frontonasal. Loreal higher than long, reaching the level of nostril. Frenocular longer than wide, pentagonal, distinctively wider than loreal and followed by seven flat subocular and postocular scales surrounding lower and posterior part of orbit. Two to four preocular granules. A semitransparent palpebral disc with 8 divisions. Eleven palpebrals in lower eyelid, 12 in upper eyelid. Eight supralabials, third and sixth the largest; center of eye between 3th. and 4 th. Temporal scales smooth or slightly striated, irregular in size and shape, those close to eye and ear slightly enlarged. Most head scales smooth, rarely with slight striations, always with scattered sensorial organs especially concentrated on posterior part of supraoculars. Ear opening large, rounded, tympanum slightly recessed.

Mental wider than long, rounded anteriorly, almost straight posteriorly. Postmental pentagonal, slightly longer than wide, wider posteriorly. Four pairs of chinshields, three of them contacting infralabials; first and second pair in contact, second pair the largest; posteriormost pair the smallest and separated from infralabials by an elongate scale. Chin scales irregular, elongate, becoming progressively larger and rounded and them grading to enlarged gular scales. Four tranverse rows of enlarged pairs of wider than long, smooth and slightly imbricated gulars. Collar distinct with five smooth and enlarged scales; collar fold covered with smooth, juxtaposed, irregularly rounded granules. Six infralabials, third the largest.

Sides of neck with small, juxtaposed, irregularly disposed and conic granules, smaller dorsally. Dorsum with four longitudinal rows of enlarged, imbricate, and almost mucronate single tubercles with highly elevated keels. Dorsolateral and paravertebral rows almost in contact anteriorly, separated by 0–2 granules anteriorly, by 4–5 at midboby and converging again towards base of tail. Less than 5 granules between posterior part of head and first enlarged dorsolateral tubercle. Dorsolateral rows of tubercles marginated externally by a series of much smaller scales, slightly larger than those of flanks. Paravertebral rows of tubercles anteriorly separated by 2–4 very small flat and imbricate scales, becoming almost parallel or in contact posteriorly where they are separated by 1–2 scales. Flanks covered with a series of juxtaposed, irregularly disposed and irregularly rounded non tubercular granules between dorsolateral row of tubercles and ventrals. Middorsal scales 105 between posterior margin of head and posterior margin of hind limb; 28 tubercles along paravertebral crest; 45 scales around midbody. Ventral scales quadrangular, in six longitudinal and 18 transverse rows; smooth, imbricate, posteriorly rounded, central ones squared, lateral ones wider than long. Preanal plate with two series of enlarged flat scales, the anteriormost with two scales, posterior one with five, the three central being the larger, wider than long. Total femoral plus preanal pores 21.

Tail with single rows of longer than wide scales, except near the dorsal part of base of tail where dorsal rows of tubercles converge becoming progressively less conspicuous although still separated by 1–2 rows of very small flat granules. Tail scales become progressively homogeneous toward tip. Scales of ventral part of tail smooth, larger than those on dorsal part, imbricate, similar to ventral scales, becoming gradually longer than wide toward extremity.

Dorsal parts of fore and hind limbs with large, strongly keeled, imbricate scales; ventral parts with smooth, imbricate, enlarged scales. Palm and sole with irregularly and juxtaposed granules. Scales on dorsal surface of palm smooth, slightly keeled on palm. Digital lamellae smooth, single: 13 infradigital lamellae under the IV finger, 18 under IV toe.

Dorsum with a light brown background coloration; head slightly lighter dorsally, with a dark spot surrounding nostril. A continuous middorsal dark brown to black stripe extends along and between the two middorsal tubercle rows from nape to anterior ¾ of body. From then to the first third of tail this middorsal stripe becomes interrupted and is replaced by an alternating series of dark brown and light areas, one tubercle size. Parallelly, and with the same length to the middorsal stripe, there are two continuous slightly wider dorsolateral light stripes externally marginated by a conspicuous black irregular line with a half tubercle size. From the posterior quarter of dorsum to the first third of tail the stripes are replaced by a series of five large light irregular ocelli surrounded by dark pigment. Flanks dark brown becoming lighter posteriorly and toward venter. A series of longitudinally arranged four small light ocelli surrounded by dark pigment are present between middle to posterior part of flanks. Lower labials and mental tan, chin and throat yellow. Between them a contrasting black line surrounds the chin and extends posteriorly along sides of throat to the arms and paraventral region, separating ventral light areas from dark olive brown dorsal ones. Venter immaculate with scattered dark fine pigmentation. Anteriorly, external part of outer row of tubercles marginated by a darker pigmentation which becomes irregular after interruption of light line. The general coloration of adult specimens in life (male and female) is represented in the Figure 4A–B (specimens uncatalogued).

