Leptolalax (Lalos) minimus ( Taylor, 1962 )— 2011

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 : 63-70

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https://doi.org/ 10.11646/zootaxa.3147.1.1

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Leptolalax (Lalos) minimus ( Taylor, 1962 )—

comb. nov.

Leptolalax (Lalos) minimus ( Taylor, 1962)— View in CoL New combination

( Fig. 16D–E View FIGURE 16 , 30–36 View FIGURE 30 View FIGURE 31 View FIGURE 32 View FIGURE 33 View FIGURE 34 View FIGURE 35 View FIGURE 36 )

Leptobrachium minimum Taylor, 1962: 320 View in CoL .

Onymophoront, by designation as “type”: holophoront (holotype), EHT 34020 (now FMNH 178228 View Materials ) ( Marx 1958: 57; examined by Dubois & Ohler in 1995); adult male, SVL 27.6 mm. Collected by Edward H. Taylor, 21 December 1957 .

Onymotope: Doi Suthep (18°46’ N, 98°58’ E; alt. about 1000 m), Chiang Mai Province, Thailand GoogleMaps .

Specimens referred to L. minimus . Thailand. Phu Kradung National Park : TNRC S1-3918 3924 , 6 adult males and 1 adult female; — Doi Inthanon : FMNH 216087 View Materials , TNRC S1-3925 , FMNH 216088 View Materials , adult males and adult female; — Doi Suthep: FMNH 178230 View Materials , protaxont (paratype); BMNH 1979.437 , BMNH 1979.436 , FMNH 178228 View Materials , holophoront; TNRC S1-3926 , TNRC S1-3927 , FMNH 213933–213938 View Materials , MNHN 1997.1450 View Materials , 11 adult males and 2 adult females; — Doi Chiang Dao Watershed: FMNH 216077–216080 View Materials , TNRC S1-3928 3931 , 8 adult females; — Khao Pleung: BMNH 1972.1473 , adult female; — Doi Nga Chang: BMNH 1972.1475 , BMNH 1972.1476 , BMNH 1972.1477 , BMNH 1972.1474 , adult males and adult female; — Samkrae, Phu Kradung: MNHN 1987.2194 View Materials , adult male .

Laos. Khammouan Province: Huey Kun Luang (17°40’ N, 104°32’ E): BMNH 1972.1467 , adult male GoogleMaps ; — Xaignabouli Province: Muang Liep (18°28’ N, 101°40’ E; alt. 290 m): BMNH 1972.1478 , BMNH 1974.3067 , adult males GoogleMaps ; — Savannahkhet Province: Pak Mat: BMNH 1972.1471 , BMNH 1972.1470 , FMNH 121844 View Materials , MCZ 8762 View Materials , adult males; — Huey Sapan [Houei Xepon] (16°45’ N, 106°09’ E), Pak Mat, Mekong: BMNH 1972.1468 , BMNH 1972.1469 , adult male and adult female GoogleMaps ; — Luang Prabang Province, Nam Kham River tributaries: Ban Dong Khan (19°49’ N, 102°49’ E; alt. 500 m): MNHN 2006.2308 View Materials 2316 View Materials , adult males, collected 3 and 4 August 2006 GoogleMaps ; — Ban Vang Thong (19°50’ N, 102°59’ E; alt. 550 m): MNHN 2006.2328 View Materials , adult male, collected 25 July 2006 GoogleMaps ; MNHN 2006.2592 View Materials , one tadpole (DNA voucher) collected 26 July 2006 ; — Ban Kengkoung (19°41’ N, 102°18’ E; alt. 360 m): MNHN 2006.2593 View Materials 2596 View Materials , four tadpoles (all DNA vouchers), and MNHN 2006.2597 View Materials 2598 View Materials collected the 28 July 2006 GoogleMaps ; — Ban Nongdi (19°41’ N, 102°22’ E; alt. 400 m): MNHN 2006.2318 View Materials 2326 View Materials , adult males, collected 6 August 2006 GoogleMaps ; MNHN 2006.2599 View Materials , 2006.2614 View Materials , two tadpoles (DNA voucher), and two tadpoles in the batch MNHN 2006.2615 View Materials 2616 View Materials collected the 6 August 2006 ; — Houey Thao (19°48’ N, 102°11’ E; alt. 300 m): MNHN 2006.2553 View Materials 2554 View Materials GoogleMaps .

