Boophis lilianae, Köhler, Jörn, Glaw, Frank & Vences, Miguel, 2008

Köhler, Jörn, Glaw, Frank & Vences, Miguel, 2008, Two additional treefrogs of the Boophis ulftunni species group (Anura: Mantellidae) discovered in rainforests of northern and south-eastern Madagascar, Zootaxa 1814, pp. 37-48 : 42-46

Boophis lilianae sp. n.

Holotype. ZSM 201/2006 (field number ZCMV 2864), adult male, from km 6 on road Ifanadiana–Tolongoina, 21°21'21'' S, 47°36'47'' E, 468 m above sea level, Fianarantsoa Province, Southern Central East of Madagascar, collected on 22 February 2006 by L. Raharivololoniaina.

Paratype. ZSM 202/2006 (field number ZCMV 2865), adult female, same data as holotype.

Remark. This species was referred to as Boophis sp. aff. rappiodes "South" by Glaw & Vences (2007: pages 174-175).

Diagnosis. A species of the B. ulftunni species group (sensu Wollenberg et al. 2008). Boophis lilianae is so far the smallest known species in the genus. It is distinguished from other species groups of Boophis containing green species as follows. From members of the B. albilabris and B. microtympanum species groups, the new species differs by green dorsal colouration with translucent shade in life (versus opaque green) and much smaller size. It mainly differs from all species in the B. rappiodes and B. mandraka groups by a pigmented ventral side (versus inner organs visible through transparent ventral skin) and smaller size. Boophis lilianae differs from all species of the B. albipunctatus and B. luteus groups by smaller size and lack of lateral dermal fringes along lower arm and tarsus. Furthermore, B. lilianae strongly differs from all the species contained in the mentioned groups by molecular characters. From the other two species in the B. ulftunni group, B. lilianae mainly differs as follows: From B. ulftunni by smaller size (SVL 18.3 versus 21-24 mm in males, 20 versus 32–38 mm in females), iris colouration (inner iris ring silvery grey versus purple) and mucronate snout shape in males. From B. baetkei by smaller adult male size (30.8 versus 18.3 mm SVL), mucronate male snout shape in dorsal view (versus rounded) and a relatively smaller tympanum. Boophis lilianae furthermore differs from B. baetkei and B. ulftunni by the lack of prominent vomerine odontophores.

Description of the holotype. Adult male, SVL 18.3 mm. Body slender; head as wide as long, wider than body; snout mucronate in dorsal view, obtuse in lateral view; nostrils directed laterally, distinctly protruding, as close to tip of snout as to eye; canthus rostralis rounded, loreal region slightly concave; tympanum distinct, rounded, TD 30% of ED; supratympanic fold weak; tongue narrowly cordiform, posteriorly distinctly bifurcated and half free; vomerine odontophores not evident; choanae small, rounded. Arms slender, subarticular tubercles small, single, round, weakly developed; metacarpal tubercles not recognizable; fingers with basal webbing and lateral dermal fringes; webbing formula 1(1), 2i (2), 2e(1), 3i (2), 3e(1.5), 4(1); relative length of fingers 1<2<4<3; finger discs moderately enlarged; distinct, medium-sized nuptial pad on inner side of first finger, unpigmented. Hindlimbs slender; tibiotarsal articulation reaching snout tip when hindlimb is adpressed along body; lateral metatarsalia separated by webbing; inner metatarsal tubercle distinct, elongated; no outer metatarsal tubercle; webbing between toes well-developed, lateral dermal fringes present; webbing formula 1(1), 2i (1), 2e(0.25), 3i (2), 3e(0), 4i (0.75), 4e(0.75), 5(0.5); relative length of toes 1<2<5=3<4; toe discs moderately enlarged. Skin smooth on dorsal surface with widely scattered minute tubercles, smooth on throat and chest, coarsely granular on belly, glandular around cloacal opening; no distinct enlarged tubercles in the cloacal region.

Measurements (in mm): SVL 18.3, HW 6.5, HL 6.5, ED 2.7, END 1.0, NSD 1.0, NND 1.9, TD 0.8, TL 9.4, HAL 5.4, FOL 7.0, FOTL 12.2.

After nineteen months in preservative, ground colour of flanks, dorsal and ventral surfaces creamy yellow. A pink canthal stripe running from tip of snout to upper eyelid. Nostril encircled by thin brown line. Upper eyelid covered by brown blotch, bordered by pink spot posteriorly. Triangular brown fleck between eyes, its tip directed posteriorly. Thin pink supratympanal line continuing as thin dorsolateral line, fading at level of urostyle. Two fine longitudinal parallel stripes on mid-dorsum formed by rows of pink spots, extending from behind scapular region to level of sacral vertebra. Few minute pink spots irregularly scattered on dorsum. Small pink fleck on knee.

