Hylarana tytleri ( Theobald, 1868 )

Hylarana tytleri ( Theobald, 1868) View in CoL

Examined materials ( 15 specimens)

BANGLADESH: Chapai Nawabganj: IABHU 3889–3890, males; Barguna: IABHU 3891, female; IABHU 3892, male; IABHU 4141–4143, males; IABHU 4147, male; Narsingdi: IABHU 3893, male; IABHU 3894, female; IABHU 4154, female; IABHU 4155, male; Panchagarh: IABHU 4214‒4215, males; Mymensingh: IABHU 4219, female.

Descriptive characters

Small-sized frog with a SVL of 28.7–34.7 mm in males and 41.2–41.8 mm in females. Snout rounded and head moderately elongated. White or off-white dorsolateral folds running from behind the eye to the groin, usually (14 of 15 specimens here observed) with a dark brown band following on dorsal side of folds, but no middorsal line (fig. 6A). Tympanum distinct and slightly smaller than the eye. Limbs slender (fig. 6C). Tips of fingers dilated into small discs. Fingers free; relative finger length F1 <F2 <F4 <F3 (fig. 7I). Tips of toes more prominently dilated into small discs with ventro-lateral grooves; relative toe length T1 < T2 < T3 < T5 < T4 (fig. 7M). Two and half phalanges of the fourth toe free of webbing (fig. 6E; 7M). Dorsal and ventral skin smooth with granular zone in the thigh region (fig. 6C).

Color in life

Body surface varying in color from brown to slightly greenish. Dorsolateral folds usually bordered by a brown band on dorsal side: numerous specimens from Bangladesh examined show brown bands, but the specimen presented in fig. 6A (reared in captive condition in the Amphibian Research Center, Hiroshima University, Japan) has a particular color pattern, with green back showing white dorsolateral fold but no brown bands. Surface of the limbs slightly yellowish with few scattered small dark spots (fig. 6A). Underside creamy white (fig. 6C).

Color in alcohol

Body surface slightly brownish or greyish, but gradually becoming faint near the vent (fig. 6A). In general, dorsolateral folds bordered with dense, deep brown bands. Dorsal surface of the femur, tibia and tarsus region showing a few longitudinal discontinuous, scattered black lines; rear of the thigh whitish with a few indistinct black spots; ventral body surface whitish; hands and feet also ventrally white to slightly yellow (fig. 7E).

Variation

Dorsal pattern variable among individuals. Of the 15 examined specimens, one ( IABHU 3893) lacked a brown borderline around off-white dorsolateral folds. Sporadically, some brown dots present on the dorsal regions of the thigh, several connected dots forming short irregular lines. Two ( IABHU 3889, 4154) specimens had indistinct dots; one ( IABHU 3893) completely lacked dots. Ventral side milky white, except in one individual ( IABHU 4219).

Habitat

Hylarana tytleri is sympatric with Fejervarya sp. , Microhyla sp. and Hoplobatrachus tigerinus (Daudin, 1802) . It was found in marshes, paddy fields and beels (confined water reservoirs) in low-altitude foothills, sometimes near human settlements. In winter, it remains hidden in loose soil, probably for hibernation, at the junction between river banks and flat paddy land.

Known occurrence of H. tytleri

The known occurrence of H. tytleri includes the Sherpur, Mymenisngh, Narsingdi (‘Dacca’, now Dhaka, original type locality), Barguna , Chapai Nawabganj and Panchagarh districts, Bangladesh (fig. 1B). Also found in Natore , Nilphamary and Dinajpur districts, Bangladesh (pers. comm. to M.A. R. Sarkar; Sarkar & Howlader 2012; Selim et al. 2013). Sampling sites ranged from north to south Bangladesh, suggesting that it also occurs in other areas beyond the study sites (fig. 1B) (see below).

The species is also present in adjacent Bhutan ( Wangyal 2013), India ( Arunachal Pradesh, Assam, Meghalaya, Nagaland, Tripura, West Bengal) ( Ohler & Mallick 2002; Ao et al. 2003; Das 2008; Ohler et al. 2018; Biju unpublished data), Myanmar ( Bago) ( Mulcahy et al. 2018) and Nepal ( Dubois 1974, 1981, as Rana taipehensis ; Ohler & Mallick 2002). Its presence east of Bago in Myanmar cannot be confirmed by identified specimens. No record of a small-sized green-backed Hylarana is known from Bago to the Bangkok region, forming thus a large distribution gap.