Tarentola panousei Pasteur, 1959

and, Thore Koppetsch & Böhme, Wolfgang, 2022, On the identity of west Saharan geckos of the Tarentola ephippiata complex (Squamata: Phyllodactylidae), with comments on an extreme case of syntopy with their close relative T. annularis, African Journal of Herpetology 71 (2), pp. 139-159 : 139-159

publication ID	https://doi.org/10.1080/21564574.2022.2055652
DOI	https://doi.org/10.5281/zenodo.15624152
persistent identifier	https://treatment.plazi.org/id/AF4CD200-F84C-FFAA-FF69-559DFB83FE0F
treatment provided by	Felipe
scientific name	Tarentola panousei Pasteur, 1959
status

Treatment

Tarentola panousei Pasteur, 1959 View in CoL

Tarentola panousei Pasteur, 1959 View in CoL (‘Hamada du Dra, Bassin du Draa moyen’, South Morocco)

Tarentola panousei View in CoL – Bons, 1959 (see above)

Tarentola ephippiata View in CoL – Bons, 1959 (Aouinet-Torkoz, South Morocco; citing Pasteur 1959, the same specimen identified later by Bons and Geniez (1996) is listed next to P. panousei View in CoL ) Tarentola hoggarensis panousei View in CoL – Pasteur, 1960 (see above)

Tarentola hoggarensis panousei View in CoL – Pasteur and Bons, 1960 (see above)

Tarentola ephippiata – Grandison 1961 (see above)

Tarentola ephippiata – Salvador and Peris, 1976 ( Rio de Oro, West Sahara)

Tarentola ephippiata hoggarensis – Joger, 1984 (SW Morocco, West Sahara)

Tarentola ephippiata – Mahé 1985 (Nouadhibou, Mauritania)

Tarentola ephippiata – Joger and Bischoff, 1989 (Icht, Morocco)

Tarentola ephippiata hoggarensis – Bons and Geniez, 1996 (SW of Aouinet-Torkoz, South Morocco)

Tarentola cf. ephippiata (‘ T. ephippiata -Gruppe’) – Böhme et al. 2001 (south of Nouadhibou, NW Mauritania)

Tarentola hoggarensis – Herrmann and Herrmann 2003 (20 km south of Aounet-Torkoz, South Morocco)

Tarentola ephippiata hoggarensis – Colacicco, 2015 (in part, South Morocco, West Sahara, Mauritania)

Tarentola ephippiata hoggarensis – Sow et al. 2015 (Parc National du Banc d’ Arguin, Mauritania)

Tarentola hoggarensis – Martínez del Mármol et al. 2019 (in part, South Morocco, Western Sahara)

Diagnosis: A relatively large (up to 85.4 mm SVL) member of the Tarentola ephippiata complex with a lumpy habitus, which is distinguished from its former conspecific T. hoggarensis ( Figure 5A View Figure 5 ) by its greater snout-vent length (max. 85 mm vs. 73 mm), a lower number of gular scales (27–31 vs. 29–37), and often a higher tail width/snout-vent length ratio (0.13–0.16 vs. 0.09–0.16). Ear openings small, sometimes concealed, with a serrated (vs. smooth) anterior margin. Dorsal tubercles irregularly arranged (vs. in longitudinal rows) and only indistinctly differentiated from the surrounding scalation. Colour pattern more or less uniformly greyish beige with, in adults, only four indistinct pale dorsal blotches and a postocular dark stripe reaching the axillary region.

T. panousei can be distinguished from T. ephippiata by the presence of indistinct and flat dorsal tubercles (vs. slightly keeled), and from T. senegambiae by a lower number of interorbital scales (11–15 vs. 14–18) and a shorter snout-vent length (maximum 85 mm vs. 129 mm).

Less marked is a different arrangement of the rostral/nasal contact (less broad and more pointy in some T. panousei ), the shape of the basal lamellae at the fourth toe (in some T. panousei replaced by scale row and not uniform), and the degree of ossification of the supraocular lamina (no clear differences). For additional differences in scalation see Table 2 View Table 2 .

Neotype: ZFMK 73503 About ZFMK , subadult female from 20 km south of Aouinet-Torkoz , Oued Torkoz, at its mouth into the Oued Dra (28°29.00’ N, 09°51.17’ W), SW Morocco, collected by Hans-Werner Herrmann, on 4 October 2000 on an Vachellia tortilis acacia trunk ( Herrmann and Herrmann 2003). GoogleMaps

The half-grown female ( Figure 4 View Figure 4 , Table 2 View Table 2 ) has a total length of (52.3 + 43.6) 95.9 mm and is consequently smaller than the lost holotype, the snout-vent length of which was 67 mm (Pasteur 1960). Broad head (HW 10.7 mm; HH 7.3 mm) with blunt snout (SED/ SVL 0.11) ( Figures 4C View Figure 4 to 4E) ( Figures 4C View Figure 4 to 4E). Eight supralabial scales, seven infralabial scales. Supranasal scales separated, internasal scale, large with a similar size like the supranasalia. Point contact between nostril and rostral. Supraocular integument smooth, ear opening serrated. Under the first hind toe, thirteen undivided lamellae, and under the fourth hind toe fourteen. Seventeen longitudinal rows of dorsal tubercles, although irregularly arranged and partially indistinct from the surrounding dorsal scalation. Fifteen interorbital scales, thirty scales from mental scale to the gular fold.

