Lygodactylus regulus, Portik, Daniel M., Travers, Scott L., Bauer, Aaron M. & Branch, William R., 2013

Portik, Daniel M., Travers, Scott L., Bauer, Aaron M. & Branch, William R., 2013, A new species of Lygodactylus (Squamata: Gekkonidae) endemic to Mount Namuli, an isolated ‘ sky island’ of northern Mozambique, Zootaxa 3710 (5), pp. 415-435 : 423-431

Lygodactylus regulus sp. nov.

Prince Dwarf Gecko ( Figs. 6–8 )

Holotype. MVZ 266138, Adult male, Mozambique, Zambézia Province, Mt. Namuli (15°23'15"S, 37°04'24"E, 1281 m a.s.l.), collected by D. M. Portik, 10 August 2011 ( Fig. 6 ).

Paratypes. Three specimens: MVZ 266137, adult male, Mozambique, Zambézia Province, Mt. Namuli (15°22’28”S, 37°03’54”E, 1421 m a.s.l.), collected by D. M. Portik, 10 August 2011 ( Fig. 7 ); PEM R14922, adult female, Mozambique, Zambézia Province, Mt. Namuli, Ridge leading to Marakuni Ridge (1537AC, 1800 m a.s.l.), collected by P. Ryan, 30 November 1998; PEM R20277, adult female, Mozambique, Zambézia Province, Mt. Namuli, Muretha Plateau (15°23’04.5”S, 37°03’13.6”E, 1878 m a.s.l.), collected by J. Bayliss, 27 May 2007 ( Fig. 8 ).

Etymology. The specific epithet is derived from Latin regulus = petty king, prince. The closest relative of this species is Lygodactylus rex , the King Dwarf Gecko or Regal Dwarf Gecko, which exhibits a larger body size and inhabits nearby Mt. Mulanje, Malawi, an overall larger massif than Mt. Namuli, Mozambique. Given the smaller body size, smaller size of the massif inhabited, and close relationship with the King Dwarf Gecko, we recommend the common name Prince Dwarf Gecko for this species.

Diagnosis. Lygodactylus regulus sp. nov. differs from all other species in the genus Lygodactylus , except for L. angularis , L. picturatus , and L. rex , in its larger body size (males 38–39 mm SVL, females 38–40 mm SVL). Lygodactylus regulus sp. nov. differs from both L. angularis and L. picturatus by having a mental with shallow lateral fissures (mental entire in L. angularis and L. picturatus ), and by having a conspicuous ocellus above the shoulder, a trait shared with L. rex . From the latter it can be distinguished by having an overall smaller body size ( L. regulus sp. nov.: males 38–39 mm SVL, females 38–40 mm SVL; L. rex : males 47–55 mm SVL, females 39–46 mm SVL), often having a condition of three postmentals rather than two postmentals ( L. regulus sp. nov.: 75%, n = 4; L. rex : 37.5%, n = 16), males possessing a greater number of precloacal pores ( L. regulus sp. nov.: 12–13; L. rex : 8–11), having more variability in the condition of contact of first infralabial with the postmental or postpostmentals ( L. regulus sp. nov.: ranging from contact with postmental only to <25% overlap with postpostmental; L. rex : ranging from <25% overlap with postpostmental to 50% overlap with postpostmental), and sometimes displaying a pale dorsolateral stripe originating behind the eye and extending down the trunk. These two species can also be distinguished genetically using mitochondrial or nuclear markers, with average p -distance values between L. regulus sp. nov. and L. rex being 12.9% (ND2), 1.2% (MXRA5), and 3.0% (RAG-1). Finally, the two species are geographically well separated by over 160 km.

