Kaloula laosensis Poyarkov, Orlov, Gorin & Milto, 2024

Gorin, Vladislav A., Orlov, Nikolai L., Bragin, Andrey M., Pawangkhanant, Parinya, Milto, Konstantin D., Le, Dac Xuan, Nguyen, Tan Van, Dufresnes, Christophe, Suwannapoom, Chatmongkon & Poyarkov, Nikolay A., 2024, Phylogeographic pattern and taxonomic revision of the Kaloula baleata species complex (Amphibia, Anura, Microhylidae) with description of two new species from Indochina, Herpetozoa 37, pp. 391-420 : 391-420

Kaloula laosensis Poyarkov, Orlov, Gorin & Milto sp. nov.

Figs 2 , 9 A , 10 , 11 , 12 , Table 4

Chresonymy.

Kaloula baleata [partim] — Orlov and Ananjeva (2007: 148); Nguyen et al. (2009: 94).

Kaloula indochinensis [partim] — Chan et al. (2013: 334, 2014: 577); Teynié et al. (2014: 29); Chandramouli and Prasad (2018: 52); Poyarkov et al. (2021 b: 39); Holden (2023: 148).

Holotype.

ZISP 15284 (field label ZISP 199), adult male, Na Home Village , Bouphala District, near the border of Nakai-Nam Theun National Park, Khammouane Province, Laos, collected by N. L. Orlov, S. N. Nguyen, and K. D. Milto on June 18, 2009 (17.544528 ° N, 105.695278 ° E; elevation 174 m a. s. l.).

Paratype

(n = 1). ZMMU A-8144 (field label ZISP 200), adult female from the same location and with the same collection data as the holotype .

Diagnosis.

Kaloula laosensis sp. nov. is distinguished from its congeners by the following combination of morphological attributes: (1) medium size (SVL ranging 44.0– 54.8 mm); (2) eyes comparatively large (eye length comprising 75 % – 100 % of snout length); (3) dark-brown dorsally, with numerous irregular dark blotches forming pericloacal ring; (4) gray or beige ventrally with dense white mottling on belly and limbs; (5) orange triangular patch on either side of the neck posterior to eyes; (6) bright-orange axillary patch present; (7) orange inguinal patch present; (8) bright-orange butterfly-shaped blotch above cloaca present; (9) gray spot on tibiotarsal articulation present; (10) dark interorbital bar present; (11) enlarged, widened finger disks (7.8 % – 7.9 % of SVL), ca. 1.53 times wider than toe disks; (12) finger subarticular tubercle formula: 1: 1: 2: 2; (13) toe subarticular tubercle formula: 1: 1: 2: 2: 2; (14) three metacarpal tubercles, median metacarpal tubercle in contact with inner metacarpal tubercle; (15) two metatarsal tubercles, inner metatarsal tubercle ca. three times larger than outer metatarsal tubercle; (16) three small supernumerary tubercles at the basis of toes I, III, IV.

