158 



E.N. ARNOLD 



Fig. 5 Tail of Holaspis. a. Proximal segment from above; b. Proximal 

 segment from below; c. Transverse section. 



lateral pairs instead of being staggered. The plates each have several 

 sense organs on their posterior border and, as the usual number of 

 sense organs per dorsal caudal scale in other lacertid lizards is one, 

 it is likely that the plates have replaced a number of smaller scales. 

 The wide double band is flanked by one or two (rarely three) 

 longitudinal rows of narrower scales, one row being frequent in H. 

 laevis and one or two in H. guentheri. The number of rows some- 

 times increases anteriorly and these scales are replaced by granules 

 on the tail base. The median part of the ventral surface of the tail is 

 formed by another row of wide, paired plates, again replacing 

 multiple small scales in other lacertid lizards. 



The lateral edges of the tail are serrated and consist of a single row 

 of strongly modified scales. In transverse section, each of these 

 scales is more or less triangular, the broad base joining the tail, the 

 apex pointing outwards; in this plane, the lateral scales curve 

 downwards. Viewed from above, these scales are again approxi- 

 mately triangular, the point being directed obliquely backwards. 

 Proximally, the longitudinal axis of these scales is parallel with that 

 of the whole tail; distally, their anterior edges tend to be twisted 

 downwards so that their longitudinal section here runs backwards 

 and slightly upwards. Each lateral scale is capable of some move- 

 ment since it is connected with contiguous scales in its whorl by 

 flexible hinge regions. However, the motion is limited by the scale 

 interlocking with its anterior and posterior neighbours. On the 

 underside of each of these scales, parallel with and close to the 

 trailing edge, is a slit-shaped cavity. The anterior portion of the 

 following scale projects into this, giving the lateral fringes consider- 

 able stiffness. 



LIMBS. The spans of the fore and hind limbs approach equality 

 more closely than in any other lacertid lizard, the index, forelimb 

 span/hindlimb span, being 0.85 in males (n = 3), and 0.85 in females, 

 (n = 4) while the total range for the Lacertidae is 0.53-0.85 (Arnold 

 1998b). 



The forelimbs are rather flattened and the single band of enlarged 

 scales, present on the anterior surface of the upper limb of most 

 lacertids, occurs in Holaspis too. However, instead of being continued 

 as a single band on the lower limb, it is replaced by two parallel ones, 

 one dorsal, the other ventral with their zig-zag line of contact forming 

 a forwardly directed edge that may sometimes be quite acute. 



The hind leg is similarly markedly depressed and the proximal, 

 femoral segment has large plates above and below the leading edge; 



a 



Fig. 6 Right manus of lacertid lizards, a. A form frequently climbing on 

 steep open surfaces (Lacerta oxycephala); b. Holaspis guentheri. 



only the lower series reaches the front of the cms. The greater part of 

 the trailing area of the hind leg is formed by a web of loose elastic 

 skin, which becomes taut when the leg is partly extended. This 

 'patagium' is continuous with a series of about four large sharp- 

 edged, sometimes interlocking, scales which make up the trailing 

 edge of the crus. These scales are generally similar in construction 

 and arrangement to those on the lateral edges of the tail 



The manus and pes of Holaspis show strong development of a 

 syndrome of features characteristic of lacertid lizards that climb on 

 continuous open surfaces (Fig. 6; Arnold, 1998b) and many features 

 are better developed than in other forms. The longest digit is number 

 4 and all digits are strongly latero-mesially compressed; some digits 

 are flexed downwards at the articulation of phalanges 1 and 2 and in 

 most there is upward flexure at the penultimate articulation. Phalanges 

 are very slender, the penultimate ones being very long and markedly 

 curved downwards. In the manus intermediate phalanges of digits 3 

 and 4 are shorter than the ones bordering them and the same is true 

 of intermediate phalanges of digits 3 and 4 of the pes. The final 

 phalanx of each digit and the claw that covers it is short, deep and 

 recurved. The large ventral digital tendons are offset from the 

 articulations in the regions where digits can be abruptly flexed 

 downwards. The articulations within the digits, except the most 

 distal, are simple involving single cup and ball arrangement and the 

 digits are abruptly flexed in the horizontal plane, both mesially and 

 laterally, especially in the area of the penultimate articulation. 



The manus of Holaspis has the following additional derived 

 features. Digits 2-5 are subequal in length, and numbers 3 and 4 are 

 conjoined for the length of their first phalanx. The shortening and 

 downward flexure of phalanx 2 digit 3 and phalanges 2 and 3 of digit 

 4 is much more marked than in other lacertid lizards. 



Digits 3, 4 and 5 of the pes each have a lateral fringe of interlock- 

 ing triangular scales, which extends distally to the base of the 

 penultimate phalange. That on the fifth toe is continuous with the 

 similar scales on the trailing edge of the crus. Digits 4 and 5 also 

 have a similar mesial fringe. 



COLOUR in life. In life, Holaspis is blue-black with several 

 longitudinal pale stripes on the dorsum, the two on the vertebral 

 plates being tinged blue posteriorly. The tail has a series of large, 

 light, intensely blue spots on its upper surface and its lateral fringes 

 are yellow, while the belly is red. 



