Homonota williamsii, Avila, Luciano Javier, Perez, Cristian Hernan Fulvio, Minoli, Ignacio & Morando, Mariana, 2012

Avila, Luciano Javier, Perez, Cristian Hernan Fulvio, Minoli, Ignacio & Morando, Mariana, 2012, A new species of Homonota (Reptilia: Squamata: Gekkota: Phyllodactylidae) from the Ventania mountain range, Southeastern Pampas, Buenos Aires Province, Argentina, Zootaxa 3431, pp. 19-36 : 24-34

Homonota williamsii sp. nov.

Fig. 3 , 4

Gymnodactylus gaudichaudii, Bell, 1843 . In: C. Darwin, The Zoology of the Voyage of H.M.S. Beagle, Reptiles, London 5, 26, Plate 13, Fig. 1 .

Homonota guidichaudi (in error), Gray, 1845. Catalogue of the Specimens of Lizards in the Collection of the British Museum, London, 171.

Homonota darwini, Boulenger, G.A., 1885 , Catalogue of the Lizards in the British Museum 1, 21, Plate 3, Fig. 7 .

Homonota darwini, Koslowsky, J., 1898 , Revista de Museo de La Plata, 8, 165.

Homonota darwini, Liebermann, L., 1939 , Physis , 16, 63.

Homonota darwinii, Kluge, A.G., 1964 , American Museum Novitates, 2193, 22.

Homonota borelli, Gallardo, J.M. 1966 , Neotropica, 12, 16.

Homonota borellii, Peters, J.A. and Donoso-Barros, R., 1970 , Bulletin of the United States National Museum, 297, 146.

Homonota borellii, Williams, J.D., 1991 , Situación Ambiental Provincia de Buenos Aires, Recursos y Rasgos Naturales Evaluación Ambiental, 1, 13.

Homonota borellii, Abdala, V., 1997 , Serie Monografias Didácticas, Facultad de Ciencias Naturales, Universidad. Nacional de Tucumán 29, 17.

Holotype. — MLP.S 2630, an adult male from Sierra de la Ventana, camino a Cerro Tres Picos por Estancia Funke (38º08'10"S, 61º59'10"W, 601 m), Tornquist Department, Buenos Aires Province, Argentina, collected by C. H. F. Perez and P. F. Petracci, 25 June 2006.

Paratypes. — LJAMM-CNP 6517, an adult male same locality as the holotype. LJAMM-CNP 11834-11835 adult males from Bahia Blanca hill (38º04'07"S, 61º59'02"W, 723 m), Sierra de la Ventana, Tornquist Department, Buenos Aires Province, Argentina, collected by C. H. F. Perez, 7 October 1999. LJAMM-CNP 11837, an adult male from Curamalal hill (37º43'17"S, 62º13'59"W, 915 m), Tornquist Department, Buenos Aires Province, Argentina, collected by C. H. F. Perez, 7 October 1999. LJAMM-CNP 11838, an adult female from Curamalal hill (37º43'17"S, 62º13'59"W, 915 m), Tornquist Department, Buenos Aires Province, Argentina, collected by C. H. F. Perez, 7 October 1999. LJAMM-CNP 11836, an adult male from Abra de Los Vascos (38º15'34"S, 61º54'37"W, 454 m), Sierra de la Ventana, Tornquist Department, Buenos Aires Province, Argentina, collected by C.H.F. Perez, 7 October 1999. BYU 47931, BYU 47933-47934, adult females from near Parque Provincial Ernesto Tornquist (38º03'18.6"S, 62º00'51.6"W, 848 m) Tornquist Department, Buenos Aires Province, Argentina, collected by C.H.F. Perez, 5 March 2002. BYU 47932, an adult male from near Parque Provincial Ernesto Tornquist (38º03'18.6"S, 62º00'51.6"W, 848 m) Tornquist Department, Buenos Aires Province, Argentina, collected by C.H.F. Perez, 5 March 2002.

Diagnosis. — Homonota williamsii sp. nov. is a medium-sized species of Homonota (maximum SVL = 48 mm) and can be distinguished from the other species of the group by the following combination of characters: a dorsal reticulate dark brown pattern on a grayish background speckled with small white spots, white belly with dark spots, keeled dorsal scales, subcaudal scales rounded, alternating in size, oblique auditory meatus with a posterior serrate edge and different average number of dorsal scales and scales around midbody than all the other species of the genus.