Description of the holotype

(Fig. 10 ). Adult male in a good state of preservation, habitus robust; head wider than long (HW / HL 1.19); snout projecting beyond lower jaw, truncated in dorsal and lateral views (Fig. 10 C ); top of head flat; upper eyelid lacking supraciliary tubercles; eye length less than snout length (EL / SL 0.75) and less than interorbital distance (EL / IOD 0.77); pupils round; nostrils rounded, placed more towards the lateral sides of snout, located closer to tip of snout than to eye, relatively close to each other (IND / IOD 0.63); supratympanic fold flat, tubercular; tympanum not visible (Fig. 10 C ); dorsal surfaces of body and limbs with sparse tubercules, getting denser backwards; ventral surfaces of body and limbs almost smooth (Fig. 10 A, B ). Cloacal opening unmodified, directed posteriorly. Forelimbs relatively long, more than a half of hind limb length (FLL / HLL 0.63); hand long, comprising more than a half of lower arm length (HAL / LAL 0.6) and almost half of forelimb length (HAL / FLL 0.47); fingers rather robust, flattened in cross section; relative finger lengths: I <II <IV <III; no webbing between fingers; terminal digits flattened into very wide transversely expanded T-shaped disks (Fig. 10 E ); finger subarticular tubercles distinct, protuberant, large and round, finger subarticular formula: 1: 1: 2: 2; metacarpal tubercles three (Figs 9 A , 10 E ), inner metacarpal tubercle elongate, flattened; outer metacarpal tubercule oval, dilated, slightly bigger than inner (OPTL / IPTL 1.05), median metacarpal tubercle the smallest, oval-shaped, contacting both the inner and outer metacarpal tubercles (Figs 9 A , 10 E ); hindlimbs robust, relatively short, not much longer than body length (HLL / SVL 1.12); relative toe lengths: I <II <V <III <IV; tarsal fold on inner surface of tarsus absent; tips of all toes widened, forming terminal oval-shaped disks (Figs 9 A , 10 D ); all toe disks having dorso-terminal groves; the disk on toe IV the largest; toe webbing well developed between all toes, reaching disks at all toes except toe IV; webbing formula i 1.5-2 ii 1.5 - 2.5 iii 1.5 - 3 iv 3 - 2 v; toe subarticular tubercules distinct, rounded, protruding; toe subarticular formula: 1: 1: 2: 2: 2; two metatarsal tubercles, inner metatarsal tubercle elongated, oval, shovel-shaped; outer metatarsal tubercle smaller, rounded; three small supernumerary tubercles at the basis of toes I, III, IV (Figs 9 A , 10 D ).

Coloration.

In life, dorsal surfaces of head and body dark brown with contrasting black spots and blotches; black interorbital bar between the upper eyelids; irregular black blotch on the snout; a series of black blotches forming a L-shaped chevron pattern in the scapular region; elongated black blotches on mid-dorsum, body flanks, and sacral area, forming a black pericloacal ring with irregular borders (Figs 2 , 11 ); dorsal surfaces of limbs grayish brown with dark-brown to black blotches; flanks of body and lateral sides of head grayish brown; on lateral sides of belly getting dark-brown with white spots and blotches; pale orange patches on the neck posterior to eyes; bright reddish-orange axillary patch edged with dark brown; bright reddish-orange inguinal patch edged with black; bright reddish-orange patch above cloaca in the center of dark pericloacal ring (Fig. 2 ); small grayish-beige spots near tibiotarsal articulation; ventral surfaces of head and body gray, darker near the jaw; belly and ventral sides of limbs densely mottled with white spots and dots (Fig. 10 ); iris chocolate brown with copper sparkles dorsally and ventrally (Fig. 11 ). In preservation after 15 years of storage in ethanol, dorsal coloration faded to dark grayish-brown; dark markings on dorsum are well descernible; light patches became less pronounced and faded to yellowish or beige in color, though the coloration pattern generally remained unchanged (Fig. 10 ).

Measurements of the holotype

(in mm): SVL 44.0; HL 10.6; HW 12.6; SL 4.6; EL 3.3; N-EL 3.2; IND 2.7; IOD 4.3; UEW 2.4; FLL 27.6; LAL 21.7; HAL 13.0; HLL 49.3; TL 37.0; FL 25.4; IPTL 2.7; OPTL 2.8; 1 FL 7.5; 1 TOEL 7.3; OMTL 2.0; 3 FDD 3.4; 4 TDD 2.2.

Variation.

Morphometric variation of the type series is presented in Table 4 . A dorsal view of a female paratype specimen is presented in Fig. 12 . In general, the female paratype specimen agrees well with the description of the holotype, diverging only in body size, which is larger than in the holotype (SVL 54.8 mm). Female paratype ZMMU - A- 8144 has comparatively fewer dark markings on the dorsum (Fig. 12 ), but generally, the coloration pattern is similar to that of the holotype. Holden (2023: 148, fig. 152) published a photo of the new species from Laos as ‘ K. indochinensis , ’ which has bright-red axillary, inguinal, and pericloacal patches and lighter grayish-brown dorsal coloration.

Tadpole morphology.

Currently, data on the larval morphology of Kaloula laosensis sp. nov. are lacking.

