Teius Merrem

Harvey, Michael B., Ugueto, Gabriel N. & Gutberlet, Ronald L., 2012, 3459, Zootaxa 3459, pp. 1-156 : 131-133

Teius Merrem

Figure 74

Teius Merrem 1820: 60 . Type species Teius viridis Merrem (= Teius teyou ) subsequently designated by Burt and Burt (1933). [Genus spelled Tejus in German text and Teius in parallel Latin text of same publication]

Acrantus Wagler 1830: 154 . Type species Lacerta teyou Daudin.

Diagnosis.— Teius is the only genus of Teiidae with a vestigial fifth toe and a high-walled, circular basin positioned between the hemipenial awns. Dicrodon and Teius are the only other extant Teiidae with bicuspid, transversely oriented teeth on the posterior maxilla and mandible.

Content.— Teius oculatus (d’Orbignyi & Bibron) , Teius suquiensis Avila and Martori , and Teius teyou (Daudin) .

Definition.—Medium lizards reaching 144 mm SVL; tail about 2.2–2.4X as long as body ( Table 12); posterior maxillary and dentary teeth transversely compressed, bicuspid; pupil reniform.

Prefrontal in contact with nasal, usually separated from first supraciliary; frontal usually entire, with longitudinal ridge, its posterior suture contacting third supraocular or, rarely, suture between second and third supraoculars; scales of frontoparietal region smooth, outwardly convex to flat (key-hole shaped depression absent); frontoparietals paired; parietals short, arrayed in oblique rows and separated by small scales ( Teius teyou ) or consisting of three regular scales ( T. oculatus ); interparietal entire; medial pair of enlarged occipitals absent; occipitals 13–15 ( T. oculatus ; character not applicable to T. teyou ), usually larger than first row of dorsals; supratemporals slightly to moderately enlarged, separated from parietals by several rows of small granular scales.

Rostral groove absent (faint indication of groove in some Teius teyou ); nostril oval and oriented anteroventrally, positioned anterior to and not touching nasal suture; loreal single; supraoculars usually eight; first supraocular entire, larger than fourth supraocular, separated from second by complete row of small scales; circumorbital semicircles consisting of 26–35 small scales, extending to posterior border of first supraocular; supraciliaries 12–14, subequal in size, separated from supraoculars by 1.5–2.5 rows of 44–100 granular scales; first supraciliary separated from ( T. teyou ) or usually in contact with ( T. oculatus ) first supraocular; angulate keel extending from first subocular to elongate subocular below eye; suboculars four; first subocular usually separated from supralabials by scale inserted between suboculars and loreal; patch of slightly to distinctly enlarged scales in front of auditory meatus; auricular flap and preauricular fold absent.

Supralabials 13–17; first supralabial smaller than ( Teius teyou ) or subequal to ( T. oculatus ) second, its ventral margin curved to “toothy”; infralabials 12–15; first pair of chinshields broadly contacting infralabials, forming medial suture of variable length; interangular sulcus absent; anterior gulars 19–34; gular patch absent; posterior gulars 8–18; intertympanic sulcus absent; larger anterior gulars undergoing sharp transition to smaller posterior gulars at intertympanic crease; mesoptychials moderately enlarged; gular fold lacking serrated edge.

Dorsals smooth; scales on flank subequal to middorsals, supported by moderate apical granules; scales on rump much smaller than proximal subcaudals; scales of chest large and flat; pectoral sulcus absent; ventrals smooth, in 32–35 transverse and eight ( T. teyou ) or ten ( T. oculatus ) longitudinal rows; lateral-most ventrals flanked by small scales (i.e., ventrals not gradually decreasing in size on flanks); preanals 4–5; preanal plate present, bordered by subtriangular scales; preanals one-half as large to larger than scale anterior to them; preanal spurs, postcloacal buttons, and postanal plates absent; scales on dorsolateral edge of tail like those on top and sides, denticulate edge and dorsolateral crests absent; caudal annuli complete; proximal subcaudals keeled ( T. teyou ) or smooth ( T. oculatus ).

Enlarged scales of brachium connected by continuous band of small subtriangular scales on dorsal surface of arm; preaxial brachial scales usually 1.5–2X as wide as long, extending proximally to or beyond center of arm; postaxial brachial scales 1–1.5X as wide as long, restricted to small patch near elbow; antebrachial scales enlarged and smooth, narrowly separated from or in continuous row with preaxial brachial scales; postaxial antebrachial scales granular; subdigital lamellae of hand homogeneous in size, 13–17 under fourth finger.

Prefemorals 6–11; femoral and abdominal pores 30–48, in continuous row on each side (abdominal pores not separated from femoral pores by gap); each compound pore-bearing scale consisting of partially fused prefemoral or abdominal scale and 2–6 granular scales; 2–4 scales separating right and left pore rows; scales at heel relatively small and numerous; tibiotarsal shields and spurs absent; lamellae under fourth toe 27–40; distal lamellae of fourth toe smooth; continuous low serrate row of scales separating subdigital and supradigital lamellae along postaxial edge of each toe; noticeably enlarged postaxial scales between fourth and fifth toe absent; fifth toe vestigial, reduced to small nub.

β- keratin containing layers of dorsal scales folded into macrohoneycomb; dorsal and caudal scales with one subterminal lenticular scale organ; ventrals lacking scale organs; generation glands present.

Snout same color as dorsal head scales. In juveniles, light vertebral stripe absent; light paravertebral stripes absent ( Teius oculatus , T. suquiensis ) or present and solid, although tending to fade anteriorly ( T. teyou ); dark dorsolateral field completely broken into blotches, although partially solid in some specimens of T. teyou ; dorsolateral light stripe solid, extending to tail; dark lateral field completely broken into blotches; upper lateral light stripes mostly solid (usually breaking into spots near insertion of forelimb), extending to groin; lower lateral light stripe absent; thigh lacking light spots. In adult males, flanks lacking light spots ( T. oculatus ), or with light blotches ( T. teyou ); turquoise ventrolateral spots present; venter immaculate, lacking melanic areas; juvenile dorsal color pattern present in adult males with only slight ( T. oculatus , T. suquiensis ) to moderate ( T. teyou ) modification. Hemipenis with pair of taβ- like and smooth apical awns; apical papillae absent; circular apical basin located between awns; asulcate expansion pleat well-developed, interrupting about 13 distal laminae; discontinuous distal laminae absent; no laminae proximal to expansion pleat; basal papillae absent.

Remarks.— In many collections, specimens of Teius oculatus are frequently misidentified. Recent keys (e.g., Cei 1993; Peters & Donoso-Barros 1970) and reviews (e.g., Avila & Martori 1991) are not very helpful for identifying these lizards. Available descriptions of the unisexual species T. suquiensis are so incomplete, that we had little option but to ignore this species in our generic account. Nonetheless, the bisexual species are remarkably different from one another. Unlike T. oculatus (characters in parentheses), T. teyou has parietals arrayed in oblique rows and separated by small scales (three regular parietals), ten longitudinal ventral rows (eight), and keeled proximal subcaudals (smooth). The habitus of these species is strikingly different. Teius oculatus is much shorter and more robust than T. teyou . The rostral frequently contacts the prefrontal in T. oculatus ; we have not observed this trait in T. teyou .