Amolops kottelati, Sheridan & Phimmachak & Sivongxay & Stuart, 2023

Sheridan, Jennifer A., Phimmachak, Somphouthone, Sivongxay, Niane & Stuart, Bryan L., 2023, Systematics of the Lao torrent frog, Amolops cremnobatus Inger & Kottelat, 1998 (Anura: Ranidae), with descriptions of four new species, Vertebrate Zoology 73, pp. 931-956 : 931

Amolops kottelati sp. nov.

Figure 9 "Clade D"

Holotype.

NUOL 00556 (field number SP 00745), adult male, Laos, Xaysomboun Province, Hom District, Ban Nam Yuak, Houay Kator, 18.72669°N, 103.35481°E, 405 m elev., coll. 1932 h on a rock 0.5 m above a stream torrent on 26 June 2015 by Somphouthone Phimmachak and Sengvilay Seateun.

Paratypes.

Laos, Bolikhamxay Province, Thaphabhat District, Phou Khao Khouay National Protected Area, Tad Leuk: NCSM 79617 (one adult male), 18.23727°N, 103.04321° E, 214 m elev., coll. 9 May 2012 by Sengvilay Seateun, Misan Keooudone, and Poklavanh Khounthavong. - Laos, Xaysomboun Province, Hom District: NCSM 86766-67, NUOL 00557 (three adult females), same data as holotype; NUOL 00555 (one adult female), Ban Nong (=Ban Sob Youak), Houay Tadkud, 18.64285°N, 103.46059°E, 987 m elev., coll. 23 June 2015 by Somphouthone Phimmachak and Sengvilay Seateun.

Referred larvae.

Laos, Xaysomboun Province, Hom District: NCSM 87612 (three larvae), Houay Kolong, first stream crossing road from Ban Houaysey to Ban Nam Youak, 18.72556°N, 103.35556°E, 415 m elev., coll. 14 February 2014 by Maurice Kottelat.

Etymology.

The specific epithet is a patronym for Maurice Kottelat, Swiss ichthyologist and specialist of the Indochinese fish fauna, collector and co-describer of the types of A. cremnobatus , and collector of the larvae of the new species. Kottelat’s larval collections proved invaluable for the present study, exemplified by A. kottelati sp. nov. being most readily diagnosed by its larval characters.

Suggested Common Names.

Kottelat’s Lao torrent frog (English); ຂຽດເກາະຜາລາວກ ົດເຕີລັດ (Khiat Korpha Lao Kottelat; Lao).

Diagnosis.

A member of the Amolops larutensis group having the combination of 3-4 vomerine teeth reliably present; relative finger lengths I<IV<II<III; mean ± SE SVL of adult males 33.3-35.0 mm (n = 2) and of adult females 39.0 ± 1.8 (range 38.0-41.7 mm; n = 4); and tadpoles with BL 17.0 ± 0.2 mm (range 16.8-17.1 mm; n = 3).

Description of holotype.

Habitus moderately slender. Head width slightly greater than head length. Snout weakly pointed in dorsal view, projecting slightly beyond lower jaw in lateral view, sloping obliquely back to lip. Nostril lateral, nearer to tip of snout than to eye. Canthus rostralis distinct. Lores oblique and slightly concave. Eye diameter subequal to snout length. Pineal body absent. Tympanum distinct, round, greater than one-third diameter of eye, slightly depressed relative to skin of temporal region, tympanic rim elevated relative to tympanum. Rictal glands small and oval, but very indistinct. Vomerine teeth (n = 4) obliquely angled, closer to each other than to choanae. Tongue cordiform, notched posteriorly. Vocal slit opening near corner of jaw very small and hard to find. No gular pouch but some extra skin at corner of jaw.

Forelimbs moderately slender. Tips of all four fingers expanded into wide discs with circummarginal grooves. Fingers slender. Relative finger lengths I<IV<II<III. No webbing on hands other than very minimal basal webbing on outer fingers. Subarticular tubercles conspicuous, surfaces rounded, formula 1, 1, 2, 2. One supernumerary tubercle at base of fingers 2-4. Irregular palmar tubercle. Velvety well-developed nuptial pads on dorsal surface of Finger I, to level of distal end of subarticular tubercle.

Hindlimbs moderately long and slender. Toes slender. Tips of toes expanded into discs, with circummarginal grooves. Outermost toe disc barely wider than toe. Web on all toes to base of disc. Subarticular tubercles conspicuous, surfaces rounded, formula 1, 1, 2, 2, 2. Disc of longest toe narrower than discs of all fingers except thumb.

Skin with fine spinose glands dorsally. No supra-tympanic fold. Glandular dorsolateral fold. Flanks with small spinose glands on upper one-third to one-quarter.

