Nepenthes Izumiae - Related Species

Related Species

Nepenthes izumiae is thought to be most closely allied to two other Sumatran endemics: N. lingulata and N. singalana.

With the former, N. izumiae shares the general morphology and colouration of its pitchers. However, it can be easily distinguished from that species as it lacks the highly developed filiform appendage that gives N. lingulata its name. It also differs in typically having an orbicular lid, as opposed to the triangular lid of N. lingulata, as well as broader pitchers with more highly developed peristome ribs and an unbranched spur. In addition, N. lingulata completely lacks nectar glands on the underside of the lid and has a very dense woolly indumentum.

Nepenthes izumiae differs from N. singalana in that it often possesses a basal crest on the underside of the lid; this structure is never found in N. singalana. Nepenthes izumiae also differs in several other vegetative features: it has broader laminae with persistent hairs on the margins, longer and narrower terrestrial traps, and a thinner peristome with finer ribs and teeth. In addition, whereas N. izumiae is typically epiphytic in growth habit, N. singalana is mostly terrestrial.

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. Nepenthes spathulata could also be confused with N. izumiae, but it can be distinguished on the basis of its wider laminae and pitchers, the latter typically also being lighter in colouration.