Lygodactylus arnei, Vences & Herrmann & Multzsch & Gippner & Razafimanafo & Rahagalala & Rakotomanga & Rakotoarison & Glaw & Miralles, 2025

Vences, Miguel, Herrmann, Cecilia, Multzsch, Malte, Gippner, Sven, Razafimanafo, Delina, Rahagalala, Ny Ando, Rakotomanga, Sandratra, Rakotoarison, Andolalao, Glaw, Frank & Miralles, Aurélien, 2025, Revision of the Lygodactylus tolampyae complex, with descriptions of three additional new dwarf gecko species from Madagascar’s North West, Zootaxa 5665 (3), pp. 301-328 : 315-318

Lygodactylus arnei sp. nov.

( Figs 7 , 9–10 )

Remark. Corresponds to L. sp. 29 of Gippner et al. (2021) and Vences et al. (2024).

Holotype. ZSM 64/2023 (field number FGZC 12012), male, collected at Baie de Baly National Park , on a forested elongated hill North to South oriented, 16.035757°S, 45.268719°E, ca. 14 m a.s.l., northwestern Madagascar, between 05:30 and 07:30 pm, on 13 October 2023, by A. Miralles and N. A. Rahagalala.

Paratypes (n=17). ZSM 63/2023 (FGZC 12011), from Baie de Baly National Park , same data as holotype. ZSM 65/2023 (FGZC 12040), ZSM 66/2023 (FGZC 12041), ZSM 67/2023 (FGZC 12042), UADBA-FGZC 12039 (= MIRZC 1282), all four collected from the Tsiombikibo Forest , in dry deciduous forest near the village of Benetsy , 15.941585°S 45.766811°E, ca. 15 m a.s.l., between 9:30 and 11:00 am on 17 October 2023, by A. Miralles and N. A. Rahagalala. UADBA-FGZC 12050, collected from Tsiombikibo Forest , in dry deciduous forest near the village of Benetsy, near a large temporary pond and a white sand area, 15.942476°S 45.776191°E, ca. 15 m a.s.l., between 06:30 and 09:00 pm on 17 October 2023, by A. Miralles and N. A. Rahagalala. ZSM 68/2023 (ZCMV 15811), collected from Tsingy de Namoroka National Park , Campsite 1, near a temporary lake located 500 m N to the Petit Tsingy (east of massif), 16.43104°S 45.36611°E, ca. 120 m a.s.l., around 08:00 pm, on 7 October 2023 by A. Miralles, N. A. Rahagalala, A. Rakotoarison, D. Razafimanafo and A. Razafimanantsoa. ZSM 71/2023 (ZCMV 15840), UADBA-ZCMV 15842, UADBA-ZCMV 15843, UADBA-ZCMV 15844, all four collected from the vicinity of Tsingy de Namoroka National Park , in a gallery forest near a natural swimming pool (500 m to the north of the massif), 16.38244°S 45.34311°E, ca. 85 m a.s.l., between 7:00 am and 9:00 am, by A. Miralles, N. A. Rahagalala, A. Rakotoarison, D. Razafimanafo and A. Razafimanantsoa. ZSM 72/2023 (ZCMV 15856), ZSM 73/2023 (ZCMV 15860), UADBA-ZCMV 15859, UADBA-ZCMV 15861, all four collected from Tsingy de Namoroka National Park , Campsite 2, near Grand Tsingy (south of the Tsingy massif), 16.46933°S, 45.34853°E, ca. 130 m a.s.l., between 03:00 and 07:00 pm, on 10 October 2023, by A. Miralles, N. A. Rahagalala, A. Rakotoarison, D. Razafimanafo and A. Razafimanantsoa. UADBA-ZCMV 15829, from Tsingy de Namoroka National Park, Petit Tsingy (east of the massif), 16.43541°S 45.36837°E, ca. 125 m a.s.l., between 5:00 pm and 7:00 pm, on 8 October 2023 by A. Miralles, N. A. Rahagalala, A. Rakotoarison, D. Razafimanafo and A. Razafimanantsoa. ZSM 296/2018, from Tsingy de Namoroka National Park, forest near caves, Petit Tsingy (east of the massif), donated by H.-P. Berghof, collected in 2018 by local collectors .

