Lygodactylus lobeke, Röll & Pinto & Lobón-Rovira, 2024

Röll, Beate, Pinto, Pedro Vaz & Lobón-Rovira, Javier, 2024, A new species of African diurnal dwarf geckos (Gekkonidae: Lygodactylus) from the Lower Guinea rainforest, Zootaxa 5538 (6), pp. 561-574 : 564-570

Lygodactylus lobeke sp. nov.

( Figs. 2–4 , 6 )

Lygodactylus sp. B ( Röll et al. 2010; Mezzasalma et al. 2017)

Lygodactylus sp. 6 ( Gippner et al. 2021)

Holotype. ZSM 59/2024 , adult female, collected in the Lobeke region , south of Goumela (Koumela), Region East, south-eastern Cameroon, at geographical coordinates N2.4557, E15.4203, about 500 m above sea level (a.s.l.), on 26 th March 2002 by Beate Röll, Alexander Pelzer & Mathias Heinze.

Paratype. FKH 1259 , probably subadult, but sexually mature male, collected in Sanga Wanda , Mayombe National Park, Cabinda Province, Angola, at geographical coordinates S4.6253, E12.4583, 221 m a.s.l., on 6 th June 2023 by Pedro Vaz Pinto & Michael Mills .

Diagnosis. A moderately sized dwarf gecko, clearly belonging to the L. scheffleri -group on the basis of the double series of transversely enlarged subcaudals ( Fig. 3c ) and phylogenetic results ( Fig. 5 ). In its coloration, L. lobeke sp. nov. differs from most other species of the L. scheffleri -group either by lacking conspicuous dark patches on shoulders and/or on the sides (as in L. scheffleri , L. laterimaculatus ) or lacking a colored underside (as in L. broadleyi , L. conradti , L. gravis ).

Comparative diagnosis. It differs from L. broadleyi by the color of the underside (whitish in belly and tail versus yellow and red), by a higher longitudinally count of dorsal scales (240–250 versus 212–235) and by a higher number of precloacal pores (9 versus 6).

It differs from L. conradti by the color of the underside (whitish versus bright yellow in males), by lacking a prominent light dorsolateral stripe, by a different number of supralabials (7 versus 8), by a higher number of dorsal scales (240–250 versus 218) and by a higher number of precloacal pores (9 versus 5–7).

It differs from L. gravis by smaller size (SVL of 32.5 mm versus 38–42 mm), by the color of the underside (whitish versus yellow to red in females and males), by the color of the scales of the pseudo-escutcheon sensu Bons & Pasteur (1977) (see description of paratype) (shiny yellowish versus beige), by a higher number of dorsal scales (240–250 versus 158–195) and by a slightly higher number of precloacal pores (9 versus 8).

It differs from L. scheffleri by lacking dark spots on the neck and on the flanks in males, by a higher number of dorsal scales (240–250 versus 163–166), by a higher number of labials (7 infralabials versus 5–6, 7 supralabials versus 5–6) and by a higher number of precloacal pores (9 versus 6).

It differs from L. laterimaculatus by the lack of large dark blotches on the flanks in males, by the color of the scales of the pseudo-escutcheon (shiny yellowish versus brown or dark brown), by a higher number of infralabials (7 versus 5–6) and by a higher number of precloacal pores (9 versus 6–7).

Other members of the L. scheffleri -group include two poorly known taxa, L. scheffleri compositus and L. ulugurensis , originally described as a subspecies of L. scheffleri . The taxon compositus is characterized by a large dark blotch on the neck and seven precloacal pores in males. Lygodactylus lobeke sp. nov. differs from the taxon ulugurensis by the color pattern of the throat (stippled with dark spots versus a dark median line flanked by convergent lines), by the numbers of post- and postpostmental scales (3 and 5 versus 2 and 4) and a higher number of precloacal pores (9 versus 5–6).

Lygodactylus lobeke sp. nov. differs from L. fischeri (holotype, BMNH 1946.8.22.45), currently placed within the L. fischeri -group, by the lack of a large dark blotch above the shoulders and of several dark blotches on the flanks, by numbers of labial scales (7 supralabials versus 9, 7 infralabials versus 6) and a slightly lower number of precloacal pores (9 versus 10).

Phylogenetics. Lygodactylus lobeke sp. nov. belongs to the L. scheffleri -group as identified by Röll et al. (2010) and confirmed by Gippner et al. (2021). The result of the phylogenetic analysis presented here recovered L. lobeke sp. nov. as an independent clade (PP: 1, BS: 100; Fig. 5 ), sister of the other members found East to the Albertine Rift (namely, L. laterimaculatus and L. gravis ), in agreement with the results found by Röll et al. (2010) and Gippner et al. (2021). However, as several members within this group still lack genetic material, the phylogenetic hypothesis of this group remains unclear and needs further investigation. L. lobeke sp. nov. differs from other members of the group by c. 9.01% and 12.99%, respectively in 16S uncorrected p-distance. The two known specimens of L. lobeke sp. nov. differ by 3.5% (16S uncorrected p-distance) to each other.