Specimens referred to L. minimus form 2. Thailand. Chiangmai Province , Doi Chiang Dao, Houey Ban: THNHM 07417– 07422 , 5 adult males, coll. Yodchaiy Chuarnkern, Stéphane Grosjean, Chantip Inthara, Annemarie Ohler, 13 July 2005 .

Diagnosis. Member of the subgenus Lalos based on the presence of lateroventral glands and molecular phylogenetic relationships ( Fig. 4 View FIGURE 4 ), distinguished from other species included in this subgenus by the following combination of characters: moderate-sized species (males 25.7–31.4 mm; females 31.6–37.3 mm) ( Table 3) with rudimentary to small webbing and no fringes on toes; tympanum distinct; dermal ridges under toes distinct; finger tips not dilated; dorsal skin smooth (Table 4); brown with darker pattern; dark spots on flanks present; ventral side whitish; iris dark gold above, grey below ( Table 5).

Description of holophoront. Size and general aspect. (1) Specimen of small size (SVL 27.6 mm), body rather stout.

Head. (2) Head of medium size, narrower (HW 9.8 mm) than long (HL 10.2 mm; MN 8.6 mm; MFE 6.7 mm; MBE 3.6 mm), flat. (3) Snout slightly protruding, its length (SL 3.4 mm) as long as horizontal diameter of eye (EL 3.4 mm). (4) Canthus rostralis angular, loreal region concave, vertical. (5) Interorbital space flat, larger (IUE 2.8 mm) than upper eyelid (UEW 2.5 mm) and internarial distance (IN 2.6 mm); distance between front of eyes (IFE 4.3 mm) about half of distance between back of eyes (IBE 8.2 mm). (6) Nostrils rounded, closer to tip of snout (NS 1.3 mm) than to eye (EN 1.7 mm). (8) Tympanum (TYD 1.8 mm) distinct, rounded; about equal to half of eye diameter, tympanum-eye distance (TYE 1.2 mm) three-fourths of its diameter. (11) Tongue not observed.

Forelimbs. (12) Forearm rather long, rather thin (FLL 7.1 mm), longer than hand (HAL 6.8 mm), not enlarged. (13) Fingers rather short and thin (TFL 3.7 mm). (15) Tips of fingers not enlarged. (16) Fingers without dermal fringe.

Hindlimbs. (19) Shanks about three times longer (TL 12.2 mm) than wide (TW 3.8 mm), shorter than thigh (FL 13.0 mm) and longer than distance from base of internal metatarsal tubercle to tip of toe IV (FOL 11.8 mm). (20) Toe IV (FTL 6.1 mm) about one-third of distance from base of tarsus to tip of toe IV (TFOL 18.3 mm). (22) Tips of toes not enlarged. (23) Webbing rudimentary: I 2 – 2 ½ II 2 – 3 ½ III 2 ⅔ – 4 IV 4 ⅓ – 3 V (MTTF 4.3 mm; MTFF 4.1 mm; TFTF 6.1 mm; FFTF 6.6 mm). (24) Fringes on toes absent. (26) Inner metatarsal tubercle moderately long, poorly distinct; its length (IMT 1.2 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 and side of head smooth; back and flanks smooth with tubercles and glandular folds. (30) Supratympanic fold distinct, extending from eye to above shoulder. (31) Dorsal parts of limbs: forelimbs, thigh, shank and tarsus smooth with tubercles and glandular folds. (32) Ventral parts of head, body and limbs: throat, chest, belly and thigh smooth. (33) Presence of macroglands: lateroventral ridges present, distinct but regularly interrupted; relatively small distinct femoral glands; indistinct axillary glands and distinct relatively large suprabrachial glands.

