Acanthodactylus longipes, BOULENGER, 1918

Crochet, Pierre-André, Geniez, Philippe & Ineich, Ivan, 2003, A multivariate analysis of the fringe-toed lizards of the Acanthodactylus scutellatus group (Squamata: Lacertidae): systematic and biogeographical implications, Zoological Journal of the Linnean Society 137 (1), pp. 117-155 : 145

ACANTHODACTYLUS LONGIPES BOULENGER, 1918

Acanthodactylus scutellatus var. longipes Boulenger, 1918: 154 . Name-bearing type: Boulenger does not refer in his original description to any specimen but he clearly used several individuals housed in the British Museum and coming from the Algerian Sahara. He latter talks about five specimens ( Boulenger, 1921), which are apparently all syntypes. These specimens are (see also Salvador, 1982): BMNH 1946.8.30 -32 (Wargla), BMNH 1946.9.3.75 (between the Wed Nça and El Alia), BMNH 1946.9.3.74 (El Wed, East of Tuggurt). As the original type series might have included more specimens, including members of other species, we select as lectotype the specimen BMNH 1946.8.4.31 (an adult male from Wargla, Algeria). Type locality: restricted by lectotype designation to Wargla [= Ouargla], Algeria.

Junior synonym. Acanthodactylus longipes panousei Bons & Girot, 1964: 327 . Name-bearing types: two syntypes MNHN 1963.1013-1014 (called ‘holotypes’ in Bons & Girot, 1964). Type locality: ‘Bord de l’Erg Chebbi au niveau de Merzouga’.

Chresonyms. Acanthodactylus longipes Boulenger, 1918 : Bons & Girot, 1964: 324; Salvador, 1982: 132; Arnold, 1983: 324.

Distribution ( Fig. 19 ). Most of the Sahara from coastal Mauritania (this study; A. Foucart, pers. com.), southern Morocco (Tafilalet, Iriki) ( Geniez & Soto, 1994), northern Mali, northern Niger, northern Chad, Algerian Sahara, Tunisia, Libya ( Salvador, 1982; this study), to Egypt ( Baha El Din, 1994).

Diagnosis. Medium-sized species (reaching 61 mm snout-vent length, mean: 52.4). The subocular in contact with three or (rarely) four supralabials in 100% of the individuals ( Table 3) distinguishes Acanthodactylus longipes from A. aureus and A. taghitensis . Dorsal scales small, very numerous (range: 55–77, mean: 66.4; Table 2), elongate, smooth except in the vertebral area where they can be weakly to moderately keeled (code 3 or less in 97% of the individuals, no individual reaching code 5; Table 3, see Fig. 16d ). Two rows or more of supraciliary granules in 86% of the individuals ( Table 3, see Fig. 20b ). Large number of longitudinal rows of ventral plates (15 or more in 95% of the individuals, range: 13–19, mean: 16.1; Table 2) arranged in oblique rows. Large number of femoral pores (range 17–28, mean = 21.5; Table 2). Coloration distinctive: flanks have a mottled pattern which usually tends to disappear towards the vertebral area ( Fig. 20a ). Females can have small, regularly disposed spots. Red spots can occur on the dorsum. Pileus weakly vermiculated with red. The combination of dorsal pattern and scale structure gives to the skin of A. longipes a fragile and translucent aspect. This species is further characterized by an elongate and pointed snout compared to A. scutellatus audouini , A. dumerili and A. senegalensis . See A. senegalensis for additional differences from that species. Several scalation characters separate A. longipes from the broadly sympatric A. dumerili and A. s. audouini. A strongly fragmented fourth supraocular is found in 73% of the A. longipes individuals but in 14% of the A. dumerili and 37% of the A. s. audouini. Granules are often inserted between the parietal plates in A. longipes , which is exceptional in A. s. audouini and A. dumerili . The number of longitudinal rows of ventrals is often nearly diagnostic: most A. longipes (81% of the specimens) have 16 ventrals rows or more, which is extremely rare in A. s. audouini (1% of the specimens) or A. dumerili (less than 1% of the specimens). Acanthodactylus longipes is the only species to possess dorsal scales small, elongate and smooth except in the vertebral area. The dorsal scales in the vertebral area are only weekly keeled, a further distinction from most A. s. audouini and A. dumerili : 84% of the A. longipes individuals have CARE code 2 or (rarely) 1, whereas less than 2% of the A. dumerili specimens have CARE code 2 or 1. The typical dorsal pattern is also characteristic. It should be noted, however, that some A. longipes females present a uniformly pinkish coloration with small dark spots, making them similar to A. dumerili or A. s. audouini, although their pattern is less contrasting than in these species. In conclusion, although no single character is fully diagnostic between A. longipes and the sympatric species, a combination of several scalation and coloration features will enable to identify the vast majority of specimens. In ambiguous cases, the elongate and pointed shape of the snout and the structure of the dorsal scales are often useful, although occasional individuals remain impossible to identify safely. It should be stressed than other characters proposed by earlier authors (number of supralabials in contact with the subocular, length of hindlegs) proved to be useless.

Geographical variation. The subspecies panousei, described from south-eastern Morocco, does not seem to be valid ( Salvador, 1982; own results). In some populations from the eastern part of the species distribution, specimens tend to have more strongly carinate dorsal scales.

Figures

Figure 16. (a) Acanthodactylus scutellatus audouini, male, paralectotype of Acanthodactylus scutellatus var. audouini, BMNH 97.10.28.316, Wadi Halfa (Egypt), close-up of dorsal scales. (b) A. senegalensis, male, EPHE Mch1, coast north of Dakar (Senegal), close-up of dorsal scales. (c) A. dumerili, male, MNHN 1997.3764, Blaouakh (Mauritania), close-up of dorsal scales. (d) A. longipes, male, EPHE AF4, Akreïdil, 50 km NE of Nouakchott (Mauritania), close-up of dorsal scales.

Figure 19. Geographical distribution of Acanthodactylus longipes. Data from Salvador (1982), Baha El Din (1994), Bons & Geniez (1996), Nouïra (1996), this study.

Figure 20. (a) Acanthodactylus longipes, male, MNHN 1997.4771, Azzefâl (Mauritania). (b) Acanthodactylus longipes, male, lectotype, BMNH 1946.8.4.31, Wargla (Algeria), close-up of head. (c) Acanthodactylus aureus, male, PHG 35, Sidi Ouassaï, near Massa (Morocco), picture by P. Geniez. (d) Acanthodactylus taghitensis, female, PHG 28, 5 km SSW of Taghit (Algeria), picture by M. Geniez.