Diagnosis. Lygodactylus arnei sp. nov. is characterized as member of the L. tolampyae complex (and thereby distinguishable from all other Malagasy Lygodactylus not belonging to the complex) by combination of a mental scale semi–divided by a suture, broad contact of the posterior projection of the mental scale with the first infralabial scale, and three postmental scales; absence of whorls on the tail, and a typical appearance of the head with relatively large eyes. Within the L. tolampyae complex, the species (at least the Namoroka population) appears to be characterized by an orange color on the ventral surface of tail, and light orange sometimes on venter and chest (whitish in all other species of the complex). Further differences, although usually with overlap of values, are as follows: distinguished from L. andavambato by a less slender appearance (vs. conspicuously slender appearance), absence of regular dark–light alternating crossbands of similar width on tail (vs. presence), 1–2 internasal scales (vs. 3 internasals in most specimens), a smaller relative eye diameter (ratio ED/SVL 0.06–0.07 vs. 0.05 in most specimens), and a lower longitudinal count of ventral scales (LCVS 102–111 vs. 110–115); from L. herilalai by a lower number of infralabials (5–6 vs. 7 in most specimens) and supralabials (7–8 vs. 9 in most individuals); from L. schwitzeri by a lower longitudinal count of dorsal scales in most specimens (LCDS 224–258 vs. 241–271); and from L. tolampyae by a larger posterior contact between mental and first infralabial scale (relative PMS 25.7–61.7 vs. 15.5–47.2). We did not note any meaningful differentiation in meristic or morphometric characters from L. morii . From a molecular perspective, the new species is characterized by numerous diagnostic nucleotide positions in the mitochondrial 16S rRNA gene (see Table 2).

Description of the holotype. Male, in good state of preservation, left front-limb removed as tissue sample, cloaca might be damaged, tail present ( Figs 9–10 ). SVL 25.9 mm, TAL 28.9 mm; for other measurements, see Table 3. Body width (6.5 mm) is slightly larger than head width (5.1 mm). However, the body width might be larger than it should be, due to a flattened preservation state. The distance from the tip of the snout to the anterior border of the eye (3.6 mm) is slightly smaller than the anterior interorbital distance (4.2 mm), and greater than the distance between the eye and ear opening (2.7 mm). Snout covered with granular scales slightly larger than those on the dorsum. Nostril surrounded by five scales: rostral, first supralabial, one postnasal and two supranasals. The mental scale is semi-divided; contact between posterior projection of mental scale and first infralabial scale is around 42.3% of the infralabial scale length; three symmetrical postmental scales, followed by four postpostmentals; six infralabial scales; seven to eight supralabial scales; two internasal scales; six preanal pores; granular dorsal scales; dorsum with small, homogeneous, granular, and unkeeled scales of similar size to those on trunk, slightly larger on limbs; 258 dorsal scales longitudinally along the body; 104 ventral scales between mental and cloaca; venter with larger homogeneous smooth scales; first finger present, small, but bearing a claw; three pairs of subdigital lamellae on the fourth toe; no dorsolateral tubercles; no observable lateral spines at the base of the tail.

