Holcosus Cope

Harvey, Michael B., Ugueto, Gabriel N. & Gutberlet, Ronald L., 2012, 3459, Zootaxa 3459, pp. 1-156 : 118-123

Holcosus Cope

Figure 69

Holcosus Cope 1862: 60 . Type species Ameiva septemlineata Duméril designated herein (see remarks).

Diagnosis.— Holcosus could only be confused with species of Ameiva and Aspidoscelis . Unlike Ameiva (characters in parentheses), species of Holcosus have a denticulate dorsolateral row of caudals (dorsolateral caudals like adjacent scales, laterally projecting mucrons absent), subarticular lamellae of hands distinctly enlarged and swollen (homogeneous), two or three large scales at the heel (scales at heel small and numerous), ventrals abruptly transitioning to scales on flanks (gradually decreasing in size in most species), and scales on flank “bristly” due to presence of large apical granules or outwardly projecting scales (not “bristly,” apical granules small). The species of Holcosus also usually have six supraoculars (eight).

Unlike Aspidoscelis , Holcosus has a tongue retractile into a basal sheath (sheath absent), heterogeneous subdigital lamellae (homogeneous, although basal lamellae are enlarged in some species), denticulate dorsolateral row of caudals (dorsolateral caudals like adjacent scales, laterally projecting mucrons absent), and the nasal suture passing through the nostril (nostril anterior to but in contact with nasal suture).

Content.— Holcosus anomalus (Echternacht) new combination, Holcosus bridgesii Cope , Holcosus chaitzami (Stuart) new combination, Holcosus festivus (Lichtenstein & Von Martens) new combination, Holcosus leptophrys (Cope) new combination, Holcosus niceforoi (Dunn) new combination, Holcosus orcesi (Peters) new combination, Holcosus quadrilineatus (Hallowell) new combination, Holcosus septemlineatus (Duméril & Duméril) , Holcosus undulatus (Wiegmann) new combination.

Definition.—Small to medium lizards reaching 88 ( Holcosus quadrilineatus ) to 135 ( H. septemlineatus ) mm SVL; tail about 2.0–2.4X ( Table 13) as long as body; posterior maxillary and dentary teeth longitudinally compressed, tricuspid; pupil reniform.

Prefrontal separated or in contact with nasal and first supraciliary; frontal entire ( Holcosus undulatus Group) or replaced by three or more irregularly keeled scales ( Holcosus orcesi and H. septemlineatus Groups ), lacking longitudinal ridge; when entire, posterior suture of frontal contacting second or third supraocular or suture between them; scales of frontoparietal region smooth, outwardly convex to flat ( H. undulatus and H. orcesi Groups ) or frontoparietals, parietals, and occipitals heavily fractured into irregular keeled scales (small irregular interparietal present in some specimens); key-hole shaped depression absent ( H. undulatus and H. orcesi Groups ) or welldeveloped, its margins formed by aligned high keels of adjacent scales ( H. septemlineatus Group); in the H. undulatus and H. orcesi Groups frontoparietals paired and parietals consisting of three (infrequently five) regular scales (small scales separating parietals in H. leptophrys ); in H. undulatus Group interparietal entire (with deep longitudinal furrow in H. chaitzami and H. undulatus ), larger than (infrequently subequal to) flanking parietals; medial pair of enlarged occipitals absent; occipitals 10–16 ( H. undulatus and H. orcesi Groups , character not applicable to H. septemlineatus Group), usually subequal to first row of dorsals; supratemporals slightly to moderately enlarged, separated from parietals by one or more scales.

Rostral groove absent (except in Holcosus niceforoi ); nostril oval and oriented anteroventrally, its position relative to nasal suture varying among species; loreal single; supraoculars six (rarely eight); first supraocular entire ( H. undulatus and H. orcesi Groups ) or heavily fractured into irregular keeled scales ( H. septemlineatus Group), larger than fourth (when present) supraocular, usually broadly contacting second supraocular ( H. undulatus Group) or separated from them by complete row of scales ( H. orcesi and H. septemlineatus Groups ); circumorbital semicircles consisting of 4–30 small scales, extending anteriorly to point medial to third supraocular or beyond suture between second and third supraoculars; supraciliaries 9–15, separated from supraoculars by 0.5–2.5 rows of 19–84 (43–111 in H. septemlineatus Group) granular scales; first supraciliary small; second supraciliary greatly elongate ( H. chaitzami , H. festivus , H. orcesi , H. undulatus , and H. septemlineatus Group) or second supraciliary small and third enlarged (most A. leptophrys , A. niceforoi , A. quadrilineatus ); angulate keel extending from first subocular to elongate subocular below eye; suboculars 4–6 (usually 4 or 5); first subocular entire, usually separated from first supraciliary by small granular scales; first subocular contacting supralabials ( H. septemlineatus , most H. festivus , H. niceforoi , and H. orcesi ) or separated from supralabials by scale inserted between suboculars and loreal or anterior expansion of second supralabial (most H. anomalus , H. bridgesii , H. chaitzami , H. leptophrys , H. quadrilineatus , and H. undulatus ); patch of slightly enlarged scales in front of auditory meatus (most species) or scales in front of meatus granular ( H. anomalus and H. bridgesii ); auricular flap and preauricular fold absent.