Coloration. In alcohol: (34) Dorsal and lateral parts of head and body: uniformly brown with dark spots on flanks, in particular two dark spots near thigh; tympanic fold with dark line. (35) Dorsal parts of limbs: dorsal part of forelimbs, of thigh, of shank and of foot brown with blackish crossbands; posterior part of thigh blackish with small white spots. (36) Ventral parts of head, body and limbs: uniformly light coloured.

In life (based on MNHN 2006.2553, not on the holophoront; Fig. 16D View FIGURE 16 ): Iris dark golden in upper part, grey in lower part. Dorsal parts of head and body dark brown grey with two round brown spots near shoulder and a few grey flecks in middle of back; upper part of flanks dark brown grey, lower part grey with black spots; loreal region, tympanic region and tympanum brown grey; upper lip brown grey with black bands; proximal part of forelimb with orange shade, distal part brown grey with dark grey crossbands; thigh, shank and foot brown grey with dark grey crossbands; posterior part of thigh dark brown with white spots; throat and chest transparent grey; border of throat grey with white spots; belly white with lemon yellow reflections; shank pinkish grey; macroglands white.

Variation of L. minimus (specimens allocated to group including onymophoront). Specimens show a rather high variation in size: the smallest males allocated to L. minimus measure 22.4 mm, whereas the largest male measures 30.5 mm (mean 27.2 ± 1.02 mm, n = 20). In the populations from Laos and Thailand allocated to L. minimus specimens of small and large size are genetically identical. Size variation within populations may be due to age of specimens. A Mann-Whitney U-test does not show significant differences between Lao and Thai populations (U = 379.5; p = 0.539). Thus the two peaks observed in the histograms may reflect the presence of two age groups in the populations ( Fig. 32 View FIGURE 32 ).

Tadpole. The external morphology is based on a DNA voucher specimen in stage 37 (MNHN 2006.2593; TOL 50.8 mm and BL 14.4 mm; genetically allocated to L. minimus ).

In dorsal view ( Fig. 33A View FIGURE 33 ), body elliptical elongate, widest at the level of the gills. In lateral view ( Fig. 33B View FIGURE 33 ), BW 122 % of BH, highest in the middle of the abdomen. Eyes moderately sized, ED 9.6 % of BL. Nares, RN 51 % of NP; NN 70 % of PP. Spiracle tubular, SS 51 % of BL; its opening on an axis which should go through just below the apex of myotomes of the caudal muscle. Tail long, TAL 253 % of BL; tail musculature, TMW 75 % BW, the lower part slightly bulging in its proximal third. Upper fin, UF 31 % of MTH, almost non-existent on its first quarter; lower fin shallow, LF 21 % of MTH; MTH 112 % of BH, tail tip obtusely pointed. Anal tube moderate-sized, slightly conical elongate. Lateral line system identical but much less visible than in L. bourreti .

Oral disc ( Fig. 33C View FIGURE 33 ), ODW 25 % of BL and 54 % of BW. Marginal papillae of the lower labium cylindrical with a rounded tip, those of upper labium faint with a very large base, especially medially; two submarginal papillae on the left side and three on the right side laterally to P1 and P2. No denticulate papillae. KRF 1:4+4/2+3:1, A1 very short, A2 the longest, A3, A4 and A5 subequal; A1 half of P4, P3 more than half of P2. Details of keratodonts not studied. Jaw sheaths black; lower sheath hidden, arranged deeply under the upper jaw sheath.

