Nepenthes izumiae may also bear a resemblance to N. bongso and N. ovata, but both of these species have entirely infundibular upper pitchers and often have spathulate laminae with glabrous margins.
In their description of N. naga, the authors compared it to the Sumatran endemics N. ovata and N. spathulata, contending that it can be distinguished from these species on the basis of its dichotomous lid appendage and frilled lid.
Nepenthes ovata was first collected as early as November 1840 or 1841 by Franz Wilhelm Junghuhn on Mount Lubukraya (Loeboekraja).
Nepenthes clipeata | Nepenthes bokorensis | Nepenthes | Nepenthes rajah | Nepenthes mantalingajanensis | Nepenthes klossii | Nepenthes faizaliana | Nepenthes epiphytica | Nepenthes abgracilis | Nepenthes rigidifolia | Nepenthes mira | Nepenthes khasiana | Nepenthes kerrii | Nepenthes deaniana | Nepenthes cid | Nepenthes aristolochioides | Nepenthes viridis | Nepenthes ovata | Nepenthes mirabilis | Nepenthes spathulata | Nepenthes rhombicaulis | Nepenthes pitopangii | Nepenthes × kinabaluensis | Nepenthes holdenii | Nepenthes × harryana | Nepenthes dubia | Nepenthes burbidgeae | Nepenthes bellii | A skeletal revision of ''Nepenthes'' (Nepenthaceae) | Rhus ovata |