Trigonodactylus persicus, Nаzаrov & Melnikov & Rаdjаbizаdeh & Poyаrkov, 2018

Nаzаrov, Romаn А., Melnikov, Dаniel А., Rаdjаbizаdeh, Mehdi & Poyаrkov, Nikolаy А., 2018, A new species of short-fingered geckos Stenodactylus (Squamata, Geckonidae) from South Iran with taxonomic notes on validity of the genus Trigonodactylus Hass, 1957, Zootaxa 4457 (1), pp. 93-113 : 100-105

Trigonodactylus persicus sp. nov.

( Fig. 3 ; 4c ; 5a .)

Holotype: Аdult male ZMMU R-14668: Iran, Khuzestan province, 100 km northwest of Аhvaz , 27°24' N 56°57' E; altitude 77 m a. s. l., June 22, 2011, coll. Daniel А. Melnikov, Roman А. Nazarov and Khosrow Rajabizadeh ( Fig. 3a ).

Paratypes: ZMMU R-14669, R-15160, R-15161, R-15162; ZISP-29581, 29582, 29583; ICSTZ-M6 H1293, M6H1294, M6H1295; with the same data as a holotype . Measurements of holotype and type series are presented in Table 3.

Diagnosis: Small sized geckos, maximum SVL 34 mm; SVL/TailL approximately 1:1. Dorsal surface covered with small homogenous granular scales. Ventral scales rounded, weakly keeled ( Fig. 3b ), 54–61 longitudinal rows at midbody (V), 190–225 scales along midbody (SLB), 88–97 scales around midbody (SАB). Nostrils surrounded by convex scales. No enlarged postmentals. Fingers and toes weakly flattened dorsoventrally, lateral edge of digits fringed by series of projecting triangular scales. No web between digits. Usually, three median lamellae present only on distal part of digits ( Fig. 3c ); no precloacal or femoral pores.

Main dorsal background color is cream with beige shade. Dark ^- shaped stripe on dorsal surface of rostral part of snout, which passes through eye above ear opening and continues on side of body. Labials white, in some cases, with grey-brown dots. Patterns on dorsum formed by dark thin irregular vermicular patches, spots, and lines. Sometimes these dark dorsal patterns blend with each other and form transverse bands. There is a dark longitudinal narrow stripe between forelimbs and hindlimbs on sides of body. Dorsal surfaces of limbs and digits with irregular dark bands. Dorsal surface of tail with 8–10 dark-brown wide bands with irregular margins, same size as light bands with which they alternate. Ventral surface of body and limbs white. Ventral surface of tail with dark spots that become more distinct posteriorly.

Description of Holotype: Аdult male, small-sized (SVL 28.7 mm, TailL 29.0 mm), HeadL 8.2 mm, HeadW 4.8 mm, HeadH 3.2 mm, SnEye 2.8 mm, OrbD 1.8 mm, EarL 0.8 mm, EyeEar 2.0 mm. Proportions as follows: SVL/ HeadL 3.5, HeadL/ HeadW 1.7, HeadL/ HeadH 2.56, SnEye/ EyeEar 1.4, HeadL/ OrbD 4.5.

Rostral width greater than height (RW 1.1 mm, RH 0.5 mm, RW/ RH 2.2) with a median groove which divides rostral at two thirds of its length; supralabials 13/13; small scales between orbit and tenth supralabial 2/1; infralabials 10/10; nares surrounded anteriorly by rostral, laterally by first supralabial, posteriorly by supranasal and two nasals; supranasals not enlarged—same size as nasals, rostral about 7 – 8 times larger than supranasal; supranasals separated from each other by 3 intersupranasals (three times smaller than supranasals); snout scales that lie medially large, granular, scales that lie laterally flattened, about 1.5 – 2 times smaller than medial ones; head scales large, granular, same size as median snout scales; mental rectangular with undulating posterior edge, slightly wider than rostral (MW 1.3mm; MH 0.9 mm, MW/ MH 1.4) ( Fig. 4m ); no enlarged postmentals; dorsal scales granular, same size as ventral scales; no enlarged dorsal tubercles; ventral scales weakly keeled, 61 longitudinal rows at midbody; lateral folds not developed; dorsal surfaces of forelimbs and hindlimbs covered with weakly keeled granular scales; fingers and toes without webbing, median lamellae present only on distal surface of digits, four under fourth finger, two under fourth toe; no enlarged precloacal and femoral scales and pores; three pairs of enlarged postcloacal spurs; tail without whorls or segments, dorsally covered with flattened and rounded weakly keeled scales; subcaudals without enlarged plate row, flat, weakly keeled, imbricate, same size as dorsal scales on tail.

Coloration: Main background color of body cream with beige shade. Dark ^- shaped band located on dorsal surface of rostral part of head, which passes through eye and above ear opening. Horseshoe-shaped thin dark line, few roundish dark brown patches at occipital region; dark brown transverse stripe on frontal between anterior margins of eyes. Labials white, with grey-brown dots. Dorsum patterns formed by dark thin irregular vermicular patches spots and lines. There is a dark, narrow, longitudinal line between forelimbs and hindlimbs on sides of body. Dorsal surfaces of limbs and digits with irregular dark bands. Dorsal surface of tail with nine dark brown wide bands with irregular margins, same size as the light bands with which they alternate ( Fig. 5a ). Ventral surface of body and limbs white. Ventral surface of tail with dark spots that become more distinct posteriorly.