Coloration in life: Upper part of body and upper part of flanks grey olive, darker behind the eyes than before; upper part of caudal muscle of the same tint than the fore part of body with nine well defined black spots. Lower part of flanks quite transparent in gradation, gills red, coiled gut grey. In profile caudal muscle of the same tint than its upper part, the black spots being smaller and more numerous towards its extremity. Lower fin immaculate, upper fin with a few small black spots on its distal part. Ventral part of body transparent, thorax immaculate, gills and heart red, coiled gut brown, caudal muscle with some rare dots.

Coloration in preservative: Most part of upper part of body occupied by extension of the caudal muscle onto body (muscle dorsalis trunci) beige orange, the rest (mostly the head) translucent grey; internal organs of the head visible coloured in beige orange but by deeper layers, snout translucent grey, lobes of nares grey. Flanks (lymphatic sacs) grey tinted with light orange brown. Ventral side of body transparent, vicera visible (muscle rectus abdominis, coiled gut, heart). Caudal muscle beige mottled with scarce, medium-sized, light brown spots on proximal part, smaller and more numerous on distal half. Fins grey translucent, upper fin with diffuse light brown pigments forming some small indistinct spots, lower fin immaculate. Upper side of hindlimbs pigmented with stellate melanophores.

Variation of tadpole morphology was assessed on the basis of 10 other specimens, except where noted (MNHN 2006.2592, 2006.2594–2599, 2006.2614-2616, in stages 25–37, TOL 44.7–55.7 mm (n = 6) and BL 12.0–17.0 mm). Only the ratio values different from those of the described specimen are given: BW 121–137 % of BH; ED 8.5–10.0 % of BL; RN 34–65 % of NP; NN 68–80 % of PP; SS 48–58 % of BL; TAL 225–254 % of BL (n = 6); TMH 70–98 % of BH (n = 8); TMH 65–75 % of MTH (n = 4); TMW 63–78 % of BW; UF 29–33 % of MTH; SU 106–152 % of BL (n = 8); LF 22–26 % of MTH (n = 6); MTH 113–140 % of BH; ODW 26–29 % of BL; ODW 45– 55 % of BW. The maximum body width can be reached in the middle of the abdomen. The more the tadpoles are in advanced stages, the more their upper fins begin close to body end. The number of submarginal papillae is variable and may reach the number of five on each side. Most of specimens examined have a KRF 1:4+4/3+3:1. In life certain individuals show relatively large spots on dorsum and upper flanks that are formed by iridiophores. In preservative, the coloration can be more extended: some specimens have a marbled caudal muscle, the distal half of upper fin smoked, and irregular blotches on lateral sacs and lateral part of head; other with more dots on caudal muscle and upper fin, and on the distal half of the lower fin.

Description of reference specimen THNHM 07417, adult male, L. minimus form 2 (fig. 34−35). Size and general aspect: (1) Specimen of small size (SVL 25.6 mm), body rather stout.

Head. (2) Head of medium size, narrower (HW 8.7 mm) than long (HL 10.2 mm; MN 8.7 mm; MFE 7.6 mm; MBE 4.2 mm), rather flat. (3) Snout slightly protruding, its length (SL 5.0 mm) longer than horizontal diameter of eye (EL 3.5 mm). (4) Canthus rostralis distinct, loreal region concave, rather vertical. (5) Interorbital space flat, larger (IUE 4.0 mm) than upper eyelid (UEW 3.2 mm) and than internarial distance (IN 3.1 mm); distance between front of eyes (IFE 5.9 mm) about two-thirds of the distance between back of eyes (IBE 7.8 mm). (6) Nostrils oval, closer to tip of snout (NS 2.1 mm) than to eye (EN 2.3 mm). (8) Tympanum (TYD 2.0 mm) distinct, rounded; twothirds of eye diameter, tympanum-eye distance (TYE 1.3 mm) three-fifths of its diameter. (11) Tongue large, cordate.