The hemipenes of the holotype were everted during preservation and the right one was removed and prepared ( Fig. 2A ). The hemipenis was only partially everted and expanded due to a small perforation on its asulcate face that we tried to patch with cyanoacrylate glue. Although this procedure allowed to further expand the hemipenis, the eversion and filling of both lobes remained incomplete, resulting in a slight size asymmetry between lobes.

The hemipenis is relatively long, extending for approximately 1.5 cm along nine subcaudals rows. The hemipenial body is globose, roughly cylindrical, with a clear constriction at base and ending by two small lobes surrounded by conspicuous folds. The sulcus spermaticus is central in position, originates at the base of the organ, and proceeds in a straight line towards the top of the hemipenial body, then bifurcating towards the lobes. The sulcus is divided by a small fleshy fold; branches extend among folds along the ventral face of the lobes ending at their tip. The sulcate face of the organ presents two large nude areas parallel to the sulcus spermaticus that enlarge laterally in the superior part of the organ, involve the lobes and circulate them in the asulcate face. A series of roughly equidistant flounces with calcareous spinules are present in the lateral and asulcate faces of the hemipenis, some of them distinctively stained in red with Alizarin. Nineteen rows of flounces with calcareous spinules are present along the body of the organ plus a small one present at the base of each lobe. The first three basal rows are straight, circulate the base of organ being discontinuous laterally by the presence of a nude area; this makes each flounce row composed by three groups of spinules: a larger central one and two smaller lateral groups. From fourth to ninth rows, the central group of flounces acquires a chevron shape and is clearly separated from the two lateral groups by large nude areas. The chevron-shaped central part of the tenth flounce row is asymmetrical, ending by an isolated group of four spinules in one side but is continuous in the opposite side. The central part of flounces is absent from the eleventh to the last row, their space being nude although a small group of roughly parallel and diagonally disposed group of spinules adjacent to their correspondent lateral parts might be present until the sixteenth flounce row. The two apical flounce rows on the hemipenial body are very small, undivided and isolated. A very small and isolated row of spinules is also present on the lateral base of both lobes.

Measurements of the holotype: snout-vent length: 64 mm; tail length: 88 mm.

Variation ( Figs. 5 A–C and 6 A–E ; Table 1). Males of Potamites flavogularis sp. nov. are slightly smaller than females: maximum SVL for males and females was 65mm and 75mm, respectively. Tail length varied respectively in males and females from 1.36 to 1.40 and 1.30 to 1.41 times SVL. No sexual differences were found in squamation. Variation in meristic characters (n=8) was the following: longitudinal dorsals 85–113; scales in paravertebral row 28–37; scales around midbody 37–49; transverse ventral rows 15–19; total gulars 13–16; transversely enlarged gulars 5–6; infradigital lamellae under finger IV 13–16; and infradigital lamellae under toe IV 15–18. All specimens show four supraoculars, except one that has 5. Supralabials varied between 7 and 8, infralabials between 5 and 6, and palpebrals between 5 and 8. Total number of femoral pores varies between 19 and 21 in males; females have 1+1 or 2+2 preanal pores.

