Liolaemus absconditus, Vega & Quinteros & Stellatelli & Bellagamba & Block & Madrid, 2018

Vega, Laura Estela, Quinteros, Andrés Sebastián, Stellatelli, Oscar Aníbal, Bellagamba, Patricio Juan, Block, Carolina & Madrid, Enrique Alberto, 2018, A new species of the Liolaemus alticolor - bibronii group (Iguania: Liolaemidae) from East-central Argentina, Zootaxa 4379 (4), pp. 539-555 : 544-549

Species Account. Liolaemus absconditus sp. nov.

( Fig. 2 )

1990. Liolaemus sp., Vega L. & Bellagamba P., Cuadernos de Herpetología, 5, 10–14.

Holotype. UNMdP 1817 . Male. ( Fig. 3 ) Estancia Paititi. Sierra de la Peregrina. Partido de General Pueyrredón. (37° 55´40.74´´ S; 57° 49´05.84´´ W). Buenos Aires Province. Argentina. 22 May 2013. Stellatelli, O., Block, C. & Isacch, J.P. cols.

Paratypes. UNMdP 0 565. Sierra de los Padres (37° 56´30.74´´ S; 57° 48´05.15´´ W), Partido de General Pueyrredón , Buenos Aires Province, Argentina . 0 1 July 1985; Vega, L. & Bellagamba P. cols. UNMdP 0 566. Sierra de los Padres (37° 56´30.74´´ S; 57° 48´05.15´´ W), Partido de General Pueyrredón , Buenos Aires Province, Argentina . 0 2 November 1986; Vega, L. & Bellagamba, P. cols. UNMdP 1782, IBIGEO-R 5459 (ex UNMdP 1783). Sierra La Brava (37° 53´53.15´´ S; 58° 00´01.70´´ W), Partido de Balcarce, Buenos Aires Province, Argentina . May 2009; Larrubia, L. & Stellatelli, O. cols. UNMdP 1817. Estancia Paititi (37° 55´40.74´´ S; 57° 49´05.84´´ W), Sierra de La Peregrina, Partido de General Pueyrredón. Buenos Aires Province. Argentina . 22 May 2013; Stellatelli, O., Block, C. & Isacch, J.P. cols. UNMdP 1818. Estancia Paititi (37° 55´04.10´´ S; 57° 49´15.73´´ W), Sierra de La Peregrina, Partido de General Pueyrredón , Buenos Aires Province, Argentina . 0 8 June 2013; Stellatelli, O. col. UNMdP 1823. Estancia Paititi. (37° 55ʹ 35.40ʹʹ S; 57° 49ʹ 09.20ʹʹ W). Sierra de la Peregrina, Partido de General Pueyrredón , Buenos Aires Province , Argentina. 0 5 May 2013; Stellatelli, O. & Rocca, C. cols. UNMdP 1824. Estancia Paititi. (37° 55ʹ 35.40ʹʹ S; 57° 49ʹ 09.20ʹʹ W), Sierra de la Peregrina, Partido de General Pueyrredón , Buenos Aires Province , Argentina. 0 5 May 2013; Stellatelli, O. col. UNMdP 1825. Sierra La Vigilancia (37° 52ʹ 00.01ʹʹ S; 58° 01ʹ 24.90ʹʹ W), Partido de Balcarce, Buenos Aires Province , Argentina. 23 March 2014; Stellatelli, O. & Rocca, C. cols. UNMdP 1826–27. Sierra de los Difuntos (37°53ʹ19.53ʹʹ S; 57°50ʹ21.23ʹʹ W), Partido de Gral Pueyrredón , Buenos Aires Province , Argentina. 30 March 2014; Bellagamba, P., Vega, L., Stellatelli, O. & Block, C. cols. IBIGEO-R 5460 (ex UNMdP 1830). Sierra de los Difuntos (37° 53ʹ 21.38ʹʹ S; 57° 50ʹ 27.64ʹʹ W). Partido de General Pueyrredón , Buenos Aires Province , Argentina. 0 5 March 2015; Stellatelli, O. & Villalba, A. cols.

