Acanthodactylus scutellatus, (AUDOUIN, 1827)

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 : 137-141

ACANTHODACTYLUS SCUTELLATUS ( AUDOUIN, 1827)

Lacerta scutellata Audouin, 1827: 172 , pl. i, fig. 7. Name-bearing type: the original description was clearly based on a single specimen (figured on the plate), which is thus the holotype. This specimen is not in the collections of the MNHN, and was perhaps never given to the MNHN collections ( Brygoo, 1988: 44–45). It should be considered as lost. A neotype should be designated to stabilize the nomenclatural status of this taxon. We refrain from doing so here pending a more complete analysis of the populations from the eastern part of the species range, including Egypt. Type locality: ‘Egypte’.

Chresonyms. Acanthodactylus scutellatus ( Audouin, 1827) : Bons & Girot, 1964: 319; Salvador, 1982: 113; Arnold, 1983: 322 (part); Arnold, 1986: 425 (part).

Distribution ( Fig. 13 ). In the Sahara, south-eastern Algeria, north-eastern Mali, northern Niger, northern Chad, northern Sudan, Egypt, Libya, and southern Tunisia ( Salvador, 1982; Nouïra, 1996; Ch. P. Blanc, pers. com.; this study). The characters given above and a careful examination of the pictures published by Bons & Girot (1964) lead us to reject the occurrence of this species in Morocco (cf. Bons & Geniez, 1996), in opposition to the opinions of Bons & Girot (1964), Mellado & Olmedo (1990) and Pérez Mellado (1992). The species is also encountered in Israel, Arabia and Iraq ( Salvador, 1982).

Diagnosis. (Remarks: the following diagnosis is based on specimens of Acanthodactylus scutellatus audouini only). The largest species of the group (reaching 72.5 mm snout-vent length, mean = 63.9; cf. Table 2, Figs 14 and 15 ). The subocular in contact with three or (rarely) four supralabials in 99% of the individuals ( Table 3) distinguishes A. s. audouini from A. aureus and A. taghitensis . Dorsal scales usually small and rather numerous (in the Sahara, range: 39–69, mean: 53.4; Table 2, see remarks below under ‘Geographical variation’), nearly equal in size between the dorsum and the flanks, and moderately to strongly carinate (codes 4 or 5 in 86% of our sample, no individual reaches code 6; Table 3, see Fig. 16 ). Fewer than two rows of supraciliary granules in 70% of the specimens, two rows in 28%, more than two rows in only 2% ( Table 3). Generally 13 or 14 longitudinal rows of ventral scales (in 83% of the specimens, range: 12–16, mean: 13.9; Table 2). Femoral pores rather numerous (range: 16–26, mean: 21.1; Table 2). Adult males with a black, highly contrasting, dorsal reticulation. Females with isolated black spots at regular spaces on the back. Pale dorsal spots often lacking in adults, which have a dorsal coloration made of only two colours; most individuals have black spots on their pileus. For separation of A. s. audouini from A. longipes and A. senegalensis , see these species. Acanthodactylus scutellatus audouini can be distinguished from the closely similar A. dumerili by its larger maximum size and by a different pileus coloration. In A. dumerili , as in the remaining species within the scutellatus group, the pileus is either uniformly pale or marked with darker vermiculations or small dots, but not with distinct and well-individualized large black spots as in A. s. audouini. In addition, a higher proportion of adults A. s. audouini have a dorsal coloration consisting of a dark pattern on a uniform background (two colours only on the dorsum, COUL code 4, in 27% of the specimens; Table 3). When other species within the scutellatus group have only two colours on the dorsum, it is usually light spots on a darker ground colour (code 2, Table 3). According to Nouïra (1996; p. 246), A. s. audouini and A. dumerili also differ in the fragmentation of the cephalic plates, A. s. audouini having the first supraocular (SO1) usually separated from the second supraocular (SO2) by a row of proximal granules and a strongly fragmented fourth supraocular (SO4). We checked the validity of these proposed differences on 116 A. s. audouini (most of them from Tunisia) and 298 A. dumerili . In A. s. audouini, 48% of the individuals have SO1 and SO2 partly or totally separated (including 18% with completely separated SO1 and SO4; Table 4), whereas in A. dumerili only 7% of the specimens have SO1 and SO2 partly separated (none having SO1 and SO4 completely separated; Table 4). In A. s. audouini, 30% of the specimens have an entire SO4, 33% have a partially fragmented SO4 and 37% have a completely fragmented SO4. In A. dumerili , 49% of the specimens have an entire SO4, 38% a partially fragmented one, and only 14% a completely fragmented SO4 ( Table 4). The differences described by Nouïra (1996) are thus real but of limited use when trying to identify single specimens.