In a preservative, brownish ground colouration dorsally, yellowish ventrally. Four white dorsal patches from snout to vent. Postocular stripe reaching axilla.

Variation: A second specimen from southern Morocco ( ZFMK 84913 About ZFMK ) is bigger than the neotype but also not full grown ( Table 2 View Table 2 ). The series collected from the acacia tree south of Nouadhibou contained eight specimens ( Figure 5B View Figure 5 ) with SVL values from 47.1 to 85.4 mm ( Table 2 View Table 2 ), consequently not reaching the size class of its syntopic congener T. annularis (up to 140 mm SVL), but with a markedly stout, robust habitus ( Figure 6 View Figure 6 ).

Systematics

Based on our morphological analysis, Tarentola panousei is phenotypically most similar to T. hoggarensis ( Figure 5A View Figure 5 ), with which it was confused by previous authors, who considered both names to be synonymous (see the synonymy-chresonymy list above). However, adult T. panousei show a higher maximal snout-vent length (up to 85.4 mm) with a lumpy appearance, compared with T. hoggarensis ( Figure 5A View Figure 5 ) and a more or less uniform greyish beige with only four indistinct, pale dorsal patches from snout to vent.

Although some of Pasteur’ s (1960) qualitative diagnostic characters can be considered as strong and justified traits for the definitive identification of T. panousei based on our comparative examination of, for example, shape of ear opening (Eoserr) (in T. panousei : ear opening serrated), shape of postocular stripe (POstripe) (in T. panousei : postocular stripe up to the axilla) and shape of dorsal tubercles (DTshape) (in T. panousei : dorsal tubercles not in rows and indistinct from surrounding dorsal scales), others do not allow a clear separation from individuals of T. hoggarensis , for example, contact between nostril and rostral (Nrcontact), shape of lamellae at the base of 4th toe (Lbshape) and shape of the supraocular integument (SOIshape).

In addition to the characters based on Pasteur’ s diagnosis ( Pasteur 1959, 1960), we showed that T. panousei have a slightly lower range of gular scale counts, compared with T. hoggarensis (27–31 vs 29–37) ( Table 1 View Table 1 ).

Overall, we conclude that Pasteur’ s (1959) recognition of a new species was correct, and that a revalidation of T. panousei as a species is fully justified. If one considers the differences between newly described or revalidated species within the T. mauritanica / T. deserti complex ( Joger 1984; Joger and Bshaenia 2010), the differences between T. hoggarensis and T. panousei are at least equivalent. Nonetheless, a future genetic corroboration of our conclusion would be highly desirable. Moreover, it must still be demonstrated that the subpopulations of T. panousei in southwest Morocco and those from south of Nouadhibou, separated by an air-distance of ca. 1 000 km ( Figure 7 View Figure 7 , map), are identical, despite their strong resemblance regarding mensural and meristic characteristics shown. It must also be determined whether the geographically intermediate populations, in particular the coastal ones, will have to be assigned to T. panousei as well.

Habitat selection

Our nocturnal survey of the single, isolated acacia tree mentioned in the introduction ( Figure 1 View Figure 1 ), which harboured two closely coexisting species of Tarentola , yielded 23 specimens, of which seven T. annularis (four adults, three juveniles: ZFMK 79476-482) and eight T. panousei (seven adults and one juvenile: ZFMK 79522-529) were collected, the remaining specimens being released. The old acacia tree ( Figure 1 View Figure 1 ) offered two types of shelter or hiding places, larger clefts in the wood and small knotholes ( Figure 8 View Figure 8 ), of which the former ( Figure 9A View Figure 9 ) were occupied by T. annularis ; whereas the latter ( Figure 9B View Figure 9 ) were used even by adult T. panousei specimens, which filled these holes completely with their bodies. Nearly all geckos were found and observed exclusively on the tree trunk. Only one big T. annularis male of 22 cm total length descended from the trunk and caught a migratory locust of c. 8–9 cm length, which was attracted by the headlight of our truck, at <1 m distance from the trunk, the distal parts of its toes were bent upwards in the fine desert sand in order to keep the adhesive lamellae clean. Three T. annularis juveniles ( Figure 10 View Figure 10 ) were also seen on the sandy ground, but escaped immediately to the nearby tree trunk. No T. panousei was observed outside of its arboreal microhabitat.