Diagnosis. Liolaemus absconditus sp. nov. is a small (Max SVL 58.3 mm), slender species member of the L. alticolor - bibronii group. It is a member of the L. alticolor - bibronii group because exhibits the character states proposed by Quinteros (2012, 2013) for this group. As a member of this group, L. absconditus sp. nov. differs in color pattern from the species members of L. belli , L. chillanensis , L. elongatus , L. kriegi , L. leopardinus , L. monticola , L. nigromaculatus , and L. pictus groups. Some of the members of the L. gravenhorsti and L. robertmertensi groups show a similar color pattern, but those species differ from those of the L. alticolor-bibronii group in the maximum SVL (65 mm in those two groups, and, 60 mm in L. alticolor-bibronii group). The members of the L. alticolor - bibronii group also have well-devolved neck folds, which are absent in some species of the L. robertmertensi and L. gravenhorsti groups. L. absconditus sp. nov. is phenetically and geographically close to L. tandiliensis and L. gracilis . But the new species exhibits a combination of character states which distinguish it from these and from all other species of the group.

Specimens of L. absconditus sp. nov. show dorsal scales with an evident mucron, whereas the mucron is absent in dorsal scales of L. tandiliensis . Temporal scales of L. absconditus sp. nov. are slightly keeled whereas in L. gracilis are smooth. Besides, temporal scales in the new species are in less number than in L. tandiliensis ( Table 1). Neck scales of L. absconditus sp. nov. are laminar and keeled, distinguishing from laminar and smooth neck scales of L. gracilis . Neck scales in a L. absconditus sp. nov. are in less number than in L. tandiliensis and L. gracilis as well ( Table 1). Subocular scale is whitish (lighter than loreal region) in L. tandiliensis , whereas in. L. absconditus sp. nov. and L. gracilis the subocular scale shows the same color than loreal region. Paravertebral spots are evident in L. tandiliensis , but absent in L. gracilis and in the new species. In L. absconditus sp. nov., dorsolateral stripes are absent or barely visible without black border, being evident in L. tandiliensis , and evident, bordered in black, and wider in L. gracilis . Vertebral line is absent in L. absconditus sp. nov. distinguishing from L. gracilis (evident and segmented) and from L. tandiliensis (evident in some specimens). Vertebral line in dorsal surface of the tail is evident in L. gracilis and L. tandiliensis , but absent in L. absconditus sp. nov. Throats of L. tandiliensis and L. absconditus sp. nov. are immaculate (spotless), differing from males of L. gracilis (black lines in throat).

Dorsal scales of L. absconditus sp. nov. show an evident mucron, differing from L. alticolor , L. chavin , L. pachacutec , L. paulinae , and L. tacnae (without mucron). Upper temporal scales are slightly keeled in L. absconditus sp. nov., being smooth in L. bibronii , L. paulinae , L. pachacutec , L. puna , L. tacnae , and L. walkeri ; and markedly keeled in L. alticolor , L. aparicioi , L. bitaeniatus , L. cyaneinotatus , L. lemniscatus , L. sanjuanensis , L. saxatilis , and L. variegatus . Scales of neck are laminar and keeled in L. absconditus sp. nov., distinguishing from L. bibronii , L. exploratorum , and L. yalguaraz (laminar and smooth), from L. abdalai , L. curicensis , and L. puna (some scales are keeled), from L. alticolor and L. yanalcu (laminar and weakly keeled), and from L. chungara (which exhibits both granular and laminar scales). Subocular scale is whitish (lighter than loreal region) in L. alticolor , L. bibronii , L. bitaeniatus , L. pagaburoi , L. ramirezae , L. variegatus , and L. walkeri , whereas L. absconditus sp. nov. exhibits the same color than loreal region. Dorsal surface of the head is smooth in L. absconditus sp. nov., being slightly rough in L. exploratorum and L. pagaburoi and markedly rough in L. bitaeniatus , L. lemniscatus , L. saxatilis , L. tacnae , and L. variegatus . In L. absconditus sp. nov. there are two scales between canthal and nasal, being one scale in L. alticolor , L. bibronii , L. bitaeniatus , L. chaltin , L. fuscus , L. incaicus , L. lemniscatus , L. pagaburoi , L. paulinae , L. puna , L. pyriphlogos , L. ramirezae , L. tacnae , L. variegatus , L. walkeri , and L. yalguaraz . Lack of precloacal pores in females distinguishes the new taxon from L. aparicioi , L. bitaeniatus , L. incaicus , L. ramirezae , L. variegatus , and L. yanalcu (females exhibit precloacal pores). The absence of paravertebral markings, distinguishes the new taxon from L. abdalai , L. bibronii , L. exploratorum , L.