Measurements of holotype (mm): SVL 35.0, HDL 10.9, HDW 11.8, SNT 5.0, EYE 4.8, IOD 3.2, IND 3.7, TMP 1.8, TEY 0.9, SHK 19.9, TGH 18.0, HND 10.0, FTL 17.2.

Coloration.

In preservative, dorsal coloration dark brown with beige markings. Dorsal surface of thighs and arms with pale beige bars on dark brown background. Posterior surface of thighs smooth, with light beige mottling on dark brown background. Ventral surfaces of chin, chest, belly, and underside of thighs and arms uniformly creamy beige. Ventral surfaces of feet are dark gray-brown, and ventral surfaces of hands are dark beige.

In life (photograph of NUOL 00555), dorsal surfaces greenish-brown with green mottling. Dorsal surfaces of thighs with green bars on dark green background. Eye mottled gray on bottom one-third, and mottled orange on remaining area. No photographs available of posterior surface of thighs, or ventral surface.

Larvae.

Based on a larva at S29 from the series NCSM 87612, which includes tadpoles between S25-29. Tadpoles are assigned to this species because they were collected at the type locality and their morphology largely agrees with the tadpole description of A. cremnobatus by Inger and Kottelat (1998), including a divided upper jaw sheath and high number of labial tooth rows [9-10(5-9, 5-10)/6(1)]. Tadpoles of A. kottelati sp. nov. belong to the exotrophic, lotic, gastromyzophorus larval type ( McDiarmid and Altig 1999), with large oral discs ventrally.

HB oval, broadly rounded, wider anteriorly than dorsally, with weak constriction near line through nares. HB width 63-65% of HBL, widest anterior to eyes. HB flat below with large abdominal sucker. Eyes dorsolateral, pointed laterad. Nares dorsolateral, closer to eyes than tip of snout. Spiracle low on side, tube free of body wall. Tail lanceolate, margins tapering in distal third to narrowly rounded tip; muscle deeper than fins in proximal half. Dorsal fin origin behind HB, origin of ventral fin distal to origin of dorsal fin. HB without spinules. Glands postocular, no glands in fins.

Oral disc nearly as wide as HB, ventral; labial teeth 10(5-10)/6(1). A1 at margin of upper lip, short, approximately one-third length of A2, with very small denticles compared to other tooth rows. Papillae short, thick, in single row, absent from middle third of upper lip, but present across entire lower lip. Jaw sheaths with outer surface smooth, upper sheath divided, gap between black halves slightly greater than depth of keratinized portions; lower jaw sheath in single piece. Jaw sheaths with fine serrae.

Color in preservative of HB brown dorsally and laterally, cream ventrally without spots. Caudal muscle brown dorsally and laterally, cream ventrally. Upper fin with melanophores throughout, and lower fin with melanophores in distal half.

Sexual dimorphism.

Males (n = 2) differ from females (n = 4) in being smaller (33.3-35.0 mm SVL vs 39.0 ± 1.8 mm SVL; Table 1 ), and in having paired vocal slits and distinct nuptial pads at base of first finger.

Variation.

Pineal body sometimes present (NUOL 00555), but often absent. Rictal glands small and indistinct in nearly all individuals. Oval thenar tubercle present in females. Skin of males with fine spinose glands dorsally, while dorsal skin of females is glandular but not spinose. Flanks of males have small spinose glands, and flanks of females are glandular but not spinose. All females except NUOL 00557 with spinose glands above arm, posterior to tympanum. Female NUOL 00555 is very dark compared to the others with much less of the pale mottling dorsally, and all individuals except this one have uniformly cream chin, chest, belly, and underside of thighs and arms. NUOL 00555 has dark stippling on a beige background on the chin and chest, becoming less stippled on the belly, ventral surface of legs, and arms.

Distribution and natural history.

This species is known from clear streams with torrents in western Bolikhamxay and eastern Xaysomboun Provinces of northern Laos.

Comparisons.

Amolops kottelati sp. nov. differs from A. cremnobatus , A. sengae sp. nov., and A. attiguus sp. nov. by having a larger number (3-4) of vomerine teeth (2-3 in A. cremnobatus , A. sengae sp. nov., and A. attiguus sp. nov.) that are reliably present (faint or sometimes absent in A. cremnobatus , A. sengae sp. nov., and A. attiguus sp. nov.). Amolops kottelati sp. nov. further differs from A. cremnobatus and A. tanfuilianae sp. nov. by having relative finger lengths I<IV<II<III (I<II<IV<III in A. cremnobatus and A. tanfuilianae sp. nov.). Amolops kottelati sp. nov. further differs from A. sengae sp. nov. by having spinose glands above the arm usually present (absent in A. sengae sp. nov.). Amolops kottelati sp. nov. differs from A. tanfuilianae sp. nov. and further differs from A. cremnobatus , and A. sengae sp. nov. by having larvae with much larger BL (Table 2 ).

Figures

Figure 9. Amolops kottelati sp. nov., NUOL 00556, in preservative.