Close syntopy on one single isolated tree trunk

This extreme syntopic situation of two similarly large gecko species suggested that T. annularis was superior in competition, because it occupied the more spacious shelter types. The smaller T. panousei specimens, in contrast, had to be content with the much smaller knotholes where adult specimens were hardly fitting in ( Figures 8 View Figure 8 and 9 View Figure 9 ), as already indicated by Böhme et al. (2001). This was surprising, because T. annularis is otherwise a rupicolous species, whereas T. hoggarensis and its close relative T. panousei seem to be specialised tree dwellers. Even if T. annularis was, in contrast to T. panousei , also observed on the sandy ground, but very close to the acacia trunk, it is extremely unlikely for both species to have had genetic exchange with conspecifics in neighbouring trees, because these were virtually absent for a radius of at least several kilometres, a distance impossible to cross for either species. Given the extreme isolation of their habitat, we hypothesise that both micropopulations might have faced a long period of inbreeding, but without breakage of the isolating mechanism between these two congeners. This is important to note, because Grandison (1961) had reported on specimens intermediate between T. annularis and ‘ T. ephippiata’ (currently T. senegambiae ) from Senegal, Gambia and Guinea Bissau and speculated on ‘a breakdown in whatever mechanism isolates’ both species from each other. However, these two species are also more similar to each other with respect to their body size. In contrast, the two strictly syntopic subpopulations of T. panousei and T. annularis , in the isolated acacia tree described here,`were well separated from each other morphologically, including in respect to size, despite the presumably long duration of their isolation from any other conspecific of either species.

Senegambian representatives of the T. ephippiata complex were separated as a subspecies T. e. senegambiae by Joger (1984) and raised to specific rank by Trape et al. (2012). According to the grid map by these authors, its Sahelian distribution range is separated from that of the Saharan T. hoggarensis , whereas T. annularis , sympatric with T. hoggarensis farther northwards, is missing from the T. senegambiae range, except for two rocky sites near Dakar (Yoff and Cap Manuel) and the rocky offshore islands Gorée, Ngor and Ile Madeleine ( Cissé 1974; Böhme 1978; Cissé and Karns 1979; Joger 1982). According to Böhme et al. (2001), these marginal points were relictual occurrences where the likewise large, robust T. senegambiae was unable to follow. Tarentola senegambiae is also a primary, but obviously less specialised tree-dweller, sometimes even referred to as ‘fig-tree gecko’ ( Cissé 1974; Cissé and Karns 1979), because it was found, in contrast to the obviously strictly tree-dwelling T. hoggarensis and T. panousei , next to trees, as well as on buildings in human settlements, for example, by WB (still as ‘ T. ephippiata’) behind shutters of an ORSTOM Institute building at Richard-Toll ( Böhme 1978).

The only reference reporting ‘ T. ephippiata’ from coastal Mauritania on house walls is by Ineich (1996). He found these geckos close to and in Nouakchott, on the walls of a veterinary station and of a military post, here in sympatry with Hemidactylus brookii (currently H. angulatus ). All other discoveries of this species, made farther northwards, were on trees (acacia). To the south, in the Diawling National Park in the Senegal River delta, close to the Senegalese border, the geckos were found on Baobab ( Adansonia digitata ) trees, with T. annularis already largely missing in this area.

However, the exact taxonomic identity of these geckos, in the light of Joger’ s (1984) revision and the present paper, should be reinvestigated, because now three taxa of the T. ephippiata species complex, viz. T. panousei , T. hoggarensis and, in the south, perhaps also T. senegambiae , might be involved. The grid maps in Trape et al. (2012) suggest sympatry between the latter and T. hoggarensis in the Senegal River delta area.

The assumption of the competitive superiority of T. senegambiae over equal-sized T. annularis , as implied by Böhme (1978) can certainly not be applied to the situation of the syntopic presence of the otherwise strictly rupicolous T. annularis with T. panousei , because in this case it seemed that the latter, because of its smaller size, was the inferior competitor, pushed back to the less favourable shelter and hiding places. T. annularis , otherwise known from Egypt and the Sudan to North Cameroon and Mauritania predominantly as a rock-dweller, has been observed on trees so far only by Sow et al. (2015) and in the present study. However, although Sow et al. (2015) found their ‘ T. e. hoggarensis’ only in bare areas in holes of acacia trees, they only occasionally found T. annularis , which they observed three times more often, in syntopy with the former. At our site near Nouadhibou, T. annularis proved to be superior in competition in a habitat structure absolutely atypical for it, whereas it was the primary microhabitat for its smaller congener.

The obviously less narrow ecological specialisation of T. annularis , compared with the taxa of the T. ephippiata complex, might also explain why it is taxonomically uniform from Egypt and the Sudan to the Atlantic Ocean, whereas the more stenoecious T. ephippiata complex is partitioned to several taxa within the same geographic area. The distribution pattern of the here revalidated T. panousei appears to be biogeographically peculiar, with only patchy and locally isolated subpopulations known so far. However, an overlooked more broad occurrence in this region cannot be ruled out, because other records assigned to T. ephippiata sensu stricto might actually represent T. panousei . These broad gaps in known distribution ranges are also known for other African geckos, for example, Hemidactylus pseudomuriceus ( Koppetsch and Böhme 2017) . Nevertheless, it can only be speculated whether the localities where T. panousei had been recorded might rather be the result of a relictual patchy distribution. The underlying determinants, for example, different dispersal abilities, and possible scenarios, for example, transformation relictual refugia in the past to the present fragmented distribution of the T. ephippiata complex as a whole, which had caused or shaped those distinct biogeographic patterns, might be identified by future more comprehensive phylogeographic analyses.