Timothy Usher, Santa Fe Institute
The Lower Ramu River family consists of of eight languages spoken around and inland of the mouth of the Ramu River on the north coast of the Bogia subdistrict of Papua New Guinea's Madang province (Z'graggen 1971: 74-79.) At least one of its members, Watam, is also spoken immediately across the border to the west in East Sepik province. It is called the Ruboni Stock in the works of Z'graggen, who first recognized the unity of the family.
The internal classification of Lower Ramu River is as follows:
Lower Ramu River
Ruboni Range
Kire (Giri)
Sepen
Mikarew
Ramu Coast
East Ramu Coast
Awar
Bosngun
North Ramu Coast
Boroi (Gamei)
Kaian
Watam
Z'graggen (1971: 78-79) gives lexicostatistical relationships between languages of the Ruboni Stock as follows:
| Giri | Sepen | Mikarew | Awar | Bosngun | Gamei | Kaian | Watam | |
| Giri | — | 60 | 42 | 22 | 19 | 19 | 16 | 18 |
| Sepen | 60 | — | 60 | 18 | 18 | 16 | 15 | 17 |
| Mikarew | 42 | 60 | — | 15 | 14 | 12 | 14 | 16 |
| Awar | 22 | 18 | 15 | — | 63 | 41 | 39 | 38 |
| Bosngun | 19 | 18 | 14 | 63 | — | 45 | 42 | 42 |
| Gamei | 19 | 16 | 12 | 41 | 45 | — | 77 | 72 |
| Kaian | 16 | 15 | 14 | 39 | 42 | 77 | — | 77 |
| Watam | 18 | 17 | 16 | 38 | 41 | 72 | 77 | — |
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| Lower Ramu | Ramu Coast | Ruboni Range |
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| Lower Ramu | Ramu Coast | Ruboni Range | |
| 1 sg. | *… | ||
| 2 sg. | *… | ||
| 3 sg. | *… | ||
| 1 pl. | *… | ||
| 2 pl. | *… | ||
| 3 pl. | *… | ||
| 1 dl. | *… | ||
| 2 dl. | *… | ||
| 3 dl. | *… |
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| Bogia Bay | Ramu Coast | Ruboni Range | |
| louse | |||
| mosquito | |||
| cassowary |