Arthroleptis langeri, Rödel & Doumbia & Johnson & Hillers, 2009

Rödel, Mark-Oliver, Doumbia, Joseph, Johnson, Alex T. & Hillers, Annika, 2009, A new small Arthroleptis (Amphibia: Anura: Arthroleptidae) from the Liberian part of Mount Nimba, West Africa, Zootaxa 2302 (1), pp. 19-30 : 20-24

Arthroleptis langeri sp. nov.

Figs 1–2

Holotype. ZMB 74038 (GenBank: GU119909 ), subadult male, Liberia, Mount Nimba, Nimba-East , forest, 567 m a.s.l., N 07.40806°, W 008.58436°, 25 January 2009, coll. J. Doumbia, A. T. Johnson & K. Camara.

Diagnosis. The genetic results and the following morphological characters: presence of a fine vertebral skin raphe, lack of webbing and lack of tarsal tubercle; characterize the new species as a member of the genus Arthroleptis . From other congeners if differs: genetically by at least 13.4% in the investigated part of the 16S rRNA gene, as well as by a combination of completely smooth skin, rounded canthal region, slender elongated body, and a unique color pattern consisting of a reddish brown back with a black bordered crown like figure in the scapular region.

Description of the holotype (measures in mm). A small Arthroleptis with an oval, slightly elongated body shape; snout-urostyle-length: 16.2; short snout, rounded in dorsal and almost spatulate in lateral view; canthus rostralis indistinct and rounded; loreal region slightly concave; head-width directly behind the eyes: 5.3; eye large, almost reaching distance eye–snout tip, eye-diameter: 1.8; distance eye-nostril: 1.7; distance nostril-snout tip: 0.7, nostril closer to snout than to eye; tympanum present but indistinct, tympanum diameter: 1.0, smaller than diameter of eye; femur: 7.8, slightly longer than tibio-fibula: 7.4; foot including longest toe: 11.5; hand with large, ovoid palmar and thenar tubercles; fingers with small round to ovoid subarticular tubercles, no additional tubercles on hands; male sex externally indicated by slightly prolonged third finger; finger without spines; relative finger length: 1<2<4<3; palmar webbing absent; tarsal tubercle absent; elongated, slender, internal metatarsal tubercle, approximately reaching one third of shortest toe length; outer metatarsal tubercle not discernible (but feet slightly dried up); relative toe length: 1<2<5<3<4; no pedal webbing; toe and finger tips slightly expanded without forming discs; dorsal and ventral skin smooth; back with fine vertebral skin raphe.

Overall coloration of the dorsum reddish-brown; dorsal part of snout and upper eyelids grayish with black and brown mottling; iris reddish; black interorbital stripe; posterior to this stripe a black flat U, encircling a gray spot, and two black comma shaped figures; slightly posterior to the scapular region a black bordered crown like figure (top of crown pointing towards the frog’s head), the interior part of this figure with the same color as the remaining back; small blackish figure in the center of back; loreal area and flanks blackish; dark pattern on flanks interrupted by a reddish brown band stretching from behind the scapular crown pattern to groin; anterior to groin area blackish pattern and blackish inguinal bands; upper and lower mandible almost uniform blackish; upper arm almost uniform reddish brown, base darker; lower arm almost black with lighter parts on elbow and towards hand; hands almost uniform gray; upper legs reddish brown with one dark transverse bar and irregular blackish spots; lower leg same color with one dark transverse bar, the lowest third with a reddish spot; feet almost uniform gray; throat, ventral parts of upper arms and lower legs dark brown; belly grayish; ventral part of upper legs whitish; color in preservation faded to grayish brown; pattern still recognizable.

Genetics. In our analysis the new species clustered together with the other species, currently placed within Arthroleptis . In the 592 investigated base pairs of the 16S rRNA gene A. langeri sp. nov. differed from Leptopelis bocagei by 21.9% and to Astylosternus diadematus by 20.0%, respectively. Against sequences of two A. aureoli the new species differed by 17.9%. We compared the 16S sequence of the new species with further 172 tissue samples from various African Arthroleptis taxa, predominantly from West African localities, including A. crusculum and A. cf. nimbaensis . The average genetic distance was 14.8 ± 0.01% (range: 13.4–16.7%, N= 172). We found the smallest difference to an Arthroleptis stenodactylus sample from Tanzania (CAS 168455; GenBank: FJ151054 ). Compared to Arthroleptis samples from Mount Nimba ( A. crusculum : N= 4; two morphologically identical species, tentatively assigned to A. nimbaensis : N= 6, see Appendix), A. langeri sp. nov. differed by 14.5–16.0% (15.2 ± 0.01%, N= 10).

Natural history. The only specimen known so far was collected in primary forest, characterized by an almost closed canopy (75%), within a nearly dry river bed. The little water that was left was running over a rocky area were small puddles formed in suppressions. The search was carried out during the dry season at daytime and the specimen was found being active shortly before midday. The guts contained remnants of 3– 4 specimens of different minute ant or termite species (differently shaped mandibles and thorax parts).

Distribution. Arthroleptis langeri sp. nov. is only known from the type locality ( Fig. 3 ). Its occurrence in other nearby forests in Liberia, as well as in Guinea and Côte d’Ivoire seems likely. At present its conservation status is Data Deficient.

Etymology. The species name is a patronym and was chosen to honor Detlev Langer, serving from August 1990 to September 2009 as technical assistant in the herpetological collection of the Museum für Naturkunde, Berlin.

Figures

FIGURE 1. Holotype of Arthroleptis langeri sp. nov. (ZMB 74038) in life.

FIGURE 2. Right hand of Arthroleptis langeri sp. nov. (ZMB 74038), showing the slightly prolonged third finger and the lack of digital spines.

FIGURE 3. Position of the type locality (star) of Arthroleptis langeri sp. nov. at the south-eastern tip of the Mount Nimba range, Liberia. The study area is indicated as black square in the inlet figure of Africa (map based on the ASTER Global Digital Elevation Model: www.ersdac.or.jp.)