Cross-linguistically, how do syllabic consonants interact with morae?

Question

I've read a bit about the moraic system found in Japanese, but as there isn't much complexity in the case of its syllabic consonants, I am left with a few questions.

1) Are there any natural languages in which syllables containing a consonantal nucleus are assigned a mora?

For example, if [l̩] is a possible word in some hypothetical language, how would it most likely be parsed moraically? Would it just have one mora? In some language could it be considered to have zero morae?

2) Could one consonant function as both an onset and a nucleus in the same syllable (demonstrated in the 1)?

A. [ll̩]

3) Is it possible for a language have a length distinction for syllabic consonants ?

B. [l̩:] ( contrastive with [l̩]?)

4) Lastly, would there be a difference in how A and B are counted moraically?

Answer 1

Answers to your questions have to be prefaced with disclaimers about how one determines that something has a mora, or not -- phonology has embraced and eschewed the concept, and used it for all sorts of things. With that caveat, it has become a matter of virtual principle that every syllable nucleus has a mora (though Piggott 1995 "Epenthesis and syllable weight" allows for amoraic syllables), so yes. In Swahili, there is a contrast between syllabic and non-syllabic preconsonantal nasal, hence [m̩buni] "coffee plant" vs [mbuni] "ostrich". The noun prefix for cl. 9, found in "ostrich", also occurs in "dog", but it is syllabic and stressable ([ˈm̩bwa]). The reason for this exceptional moraicity of the nasal is a minimality condition requiring words to have two moras. To the extent that a language has diagnostics for moraicity, any phonologically syllabic consonant will pas the test of being moraic. However, also note that "syllabicity" is not a self-evident property that can be read trivially off the speech stream.

An example of a consonant being both onset and nucleus, specifically, [mm̩], is discussed for Hehe in Odden & Odden "Kihehe Syllable Structure", where that language phonetically contrasts "moraic" nasals and "syllabic" nasals. In this case, both moraic [m̩] and "syllabic" [mm̩] count as a single mora.

Classical Sanskrit is an example of a language with a contrast between long and short syllabic /r/ (and /l/, though that is more about grammarian's theory), and Slovak also has long and short syllabic /r,l/.