Geographical variation. Three subspecies have been recognized. The subspecies hardyi is recognized as a valid taxon in most of the recent works on the genus (e.g. Bons & Girot, 1964; Salvador, 1982; Arnold, 1986; Nouïra, 1996). Harris & Arnold (2000) even propose to give specific status to this taxon, although without justification. In addition, Bons & Girot (1964) recognized the subspecies audouini, based on an analysis of large series of specimens. We follow their opinion here, based on a preliminary examination of a number of specimens from Egypt and Israel.

Subspecies. Acanthodactylus scutellatus scutellatus in Israel, Sinai and Egypt.

Acanthodactylus scutellatus audouini Boulenger, 1918 Acanthodactylus scutellatus var. A udouini Boulenger (1918): 154. Name-bearing type: Boulenger did not refer to any precise specimen in his original description, but stated that he used specimens in the British Museum, especially specimens collected by F. Lataste. These specimens came from ‘ Egypte, Nubie, Tripoli, sud de la Tunisie’. The following specimens are probably all syntypes (see Salvador, 1982): BMNH 97.10.28.315-319 (Wadi Halfa, Sudan), BMNH 1913.12.30.6-10 (Homs, Tripoli), BMNH 91.5.4.85-91 (Duirat, southern Tunisia), BMNH 1920.1.20.3006 (Wed El Kreil, Tunisia). Considering the uncertainties over the limits of the range of audouini, we feel it is important to select a lectotype from an area where audouini (as generally understood) is certainly present. We select the specimen BMNH 1920. 1.20.3006 as lectotype. Type locality: Wed El Kreil, Tunisia.

Distributed in the west of the species range, east to north-eastern Sudan ( Bons & Girot, 1964).

A. s. hardyi Haas, 1957

Acanthodactylus scutellatus hardyi Haas, 1957: 72 . Name-bearing type: holotype by original designation: Hebrew University of Jerusalem 2682. Type locality: ‘ Hirmas Station, Saudi Arabia’ .

Distributed in Northern Saudi Arabia, Kuwait, and Iraq ( Salvador, 1982).

We retain for the time being the subspecies audouini for the Saharan specimens, characterized by a lower number of more strongly keeled dorsal scales (73 on average in scutellatus ( Bons & Girot, 1964) against 53 on average, and not more than 68 in audouini [own data]) and a smaller size ( Boulenger, 1921; Bons & Girot, 1964). A revision of the material included in Acanthodactylus scutellatus is needed before any firm conclusion can be drawn. The limits of the range of A. s. scutellatus and A. s. audouini follow Bons & Girot (1964).

There is a slight morphological variation among populations of Acanthodactylus scutellatus audouini in the Sahara. In Tunisia, most of the individuals have a grey throat and a reddish tail, whereas this coloration is exhibited, more or less markedly, by only a small number of individuals from southern Sahara.

Remarks. Victor Audouin published the description of Lacerta scutellata in 1827 and not in 1809 ( Salvador, 1982; according to his birth date, V. Audouin was only 12 years old in 1809 [R. Bour, pers. com.]) or 1829 ( Arnold, 1983; Brygoo, 1988).

Figures

Figure 13. Geographic distribution of Acanthodactylus scutellatus in the Sahara (thus excluding part of the species range, see text). Dotted lines indicate the approximate limits of the distribution of A. dumerili. Data from Salvador (1982), Baha El Din (1994), Joger & Lambert (1996), Nouïra (1996), this study.

Figure 14. Snout-vent length of males in our samples of continental Sahara Acanthodactylus dumerili and A. scutellatus audouini.

Figure 15. Snout-vent length of females in our samples of continental Sahara Acanthodactylus dumerili and A. scutellatus audouini.

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.