Variation of paratypes: Table 3 shows variation of type specimens. Dorsal surface pattern is somewhat variable. Sexual dimorphism weakly developed, males smaller than females (SVL max 31 mm versus 34 mm) and males have better developed postcloacal spurs.

Comparisons: Trigonodactylus persicus sp. nov. is closely related to T. arabicus Hass,1957 and can be distinguished by the shape of forelimbs and hindlimbs. The new species does not have any webbing between the fingers and toes, but T. arabicus has well-developed webs ( Fig.6a ). Moreover, T. arabicus has very large eyes: Its HeadL/OrbD ratio is 3.65, while this value for the new speicies is 4.35. The shape of the mental can be used as an additional character distinguish the new species from T. arabicus . Trigonodactylus persicus sp. nov. has a relatively wider and deeper mental plate than T. arabicus ( Fig.4 ).

Trigonodactylus persicus sp. nov. differs from the recently described Trigonodactylus [ Stenodactylus ] sharqiyahensis by the form of the digits. The new species has more elongated, thinner fingers, and there is no webbing between them. The dorsal patterns specific for T. sharqiyahensis , which comprise longitudinal dark bands, can also be used to distinguish this species from T. persicus sp. nov. (dorsal patterns consist of small separate irregular spots and dots). The posterior edge of the mental plate in the new species is undulating, whereas in T. sharqiyahensis it has a roundish posterior edge ( Fig. 4 ).

Discriminant analysis of 16 morphometric measurements of the three species of the genus Trigonodactylus has shown that the major contributing factors to the diversification of these species are the diameter of the eye (OrbD) and the length of the fourth finger and toe (LD4А, LD4P). А separate comparison of males and females has shown that morphometric differences between females of these species are deeper than in males ( Fig.7 ).

The new species is significantly smaller in size, shape and proportions of the body and the head compared to all Stenodactylus s. s. except one species, S. pulcher ( Fig. 8 ), which has approximately the same size as Trigonodactylus persicus sp. nov. The following characteristics enable us to distinguish S. pulcher from the new species: gular and ventral scales smooth, granular, without keels (versus keeled oval gular and ventral scales in the new species); relatively smaller eyes: HeadL/OrbD is 4.94 (4.35 in the new species); elongated fingers: SVL/ LD4А 14.4 (versus 16.9 in the new species). Detailed diagnostic characteristics of the two genera ( Trigonodactylus and Stenodactylus ) are presented below.

Etymology: The new species was named after the geographic region, where it was found, Persia.

Natural history: Trigonodactylus persicus sp. nov. usually inhabits slopes of sand dunes, where they burrow under the bushes of desert grass.These nocturnal lizards were found just after the sunset and could be seen during the entire night. Their activity decreased after midnight. The following sympatric reptile species were found in the same biotope: Stenodactylus doriae (Blanford) , Scincus mitranus Аnderson , Acanthodactylus schmidti Haas , Eryx jayakari Boulenger , Phrynocephalus ahvazicus Melnikov et al. , Cerastes gasperettii Leviton & Аnderson , Bunopus tuberculatus Blanford , and Trapelus persicus (Blanford) .

Distribution: The new species are known only from the type locality ( Fig.1 ): Iran, Khuzestan Province, 80 km northwest of Аhvaz, 31°44' N, 48°06' E, 30 m a. s. l.

Figures

FIGURE 1. Distribution of the genus Trigonodactylus: circle—Trigonodactylus persicus sp. nov., squares—T. arabicus, diamonds—T. sharqiyahensis, triangles—T. pulcher; red colour denotes type localities of abovementioned species; blue colour—records from previously published data; green colour—our findings.

FIGURE 3. Holotype of Trigonodactylus persicus sp. nov.: (a) specimen in situ; (b) ventral view sowing roundish and keeled ventral scales; (c) thenar surface of fingers showing fringes and few median lamellae on distal edge of digits.

FIGURE 4. Dorsal (upper row), lateral (median row) and mental (lower row) views of heads of all members of the genus Trigonodactylus: T. arabicus holotype CAS 84321 (a; f; k); T. arabicus ZMMU R-14666-1 (b; e; l); Trigonodactylus persicus sp. nov. ZMMUR-14669 (c; h; m); T. sharqiyahensis ZMMU R-14667-1 (d; i; n); T. pulcher holotype BMNH 1946.8.23.38. (e; j; o).

FIGURE 5. Members of the genus Trigonodactylus in situ: a—Trigonodactylus persicus sp. nov.; b—T. sharqiyahensis (Metallinou & Carranza, 2013); c—T. arabicus Hass, 1957.

FIGURE 6. Thenar views of fore- (upper row) and hindlimbs (lower row) of the genus Trigonodactylus representatives: (a; b)—T. arabicus with well-developed webbing between fingers and toes; (c; d)—Trigonodactylus persicus sp. nov. and (e; f)— T. sharqiyahensis without webbing on fingers and toes.

FIGURE 7. Results of discriminant analysis of T. arabicus (diamonds), Trigonodactylus persicus sp. nov. (circles), and T. sharqiyahensis (squares) based on 16 morphometric characters (SVL, TailL, HeadL, HeadW, HeadH, SynEye, OrbD, EarL, EyeEar, TrunkL, LS, ForeaL, FemurL, CrusL, LD4A, LD4P) (a—males; b—females; c—both sexes analyzed together).

FIGURE 8. Holotype of Stenodactylus pulcher Anderson BMNH 1946.8.23.38 in dorsal, ventral and lateral aspects (photo by Patrick Campbell and Stephen Mahony; courtesy of BMNH).