Description of the holotype. Adult female, in good state of preservation, tongue removed for genetic investigations ( Fig 4a–d ). SVL 32.5 mm, TL 32 mm, tail doubly regenerated (last 18 + 5 mm), HW 5.2 mm; HL 7.7 mm.

Rostral scale slightly smaller in width than the mental scale. Posterior margin of the nostril exactly above the suture of rostral and first supralabial scale; nostril surrounded by following scales: rostral and first supralabial, one postnasal, one supranasal and nasal. Two internasal scales. Seven infralabial scales, seven supralabial scales (right and left sides, respectively). Mental scale bell-shaped and semi-divided with sutures ( Fig. 3a ). Three postmental scales, outer scales of same shape and size, separated by a smaller one. Five postpostmental scales. Gulars decrease gradually in size until the posterior margin of the eyes, after that the gulars are distinctly smaller and similar in size. Number of dorsal scales 246, number of ventral scales 98. Nine precloacal spots corresponding to precloacal pores in males. Fourth toe with four pairs of subdigital lamellae. Original part of tail with two median rows of subcaudal scales distinctly enlarged transversely ( Fig. 3c ). Scales of the regenerated parts (regenerates 1 and 2) below irregularly arranged. Tip of tail (regenerate 2) tapered, caudal adhesive pad consisting of small irregularly arranged scales with setae ( Fig 4d ).

In life (after capture), the holotype had a fawn to beige-brownish ground coloration on dorsum and tail, with a slightly lighter streak dorsolaterally ( Fig. 2a–b ). Additionally, head, dorsum, flanks und upper side of the legs exhibited dark and light mottling.A dark line extended from the tip of the snout through the eye and ended above the ear opening. Several rows of light, partly dark-edged spots were arranged longitudinally on the dorsum. The short original part of the tail had two adjoining light spots followed by a light cross-band. Throat, belly and underside of the tail were whitish, the throat was stippled with dark spots. (see also Results: Natural history.)

After 17 years in ethanol, the holotype is faded and appears almost homogenous fawn. However, the dark line from the tip of the snout in direction of the ear opening and the light spots as well as the light crossband on the tail are still visible.

Description of the paratype. Subadult male in moderate state of preservation ( Fig. 4e–h ). Visceral cavity opened for tissue removal for genetic analyses. Tail broken close to the body and with necrotic tissue of older date shortly before the tail tip. SVL 26.5 mm, TL 25.7 mm, HW 5.1 mm, HL 9.5 mm.

The scalation of the paratype is the same as in the holotype ( Fig. 3b, d ). Due to epidermal injuries the numbers of dorsal and ventral scales cannot be counted. Tail with two rows of distinctly enlarged subcaudals. Typically arranged caudal adhesive lamellae are missing. The male paratype has nine precloacal pores ( Fig. 3d ). The pseudo-escutcheon, also called ss-glands or ss-scales ( Maderson 1968; Bons & Pasteur 1977), consists of shiny yellowish scales in the precloacal and postcloacal region and on the inner sides of the thighs.

The coloration of the live male paratype (after capture) corresponds largely to that of the holotype except for the numbers of longitudinally rows of spots on the dorsum ( Fig. 2c–d ). In the paratype, there were two rows of light spots, partially edged dark brown towards the spine. The freshly broken tail had indistinct, nearly equidistant light crossbands.

After almost one year in formalin and ethanol, the head of the paratype has become dark ( Fig. 4e, g ). The upper sides of the body and the tail have a grey-brownish ground coloration with some dark mottling. The pattern consisting of light, dark-edged blotches is hardly visible. The modified scales of the pseudo-escutcheon have lost their color ( Fig. 4f ).

Etymology. The name ‘lobeke’ is a noun in apposition and refers to the Lobeke region in south-eastern Cameroon, where the holotype of this species was found. The species is named in honor of this tropical rainforest region, which is also home of the Lobeke National Park (Parc National de Lobéké). The name indirectly honors Mathias Heinze (German Agency for Technical Cooperation [GTZ], at that time Yokadouma), who was one of the ‘architects’ of Lobeke National Park and suggested the name in September 2022. Mathias died suddenly and unexpectedly on 6 th December 2022. As common names we suggest ‘Lobeke Dwarf Gecko’ in English, ‘Lobeke-Zwerggecko’ in German, and ‘Osga-Anã de Lobeke’ in Portuguese.

Distribution. Lygodactylus lobeke sp. nov. is known from two localities of the western rim of the Congo Basin in Central Africa with a linear distance of about 850 km from each other ( Fig. 1 ). The Congo Basin includes the forests between the western edge of the Albertine Rift highlands and the Gulf of Guinea, comprising the largest contiguous African rainforest block. Specifically, both localities of L. lobeke sp. nov. lie in the Lower Guinea rainforest that constitutes the western component of the Congo Basin ( Hardy et al. 2013). As L. lobeke sp. nov. apparently is an arboreal and forest-dependent species, its area of distribution presumably includes further parts of the Lower Guinea region, possibly including Gabon, Equatorial Guinea, Republic of the Congo, and western Democratic Republic of the Congo.