Description of holotype. MVZ 266138; Adult male; SVL: 38.9 mm; TrunkL: 18.5 mm; CrusL: 5.9 mm; TaiIL: 49.2 mm; TaiIW: 4.7 mm; HeadL: 11.2 mm; HeadW: 7.0 mm; HeadH: 4.5 mm; EarL: 0.9 mm; ForeaL: 5.3 mm; OrbD: 1.9 mm; NarEye: 3.5 mm; SnEye: 4.7 mm; EyeEar: 3.2 mm; Internar: 2.0 mm; Interorb: 4.1 mm. Build moderate; head very broad and distinct from neck. Snout long and broad, the distance from the tip to anterior border of the eye slightly greater than the interorbital distance anteriorly, greater than the distance between eye and ear opening. Snout covered with heterogeneous flattened granular scales, medium-sized on crown of head and middle of snout, becoming smaller laterally above eye, and larger anteriorly on snout, reaching largest size in loreal region. Scales on the snout larger than those on the occiput, which are, in turn, much larger than the small convex dorsal granules. Canthus rostralis not prominent. Rostral pentagonal, wider than high. Nostril oval and directed slightly posteriorly, bordered by rostral, first supralabial, supranasal, and two postnasals; supranasals separated by a single small internasal granule. Spiny superciliaries present. Mental heptaganol with shallow lateral fissures, followed by two large postmentals. Scales behind postmentals enlarged, decreasing in size towards base of throat, then increasing in size on chest and belly. Supralabials 8-8; infralabials 8-8. Gulars imbricate, 26 between posteriormost infralabials. Dorsal granular scales roughly homogeneous, slightly larger on ventrolateral portions of trunk. Limbs well developed but short, pentadactyl, 1st digit greatly reduced and lacking claw. Distal portions of remaining digits expanded, bearing claw. Six pairs of lamellae under fourth finger; 8 enlarged subdigital scales occur proximally to manual lamellae; six pairs of lamellae beneath fourth toe. Granular scales on dorsal surface of limbs roughly homogeneous and similar size to those on trunk; scales on ventral surface of thighs subhexagonal, subimbricate, and same size as those on trunk; scales on ventral surface of arms subhexagonal, subimbricate, and smaller in size than those on trunk. Precloacal pores 12, arranged in a chevron roughly 6 scale rows anterior to cloaca posteriorly. Three rows of 4–6 enlarged, glandular scales (β-glands) present along the ventral surface of thighs. Tail shape cylindrical, caudal scales dorsally semi-flattened, imbricate, largely homogeneous; subcaudal scales large, flattened, subhexagonal, subimbricate, and arranged in a single broad row. Further measurements are recorded in Tables 4 and 5.

Coloration in ethanol. Above, a more-or-less uniform cinnamon brown background coloration, with a broad continuous kingfisher rufous lateral stripe extending from the shoulder to the base of the tail ( Fig. 6 B). Anterior to the shoulder the stripe breaks and continues irregularly to the posterior border of the eye, narrowing substantially in width. Just above the shoulder is a large black patch with a small white spot in the center. Dorsum of head anterior to crown is uniform burnt umber, throat is sulphur yellow with three pairs of irregular black stripes approximately two granules wide which converge from the labials towards the chest, with the two most distal pairs meeting and the most proximal pair remaining separated by three granules. Dorsal surfaces of limbs cinnamon brown, with irregular lighter markings. Body venter smoky white with no markings or speckling. Gular region suffused with pale sulphur yellow and bearing medium neutral gray markings ( Fig. 6 C, yellow lacking in paratype MVZ 266137 – Fig. 7 D). Dorsum of tail cinnamon brown with lighter chevron pattern (kingfisher rufous to pale pinkish buff), laterally exhibiting 19 cinnamon brown rectangular markings separated by kingfisher rufous background with minute pale pinkish buff spots, ventrally smoky white suffused with grey posteriorly.

Measurements recorded to the nearest 0.1 millimeter. Note: Paratype PEM R20277 has a damaged head and several measurements were unable to be recorded. Museum abbreviations: MVZ, Museum of Vertebrate Zoology, University of California, Berkeley; PEM, Port Elizabeth Museum.

Coloration in life. Recently euthanized specimens prior to fixation ( Figs. 6 A, 7A) are smoke gray to cinnamon-drab in background coloration with darker brown to black markings and a paler thick dorsolateral stripe. In the holotype this stripe contains a series of well-defined circular to oval markings ranging from cinnamon-drab anteriorly to cream white posteriorly. The ocellus anterior to the forelimb insertion is bright white with a black border. In paratype MVZ 266137 the pale dorsolateral stripe extends to the posterior border of the orbit. Paratype PEM R20277 ( Fig. 8 ) exhibits a much more mottled pattern than seen in other members of the type series or in L. rex . This is dominated by brick red and dusky brown to smoky white dorsal markings, including a series of light lateral blotches. The ocellus near the limb insertion is bright white with a blackish surround. Venter of throat and chest bright white; abdomen, thighs and tail venter yellow (between pale greenish yellow and sulphur yellow) with area of β-glands trogon yellow (based on MVZ 266137, Fig. 7 B). The iris is crimson.

Paratype variation. MVZ 266137: Nostril bordered by rostral, first supralabial, supranasal, and one postnasal; mental hexaganol with shallow lateral fissures, followed by three postmentals (two large, one small); supralabials 7-7; infralabials 7-7; precloacal pores 13; gulars between posteriormost infralabials 28. Color in ethanol: Broad kingfisher rufous lateral stripe extends unbroken from base of tail to posterior border of eye, narrowing significantly in width approaching eye. Dorsum of anterior part of head is uniform burnt umber, with 3 to 4 minute cream spots along canthus rostralis. Throat is white with three pairs of irregular black stripes that converge from the infralabials towards the chest. Lateral dark rectangles on tail less conspicuous, but a line of minute pale pinkish buff spots still discernable. PEM R14922: Five pairs of lamellae under 4th finger; mental with shallow lateral fissures, followed by three postmentals (two large, one small); supralabials 7-7; infralabials 8-8. PEM R20277: Five pairs of lamellae under 4th toe; mental with shallow lateral fissures, followed by three postmentals (two large, one small). Additional differences in morphological measurements are recorded in Tables 4 and 5.