Distribution and natural history.

Kaloula laosensis sp. nov. is currently reliably known only from two localities in the Khammouane Province of Laos; the distribution of the new species is shown in Fig. 5 , and the locality information is detailed in Appendix 1. In Nakai-Nam Theun NP and in Hin Nam No NP, Khammouane Province, Laos, the new species was recorded from limestone evergreen tropical forests at relatively low elevations of ca. 100–300 m asl. The data on the natural history of Kaloula laosensis sp. nov. is scarce; it inhabits primarily lowland forests and is quite secretive, emerging only after heavy rains from June to September, when depressions in the forest floor are flooded and form temporary pools. The new species is likely associated with limestone karst landscapes of central Laos; the actual distribution of Kaloula laosensis sp. nov. is unknown, but we suppose that this species is likely to occur in adjacent provinces of Vietnam (Ha Tinh and Quang Binh), which harbor limestone forests similar in composition. Details about the new species’ reproductive biology and diet are unknown.

Comparisons.

Kaloula laosensis sp. nov. most closely resembles other members of the K. baleata species complex in overall morphology, and comparison with these species appears to be the most pertinent. Most specifically, the new species superficially resembles K. indochinensis , with which it was previously confused. From K. indochinensis , Kaloula laosensis sp. nov. can be distinguished by having relatively longer head in males (HL / SVL 0.24 [n = 1] by our data or mean 0.25 ± 0.1 [n = 4] reported by Chan et al. 2013) vs. mean 0.23 ± 0.1 [n = 18] by our data or [n = 25] reported by Chan et al. 2013); relatively wider disk of finger III in males (3 FDD / HAL 0.26 ± 0.1 [n = 1] vs. mean 0.23 ± 0.1 [n = 18]); relatively longer first toe in males (1 TOEL / FL 0.29 ± 0.1 [n = 1] vs. mean 0.26 ± 0.1 [n = 18]); by having three metacarpal tubercles with median metacarpal tubercle touching both the inner and outer metacarpal tubercles, see Fig. 9 A (vs. median metacarpal tubercle small, not touching the inner metacarpal tubercle, see Fig. 9 B ); by having two subarticular tubercles on toe IV, see Fig. 9 A (vs. three well-developed subarticular tubercles, see Fig. 9 B ); by having supranumerary tubercles at the basis of toes I, III, and IV, see Fig. 9 A (vs. supranumerary tubercles absent, see Fig. 9 B ); by the presence of numerous contrasting black markings on dorsum (vs. absent or indistinct); and brownish dorsal coloration (vs. chocolate to dark grayish-brown).

From K. baleata , Kaloula laosensis sp. nov. can be distinguished by having a relatively larger distance between nares in males (IND / HW 0.21 [n = 1] by our data or [n = 6] reported by Chan et al. (2013) vs. 0.18 ± 0.1 [n = 10] reported by Chan et al. (2013)); wider finger III disks in males (3 FDD 3.4 ± 0.1 mm [n = 1] by our data) or mean 3.1 ± 0.3 mm [n = 6] reported by Chan et al. (2013) vs. 1.7 ± 0.2 mm [n = 10] reported by Chan et al. (2013)); by having two subarticular tubercles on toe IV, see Fig. 9 A (vs. three well-developed tubercles); and by having supranumerary tubercles at the basis of toes I, III, and IV, see Fig. 9 A (vs. supranumerary tubercles absent).

From K. latidisca , Kaloula laosensis sp. nov. can be distinguished by having relatively shorter heads in males (HL / SVL 0.24 [n = 1] by our data or mean 0.25 ± 0.1 [n = 4] reported by Chan et al. (2013) vs. mean 0.27 ± 0.1 [n = 4] reported by Chan et al. (2014)); relatively smaller distance between eyes in males (IOD / HW 0.34 [n = 1] by our data or mean 0.33 ± 0.1 [n = 6] reported by Chan et al. (2013) vs. mean 0.30 ± 0.1 [n = 4] reported by Chan et al. (( 2014); by the presence of numerous black markings on the dorsum (vs. black markings on dorsum absent or few); and by having two subarticular tubercles on toe IV (vs. three well-developed tubercles).

