Amolops kohimaensis, Biju & Mahony & Kamei, 2010

Biju, S. D., Mahony, Stephen & Kamei, Rachunliu G., 2010, Description of two new species of torrent frog, Amolops Cope (Anura: Ranidae) from a degrading forest in the northeast Indian state of Nagaland, Zootaxa 2408 (1), pp. 31-46 : 38-43

Amolops kohimaensis sp. nov.

( Figs. 1 , 4–6 ; Table 2)

Holotype. ZSI A 10972 , adult male, collected by SDB and RGK on 27 June 2007 from Lorü , 25°38’23’’N 94°03’31”E, 1575 m asl., Jotsoma village, Kohima district, Nagaland, northeast India ( Fig. 1 ).

Paratypes. BNHS 5282 , ZSI A10966 and ZSI A 10971, three adult males collected along with holotype.

Referred specimen. SDB 2007.129 , one adult male, collected along with holotype .

Diagnosis. Amolops kohimaensis sp. nov. is here placed in the genus Amolops , based on its overall morphological similarity to A. granulosus . Recently the systematic status of the latter species has been confirmed phylogenetically ( Cai et al. 2007). Amolops kohimaensis sp. nov. is characterized by a combination of the following attributes: (1) SVL of adult males 42.8–48.6 mm; (2) head longer than wide, HW:HL 91– 95%; (3) entire tympanum distinct, TYD:EL 40.4–45.5%; (4) circummarginal groove present on all digits of hands and feet; (5) outer metatarsal tubercle absent; (6) fourth toe webbed to the distal subarticular tubercle; (7) external vocal pouches, dorsal spinules and asperities present in males; (8) male with nuptial pad on digit I covered with microgranules; (9) dorsolateral folds present; (10) absence of glandular tarsal ridge; (11) microgranules in a crescentic patch on ventral surface of jaw and second broad patch covering the entire chest, extending onto posterior throat, to the level of vocal pouches.

Comparisons. Amolops kohimaensis sp. nov. differs from A. bellulus , A. caelumnoctis , A. cremnobatus , A. daiyunensis , A. formosus , A. granulosus , A. hainanensis , A. hongkongensis , A. jinjiangensis , A. kangtingensis , A. kaulbacki , A. lifanensis , A. loloensis , A. mantzorum , A. medogensis , A. nidorbellus , A. ricketti , A. splendissimus , A. torrentis , A. tuberodepressus , A. viridimaculatus and A. wuyiensis , by presence of externally visible vocal sacs on males (vs. absence); from A. aniqiaoensis , A. assamensis , A. himalayanus , A. jaunsari , A. marmoratus , A. panhai and A. spinaspectoralis , by fourth digit of the feet webbed to the distal subarticular tubercle (vs. feet fully webbed to disks or beyond the distal subarticular tubercle); from A. archotaphus , A. compotrix , A. cucae , A. larutensis and A. vitreus , by absence of a distinct outer metatarsal tubercle (vs. presence); differs from A. chunganensis , A. gerbilis , A. iriodes , A. liangshanensis , A. mengyangensis and A. minutus by presence (vs. absence) of extensive dorsal spinules on males in breeding condition; from A. monticola by presence (vs. absence) of dorsal spinules on males in breeding condition, larger tympanum, TYD:EL 40.4–45.5% (vs. TYD:EL 33.3–36.6%) and circummarginal groove on first finger weakly developed (vs. strongly developed); from A. daorum by larger adult male size, SVL 42.8–48.6 (vs. male SVL 32–38), dorsum brown (vs. green) and larger male tympanum, TYD:EL 40.4–45.5% (vs. male TYD:EL 29%); from A. chakratensis known only by the female holotype, by HW<HL (vs. HL<HW), absence of elongated glands on the lateral aspect of belly and shoulder (vs. presence), and brown flanks (vs. green flanks); differs from A. longimanus by EN<SN (vs. SN<EN) and a considerably larger tympanum, TYD:EL 40.4–45.5% (vs. TYD:EL ~25%).

