Leptolalax (Lalos) pluvialis Ohler, Marquis, Swan & Grosjean, 2000

Ohler, Annemarie, Wollenberg, Katharina C., Grosjean, Stéphane, Hendrix, Ralf, Vences, Miguel, Ziegler, Thomas & Dubois, Alain, 2011, Sorting out Lalos: description of new species and additional taxonomic data on megophryid frogs from northern Indochina (genus Leptolalax, Megophryidae, Anura) 3147, Zootaxa 3147 (1), pp. 1-83 : 44-46

Leptolalax (Lalos) pluvialis Ohler, Marquis, Swan & Grosjean, 2000

( Fig. 17–18 )

Leptolalax pluvialis Ohler, Marquis, Swan & Grosjean, 2000: 74 .

Onymophoront: holophoront, by original designation as “ holotype ”, MNHN 1999.5675 , adult male, SVL 22.0 mm .

Other protaxonts: MNHN 1999.5674 and MNHN 1999.5676 , 2 adult males (paratypes), SVL 21.3–22.3 mm .

Onymotope : Fan Si Pan mountain range (22°19’ N, 103°47’ E; 1900 m), Lao Cai Province, Vietnam. Collected by Annemarie Ohler and Stéphane Grosjean, 28 July 1998 .

Material examined. Vietnam. Lao Cai Province, Fan Si Pan mountain range (22°19’ N, 103°47’ E; 1900 m): MNHN 1999.5674 – 5676 , adult males (hypodigm) . Coll. Annemarie Ohler and Stéphane Grosjean, 28 July 1998.

Comment. All three specimens of the hypodigm have been included in the molecular analysis. They form the sister group of specimens allocated to a clade that includes L. aereus , L. minimus , L. nyx and L. ventripunctatus . They can be distinguished morphologically from the other representatives of this clade by their smaller size and the dense brown spotting on belly and chest. The holophoront is redescribed to allow easier comparison and in order that all characters used for the new species are described in the same way.

Diagnosis. Member of the subgenus Lalos based on the presence of lateroventral glands and molecular phylogenetic relationships ( Fig. 4 ), distinguished from other species included in this subgenus by the following combination of characters: very small-sized species (males 21.0–22.0 mm) ( Table 3) with rudimentary webbing and no fringes on toes; tympanum distinct; dermal ridges under toes distinct; finger tips not dilated; dorsal skin smooth (Table 4); dorsum greyish brown with dark pattern; few black spots on flanks; ventral side with dense brown spots; iris dark golden above ( Table 5).

Description of the holophoront, adult male MNHN 1999.5675. Size and general aspect. (1) Specimen of small size (SVL 22.0 mm), body moderately slender.

Head. (2) Head of medium size, narrower (HW 8.1 mm) than long (HL 8.5 mm; MN 6.7 mm; MFE 5.5 mm; MBE 2.2 mm), convex. (3) Snout slightly protruding, its length (SL 4.0 mm) longer than horizontal diameter of eye (EL 3.3 mm). (4) Canthus rostralis angular, loreal region concave, vertical. (5) Interorbital space convex, slightly larger (IUE 2.8 mm) than upper eyelid (UEW 2.7 mm) but narrower than internarial distance (IN 3.0 mm); distance between front of eyes (IFE 4.6 mm) about two-thirds of the distance between back of eyes (IBE 7.5 mm). (6) Nostrils oval, closer to eye (EN 1.4 mm) than to tip of snout (NS 2.0 mm). (8) Tympanum (TYD 1.7 mm) distinct, rounded; about half of eye diameter, tympanum-eye distance (TYE 0.7 mm) two-fifths of its diameter. (11) Tongue moderate, cordate.

Forelimbs. (12) Forearm short, thin (FLL 6.2 mm), longer than hand (HAL 6.0 mm), not enlarged. (13) Fingers I–II and IV rather short and rather strong; finger III long and rather strong (TFL 4.0 mm). (15) Tips of fingers not enlarged. (16) Finger II with dermal fringe.

Hindlimbs. (19) Shanks about four times longer (TL 11.4 mm) than wide (TW 3.1 mm), longer than thigh (FL 10.9 mm) and than distance from base of internal metatarsal tubercle to tip of toe IV (FOL 10.8 mm); heel reaching nare when limbs folded forward. (20) Toe IV (FTL 6.35) about one-third of distance from base of tarsus to tip of toe IV (TFOL 17.2 mm). (22) Tips of toes not enlarged. (23) Webbing absent (MTTF 3.9 mm; MTFF 3.7 mm; TFTF 6.6 mm; FFTF 6.7 mm). (24) Dermal fringe along toe V absent. (26) Inner metatarsal tubercle rather long and prominent; its length (IMT 1.7 mm) 1.9 times in length of toe I (ITL 2.2 mm).