From Kaloula discordia sp. nov. (described above), the new species can be distinguished by having a relatively longer head in males (HL / SVL 0.24 [n = 1] by our data or mean 0.25 ± 0.2 [n = 6] reported by Chan et al. (2013) vs. mean 0.22 ± 0.2 [n = 14]); relatively shorter snout in males (SL / HL 0.43 [n = 1] by our data or mean 0.40 ± 0.1 [n = 6] reported by Chan et al. (2013) vs. mean 0.47 ± 0.1 [n = 14]); relatively narrower head in males (HW / HL 1.19 [n = 1] vs. mean 1.31 ± 0.2 [n = 14]); wider finger III disks (3 FDD / HAL 0.26 [n = 1] vs. mean 0.23 ± 0.10 [n = 14]); shorter toe I (1 TOEL / FL 0.29 [n = 1] vs. mean 0.25 ± 0.1 [n = 14]); by having three metacarpal tubercles, see Fig. 9 A (vs. two metacarpal tubercles, see Fig. 9 C ); by having supranumerary tubercles at the basis of toes I, III, and IV, see Fig. 9 A (vs. supranumerary tubercles absent, see Fig. 9 C ); by the brown coloration of the dorsum (vs. olive); and by the presence of numerous black markings on the dorsum (vs. black markings on dorsum absent or few).

Furthermore, Kaloula laosensis sp. nov. differs from K. aureata by having a brownish dorsum with no reticulations (vs. golden dorsum with dark brown reticulations); from K. borealis by having wide finger disks (vs. finger tips dilated but not forming wide disks); by the absence of yellowish blotches on flanks (vs. present); an by brownish dorsal coloration (vs. gray-brown). Kaloula laosensis sp. nov. further differs from K. conjuncta by the stratified coloration on flanks absent (vs. present); by having distinct outer metatarsal tubercle (vs. weak or indistinct); from K. ghoshi by the presence of axillary and inguinal spots (vs. axillary and inguinal spots absent); by tuberculated dorsum and venter (vs. smooth or with small flat granules dorsally); by brownish dorsal coloration (vs. orange-brown). The new species differs from K. kalingensis in that it has tubercles on the dorsum (vs. dorsum smooth), a distinct outer metatarsal tubercle (vs. indistinct), and yellow or orange axillary and inguinal spots (vs. usually absent or small and red if present). Kaloula laosensis sp. nov. further differs from K. kokacii by the presence of dorsal tubercles, axillary and inguinal spots, and a light pericloacal ring (vs. absent). The new species differs from K. mediolineata by dorsolateral stripes and sacral stripe absent (vs. present); by having enlarged, wide finger disks (vs. finger tips slightly dilated but not forming wide disks); from K. nonggangensis by protuberant tubercles on the upper surface of finger tips absent (vs. present); from K. picta by the absence of dorsolateral stripes and stratified coloration on flanks (vs. present); by having enlarged, wide finger disks (vs. finger tips slightly dilated but not forming wide disks). The new species can be readily diagnosed from K. pulchra by the absence of dorsolateral stripes (vs. present) and by having axillary and inguinal spots (vs. absent). Kaloula laosensis sp. nov. further differs from K. rigida by having enlarged, wide finger disks (vs. finger tips slightly dilated but not forming wide disks), by the absence of dorsolateral stripes and stratified coloration on flanks (vs. present), and by having axillary and inguinal light spots (vs. absent). The new species differs from K. rugifera by having enlarged, wide finger disks (vs. slightly dilated small finger disks) and by having axillary and inguinal spots (vs. absent) and is further different from K. verrucosa by having very wide finger disks (vs. small finger disks) and by having axillary and inguinal spots (vs. absent). The new species differs from K. walteri by having very wide finger disks (vs. slightly dilated small finger disks), by the absence of stratified coloration on flanks (vs. presence), by having axillary and inguinal light spots (vs. absent), and by having a distinct outer metatarsal tubercle (vs. indistinct or absent). Except for K. pulchra , which can be found in central Laos in syntopy with the new species, Kaloula laosensis sp. nov. is geographically separated from most of its relatives.