A strong sexual dichromatism is present in Potamites flavogularis sp. nov.. Like the holotype all other males have a light brown dorsum, a yellow chin and throat separated from the tan colored lower labials by a contrasting black line surrounding chin and extending posteriorly along sides of throat to the arms, and a venter immaculate with scattered dark fine pigmentation. In most females the dorsum is uniformly dark brown and the throat is dark brown irregularly spotted with black without the contrasting yellow/tan colour present in males. An inconspicuous pair of symmetric white stripes irregularly emarginated by black extends diagonally between posterior part of eye and 4 th pair of chinshields. Posteriorly and parallel to them another pair of irregular narrower white stripes, begins in the lower part of ear. A wider irregular stripe extends almost vertically from anterior margin of eye to the ventral part of infralabials. Ventral color is extremely variable in females but is generally gray with irregularly disposed black punctuation, more intense in the ventral surface of hindlimbs. In one specimen the ventral parts are entirely black, in others the venter varies from light to dark gray with a vestigial black punctuation.

Comparisons. Potamites flavogularis sp. nov. and P. cochranae differ from all other congeners by presenting a short and slightly compressed tail (1,31– 1,41 times SVL), lateral body scales lacking conspicuous enlarged tubercles, four longitudinal rows of dorsal tubercles and a conspicuous black or brown spot surrounding nostril. They additionally differ from all other species by presenting six transverse series of ventral scales, absence of tubercules on sides of neck and gular regions, and by lacking of intercalated scales along sides of tail. Although very similar, P. flavogularis sp. nov. differs from P. cochranae by a number of characters. Tail length is slightly shorter in P. flavogularis sp. nov. (1,31–1,41 times SVL) than in P. cochranae (1,22–1,58 times SVL). In P. flavogularis sp. nov. both dorsolateral and paravertebral longitudinal rows of tubercles along body are formed by a single row of distinctive and homogeneously enlarged, strongly keeled, almost mucronate tubercles. In P. cochranae longitudinal rows of tubercles along the body are irregular and heterogeneous, containing irregularly disposed enlarged tubercles involving one or two adjacent tubercles that are more rounded and less keeled than those observed in P. flavogularis sp. nov. ( Fig. 3 ). The new species retains enlarged dorsolateral and paravertebral rows of tubercles that are highly differentiated anteriorly, approaching closely the scales from the posterior region of the head, there are less than 5 granules between the posterior part of the head and the first enlarged dorsolateral tubercle. In P. cochranae , the dorsolateral and paravertebral rows of tubercles are indistinct anteriorly and are more widely separated from the scales of the posterior part of the head; there are more than 10 granules between the posterior part of the head and the first enlarged dorsolateral tubercle. P. flavogularis sp. nov. retains some (mostly three) scattered enlarged tubercles in the flanks, while in P. cochranae the scales marginating those tubercles are much smaller. In P. flavogularis sp. nov., the nasal suture with the loreal corresponds to less than half of the nasal suture, while in P. cochranae the largest part of nasal suture corresponds to its contact with the loreal. Even considering eventual anomalies in scales ornamenting the dorsal surface of the head, it seems that in P. flavogularis sp. nov. the frontal scale is not anteriorly divided, while in P. cochranae the frontal is divided anteriorly. In P. flavogularis sp. nov., there are more or less enlarged scales in the posterodorsal part of thigh whereas in P. cochranae only granules are present. Additional differences in scale counts between the two species are listed in Table 1.

Although both species present a more or less conspicuous dark surrounding nostril, color differences are striking. Potamites flavogularis sp. nov. shows strong sexual dimorphism in color pattern. Males are dorsally light brown to tan with a lighter area extending all along the dorsolateral rows of tubercles; continuous and emarginated by a darker coloration until the anterior third of the body, becoming posteriorly interrupted and lacking darker margination towards the third part of tail. The lower labials and mental are tan, and the chin and throat are bright yellow; a contrasting black line surrounds the chin and extends posteriorly along the sides from the throat to the arms, separating ventral light areas from dark olive brown dorsal ones. The venter is almost immaculate in males with scattered dark fine pigmentation. Females of P. flavogularis sp. nov. are uniformly dark brown dorsally. Contrary to males, throat is dark brown and irregularly spotted with black. An inconspicuous pair of continuous symmetric white stripes, irregularly emarginated by black, extends diagonally between the posterior part of the eye and 4 th pair of chinshields. Posteriorly and parallel to these stripes, another pair of irregular narrower white stripes begins in the lower part of the ear. A wider irregular stripe extends almost vertically from the anterior margin of the eye to the ventral part of infralabials. Ventral color is extremely variable in P. flavogularis sp. nov., varying from gray with irregularly disposed black punctuation to entirely black.