Description of the holotype. — Body long, 5.1 times the head length. Head sub-triangular, neck well defined, with a blunt snout and very broad head. Eyes moderately large with vertical scalloped-edged pupil. Tail broken, incomplete. SVL 42.1 mm, TrunkL 18.7 mm, HL 6.9 mm, HW 7.8 mm, HH 4.8 mm, ESD 4.2 mm, END 3.2 mm, EMD 3.3 mm, IND 1.2 mm, horizontal diameter of the eye 2.4 mm, AL 10.6 mm, TL 7.1 mm, FL 8.9 mm. Dorsal surface of head covered by smaller granular scales increasing in size toward the anterior region of snout. Rostral pentagonal, wider than high (1.6 x 1.1 mm), with marked rostral crease. Six supralabial scales on each side. Five infralabial scales on each side. Nostril bordered by the first supralabial, rostral, supranasal and two postnasals. Orbit edged by cycloid supraciliary scales on its anterodorsal side. Parietal and temporal regions covered by almost equal-sized granular scales. Auditory meatus small, elongated and oblique with serrated borders, higher than wide (1.45 x 0.25 mm), 15–16 scales around auditory meatus. Mental pentagonal, elongated, 1.8 mm long, widest in the anterior region (2.1 mm) than in the posterior (1.4 mm). Two postmentals. Scales of the gular and throat region imbricate, of equal size and cycloid in shape. Along the vertebral line are rows of cycloid scales, juxtaposed on the anterior half and imbricate on the posterior. Dorsal surface with series of strongly keeled scales. Fifty-four scales around midbody. One hundred fifty-two dorsal scales. Fifteen series of keeled scales on the dorsal region of the midbody. First two longitudinal keeled series on each side of the vertebral line separated by three smooth and smaller cycloid scale series. Laterally, scales smooth and imbricate. Axillary and inguinal zones covered with small granular scales. Ventral scales cycloid, with posterior edge 4–5 lobed. Eighty-five ventral scales. Scales on the anterior region of the arm and forearm imbricate, cycloid, smooth and 3–7 lobed. Scales on the posterior and inner region of the arms very small and granular. Scales on hindlimb imbricate, cycloid, enlarged, smooth and 3–4 lobed. Subdigital lamellae of the manus imbricate, smooth, numbering: I:7; II:11; III:12; IV:12; V:11. Subdigital lamellae of foot imbricate, smooth, numbering I:8, II:11, III:15, IV:17, V:12. Dorsal and lateral regions of the tail covered with imbricate, smooth cycloid scales. Subcaudal scales imbricate, cycloid or quadrangular, lateral margin bordered by two smaller scales. Three conical postcloacal scales are present laterally at the base of the tail.

Meristic traits

(p<= 0.05) between continuous variables are shown. Abbreviations: TrL, trunk length; FL, foot length; TL, tibial length;

AL, arm length; HL, head length; HW, head width; HH, head height; END, eye-nostril distance; ESD, eye-snout

distance; EMD, eye-meatus distance; ID, interorbital distance; IND, inter-nostrils distance. Continuous traits

Coloration.—Coloration is similar between live and preserved specimens, but the general coloration darkens in preserved specimens. General background body coloration grayish. Trunk with a uniform and fine reticulate dark brown dorsal pattern, speckled white spots, one scale in size, spots extending onto the sides of the trunk and reaching the insertion of the forelimb. Dorsal reticulated pattern forming a clear vertebral midline, from the occiput region to the pelvic girdle. Lateral areas at the forelimb insertion and belly predominantly grayish, with irregular brown spots on each scale. Dorsal background of the head brown, faintly reticulated, with some areas dark brown. Head with a transverse grayish band, semicircular, faintly extended to the posterior edge of the eye. A band 3–4 scales wide continuous from the front of the eyes to the nostrils. Dorsal limb surfaces with a grayish background, reticulated with darker lines. Surface of the chest and belly whitish. Gular and ventral region of the tail dark gray but variable according to the degree of development of the chromatophores.

