Meristogenys poecilus was originally described by Inger & Gritis (1983). The name of the frog refers to the blotched backside of the thighs and we coin the common name Blotched Torrent Frog here to point to that feature. We tentatively assign two individualts from Batant Ai National Park, Sarawak to this species.

We extract the following features from the original description with modifications:  A large form of the Meristogenys jerboa species group. The males usually measure 34-52 mmin snout-vent length (SVL). commonly over 41 mm. Females grow considerably larger, 60-78 mm in SVL, usually over 69 mm. The length of the tibia relative to SVL is usually greater than 0.72.

The head has a triangular shape, with a bluntly pointed snout that projects a little beyond the lower jaw. The ridge from the snout to the eye (the canthus) is sharp and slightly concave. A small pineal spot is visible on top of the head, in line with the front corners of the eyes. The eardrum (tympanum) is clearly visible. Its diameter is a little less than half the length of the eye, and it is separated from the eye by almost its own width. The fingers are slender, with the first and second being about equal in length. Their tips are widened into round disks with grooves around the edges; the disks of the third and fourth fingers are the largest, about two-thirds the size of the eardrum. The fingers lack skin fringes and do not have extra tubercles on the palm.

The toes also have round disks like the fingers, with the disk of the fourth toe slightly larger than those of the outer fingers. The toes are fully webbed.The first toe has only a narrow fringe of skin on its inner edge. The inner sole of the foot has an oval (metatarsal) tubercle, slightly shorter than the distance to the first toe’s joint tubercle. A smaller, round, raised (metatarsal) tubercle is present on the outer side of the sole. The skin on the back shagreened and shows a faint dorsolateral fold. The sides of the body are coarsely granular. The throat is smooth, while the chest and belly are wrinkled. 

The color is chocolate brown dorsally on head and body; side of snout is darker. The upper lip is whitish, the lower lip is barred black and white. The iris is brown with a crimson spot behind pupil. A dark brown to blackish brown band extends from the eye to the inguinal region; its dorsal edge is sharp below the dorsolateral fold, ventral margin ragged, fading into spotted lower side. The throat is white to pale yellow; venter yellow. The forelimb is medium brown with dark brown speckles. The legs are dorsally barred with gray brown and blackish brown, yellow below. The rear of thighs are pied or blotched dark brown and cream (yellow in life).