After one year of preservation in ethanol ( Fig. 9 ), the specimen appears dorsally and laterally grayish in colouration and displays a distinct broad stripe of brighter colouration on each side. Beneath these a narrow darker stripe is located that starts at the snout while the brighter one starts at the eye. Both whitish stripes appear to merge at the start of the tail, but stay separated by a thin darker line which continues along the tail. The head might display a darker spot. The remaining forelimb is irregularly patterned in contrast to the hindlimbs where colouration appears more uniform, whereas toes are striped. The dorsal surface of the tail is not banded, lateral surfaces are grayish. Each side of the neck has a tubercle with a whitish tip. The ventral side of the body, the tail and of the limbs appears uniformly whitish, the anterior part of the ventral body displays isolated darker spots especially on the throat. A distinct line running in anterior-posterior direction is visible on the lower part of the belly which might be a scar. In life ( Fig. 7 ), colouration appears more intense and of higher contrast, especially the whitish stripes, which show a more patterned colouration of whitish and brownish bands. Photo of ventral coloration in life is not available.

Variation. All paratypes examined differ from the holotype by having an unstriped dorsum with limited dorsal pattern ( Fig. 7 ), suggesting that the striped phenotype is likely rare in this species.As shown in Fig. 7 , paratype ZSM 72/2023 (ZCMV 15856) from Namoroka shows a distinctly orange color ventrally on the tail, and (less bright) on the belly and chest. At least some orange color on the anterior tail is also visible in all paratypes from Namoroka for which life images of the ventral side are available, i.e., ZSM 73/2023 (ZCMV 15860), UADBA-ZCMV 15859, and UADBA-ZCMV 15861. An orange ventral color was also remarked by I. Ineich (pers. comm.) in several specimens he collected in Namoroka and which therefore may belong to this species. Unfortunately, no ventral side images from living specimens from Baie de Baly and Tsiombikibo are available, and presence of orange color (which may fade in preservative) cannot be reliably ascertained from these populations. For morphometric and meristic data of paratypes, see Table 3 .

Etymology. The species name is a patronym for the wildlife photographer and gecko specialist Arne Hartig, in recognition for his contributions to the exploration of Madagascar’s gecko fauna and the important support he provided for this study by making photos and information from his previous Namoroka expeditions available.

Habitat and natural history. Lygodactylus arnei is an arboreal species found in dry deciduous forest areas. In Baie de Baly National Park, Lygodactylus arnei has been found at night in an area of the well-developed forests that partly burnt in September 2022 (one year prior to the fieldwork). Although trees in this sector seem to have been relatively spared by the fire, a significant number of smaller trees were dead and in many places the leaf litter on the ground appeared to have been burnt and vegetation had only slightly recovered. In the Tsiombikibo Forest, L. arnei has been found in a forested area where trees are relatively small and densely implanted, and where a relatively thin layer of leaf litter mostly rests on a bed of almost pure white sand. In Namoroka, this species has been more frequently found on tree trunks – or at their base, close to the leaf litter – growing in the border of the Tsingy karstic formation.

Distribution. The species is known from three main locations: (1) The type locality, Baie de Baly (= Baly Bay) National Park, (2) Tsingy de Namoroka National Park, and (3) Tsiombikibo Forest. All three sites are relatively close to each other in the North West of Madagascar, at distances around 50 km from each other. In Namoroka, the species was collected from different sites, suggested it is relatively widespread across the massif.

Figures

FIGURE 7. Specimens of Lygodactylus arnei sp. nov. in life, photographed in October 2023. A, holotype ZSM 64/2023 (field number FGZC 12012) from Baie de Baly; B–C, paratype ZSM 72/2023 (ZCMV 15856) from Namoroka; D, paratype ZSM 68/2023 (ZCMV 15811) from Namoroka.

FIGURE 9. Dorsal and ventral views of the preserved name-bearing types of three new species of the Lygodactylus tolampyae complex described herein.

FIGURE 10. Lateral and ventral views of the head of the preserved name-bearing types of three new species of the Lygodactylus tolampyae complex described herein (not to scale). The images of the ventral views have been modified by a sharpening filter to better appreciate the boundaries between scales. Inset images show enlarged views of the mental (light green), first infralabial (dark green) and postmental (light blue) scale arrangements in the three specimens. The small red arrow points to the contact between posterior projection of mental and first supralabial which is typically broad in the L. tolampyae complex (only moderate in L. andavambato sp. nov.).