Acoustic data.

The male advertisement call of Kaloula laosensis sp. nov. has not been recorded, and the bioacoustic data on this species is absent.

Etymology.

The specific epithet “ laosensis ” is an adjective in the nominative case, given in reference to the new species’ distribution in central Laos. The name also mirrors the specific epithet of K. indochinensis , with which the new species was previously confused. We recommend “ Laotian Painted Frog ” as the common English name, “ Laosskiy bychiy uzkorot ” as the common name in Russian, “ Ễnh ương Lào ” as the common name in Vietnamese, and “ ອ ື ່ ງຢາງລາວ ” (“ Ung Yang Lao ”) as the common name in Lao languages.

Conservation status.

At present, the new species is known only from two localities in Khammouane Province of Laos (Fig. 5 ). The main threats to this species in Laos are habitat loss and degradation due to intensified logging and deforestation, namely Nakai-Nam Theun NP and Hin Nam No NP. We propose that the IUCN’s Red List categories ( IUCN 2019) classify Kaloula laosensis sp. nov. as Data Deficient (DD) due to the absence of comprehensive studies in the adjacent territories.

Comments.

We assume, based on the distribution of the new species, that several specimens from the type series of K. indochinensis in the original description by Chan et al. (2013), collected in Khammouance Province of Laos and labeled as ‘ K. indochinensis Laos’ or ‘ Laos OTU’ throughout the text, actually represent Kaloula laosensis sp. nov. These specimens include six adult males stored in the Field Museum of Natural History ( FMNH), Chicago, USA, under voucher numbers FMNH 270360–65. The lack of genetic information on these specimens in the original description of K. indochinensis prevented Chan et al. (2013) from recognizing their taxonomic distinctiveness.

Figures

Figure 2. Genealogical relationships of the genus Kaloula based on the analysis of mtDNA fragments, including 12 S rRNA, tRNAVal, and 16 S rRNA gene sequences. Numbers at tree nodes correspond to PP / UFB support values, respectively. Black circles correspond to well-supported (PP ≥ 0.95 or UFB ≥ 90) nodes. Numbers in bold following sample names correspond to localities in Fig. 1 and Table 1. The information on GenBank Accession Numbers, museum vouchers, and localities of origin for sequences used in this study is summarized in Table 1. The holotypes of Kaloula discordia sp. nov. and Kaloula laosensis sp. nov. are marked with asterisks (* H). Photographs by N. A. Poyarkov and N. L. Orlov.

Figure 5. Known distribution of the Kaloula baleata species complex members in Indochina. Dots within symbols denote type localities. Symbol colors correspond to mitochondrial DNA lineages (Figs 1, 2. Note that the tentative assignment of the populations that were not sequenced is based on geographic proximity and / or examination of morphological or photographic data from these populations). Symbol numbers correspond to locality numbers given in Appendix 1.

Figure 9. Morphological details of feet and hands in the three species of the Kaloula baleata species complex of eastern Indochina. A. Volar view of the left hand and plantar view of the right foot of Kaloula laosensis sp. nov.; B. Volar view of the left hand and plantar view of the right foot of K. indochinensis; C. Volar view of the left hand and plantar view of the right foot of Kaloula discordia sp. nov. Scale bar equals 5 mm. Drawings by N. A. Poyarkov.

Figure 10. Holotype of Kaloula laosensis sp. nov. (ZISP 15284), adult male. A. Dorsal view; B. Ventral view; C. Head in a lateral view; D. Plantar view of left foot; E. Volar view of left hand. Photographs by V. A. Gorin.

Figure 11. Dorsolateral (A) and frontal (B) views of the holotype of Kaloula laosensis sp. nov. in situ (ZISP 15284, male). Photographs by N. L. Orlov.

Figure 12. Dorsal coloration in a single paratype of Kaloula laosensis sp. nov. (ZMMU - A- 8144, female) Scale bar equals 5 cm. Photograph by V. A. Gorin.