Forelimbs. (12) Forearm long, thin (FLL 7.7 mm), longer than hand (HAL 6.6 mm), not enlarged. (13) Fingers short and thin, but finger III, long and thin (TFL 3.7 mm). (15) Tips of fingers not enlarged. (16) Fingers without dermal fringe. (18) Palmar tubercles very prominent, spine like.

Hindlimbs. (19) Shanks about four times longer (TL 13.2 mm) than wide (TW 2.9 mm), longer than thigh (FL 12.1 mm) and distance from base of internal metatarsal tubercle to tip of toe IV (FOL 12.1 mm). (20) Toes rather short and thin; toe IV (FTL 6.1 mm) about one-third of the distance from base of tarsus to tip of toe IV (TFOL 18.9 mm). (22) Tips of toes not enlarged. (23) Webbing rudimentary, narrow ridges on toes: I 2 – 2 ½ II 2 – 3 III 2 ½ – 3 ¾ IV 4 – 3 V (MTTF 4.5 mm; MTFF 4.5 mm; TFTF 6.6 mm; FFTF 7.1 mm). (24) Dermal ridge along toe V absent. (26) Inner metatarsal tubercle rather long, very prominent, spine like; its length (IMT 1.3 mm) 1.8 times in length of toe I (ITL 2.3 mm). (27) Tarsal fold absent.

Skin. (29) Dorsal and lateral parts of head and body: snout and region between eyes with glandular warts; side of head smooth; back and upper part of flanks with glandular warts forming longitudinal ridges; lower part of flanks with glandular warts. (30) Supratympanic fold distinct, from eye to above forelimb. (31) Dorsal parts of limbs: forelimbs, thigh, shank and tarsus with a few glandular warts. (32) Ventral parts of head, body and limbs: smooth. (33) Presence of macroglands: lateroventral glands present, continuous; relatively small distinct rounded femoral and surpabrachial glands; indistinct axillary glands.

Coloration. In alcohol: (34) Dorsal and lateral parts of head and body: Dark greyish brown with poorly distinct patterns including an interorbital triangle and longitudinal lines, blackish small spots on flanks; loreal and tympanic region light greyish brown; tympanum dark brown; upper lip light greyish brown with dark brown bands. (35) Dorsal parts of limbs: forelimb beige with dark brown crossbands on distal part; thigh, shank and foot light brown with dark brown crossbands; posterior part of thigh brown with a blackish brown triangular region near vent, all speckled with small white dots. (36) Ventral parts of head, body and limbs: throat whitish; margin of throat light brown with whitish spots; chest and belly whitish; posterior part of thigh brown, anterior part whitish; webbing brown; macroglands white.

In life ( Fig. 16B–C View FIGURE 16 ): Iris copper orange in upper part, dark grey in lower part. Dorsal parts of head and body, and upper flanks greyish brown with dark brown pattern showing whitish outline; lower flanks greyish brown with black spots and orange dots; loreal and tympanic region greyish brown; tympanum blackish brown; forelimb in its proximal part orange, distal part greyish brown with black crossbands; shank and foot greyish brown with black crossbands; posterior part of thigh dark brown with white spots; throat light grey, transparent; border of throat greyish brown with white spots; chest and belly ivory white with light yellow reflections; lower part of shank pinkish grey; femoral glands white.

Male secondary sexual characters: (38) Vocal sacs present, indistinct on throat; slit-like paired openings posterior on mouth floor. (39) Other male secondary sexual characters not observed.

Distribution. Thailand: Chiang Mai Province; Laos: Khammouan Province, Luang Prabang Province, Savannahkhet Province ( Fig. 9 View FIGURE 9 ).