incaicus , L. lemniscatus , L. pagaburoi , L. robertmertensi , L. sanjuanensis , L. saxatilis , and L. variegatus . Vertebral line is absent in L. absconditus sp. nov. differing from L. alticolor , L. aparicioi , L. bibronii , L. chavin , L. curicencis , L. cyaneinotatus , L. gracilis , males of L. incaicus , L. pachacutec , females of L. puna , L. pyriphlogos , L. sanjuanensis , L. tacnae , L. variegatus , L. walkeri , and L. wari . Throat of the new species is immaculate, differing from L. alticolor , L. chungara , L. pagaburoi , L. puna , L. pyriphlogos , L. variegatus , L. walkeri , and L. yalguaraz . Males of L. chavin , L. pachacutec , L. wari , and L. walkeri exhibit partial or total ventral melanism, which is absent in L. absconditus sp. nov.

Description of the holotype. Adult male. Snout-vent length (SVL) 50.1 mm; Axilla-groin distance 20.8 mm. Head 11.5 mm long (from anterior border of auditory meatus to tip of snout), 8.8 mm wide (at anterior border of auditory meatus), 6.1 mm high. Interorbital distance (between postorbital semicircles) 5.9 mm. Eye-nostril distance 4.4 mm. Tibia length 8.3 mm. Foot length 6.4 mm (from ankle to tip of claw on fourth toe). Tail length 96.3 mm. Dorsal head scales smooth between rostral and anterior border of auditory meatus. Seven temporals, uppers slightly keeled. Interparietal subpentagonal, smaller than parietal, surrounded by five scales. Frontal azygous. Six scales between frontal and rostrals, five between frontal and supercilliaries. Two postrostrals with seven (left) and five (right) scale organs each. Supraorbital semicircles incomplete. Five supraoculars, three of them enlarged. Six supercilliaries flat, elongate, imbricate. Canthal separated from nasal by two scales. Loreal region flat. Six scales, including rostral, surrounding nasals. Nasals in broad contact with rostral. Six lorilabials, lorilabials 4–6 contacting subocular. Six enlarged supralabials; supralabial 4 curved dorsal posteriorly, not contacting subocular. Four infralabials, slightly taller than supralabials. Orbit with 13 upper and 11 lower ciliaries. Subocular scale elongate, 3.6 mm long. Preocular unfragmented, 0.8 mm long. Postocular length 1.6 mm. Longitudinal ridge along upper margin of the three ocular scales. Rostral scale 3.1 times wider (2.8 mm) than high (0.9 mm). Mental 1.8 times wider (2.5 mm) than high (1.4 mm), followed posteriorly by two rows of four chinshields. Two scales in contact with second infralabial ventrally. Scales of throat between chinshields sub-imbricate. Twenty-nine gulars, between both auditory meatuses. Auricular scale evident, four (one enlarged) outward projecting laminar scales along anterior border of auditory meatus. Auditory meatus higher (2.3 mm) than wide (0.6 mm). Scales of neck laminar and keeled. Antehumeral fold distinct. Nineteen scales on neck (between posterior margin of auditory meatus and shoulder). Forty-one dorsal scales between occiput and anterior surface of thighs. Dorsal body scales lanceolate, imbricate, keeled, and with evident mucron. Forty-four scales around midbody. Seventy-three ventrals between mental and precloacal pores row. Four precloacal pores. Fourth finger with 22 subdigital lamellae. Fourth toe with 24 subdigital lamellae.