Supralabials 12–15; first supralabial smaller than or subequal to second, its ventral margin straight to curved; infralabials 10–13; first pair of chinshields broadly contacting infralabials and forming a medial suture of variable length (infrequently partially separated from infralabials by row of small granular scales in some specimens of Holcosus septemlineatus Group); interangular sulcus absent; anterior gulars 18–30 (24–60 in H. septemlineatus Group); gular patch present (most Central American species) or absent ( Holcosus orcesi , H. septemlineatus Group, and some H. quadrilineatus ); posterior gulars 7–22; intertympanic sulcus absent; larger anterior gulars undergoing sharp transition to smaller posterior gulars at intertympanic crease ( H. orcesi and H. undulatus Groups ) or gulars uniform in size with no evident transition to smaller posterior gulars at intertympanic crease ( H. septemlineatus Group); in most species mesoptychials greatly to moderately enlarged, forming differentiated transverse row (not to slightly enlarged in H. anomalus and H. bridgesii ); when present, gular fold lacking serrated edge.

Dorsals smooth ( Holcosus orcesi and H. undulatus Groups ) or keeled ( H. septemlineatus Group); scales on flank subequal to middorsals, projecting laterally and supported by large apical granules ( H. undulatus Group) or subpyramidal ( H. septemlineata Group); scales on rump much smaller than proximal subcaudals; scales of chest large and flat (small, granular, and weakly keeled in H. anomalus ); pectoral sulcus absent; ventrals smooth, in 25–32 transverse and six ( H. septemlineatus Group) or eight ( H. undulatus and H. orcesi Groups ) longitudinal rows; lateral-most ventrals flanked by small scales (i.e., ventrals not gradually decreasing in size on flanks); preanals 5–17; preanal plate present, bordered by small granular (larger subtriangular scales in Holcosus chaitzami and H. undulatus ) scales; preanals paired and small, less than one-half as large as scale anterior to them (except H. chaitzami , H. undulatus , and female H. quadrilineatus ); preanal spurs and postcloacal buttons absent; postanal plates present in males; dorsolateral row of caudals with laterally projecting mucrons forming denticulate edge; dorsolateral crests absent; caudal annuli complete; proximal subcaudals smooth (most species) or keeled ( H. anomalus and H. bridgesii ).

Enlarged scales of brachium separated by small granular scales on dorsal surface of arm; preaxial brachial scales 1–2X as wide as long, extending proximally beyond middle of arm (most species) or relatively small, longer than wide, and restricted to patch near distal end of brachium ( Holcosus anomalus and H. bridgesii ; postaxial brachial scales 1–2X as wide as long (most species) or small and mostly longer than wide ( H. anomalus ); postaxial brachials forming patch near elbow ( H. anomalus , H. bridgesii , H. leptophrys , H. orcesi , H. quadrilineatus ) or extending beyond center of arm (remaining species); antebrachial scales enlarged and smooth, narrowly separated from or in continuous row with preaxial brachial scales; postaxial antebrachial scales granular ( H. anomalus , H. bridgesii , and H. quadrilineatus ), slightly enlarged ( H. festivus , H. leptophrys , H. niceforoi , H. septemlineatus , and H. orcesi ), or distinctly enlarged ( H. chaitzami , H. undulatus ); lamellae under fourth finger 12–19; subarticular lamellae of hand distinctly enlarged and swollen.