There are no marked sexual differences in color pattern in Potamites cochranae . The body, head and tail are dark brown dorsally with linearly arranged irregular spots of light color. A continuous light cream, longitudinal stripe extends from the posterior part of superciliaries to the level of the arms, running along the enlarged dorsolateral row of tubercles. Posteriorly, this stripe follows until the third part of tail as a series of irregular longitudinally aligned blotches of the same color, interspersed by black somewhat rectangular blotches, becoming inconspicuous towards their end. There are two parallel, posteriorly oriented and diagonally disposed, wide light stripes emarginated by dark color on the sides of the head. The first extends from the posterior part of the eye to the gular region and converges with its symmetric in the middle of gular area; the second begins right in front of the lower margin of the ear and fades near the collar. Except for the gular stripes and scattered parts of dark brown spots, the ventral parts are immaculate. Although females of P. flavogularis sp. nov. approach the color pattern present in both sexes of P. cochranae , their gular stripes are narrower and much less conspicuous, they lack the two dorsolateral rows of ocelli present on the anterior part of body of P. cochranae , and their ventral parts are darker. The hemipenial morphology of P. cochranae and P. flavogularis sp. nov. is relatively similar, although presenting few important differences. In P. cochranae , the basalmost flounces of the hemipenial body are shorter and limited to the central area of the asulcate surface of the hemipenis (usually the 3–4 more basal ones), while in P. flavogularis sp. nov. these flounces extend laterally, crossing all the asulcate surface to reach the lateral surface of the organ ( Fig. 2 ).

Distribution and natural history. The Narupa Biological Reserve is located in the Napo province, between the Hollín Chico and Hollín Grande rivers, and northeast Narupa, through the Gaucamayos’ Cordillera. It constitutes the amazon plateau in the eastern slope of the Andes, located between elevations from 1000 until 1500 m ( Fig. 7 ). Inside the reserve there are a variety of habitats observed: pastures, regeneration zones, bamboo forests, secondary and mature forests.

Male and female individuals of Potamites flavogularis sp. nov. were collected at night, in secondary and mature forest patches located among pastures with small rivers crossing those sites, sleeping over ferns, herbs ( Araceae , Heliconiaceae ) and broad-leaved shrubs ( Fig. 8 ).

Figures

FIGURE 1. Dorsal (A), ventral (B) and lateral (C) views of the head of the holotype of Potamites flavogularis sp. nov. (DHMECN 4581).

FIGURE 2. Sulcate and asulcate views of the right hemipenis of the (A) holotype of Potamites flavogularis sp. nov. (DHMECN 4581) and of the left (B) hemipenis of Potamites cochranae (DHMECN 4585). The white arrows indicates the distinct conditions of the basal flounces of the hemipenial body, diagnostic for the new species.

FIGURE 3. Cross section of the scalation at midbody. A—Potamites flavogularis sp. nov. (DHMECN 4581); B—Potamites cochranae [modified from Burt and Burt (1931), Fig. 9].

FIGURE 4. Specimens of Potamites flavogularis sp. nov. in life. (A) male; (B) female.

FIGURE 5. Morphological variation in male specimens of the type-series of Potamites flavogularis sp. nov.: (A) DHMECN 4583; (B) DHMECN 4581 (holotype); (C) DHMECN 10052. Scale bar = 2 cm.

FIGURE 6. Morphological variation in female specimens of the type-series of Potamites flavogularis sp. nov.: (A) DHMECN 10054; (B) DHMECN 10050; (C) DHMECN 10056; (D) DHMECN 10055; (E) DHMECN 10051. Scale bar = 2 cm.

FIGURE 7. Records of Potamites flavogularis sp. nov. in Ecuador. The numbers in map correspond to: 1—Reserva Biológica Narupa (Type locality); 2—Reserva Río Zuñac; 3—Río Negro.

FIGURE 8. General aspect of the habitat of Potamites flavogularis sp. nov.