In life, ground colour of upper surface of head, dorsum and flanks translucent yellowish green, slightly transparent in groin. A reddish canthal stripe running from tip of snout to upper eyelid. Thin reddish supratympanic line continuing as fine red dorsolateral line and fading at level of urostyle. Upper eyelid covered by reddish brown blotch. Weak brownish triangular fleck between eyes, its tip directed posteriorly. Two fine longitudinal parallel stripes on mid-dorsum formed by rows of reddish to pink spots, extending from behind scapular region to level of urostyle. Between these stripes, some irregular pink marbling on mid-dorsum. Few minute irregularly scattered reddish brown spots on dorsum. Irregular reddish brown spots on heel and knee. Dorsal surfaces of fingers, toes and terminal discs yellowish green. Ventral surfaces of limbs, chest and posterior half of throat translucent turquoise green, anterior half of throat translucent yellowish green. Belly white with a turquoise shade. Bones green. Inner iris silvery grey, with a fine brownish circular line. Outer iris golden yellowish, with a black triangular fleck median above and below pupil, respectively. Posterior iris periphery black, followed by light blue ( Fig. 3 ).

Variation. Measurements (in mm) of the female paratype are as follows: SVL 20.0, HW 7.2, HL 7.1, ED 2.7, END 1.5, NSD 1.3, NND 1.9, TD 1.0, TL 11.0, HAL 5.8, FOL 8.3, FOTL 13.6. The snout is rather truncate in dorsal view in the paratype, compared to the distinctly mucronate shape in the holotype. In preservative, the paratype exhibits more extensive pink colour on dorsum, formed by several irregular blotches and flecks on mid-dorsum. The pink dorsolateral lines are partly interrupted, generally wider and more irregular in outline. The brown flecks on upper eyelids contain a layer of pink colour. Two distinctly separated pink middorsal spots are present posteriorly to the triangular brown fleck between eyes. In life, the red dorsolateral stripes are bordered by bold silvery white blotches. Minute white spots are scattered on dorsal surfaces of limbs. The skin in groin and posterior dorsum is almost completely transparent ( Fig. 4A ). Tentatively judging from the two available specimens, a difference of only 8.5% in the SVL between the adult male and adult female, sexual dimorphism in body size is less pronounced than usually observed in species of green Boophis (see Fig. 4 B).

Molecular differentiation. A 16S rRNA sequence (462 bp) of the holotype of B. lilianae has been deposited in Genbank (accession number EU314953 ). This sequence had an uncorrected sequence divergence of 8.7% (40 substitutions) as compared to the holotype of B. baetkei , and of 10.0% (46 substitutions) to B. ulftunni .

Distribution and natural history. So far only collected from the type locality. The two type specimens were collected at night in amplexus. They were sitting on low vegetation in a swampy area formed by a slowly moving stream that flooded large parts of a small patch of dense palm forest next to highly degraded rainforest. The female contains yellowish eggs (each approximately 1.6 mm in diameter) in its oviducts as visible through the transparent skin on flanks, indicating that reproduction was taking place at the time of collecting (during the rainy season). Boophis lilianae occurs in sympatry with B. madagascariensis , B. opisthodon , and B. pyrrhus . Despite intensive searches at the type locality, on the same day the amplecting specimens were collected, and on at least 5 other occasions, no further specimens could be found and no calls potentially assignable to this species were heard. In 2007, we collected, at the type locality, tadpoles assignable to this species which will be described elsewhere. One further pair in amplexus, tentatively assignable to this species, has been observed and photographed by A. Strauß and J. Glos on 22 January 2008 at a site locally known as Imaloka in the Ranomafana National Park (21°14’32’’ S, 47°27’55’’ E, approximately 900-1000 m a.s.l.). The specimens were sitting about 1.5 m high on leaves of a shrub above a small, rather slow moving stream with sandy substrate. According to our observations, B. lilianae may either be very secretive or seasonal in its calling behaviour.

Etymology. This species is dedicated to Liliane Raharivololoniaina who collected the two type specimens, in recognition of her contribution to the study of Madagascan amphibians and her continuous help during our field expeditions. The terminal "e" in "Liliane" has intentionally been omitted in the species name for easier pronunciation.

Figures

FIGURE 3. Male holotype of Boophis lilianae sp. n. (ZSM 201 / 2006) in life. A. Dorsolateral view, B. Ventral view. SVL 18.3 mm.

FIGURE 4. A. Female paratype of Boophis lilianae sp. n. (ZSM 202 / 2006) in life, dorsolateral view. Note eggs visible through transparent skin. SVL 20.0 mm. B. Male and female of Boophis lilianae sp. n. in amplexus, showing the minimal sexual dimorphism in body size.