Variation. — Based on six adult males and one adult female ( Table 5 ): SVL 38.4–44.4 mm. Axilla groin distance 17.8–20.3 mm. Foot length 7.2–9.3 mm. Tibial length 5.5–7.1 mm. Arm length 9.3–10.9 mm. Head length 6.4–7.7 mm. Head width 6.7–7.8 mm. Head Height 4.1–5.5 mm. Midbody scales 50–56. Dorsal midbody keeled scale series 13-17. Dorsal scales 146–161. Ventral scales 80–94. Supralabials 6–8. Infralabials 5–6. Third finger lamellae 11–14. Fourth toe lamellae 16–20.

Males Females

(N=7) (N=4) Dorsal background varies between individuals, from finely reticulated to a pattern of transverse bands, but always less well-developed than in Homonota darwinii ; the clear longitudinal vertebral band gets wider and obvious in some specimens. In two specimens the reticulation is finer than in the holotype, so this vertebral band is not noticeable. In four specimens the dorsal white spots are not prominent, probably due to the action of the preservative. In specimens with the most developed transverse bands, the occipital semicircular band is wider and very evident. The venter is white or dark gray and varies with the degree of chromatophore development.

Etymology.—Dedicated to Jorge Daniel Williams, Argentinean herpetologist from the La Plata Museum, Buenos Aires Province. He is in charge of the herpetological collection of the La Plata Museum, and his work is mainly focused on the herpetofauna of Buenos Aires Province. He was one of the founders of the Asociación Herpetólogica Argentina (AHA), president for a decade, and always an enthusiastic advocate.

Comparison with other taxa.—(see Table 1, Figs. 5 , 6 , 7 ). Homonota williamsii sp. nov. differs from H. andicola by its larger size (maximum SVL=48 vs. 38 mm), higher number of dorsal scales (146–161 vs 99–107) and scales around midbody (48–60 vs 45–48), and presence of keeled dorsal scales. It differs from H. borellii by its larger size (maximum SVL=48 vs. 35 mm), higher average number of scales around midbody (53.3 vs 47.8), different shape and size in the subcaudal scales, and in having an oblique and serrate auditory meatus. The new species differs from H. darwinii in its smaller size (maximum SVL=48 vs. 53 mm), keeled dorsal scales, small number of scales around midbody (53.3 vs 56.9), larger dorsal scale count (146-161 vs 101-136), and different shape and size in subcaudal scales. Homonota williamsii sp. nov. differs from H. fasciata because its smaller size (maximum SVL=48 vs. 56 mm), higher average number of scales around midbody (53.3 vs 50.8), higher number of dorsal scales (146–161 vs 90–106) and a very different coloration pattern. Homonota williamsii sp. nov. differs from H. rupicola by its larger size (maximum SVL=48 vs. 36 mm), shape and size of its auditory meatus and different color pattern. It differs from H. underwoodi in its smaller size (maximum SVL=48 vs. 54 mm), presence of ventral chromatophores, keeled dorsal scales, smaller average number of scales around midbody (53.3 vs 56.5), higher average number of dorsal scales (153.2 vs 147.2), and lighter coloration. Homonota williamsii sp. nov. differs from H. uruguayensis by its larger size (maximum SVL=48 vs. 43 mm), higher average number of scales around midbody (53.3 vs 51.6), higher average number of dorsal scales (153.2 vs 148.1) and different color pattern. Finally, the new species differs from H. whitii by it larger size (maximum SVL = 48 mm vs. 40 mm); presence of keeled dorsal scales; and fewer dorsal scales at midbody (146-161 vs. 105-111).

Geographic distribution. — Homonota williamsii sp. nov. was collected only in rocky outcrops from an elevation of 454 to 915 m in the Ventania System, Buenos Aires Province, Argentina ( Figs. 8 , 9 ). Its distribution probably extends to other neighboring mountain systems such as the Tandilia system where other Homonota populations assigned to Homonota borellii have been cited ( Vega & Bellagamba 1990; Williams 1991).

