Trapelus mutabilis, (MERREM, 1820)

Wagner, Philipp, Melville, Jane, Wilms, Thomas M. & Schmitz, Andreas, 2011, Opening a box of cryptic taxa - the first review of the North African desert lizards in the Trapelus mutabilis Merrem, 1820 complex (Squamata: Agamidae) with descriptions of new taxa, Zoological Journal of the Linnean Society 163 (3), pp. 884-912 : 893-896

TRAPELUS MUTABILIS ( MERREM, 1820)

1820 Agama mutabilis Merrem, Tent. Syst. Amph. 50. – Terra typica: in Aegypto.

1823 Agama deserti Lichtenstein, Verz. Doubl. Mus. berolin. 101. – Terra typica: Aegyptius.

1833 Agama inermis Reuss, Mus. Senckenberg., Frankfurt am Main 1: 33. – Terra typica: Ober-Ägypten.

1833 Agama gularis Reuss, Mus. Senckenberg., Frankfurt am Main 1: 36. – Terra typica: Ober-Ägypten.

1885 Agama latastii Boulenger, Cat. Liz. Brit. Mus. 1: 344. – Terra typica: Egypt.

1893 Agama aspera Werner, Zool. Anz., Leipzig 16: 359. – Terra typica: Algerische Sahara zwischen Kef-el-Dhor und Chegga; Biskra-Bordj-Saada; Zabel-Zig südlich von El Meranyer.

Neotype: ZFMK 64395 : Egypt, 10 km north-west of Cairo; leg. Hans-Werner Herrmann, ix.1990 ( Fig. 5).

Diagnosis: Trapelus mutabilis is a small [largest voucher from Egypt SVL 90 mm ( Baha el Din, 2006)] species within the genus, possessing irregular dorsal scalation. This species differs from its probable closest relative, T. pallidus , in having a heterogeneous dorsal scalation with rhomboidal and scattered enlarged scales. In contrast, T. pallidus has a matrix of comparatively uniform, smooth dorsal scales, with some scattered larger keeled scales. In addition, T. mutabilis differs from T. pallidus in having homogeneous scalation on the hindlimbs and base of the tail.

Coloration in life is uniformly sandy grey with four to five transverse bands and a barred tail. Male T. mutabilis have nuptial coloration of violet-blue flanks and throat; in contrast male T. pallidus coloration is restricted to having a completely blue head.

Trapelus mutabilis differs from two specimens from Libya in not possessing scale rows of enlarged vertebral scales (for details see description below) .

Trapelus mutabilis differs from T. savignii in having smooth ventral scales and no gular pouch, from T. schmitzi in having heterogeneous dorsal scalation and from T. tournevillei in having a shorter tail (average of ratio TL/SVL 1.39 in T. mutabilis instead of 1.60 in T. tournevillei ), no gular pouch, a heterogenous dorsal scalation, and the lack of longitudinal stripes on the belly.

Description of the neotype: Habitus: stout; tail only moderately longer than the body; hindlimbs relatively long.

Measurements. Snout-vent length 74.2 mm; tail length 90.5 mm; head length 22.3 mm; head height 11.8 mm; head width 18.1 mm; length of left forelimb 33.9 mm; length of left hindlimb 54.5 mm.

Scalation. Nostril sits on the canthus rostralis, piercing the posterior portion of a large, flat nasal scale; nostril is directed obliquely upwards. Head scales heterogeneous in size and shape, supraocular scales smooth, interorbital region with a median row of three longitudinal scales separating the sideward originating scales. Interparietal scale small, more or less rectangular, surrounded by eight enlarged scales; parietal organ visible and half of the size of the parietal scale. A median series of longitudinal and quadrangular scales is visible from the parietal scale to the rostral. Scales originating from both sides of the parietal midline have imbrications directed laterally and the free anterior margins of the scales have sensory pits. Mucronate scales on the eyelids form a ring. The ear openings are small, approximately one third of the diameter of the eye, with the superior margin having six spinous, mucronate scales in two rows on both sides of the ear opening. The tympanum is sunken and not clearly visible. A rudimentary nuchal crest is present, consisting of ten spiny, mucronate scales. Gular scales are smooth, being enlarged and imbricate at the posterior margin, and are slightly smaller on the gular fold. A very weakly defined gular pouch is present. Ventral scales are smooth, slightly imbricate, and equal in size. Dorsal scales are heterogeneous, rhomboidal, smooth to keeled, slightly imbricate; larger scales are keeled and mucronate, being two to three times larger than the other scales and intermixed with smaller scales across the dorsum. Scales on tail are strongly keeled and mucronate, not arranged in whorls. The tail is cylindrical and relatively short – only 22% longer than the snout-vent length. Two rows of 21 (11 anterior, 10 posterior) precloacal pores. Forelimbs have strongly keeled scales on the upper side, becoming smooth on the underside, being homogeneous in size; fourth digit longest, digital length decreasing 4-3-2-5-1, plantar scales and subdigital lamellae (with two keels) strongly keeled. Hindlimbs have keeled scales on the upper side, becoming smooth on the underside, scales on upper side are homogeneous in size, becoming smaller on the underside; digits are long with long claws, fourth digit longest, approximately 25% longer than the third digit, digital length decreasing 4-3-5-2-1, plantar scales and subdigital lamellae (with two keels) strongly keeled. Hindlimbs are relatively long, reaching the eye with the tip of the longest digit. Coloration in alcohol. Uniform dirty white but a blue throat and blue flanks are visible.