Color of the holotype in ethanol. Dorsal background color uniform brown. Paravertebral spots, and vertebral line absent. Dorsolateral stripes faded, barely visible. Lateral field slightly darker than dorsum. Ventrolateral region lighter than dorsum. Ventrolateral line absent. Dorsal and lateral region of head same color as dorsum. Granular scales of eye, light gray. Mental, and first lorilabial scales (left and right) gray (owing to fixation). Temporal and neck region same color as dorsum. Region below auditory meatus gray. Subocular scale same color than loreal region. Fore and hind limbs same color as dorsum. Tail, dorsally same color as dorsum, without vertebral line. Throat, chest, and belly gray. Throat darker than chest and belly. Ventral scales with tiny black spots. Femoral regions cream-colored. Cloacal region gray. Tail ventrally light brown.

Variation. Based on eleven paratypes (six females and five males). Snout-vent length 32.7–58.3 mm (X = 46.5 ± 11.1) in males and 26.3–49.5 (X = 41.3 ± 11.4) in females; Axilla-groin distance 15.4–29.8 mm (X = 22.0 ± 6.1) in males and 13.2–28.6 mm (X = 20.0 ± 6.5) in females; Head length 8.2–14.0 mm (X = 10.8 ± 2.5) in males and 10.2–11.2 mm (X = 9.6 ± 1.4) in females; Head width 5.8–10.0 mm (X = 7.9 ± 1.7) in males and 5.0– 8.7 mm (X = 6.9 ± 1.4) in females; Head height 4.1–6.8 mm (X = 5.5 ± 1.1) in males and 3.3–5.9 mm (X = 4.8 ± 1.0) in females; Foot length 10.5–17.4 mm (X = 14.3 ± 2.5) in males and 9.8–14.7 mm (X = 13.1 ± 2.9) in females; Tail length 63.0–113.0 mm (X = 80.4 ± 22.3) in males and 51.3–92.9 mm (X =75.2 ±19.7); Midbody scales 39–46 (X = 43.2 ± 2.5); Dorsal scales 40–49 (X = 42.8 ± 2.7) between occiput and anterior surface of thighs; Dorsal head scales 11–14 (X = 12.6 ± 0.7); Ventrals 70–80 (X = 73.3 ± 2.8); Scales around interparietal 5–7 (X = 5.7 ± 0.7); Supraoculars 4– 5, three to four of them enlarged; Preocular not divided, not fused to subocular; Temporals 6–7 (X = 6.8 ± 0.4), upper slightly keeled; Neck scales from posterior edge of auricular meatus to shoulder 19–23 (X = 20.8 ± 1.5), keeled; Gulars 24–30 (X = 27.2 ± 1.9); Supralabials 5–6 (X = 5.7 ± 0.4); Infralabials 4–5 (X = 4.1 ± 0.4); Posterior tip of fourth supralabial upturned, contacting subocular in 50% of specimens; Six to seven (X = 6.7 ± 0.5) scales around nasal; Internasals 4; Scales between rostral and frontal 5–7 (X = 5.7 ± 0.7); Postrostrals 2 with 2–9 scale organs on the left one (X = 6 ± 2.2) and 3–8 on the right one (X = 4.9 ± 1.4); Lorilabials 6–7 (X = 6.2 ± 0.4), 3–4 of them contacting subocular scale; Subdigital lamellae on fourth finger 17–18 (X = 17.2 ± 0.5), on fourth toe 21–26 (X = 23.2 ± 1.5); Precloacal pores 3–5 in males (X = 4.5 ± 1.2), absent in females.