Prefemorals 5–10 (9–14 in Holcosus anomalus and H. bridgesii ); femoral and abdominal pores 29–56, in continuous row on each side (abdominal pores not separated from femoral pores by gap, not reaching abdomen in H. septemlineatus Group); each compound pore-bearing scale consisting of partially fused prefemoral or abdominal scale and 2–6 granular scales; 4–21 scales separating right and left pore rows; two wide ( H. septemlineata Group, H. festivus , H. niceforoi , and most H. leptophrys ) or 3–4 large ( H. chaitzami , H. orcesi , H. quadrilineatus , H. undulatus ) scales at heel; tibiotarsal shields and spurs absent; lamellae under fourth toe 21–34; distal lamellae of fourth toe sharply keeled (except H. orcesi ); scales between subdigital and supradigital lamellae of toes small and mostly restricted to phalangeal articulations; noticeably enlarged postaxial scales between fourth and fifth toe absent; fifth toe well-developed ( H. festivus , H. niceforoi , H. orcesi , H. quadrilineatus , and H. septemlineatus Group) or shortened ( H. chaitzami , H. leptophrys , and H. undulatus ) so that base of claw not extending to level of skin between third and fourth toes when adpressed.

β- keratin containing layers of dorsal scales folded into macrohoneycomb ( Holcosus orcesi and H. undulatus Group) or short macroridges ( H. septemlineatus Group); dorsal and caudal scales with one subterminal lenticular scale organ; ventrals lacking scale organs; generation glands absent.

Snout same color as dorsal head scales; adult male Holcosus festivus , H. quadrilineatus and H. undulatus (at least in some populations) with sides of head, chin and throat red or orange (at least during breeding season) but color not restricted to or most conspicuous on snout. In juveniles, light vertebral stripe solid and straight ( H. festivus and H. septemlineatus Group), solid anteriorly and breaking into blotches posteriorly ( H. chaitzami , H. niceforoi ) or absent ( H. leptophrys , H. quadrilineatus , H. undulatus ); light paravertebral stripes absent; dark dorsolateral field broken into blotches (condition in H. anomalus and H. bridgesii unknown); dorsolateral light stripe solid and extending to tail ( H. anomalus , H. chaitzami , H. niceforoi , H. quadrilineatus ) or broken ( H. bridgesii , H. festivus , H. leptophrys , H. septemlineatus , H. undulatus ); dark lateral field solid; upper lateral light stripe solid ( H. anomalus and H. quadrilineatus ) or broken and extending to groin ( H. bridgesii , H. chaitzami , H. festivus , H. leptophrys , H. niceforoi , H. septemlineatus H. undulatus ); lower lateral light stripe absent ( H. leptophrys , H. undulatus ) or broken and extending to groin ( H. chaitzami , H. festivus , H. niceforoi , H. quadrilineatus , and H. septemlineatus Group); thigh lacking light spots. In adult males, flanks lacking light spots or ocelli (adult males of H. undulatus have very conspicuous, wide, transverse bands on flanks); turquoise ventrolateral spots present ( H. undulatus ) or absent ( H. festivus , H. leptophrys , H. quadrilineatus , H. septemlineatus , condition unknown in other species); venter immaculate, lacking melanic areas; juvenile dorsal color pattern present in adult males with only slight ( H. leptophrys ) to conspicuous ( H. festivus , H. H. quadrilineatus , H. septemlineatus , H. undulatus ) modification (condition of other species unclear).

Hemipenis with pair of taβ- like and smooth apical awns; apical papillae and apical basin absent; asulcate expansion pleat well-developed, interrupting 10–11 (14–26 in Holcosus septemlineatus Group) distal laminae; discontinuous distal laminae absent (Central American species) or 5–7 ( H. septemlineatus Group) on asulcate side; 2–50 laminae proximal to expansion pleat; basal papillae absent.

Etymology.— Cope (1862) did not discuss the derivation of Holcosus . He may have been inspired by the masculine Latin noun holcos (from Greek holkos), meaning a kind of grain. The name may be a reference to the many cephalic shields that have fragmented into numerous small and, therefore, grain-like keeled scales in the type species H. septemlineatus . Holcosus is a masculine noun in the nominative singular.

Distribution.— The species of Holcosus extend from Mexico to trans-Andean Colombia and Ecuador.

Interspecific Relationships.— Most species of Holcosus have not been included in recent phylogenetic analyses of teiids. Echternacht (1971) assigned H. festivus and H. leptophrys to his Group II, characterized by relatively high numbers of femoral pores and a tendency for scales in the frontoparietal region to exhibit irregular patterns. He assigned H. quadrilineatus , H. chaitzami , and H. undulatus to his Group III characterized by nasal-prefrontal contact, a normal pattern of scales in the frontoparietal region, a color pattern that emphasizes stripes rather than spots, and a broad vertebral field lacking a vertebral stripe. Furthermore, he hypothesized that H. undulatus and H. chaitzami are more closely related to each other than either is to H. quadrilineatus . Finally, he appreciated that Ameiva praesignis (his Group I) is “farther removed phylogenetically from Groups II and III than these are from each other.”

