1. Phonology

Proto-Trans–New Guinea is reconstructed with a typical simple Papuan inventory: five vowels, /i e a o u/, three phonations of stops at three places, /p t k, b d ɡ, m n ŋ/ (Andrew Pawley reconstructs the voiced series as prenasalized /mb nd ŋɡ/), plus a palatal affricate /dʒ ~ ndʒ/, the fricative /s/, and the approximants /l j w/. Syllables are typically (C)V, with CVC possible at the ends of words. Many of the languages have restricted tone systems.

In the most recent version, Pawley (2018) gives the following consonant inventory for Proto-Trans–New Guinea.^[1]:136

Consonants

	bilabial	apical	palato-alveolar	palatal	velar
oral stops	p	t			k
fricatives		s
prenasalised obstruents	ᵐb	ⁿd	ᶮʤ		ᵑg
nasals	m	n		ɲ	ŋ
laterals		l
glides	w			j

The Proto-Trans–New Guinea vowels are reconstructed as having a cross-linguistically frequent five-vowel system:^[1]

Vowels

	Front	Central	Back
Close	i		u
Mid	e		o
Open		a

2. Pronouns

Ross reconstructs the following pronominal paradigm for Trans–New Guinea, with *a~*i ablaut for singular~non-singular:

I	*na	we	*ni
thou	*ga	you	*gi
s/he	*(y)a, *ua	they	*i

There is a related but less commonly attested form for 'we', *nu, as well as a *ja for 'you', which Ross speculates may have been a polite form. In addition, there were dual suffixes *-li and *-t, and a plural suffix *-nV, (i.e. n plus a vowel) as well as collective number suffixes *-pi- (dual) and *-m- (plural) that functioned as inclusive we when used in the first person. (Reflexes of the collective suffixes, however, are limited geographically to the central and eastern highlands, and so might not be as old as proto-Trans–New Guinea.)

3. Morphology

Pawley and Hammarström (2018: 147-148), following Suter (1997),^[2] group Madang, Finisterre-Huon, and Kainantu-Goroka together as part of a larger Northeast New Guinea (NENG) group on the basis of morphological evidence, such as mutually reconstructable verbal suffixes that mark subject:

Proto-Northeast New Guinea subject-marking verbal suffixes

	singular	dual	plural
1st person	*-Vn	*-u(l,t)	*-un, *-i
2nd person	*-an	*-i(l,t)	*-ai, *-i, *-a
3rd person	*-a, *-i		*-ai

Comparison of reconstructions of subject-marking verbal suffixes

	proto-Northeast New Guinea	proto-Madang	proto-Finisterre-Huon	proto-Kainantu-Goroka	proto-Trans–New Guinea (tentative)
1sg	*-Vn	*-in	?	*-u	*-Vn
2sg	*-an	*-an,*-i	*-an	*-an	*-Vn
3sg	*-a,*-i	*-a,*-an	*-a,*-i	*-ai,*-i	*-a,*-i
1du	*-u(l,t)	-*-u(l,t)	*-u(l,t)	*-ur	*-u(l,t)
2/3du	*-i(l,t)	*-i(l,t)	*-i(l,t)	?	*-i(l,t)
1pl	*-un,*-i	*-un	*-un	*-un
2/3pl	*-ai,*-i,*-a	*-ai,*-i	*-e,*-i	*-a

4. Lexicon

Lexical words, such as *niman 'louse', may also be reconstructed:

Reflexes of *niman 'louse', which attest to an intermediate *iman in the east:

Chimbu: Middle Wahgi numan

Engan: Enga & Kewa lema

Finisterre–Huon: Kâte imeŋ, Selepet imen

Gogodala mi

Kainantu–Goroka: Awa nu, Tairora nume, Fore numaa, Gende (tu)nima

S. Kiwai nimo

Koiarian: Managalasi uma

Kolopom: Kimaghana & Riantana nome

Kwale nomone

Madang: Kalam yman, Dumpu (Rai Coast) im, Sirva (Adelbert) iima

Mek: Kosarek ami

Moraori nemeŋk

Paniai Lakes: Ekari yame (metathesis?)

Timor–Alor–Pantar: West Pantar (h)amiŋ, Oirata amin (metathesis?)

Wiru nomo

Questionable branches:

Pauwasi: Yafi yemar

C. Sentani mi

The Proto-Trans–New Guinea negative is reconstructed as *ma- (Pawley and Hammarström 2018). Negatives in Trans–New Guinea languages usually have either an mV- or nV- form.^[1]

• mV (often ma): Angaatɨha (Angan); Apalɨ, Waskia, Kalam (Madang); Kâte, Kombe (Finisterre-Huon)
• na ~ naa: Awara (Finisterre-Huon); Enga, Ku Waru, Middle Wahgi (Chimbu-Wahgi); Oksapmin

5. Reconstructions

The following Proto-Trans New Guinea reconstructions are from Andrew Pawley and Harald Hammarström (2018).^{[1]:141–146}