Natural history.—Little information is available about natural history and biology of this new species. Homonota williamsii sp. nov. was always found under stones and crevices in rocky outcrops above 400 m ( Fig. 9 ), usually surrounded by mountain grassland, characteristic of the Pampeano Austral Phytogeographic District. This system includes grass species such as Briza subaristata , Piptochaetium napostaense , Poa bonariensis , and several endemic species of grasses and shrubs as Festuca ventanicola , Stipa pampeana , S. ventanicola , Plantago bismarkii , Senecio ventanicola and Grindelia ventanensis ( Cabrera 1971; Frangi & Bottino 1995). Homonota williamsii sp. nov. is sympatric with an endemic lizard, Pristidactylus casuhatiensis , and others lizard species such as Cnemidophorus lacertoides , Cercosaura schreibersii , Anops kingii , Tupinambis merianae , and Ophiodes vertebralis , as well as the amphisbaenid Amphisbaena darwinii . Homonota williamsii sp. nov. shares the general habitat with several species of amphibians and snakes, some of them endemic to the sierras. Among the amphibians we observed Melanophryniscus sp., an endemic undescribed taxon, and Hypsiboas pulchellus . Snakes observed in the area were Oxyrhopus rhombifer , Philodryas agassizi , P. patagoniensis , Clelia rustica , Xenodon dorbigni , Rhinocerophis alternatus and Liophis elegantissimus (an endemic taxon), all potential predators of Homonota williamsii . The new species usually occupies the microhabitat in the rocky outcrops, while the other species were found in rocky patches or open substrate. No data about reproduction, diet or other biological characteristics are available, but as in other related species of Homonota , H. williamsii sp. nov. is probably oviparous and feeds on arthropods.

Remarks.—Ventania and Tandilia are the only two mountain ranges located in the grassy steppe called “pampas” in Argentina. Both systems are known to have a particular diversity of taxa, with high levels of endemism, and this particular characteristic has led to the consideration that these areas have functioned as “orographic islands” ( Crisci et al. 2001; Kristensen & Frangi 1995). The Ventania range is a discontinuous chain of mountains, hillocks and mounds named Sierras de Puan, Pigüe, Bravard, Curamalal, La Ventana, Las Tunas and Pillahuinco ( Fig. 8 ). It is completely unconnected with other mountain ranges, and was originally surrounded by grasslands belonging to the Pampa Phytogeographic Province, Pampeano Austral District on the north, and an ecotone of three phytogeographic provinces: Pampa, Espinal and Monte scrublands to the south ( Cabrera 1971; Frangi & Bottino 1995). It is the most important outcrop on the South American Plate of what formerly was a continuous basin fringing the south-western margin of Gondwana during Palaeozoic times. The highest peak in this system reaches 1,239 m above sea level and the system extends about 180 km from NW to SE, with a width of 50–70 km in its central part. A number of endemic species of plants and other animals have been described from this mountain system ( Frangi & Bottino 1995). Several endemic lizard species are known from these highland islands (Ventania and Tandilia), including Pristidactylus casuhatiensis from the Ventania range and Liolaemus tandiliensis from the Tandilia mountain range, 145 km to the East. Land use for agriculture (mainly soy and maize crops) and cattle grazing in the last 120 years has almost completely destroyed the natural environments surrounding these ranges, reinforcing their character as biogeographic islands. Only rocky areas escape from agricultural activities but not from cattle grazing, stone exploitation, and pine plantation; additionally, feral horses and exotic deer and goats introduced for hunting activities survive in some areas. At this time we cannot analyze the conservation status of this new species, but the type locality is protected by a provincial conservation unit.

Homonota darwinii was described by Boulenger in 1885 for Puerto Deseado, Santa Cruz Province, and is distributed over a wide range from the province of Mendoza to Santa Cruz throughout the Patagonian phytogeographic province. In the original description, Boulenger (1885) identified Eastern Patagonia, Buenos Aires and Uruguay as likely parts of the natural distribution of Homonota darwinii . Koslowsky (1898) identified Homonota darwinii for the provinces of Chubut and Santa Cruz in Patagonia, in Sierras de la Ventana, Tandil and Balcarce in the eastern part of Buenos Aires Province and in the easter Republic of Uruguay, near Montevideo. Gallardo (1966) based on the dorsal keeled scales, rostral crease or posterior groove, scale and color of the ventral region, regarded Homonota darwinii of the Sierras de la Ventana, Balcarce and Tandil as Homonota borellii . Since these studies, no comprehensive studies of species limits in Homonota have been carried out, but several studies have focused on the study of phylogenetic affinities of described species ( Abdala 1992a, b, 1997, 1998; Abdala & Moro 1996). This work, with a detailed morphological comparison between populations of H. darwinii from Southern Argentina and this isolated population in Ventania, reveals its diagnosibility as a new species, and molecular data (mitochondrial and nuclear genes) indicates its closer phylogenetic relationship with H. darwinii than with H. borellii (Morando et al. unpublished data).