In the ordered phylogenetic analyses, Holcosus is a well-supported clade sister to Aspidoscelis ( Fig. 70). The Ecuadorian endemic H. orcesi is the sister species of all other congeners in the ordered analysis and sister to the Central American species in the unordered analysis. Herein, we assign this species to its own species group.

Holcosus anomalus , H. bridgesii , and H. septemlineatus form a well-supported clade, which we refer to as the Holcosus septemlineatus Group. These three distinctive species share a suite of characters not present in any other Holcosus . Echternacht (1977) realized that H. anomalus is most closely related to H. bridgesii and H. septemlineatus , but he did not speculate about which of the two might be its sister species. There can be little doubt that H. anomalus and H. bridgesii are each other’s closest relatives. Unlike H. septemlineatus (characters in parentheses), these two species share the first subocular usually separated from the supralabials by anterior expansion of the second subocular (first subocular in contact with supralabials), granular scales in front of the auditory meatus (slightly enlarged scales), not to slightly enlarged mesoptychials (greatly enlarged and forming transverse row), small preaxial brachials (enlarged), both preaxial and postaxial brachials restricted to small patch near distal end of brachium (extending to center of arm), granular postaxial antebrachials (slightly enlarged), and 9–14 prefemorals (5–7).

The three species of the Holcosus septemlineatus Group are restricted to humid forests of the lowlands and piedmont of western Colombia and Ecuador. Interestingly, the group bears special resemblance to Kentropyx . The H. septemlineatus Group and Kentropyx are the only teiids with β- keratin containing layers of the epidermis folded into macroridges. Unlike H. orcesi and the Central American species, the H. septemlineatus Group and Kentropyx also share keeled dorsals and a well-developed keyhole shaped depression in the parietal region.

When all characters were included in the ordered phylogenetic analysis, the Holcosus septemlineatus Group was deeply nested within Holcosus as the sister group to H. festivus ( Fig. 70). This placement seems counterintuitive, because extreme morphological divergence of the group suggests great age. Holcosus festivus and the H. septemlineatus Group are the only congeners with a narrow light vertebral stripe in juveniles, and this character seems to be largely responsible for the surprising placement of the H. septemlineatus Group. When color characters were excluded from the analysis, the Central American species formed a clade sister to the H. septemlineatus Group, whereas the Central American species formed a clade sister to H. orcesi in the unordered analysis ( Fig. 70). Both hypotheses make more sense on biogeographic grounds and better account for the extreme morphological divergence of the H. septemlineatus Group. For these reasons, we accept monophyly of the Central American species and H. niceforoi as the most likely phylogeny of the group and assign these species to the H. undulatus Group.

Complete absence of Holcosus from cis-Andean South America and their recovered phylogeny clearly point to a trans-Andean or Central American origin for the genus. The H. septemlineatus and H. orcesi Groups are old lineages that evolved in northern South America. The H. undulatus Group likely diversified in lower Mesoamerica with H. festivus and H. niceforoi only recently reaching the continent, perhaps after formation of the Panamanian Portal.

Holcosus niceforoi has been compared to Holcosus festivus (e. g., Echternacht 1970). We recovered these species as sister taxa in the unordered analysis, but found H. niceforoi to be closely related to H. undulatus in all ordered analyses. We did not examine H. chaitzami and did not include it in the phylogenetic analysis. Nonetheless, we examined photographs of the holotype of this species on the UMMZ website. Echternacht (1971, p. 64) remarked that, “ Ameiva chaitzami is very closely related to undulata ,” and we suspect that he is correct. As we noted in the synopsis of characters, these species share partially divided interparietals and we did not observe this trait in congeners.

Remarks.— Peters and Donoso-Barros (1970) attribute Cope (1869a) as the author of Holcosus and list H. bridgesii as the type species. However selection of H. bridgesii as type species is not valid, because Cope (1869a) described it after he (1862) erected Holcosus to accommodate Ameiva septemlineata Duméril and Duméril and A. sex-scutata Günther (= Holcosus septemlineatus actuorum ). Accordingly, we here designate Ameiva septemlineata Duméril and Duméril 1851 , as type species of Holcosus Cope 1862 .