Size. Largest male (MVZ 266138) 38.8 + 49.2 = 88.0 mm; largest female (PEM R14922) 40.7 + 38.0 = 78.7 mm (tail truncated).

Distribution and habitat. The holotype (MVZ 266138) was collected from the rafters of a village hut, similar to the structure appearing in the foreground of Fig. 9 A. The immediate surrounding vegetation had been cleared for agricultural plots, however a riparian forest strip was approximately 40 m west of the plot. This limited riparian forest followed the flowing Nanchili drainage below Nanchili Falls, and during a visual survey no specimens were located in this habitat. The paratype, MVZ 266137, was found basking on wooden debris adjacent to a local residence, surrounded by cultivated plots. The paratype PEM R14922 was collected on rock in an open grassy area west of Ukalini Forest on the southern side of Mt. Namuli (15°22’S, 37°03’E, 1800 m a.s.l.) ( Fig. 9 B, C). This area consists of a large granite whaleback with a thin layer of peaty soil that dries seasonally, thereby exfoliating and exposing the rock below (similar to Fig. 9 C). Branch and Ryan (2001) report another individual (presumably L. regulus sp. nov.) was seen on a dead tree stump in similar habitat bordering the forest edge at the southern flank of Peseni, a peak 4 km southwest of Mt. Namuli (15°23’S, 37°02’E). Another paratype (PEM R20277) was collected on the Muretha plateau on an exfoliating rock flake (15°23’04.5”S, 37°03’13.6”E, 1878 m a.s.l.).

Based on the limited number of specimens and observations, Lygodactylus regulus sp. nov. has been found in open grassy habitat between 1281–1878 m a.s.l. and utilizes a variety of basking sites, including exposed rock, tree stumps, woody debris, and artificial habitat. The exposed granite domes forming the main peaks throughout the Namuli massif may also serve as suitable habitat, provided some retreat is available. Lygodactylus regulus sp. nov. has not been recorded in Ukalini Forest, which consists of Afromontane forest vegetation, despite concerted attempts to locate it. All reports indicate this species does not require montane forest or mid-elevation forest habitat, and is often found adjacent to forest habitats. This contrasts with L. rex which is known only from midelevation forest habitats (Lukubula Forest Station, 825 m a.s.l.; Ruo Gorge riverine forest along Lujeri River, 995 m a.s.l.), except for a population on Lichenya Hut on Mt. Mulanje (1858 m a.s.l.). There are no other records of the species on the summit of Mt Mulanje, indicating that the Lichenya Hut population is possibly introduced as the hut is the largest on the mountain and was constructed in the 1920’s for use as a ‘hill station’ allowing families from the tea estates to escape the summer heat (Eastwood 1988). The species has only been observed on trees or buildings, and has not been observed on rocks. However, a series of L. rex eggs were found in a crumbling rock crack sheltered by forest trees in Ruo Gorge.

The broader Namuli massif covers an area of roughly 200 km 2 above 1200 m, with an estimated 300 ha of higher elevation grasslands (Timberlake et al. 2009), and it is likely that L. regulus sp. nov. is dispersed throughout this habitat. A survey at the nearby lower elevation town of Gurué produced only L. capensis , which seems to replace L. regulus sp. nov. at elevations below 800 m (Portik et al. 2013).

Figures

FIGURE 6. Adult male Lygodactylus regulus sP. nov. (holotype MVZ 266138): A) lateral view shortly postmortem (specimen wet from rinse with water), B) dorsal view after preservation, C) ventral view after preservation.

FIGURE 7. Adult male Lygodactylus regulus sP. nov. (paratype MVZ 266137): A) lateral view shortly postmortem (grayish blotch extending from right forebody onto dorsum resulted from injection), B) ventral view shortly postmortem, C) dorsal view after preservation, D) ventral view after preservation.

FIGURE 8. Adult female Lygodactylus regulus sP. nov. in life (paratype PEM R 20277, Muretha Plateau, Mt. Namuli; photo: J. Bayliss).

FIGURE 9. Habitat surrounding localities where Lygodactylus regulus sP. nov. has been collected: A) Cultivated areas immediately south of Mt. Namuli, with typical native residence; B) View of grassy area above Nanchili Falls, adjacent to the southern face Mt. Namuli. Ukalini forest can be seen in the left background, along with areas being modified for agriculture. C) Same location as in (B) but facing west. Exposed granite rock underneath vegetation is visible in the foreground. The large granite whaleback where paratype PEM R 14922 was collected can be seen in the center background. It extends to the right and connects to Mt. Namuli.