Natural history. Specimens of L. minimus collected in July and August 2006 were in breeding condition. The males were found on the edges of small or moderate secondary streams ( Fig. 36C View FIGURE 36 ) sitting on leaves, branches, stones and rocks, on or near the ground (0–0.2 m) at short to moderate distances (0–6 m) from the water. Most were on the edge of the water (0–0.2 m distance). Two breeding males, MNHN 2006.2322 and 2006.2323, were observed touching one another with their head region and then separating. This is interpretated as a territorial behavior. In several of these streams Sylvirana nigrovittata , Limnonectes cf. kuhlii and L. gyldenstolpei , and rarely Xenophrys parva , Kurixalus odontotarsus , Microhyla berdmorei and Chirixalus doriae , were observed.

Tadpoles of L. minimus were hidden under dead leaves during daytime. At night, they were found either uncovered in the side pools of the streams or in pools connected to the streams but devoid of current, or between the gravels where the water only outcrops. They were found in the same streams as the tadpoles of Xenophrys parva although not in the same microhabitats. No other tadpole species were found in association.

Specimens of form 2 were collected at night in the forest near a small stream ( Fig. 36B View FIGURE 36 ) and artificial pools. The specimens were sitting on the ground (maximum 0.2 m high) either close to the water or at distances up to 4 m. They were mainly on branches and leaves, dead leaves, or rocks. Adult males took a very particular calling position exposing the suprabrachial gland and the orange coloured upper part of their forelimbs which gave them an insectlike appearance ( Fig. 16C View FIGURE 16 ). The adult female THNHM 07421 had large (diameter 2.0 mm) whitish oocytes in ovary.

Placement in molecular phylogeny. Leptolalax minimus is part of a highly supported clade that groups the clades of L. aereus , L. ventripunctatus , L. nyx and L. pluvialis . The specimens allocated to L. minimus form 1 form a well supported clade which is the sister group to L. minimus form 2 both together forming a well-supported clade.

Etymology. From latin minimus , small. Adjective, agreeing in gender with generic nomen.

Comment. In the molecular analysis, specimens originally identified as Leptolalax minimus from Thailand and Laos form a clade with two distinct branches, one including specimens from Thailand only, and a second branch including specimens from Thailand and Laos. These two branches show a p distance of 3.46 %. The amount of molecular divergence (3.46 %) is above the threshold of 3 % recently proposed to recognize candidate species in frogs ( Fouquet et al. 2007; Vieites et al. 2009). High pairwise sequence divergences do not suggest a species status of two specimens or lineages but are simply a probabilistic support: the more a divergence is above the empirically calculated threshold value, the less likely is the alternative explanation of deep haplotype sharing. The discriminant analysis based on morphometric ratios of measurements on specimens allocated by 16S sequences to distinct clades allows separating the two forms and also gives allocation for the holophoront of Leptobrachium minimum to the clade then named L. minimus ( Table 11). To support species discrimination we searched for morphological characters that would correlate with the groups defined by DNA sequences but failed. Morphologically these two groups cannot be distinguished. The specimens of form 2 fall within the variation observed in those specimens allocated to L. minimus . There is no evidence for morphological divergence. Despite the presence of molecular differentiation and in absence of morphological differentiation we tentatively keep the two forms in a single species looking for further evidence. Nevertheless we give here a description of a voucher specimen of L. minimus form 2.

Another (larval) specimen from the same locality in Thailand, based on the molecular data, is grouped with L. oshanensis AY 561306 and L. bourreti , and might represent another distinct species but this lineage is so far known from this tadpole only. More data, in particular on adult specimens, are necessary for sound taxonomic conclusions on this third form.

Conservation status. This species was considered a synonym of L. oshanensis and thus has not been evaluated previously. It is known from a large range. Though its habitat encounters threats from deforestation, we propose to allocate the status Least Concern to L. minimus on the basis of its large extent of occurrence.














Leptolalax (Lalos) minimus ( Taylor, 1962 )—

Ohler, Annemarie, Wollenberg, Katharina C., Grosjean, Stéphane, Hendrix, Ralf, Vences, Miguel, Ziegler, Thomas & Dubois, Alain 2011

Leptobrachium minimum

Taylor, E. H. 1962: 320
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