Figures

FIGURE 1. Species of Homonota from Argentina: (A) Homonota underwoodi, (B) H. whitii, (C) H. fasciata, (D) H. andicola, (E) H. borellii, (F) H. darwinii.

FIGURE 3. Homonota williamsii sp. nov., adult from Sierra de la Ventana, Tornquist Department, Buenos Aires province, Argentina. (not the holotype).

FIGURE 4. Homonota williamsii sp. nov., holotype adult male in dorsal and ventral view (MLP. S 2630), from Sierra de la Ventana, Tornquist Department, Buenos Aires province, Argentina.

FIGURE 5. Midbody dorsal scales of: (A) Homonota williamsii sp. nov. (MLP. S 2630), moderately keeled series along the dorsum; (B) H. darwinii (LJAMM-CNP 9789), smooth scales series.

FIGURE 6. Subcaudal scales of: (A) Homonota williamsii sp. nov. (MLP. S 2630), enlarged, rounded and rectangular longitudinally elongated; (B) H. borellii (LJAMM-CNP 14378), enlarged, elongated and transversely rectangular; (C) H. darwinii (LJAMM-CNP 9789), enlarged, rhombic and scalloped.

FIGURE 7. Meatus auditory on: (A) Homonota williamsii sp. nov. (MLP. S 2630), large, oval, oblique and serrated; (B) H. borellii (LJAMM-CNP 14378), round, small and not serrated.

FIGURE 8. Map of southern Buenos Aires region showing the complex landscape of the Ventania mountain range. The black circle marks the Homonota williamsii sp. nov. type locality and white circles paratype localities. Main mountain ranges, rivers, and roads are marked. Gray circles: cities. Inset: Region in South America.

FIGURE 9. Type locality of Homonota williamsii sp. nov.. Above: general view of the area. Below: close view of the common outcrops where lizards were collected.

Tables

TABLE 5. Morphometric and meristic variation in Homonota williamsii sp. nov. type series. Means and standard deviations (SD) of the main morphometric and meristic characters. Measures in mm and scales in numbers. Abbreviations: SVL, snouth-vent length; TrL, trunk length; HL, head length; HW, head width; HH, head height; FL, foot length; TL, tibial length; AL, arm length; SAM, scales around midbody; DS, dorsal scales; VS, ventral scales; 4 TL, fourth toe lamellae; SL, supralabial scales; IF, infralabial scales.

	Mean	SD	Range	Mean	SD	Range
SVL	41.9	2.9	38.4–46.6	42.0	6.9	33.3–48.1
TrL	19.5	1.2	18.6–22.0	20.8	3.8	17.4–24.9
HL	6.8	0.4	6.4–7.7	6.7	0.9	5.2–7.3
HW	7.4	0.8	6.7–8.9	7.7	1.3	6.3–9.0
HH	4.7	0.4	4.1–5.5	4.6	0.7	3.6–5.3
FL	8.4	0.9	7.2–9.7	8.6	1.1	7.7–9.9
TL AL	6.5 10.2	0.7 0.6	5.5–7.8 9.3–11.0	6.5 10.2	0.9 1.6	5.6–7.5 8.4–11.7
SAM DS	54.7 152.5	2.9 5.5	51–60 146–161	51.0 154.5	2.5 5.8	48–54 146–159
VS	88.7	4.8	80–94	89.7	1.7	88–92
4TL	17.8	1.4	16–20	18.0	0.8	17–19
SL IF	7.1 5.4	0.6 0.5	6–8 5–6	7.2 5.5	0.5 0.5	7–8 5–6