Color in life. Dorsal background color brown to gray. Two light brown dorsolateral stripes are evident. Those begin on posterior margin of auditory meatus and extend to hindlimbs. Paravertebral spots and vertebral line absent. Lateral field darker than dorsum. Ventrolateral line absent. Ventrolateral region brownish gray or light brown. Lateroventral region and ventral surface of hindlimbs and tail bright orange during reproductive season. Dorsal head with same background as dorsum. Lateral head same background as dorsum. Neck same color as lateral field. Fore and hind limbs dorsally same color as dorsum. Tail dorsally same background color as dorsum, without vertebral line. In some specimens, tail can be lighter than dorsum. Throat, chest, and belly, gray spotless. Cloacal region and ventral surface of thighs yellow-orange in males, gray in females. Ventral surface of tail, light brown.

Natural history. In general terms, components of habitat structure of L. absconditus sp. nov. are similar to those of the sympatric Liolaemus tandiliensis , that is, patches of rocks within a mosaic landscape of mountains that rises up at 50–250 m over the plain. The new species is a genuine saxicolous form, whose individuals are moving over nearly flat and also inclined rocky substrates, even though when threatened they may flee to proximal vegetated patches or crevices between rocks. Preferred microhabitats are mainly under the eaves of large quartzite rocks that cover smooth rocky platforms and medium to large rocks at the upper raised area of the range of mountains. Individuals are mainly seen basking in sunny patches of less exposed sites between rocks, rather in the open sunny surfaces of the vertical walls. Two aggressive encounters between adult individuals of L. absconditus sp. nov. and L. tandiliensis were observed, in both occasions initial attacks corresponded to L. tandiliensis obtaining withdrawal of the new species. Individuals of L. absconditus sp. nov. are mostly active from late winter (August) through spring and summer, to early autumn (May), although some may be seen in sunny days of winter. Daily activity starts with basking behavior at approximately 9.00–10.00 h and activity continues to the afternoon (approximately 17.00-18.00 h). Field body temperatures were recorded in seven individuals ranging from 34.2 to 38.2°C, being the mean body temperature of 35.92 °C.

Liolaemus absconditus sp. nov. is probably oviparous like L tandiliensis , L. gracilis , and L. saxatilis . ( Avila et al. 1992; Vega & Bellagamba 2005, Vega et al. 2008), although due to the low sample of females no oviductal eggs were detected, which it might confirm this mode of reproduction. Yolked follicles were registered in a number of 1–2 per ovary, so, based on this number, clutch size might vary between two and four eggs. This species appears to feed on a variety of insects and other small arthropods. Stomach contents (n = 12) showed mainly adult individuals of Coleoptera. External parasites (Acarina) were extracted from five of the twelve specimens collected.

Distribution. L. absconditus sp. nov. is known only from the Tandilia Mountain Range System ( Fig. 4 ). Localities where this species was found included Sierra de los Padres, Sierra de los Difuntos (both in Sierra de la Peregrina of Mar del Plata subsystem), Sierra La Brava and Sierra de la Vigilancia (included in the Balcarce subsystem) The range of the new species could be constant all over the area of Tandilia, but as the extreme NW and the central part of these range was not surveyed yet, we cannot confirm this range.

Etymology. The name absconditus comes from Latin and means hidden, concealed, and secret. This name refers to the secretive and underexposed habits of this lizard.

Figures

FIGURE 2. Color in life of A- a male of Liolaemus absconditus sp. nov. (Photo: Oscar Stellatelli) and B- a female of Liolaemus absconditus sp. nov. (Photo: Carolina Block) in rocky outcrops of Sierra de los Difuntos, Mar del Plata, Buenos Aires, Argentina (37° 53ʹ 19.53ʹʹ S; 57° 50ʹ 21.23ʹʹ W).

FIGURE 3. Holotype (UNMdP 1817) of Liolaemus absconditus sp. nov. Snout-vent length: 50.1 mm. (A) Dorsal view and (B) ventral view.Photos: Carolina Block.

FIGURE 4. Known distribution of Liolaemus absconditus sp. nov. in Buenos Aires province of Argentina.