The stornello is an Italian verse form dating back to at least the 15th century. The most common modern interpretations list it as a tercet form in which all three lines rhyme, with hendecasyllabic lines. There are other interpretations of the form from older time periods, including a couplet form still seen in Sicily today.
The somonka is a type of Japanese poem that actually consists of two shorter poems called tanka, a brief 31-syllable form, with somonka usually being exchanged by lovers or between two poets. Generally speaking, the first tanka is a love poem to the second person and the second tanka is the lover’s response.
The Sicilian Octave is an Italian offshoot of the older strambotto. It consists of eight lines with an alternating rhyme scheme (ABABABAB), traditionally with hendecasyllabic verse. English adaptations of the form commonly use iambic pentameter instead. The form’s popularity has waned since its introduction.
The sijo is an old Korean verse form that has roots as far back as the Goryeo era (around the 14th century). Modern interpretations describe a 42-48 line poem divided up into three lines, with a caesura on each line. Older interpretations are far more strict, encompassing a very specific arrangement of syllables.
The séadna is a type of Irish verse written in quatrains. The lines have alternating lengths and there are various rules regarding the rhymes and syllable counts of the poem. Techniques common in Gaelic poetry, such as dunadh (a special type of refrain) and cywddydd (harmony of sound), are typically used.
The shadorma is a poem written as a sestet with a 3/3/5/3/7/5 syllable structure. It is supposedly an old Spanish form, though I’ve yet to see any hard evidence of its origins. Nor has anyone else, judging from the sources available. It’s more likely to be a modern response to the haiku’s popularity.
Rimas Dissolutas is a troubaderic verse form in which verses rhyme with each other instead of having the lines of each verse rhyme internally. A poem in quatrains would have a rhyme scheme of ABCD ABCD, etc. Lines can be of any length but are generally isosyllabic while verses can be any number of lines.
The treochair is an Irish poem form consisting of three-line stanzas in which both the stresses and syllable counts are traditionally counted. Each verse has a 3-7-7 syllable pattern, with the first and third lines rhyming with each other. The traditional “harmony of sound” that Irish forms pride themselves on is expected.
The seguidilla is a Spanish verse form that branched off from a category of folk songs that go by the same name. This poem form consists entirely of seven-line verses that typically utilize assonance instead of true rhyme, leading to a subtle but noticeable rhythm that hints at the form’s musical origins.
Vocabularycleft poems are a type of found poetry proposed by Howard Bergerson in 1969. They’re made by scrambling the words from a preexisting poem into a list and then using them to create a new poem. Functionally, they’re similar in nature to a collage. The form’s main exposure was in issues of Word Ways.