Description of holotype. (all measurements in mm): adult male (SVL 48.6), body habitus slender ( Figs. 4A–B , 5 ); head dorsally subovoid, longer than wide (HW 15.2, HL 16.3, HW:HL 93%), flat above; snout rounded and strongly protruding in profile ( Fig. 4C ), its length (SL 6.9) longer than the horizontal diameter of the eye (EL 5.9); canthus rostralis distinct, rounded, loreal region concave, obtuse; interorbital space slightly convex, interorbital distance (IUE 4.1) slightly less than width of the eye lids (UEW 4.2) and narrower than the internarial distance (IN 5.0); nostrils laterally positioned, vertically ovular with raised rim anteriorly and posteriorly, slightly closer to the eye (EN 3.2) than to the snout (SN 4.0); pupil horizontal; tympanum fully exposed (TYD 2.6), circular with raised rim, tympanum–eye distance (TYE 1.3); pineal ocellus distinct; vomerine ridges moderately well developed, obtuse, bearing 5 short teeth each, slightly closer to each other than to choanae, positioned level to posterior border of choanae which are large, oval and slightly acute; tongue long, narrow and deeply emarginated.

Arms moderately long, thick, forearm enlarged, length (FAL 12.5) shorter than the hand (HAL 14.7); relative length of fingers I<II<IV<III (FIL 6.0, FIIL 7.0, FIIIL 10.7, FIVL 7.2); finger tips on II–IV dilated with wide oval disks ( Fig. 4F ), largest on digit III (FDIII 1.7 mm, FWIII 1.1), finger I with distinct disk but only slightly dilated in relation to adjoining finger width, relative width of finger disks I<II=III=IV, circummarginal grooves present on all digits, but only weakly developed on digit I; terminal phalange shape unknown; fingers without distinct lateral fringes, webbing on fingers absent; subarticular tubercles prominently domed, circular, prepollex indistinct, outer and inner metacarpal tubercles oval, flat, barely visible; supernumerary tubercle on the base of all fingers, flat and barely visible.

Hind limbs long, shank (SHL 30.2) longer than thigh (TL 26.1 mm) and foot (FOL 28.0); toes long and thin, relative lengths I<II<III<V<IV; tips of all toes expanded with transversely oval disks, subequal in width to those of the fingers (TDIII 1.6), relative width of toe disks 1<5<4<2<3, all with circummarginal grooves; toes moderately webbed ( Fig. 4G ); post axial groove on toe V extends from tip of toe to the basal subarticular tubercle, pre axial groove on digit I extends from the base of the disk to the inner metatarsal tubercle; subarticular tubercles all present, prominent, longitudinally ovoid, inner metatarsal tubercle prominent, oval and relatively long (IMT 2.1); tarsal glandular ridge, outer metatarsal and supernumerary tubercles all absent ( Fig. 4G ).

Skin on almost entire dorsal and ventral surface of head, body, limbs and flanks smooth, with the following exceptions: two patches of microgranules with granule size subequal to those of the nuptial pad. One forms a crescent shaped patch following the curvature of the lower jaw, and the other covers the entire chest extending anteriorly to a rounded apex between the vocal pouches ( Fig. 4E ). A patch of dense tubercles on the proximal surface of the posterior thighs below the vent; dorsal and lateral tubercles or pustular warts absent; dorsolateral fold wide and continuous from posterior border of the eye to above the vent; supratympanic folds present, barely distinguishable; co-ossified skin absent; enlarged rictal glands absent replaced by a patch of small tubercles; humeral glands absent; conspicuous yellow/white horny spinules present ( Fig. 4A, C, D ), covering the dorsal aspect of the body from the vent anteriorly to the level of the insertion of the forelimbs, extending further anteriorly the length of dorsolateral ridges, a patch on the posterior upper eye lids, temporal area posterior to the supratympanic region, at the rear axis of the mandibles and between the tympanum and eye, densely covering granular area below the vent, extending in a narrow row along the posterior outer dorsal surface of the thigh, and entire outer surface of the tibia; those of the outer tarsus, lores and lips reduced to fine white asperities; asperities or spinules absent on the ventral aspects of the body.