Skin. (29) Dorsal and lateral parts of head and body: snout, region between eyes, side of head and back smooth; flank with flat glandular warts. (30) Supratympanic fold distinct, from eye to shoulder. (31) Dorsal parts of limbs: forelimbs, thigh, shank and tarsus smooth. (32) Ventral parts of head, body and limbs: throat, chest, belly and thigh smooth. (33) Presence of macroglands: lateroventral ridges present as continous ridges of small glands; large, distinct rounded femoral and oval axillary glands; smaller distinct oval suprabrachial glands.

Coloration. In alcohol: (34) Dorsal and lateral parts of head and body: dorsal parts of head and dorsum and upper part of flanks greyish-brown with black band between the eyes, a black W-shaped pattern in the shoulder region and a black V in the sacral region; lower part of flanks dark greyish-brown; loreal region blackish-brown; tympanic region including tympanum dark brown with a white band under the tympanum; upper lip dark brown with white and blackish spots. (35) Dorsal parts of limbs: dorsal part of forelimbs, of thigh, of shank and of foot grey-brown with blackish crossbands; posterior part of thigh blackish with small white spots. (36) Ventral parts of head, body and limbs: throat dirty white; margin of throat dark brown with small white spots; chest and belly dirty white with dark brown marbling; thigh brown with some white spots; macroglands white.

In life: Iris dark golden above. Upper parts of head and dorsum, flanks and tympanic region grey brown with dark brown pattern, particularly in tympanum and loreal region; upper lip grey-brown with dark brown and whitish-grey bands. Upper part of forelimbs ochre, forearms grey-brown and dark brown; hindlimbs with dark brown and grey-brown crossbands; heels ochre; posterior part of thigh grey-brown with ventrally a dark brown zone. Throat transparent light grey-brown with dark brown margin bearing white spots; chest and belly grey with dark grey marbling; lower part of thigh transparent dark brown with whitish spots. Macroglands whitish grey.

Male secondary sexual characters: (38) Vocal sacs inconspicuous, skin of gular region not modified; inner openings of vocal sacs present, located laterally and posteriorly in the floor of the mouth, distinct; rounded.

Variation. The two other male protaxonts resemble strongly the holophoront in coloration and morphology. Female sexual characters: Not observed.

Distribution. Known only from onymotope ( Fig. 9 ).

Natural history. Three adult male specimens of this species were collected calling during heavy rain, while sitting on branches and leaves near a small forest stream. They can be distinguished from sympatric Leptolalax bourreti by their smaller size, ventral coloration and absence of dark spots on flanks. L. bourreti was very abundant in October and November 1997, and was collected in the precise locality of L. pluvialis , but was rather rare in July, when L. pluvialis was breeding.

Etymology. From Latin pluvialis : created by the rain, commanding the rain, rainy.

Placement in molecular phylogeny. Leptolalax pluvialis is part of a clade that groups with high support L. aereus , L. minimus , L. nyx and L. ventripunctatus . The specimens allocated to L. pluvialis form a well-supported clade which, with high support, is the sister taxon of a poorly supported clade including all the other taxa mentioned.

Conservation status. L. pluvialis is still only known from the original description. Its conservation status remains unchanged: Data Deficient.

Figures

FIGURE 4. Combined 16SrRNA Bayesian phylogeny and haplotype networks of 113 Leptolalax specimens with hierarchical outgroups (schematic representation in the grey box) The tree topology corresponds to the Bayesian topology obtained with three million generations, values on nodes indicate posterior probabilities (asterisks> 95 %, double asterisks> 99 %), and Maximum Likelihood bootstrap support values (> 70 %). Red numbers are the percentage of uncorrected p - sequence divergence between selected sister clades. Minimum spanning haplotype networks for two Leptolalax-clades (connected to phylogenetic tree nodes marked grey) were obtained with TCS. Numbers on haplotype connections represent number of nucleotide substitutions. Numbers of specimens included in haplotype networks are: B5-1(12); B5-2(17); B5-3(6); B5-4(1); B4-1(8); B4- 2,3,4,7,8(1); B4-5(2); B4-6(3). Sampling localities are provided as pie charts within haplotype circles, circle size corresponds to the number of sampled individuals. Abbreviations for country of origin are as follows: L—Laos, M—Malaysia, T—Thailand, V—Vietnam. Newly described species and haplotype networks are coloured.

FIGURE 9. Distribution of localities of specimens of subgenus Lalos studied in this work. Onymotopes are indicted as stars. Olive green—pelodytoides; blue—L. minimus form 2; orange yellow—L. minimus; red—L. aereus; grey—L. eos; light green – L. ventripunctatus; white—L. bourreti; black—L. pluvialis; yellow—L. nyx.

FIGURE 17. Leptolalax pluvialis, MNHN 1999.5675, holophoront, adult male, SVL 22.0 mm. (A) Dorsal and (B) ventral view.

FIGURE 18. Leptolalax pluvialis, MNHN 1999.5675, holophoront, adult male. (A) Lateral view of head, ventral view of (B) right hand and of (C) right foot. Scale bar = 5 mm (3 + 2 mm).