Natural history. The species apparently inhabits humid rainforests. The holotype was found during the day, resting under a sliver of bark at a height of about 1.5 m. Careful search with binoculars for several days did not yield a second specimen. The species also seemed to be unknown to local people. The paratype has been found among leaf litter while preparing a camp site in the forest. It may have fallen from the tree canopy above. Subsequent attempts to find more specimens in the area also did not produce results. Presumably, L. lobeke sp. nov. inhabits the canopy region and therefore is rarely met in lower heights.

The holotype of L. lobeke sp. nov. lived for about 5 years in a laboratory colony of several species of Lygodactylus . Thus, the animal could be observed much more thoroughly than had been possible in the natural habitat. Like several other species of the genus Lygodactylus ( Röll 2013, Röll et al. 2023), it possessed distinct ‘mood dependent’ colorations, comprising a ‘neutral’, a ‘distress’, a ‘display’, and a ‘pyjamas’ coloration ( Fig. 6 ). In the neutral coloration, the ground color was beige to light brown and the dorsolateral streak was only indistinct ( Fig. 6c ). In the display coloration, L. lobeke sp. nov. has a fawn ground coloration. Dorsal pattern elements, e.g., light patches, are hard to recognize ( Fig. 6d ). In response to stress, the animal became darker, the dorsal pattern was richer in contrast and the dorsolateral streak was clearly visible (‘distress’ coloration, Fig. 6a–b ). At night, the animal generally rested on leaves of plants in the terrarium. Asleep, it showed a characteristic ‘pyjamas’ coloration with conspicuously whitish lateral bands extending from the neck over the flanks and the tail to the tail tip ( Fig. 6e ).

Figures

FIGURE 1: Habitats and geographical distribution of Lygodactylus lobeke sp. nov. on a hybrid map of the major vegetation divisions (Sayre et al. 2013) and 1 arc-second elevation map across tropical Africa (NASA 2000). Photos of habitats from (a) type locality (holotype) near Goumela, southeastern Cameroon, and (b) second locality (paratype) near Sanga Wanda, Mayombe National Park, Cabinda Province, Angola. Photographs by B.R. (a) and J.L-R. (b).

FIGURE 2: Lygodactylus lobeke sp. nov. in life, shortly after capture. Female holotype: lateral (a) and dorsal views (b). Male paratype: lateral (c) and dorsal views (d). Photographs of holotype: ambient light, analog (Kodachrome 200) (2002), photographs of paratype: flash, digital (Canon EOS 6D Mark II) (2023). Photographs by B.R. (a, b) and P.VP. (c, d).

FIGURE 3: Lygodactylus lobeke sp. nov. in life. (a) Chin and (c) precloacal region and proximal part of the tail of the female holotype. Precloacal region with 9 precloacal spots, corresponding to the precloacal pores in the male specimen. Arrowheads in (c) mark row of precloacal scales with spots. Original part of tail with double row of enlarged subcaudal scales, two of which are marked with circles. Inset: same, contrast enhanced. (b) Chin and (d) precloacal region and pseudo-escutcheon (yellow scales) of the male paratype. Precloacal region with 9 precloacal pores. Arrowheads in (d) mark row of precloacal pores. Photographs by B.R. (a, c) and P.VP. (b, d).

FIGURE 4: Lygodactylus lobeke sp. nov. type material in preservative. a) to d) female holotype (ZSM 56/2024): a) dorsal and b) ventral views; c) dorsal view of head, d) ventral view of (regenerated) tail tip. e) to h) male paratype (FKH 1259): e) dorsal and f) ventral views; g) dorsal view of head, h) ventral view of (regenerated) tail tip. Photographs by B.R. (a–d) and P. VP. (e–h).

FIGURE 5: Phylogenetic relationships of Lygodactylus lobeke sp. nov. (Left) Maximum likelihood tree based on partitioned multigene analysis constructed with iQtree, including information from Gippner et al. (2021), plus all available samples of the L. scheffleri group, with collapsed groups defined by Gippner et al. (2021). (Right) Detailed phylogenetic placement of Lygodactylus lobeke sp. nov. within the L. scheffleri group. Support values are shown above (PP = Bayesian Inference posterior probabilities) and below (BS = Maximum Likelihood bootstrap values) the nodes.

FIGURE 6: Lygodactylus lobeke sp. nov. female holotype in life: ‘Mood dependent’ colorations. (a) and (b) ‘distress’ coloration (compare coloration shortly after capture, see Fig. 2a); (c) ‘neutral’ coloration; (d) ‘display’ coloration; (e) ‘pyjamas’ coloration (resting at night on a leaf). Photographs by B.R.