Colour of holotype. In preservation ( Fig. 4 ): As in life but dorsal surface has darkened to dull brown; yellow orange colouration on the groin has completely faded to cream white. Entire ventral surface of body, and limbs cream white with some faint grey mottling on the chest and along the lower margin of the jaw; ventral surface of the hands and feet mottled cream and grey; ventral nuptial pad grey; ventral tarsus solid dark brown, posterior thighs marbled dark brown and cream; crescentic faded yellow marking posterior to the microgranular patch on the throat. In life ( Fig. 5 ): Dorsal surface of head, body, limbs and lores primarily medium brown. Dorsal head and body with randomly arranged patches of dark brown speckling; dark brown stripe from snout tip, through nostril to eye, tympanic region and upper flanks dark brown, fading to light greyish brown on the lower flanks; groin with hint of yellowish orange. Dorsal surface of thighs with 5 dark brown transverse stripes with poorly defined borders, four on shank and two on tarsus; outer forelimb with extensive dark brown mottling and dark patch covering the proximal anterior humeral region posterior to the vocal patches. Dorsal surface of hands, feet, and lips with dark mottling; webbing plain light brown, opaque; nuptial pads pale pink above. Upper third of iris pale yellow, lower two thirds dark reddish brown. Ventral surface greyish white with some brown mottling on the chest and a crescent shaped blotch on the throat.

Condition of type series. All specimens are fully intact, with the exception of ZSI A 10972 (holotype), which has a portion of the ventral thigh muscle removed for molecular analysis .

Secondary sexual characters. Male: large nuptial pad on the proximal dorsal surface of first finger, covered in microgranules; forearms are enlarged relative to upper arm; a pair of externally visible vocal pouches at the rear axis of the jaws.

Variation. Mensural differences are provided in Table 2. Considerable variation exists in several characters: relative finger lengths of ZSI A 10966 is I<IV<II<III, all others including holotype and referred specimen have I<II<IV<III; pineal ocellus is not visible on BNHS 5282 , but is weakly visible on the remaining type series and referred specimen. Considerable variation is also apparent with regards to vomerine ridges and teeth : SDB 2007.129 has moderately well developed ridges and teeth 5/3 (right/left) ; BNHS 5282 and ZSI A 10966 both have weakly developed ridges, the former without vomerine teeth, the latter with 6 short teeth on each ridge ; ZSI A 10971 has one weak vomerine ridge on the left side only, without teeth. Markings vary considerably between specimens: the dark dorsal blotches may be well defined e.g ., SDB 2007.129 , or reduced to fine scattered speckling as seen in the holotype ; ZSI A 10971 has a considerable amount of dark grey mottling on the throat, chest and anterior abdomen and some fine speckling on ventral hind limbs; ventral markings on SDB 2007.129 are restricted to the throat and ventral shanks only .

Natural history. This species is also known only from the type locality, Lorü, Jotsoma village, about 5 km west of Kohima town ( Fig. 6 ). All specimens were collected from a small side pool of the same stream described above for Amolops nidorbellus sp. nov. between 20:00–24:00 h. The pool was formed by a diversion of the stream made by locals for trapping fish. Males were found calling from stones lining this pool, rather than the adjoining, fast flowing portion of the stream. It appears that males congregate for breeding, however no females or tadpoles were observed at this locality. The 2009 visit to this same stream, three weeks earlier in the season than the previous visit in 2007, resulted in no observations of this species. No further individuals were observed elsewhere along this stream during either visit.

Etymology. Named after Kohima district, Nagaland, where the type series was collected.

Suggested common name. Kohima Spiny Torrent Frog.

Figures

FIGURE 1. Map of northeast India showing the type locality of the new Amolops species: 1. Amolops nidorbellus sp. nov., 2. Amolops kohimaensis sp. nov.. Positioning of symbols is approximate; for exact coordinates, see text.

FIGURE 4. Holotype of Amolops kohimaensis sp. nov. (ZSI A 10972) in preservation: A. dorsal view, B. ventral view, C. lateral view of head, D. anterior dorsal view, E. anterior ventral view, F. ventral view of hand, G. ventral view of foot.

FIGURE 5. Referred specimen of Amolops kohimaensis sp. nov. (SDB 2007.129) in dorsal view showing typical live colouration.

FIGURE 6. Habitat photograph depicting the current scale of habitat destruction of the primary stream (main) ca. 30 m from the adjoining side stream and collection locality of Amolops nidorbellus sp. nov. and Amolops kohimaensis sp. nov. (inset).