Meaning of さもあろう

Question

In Mushibugyou there is this sentence:

実物の蟲もさもあろうというリアルな夢だな

The speaking character sees a giant mosquito (giant insects are common in the setting), thinks to be in a dream, and that he says that sentence; while I guess it means something along the lines of "It's a realistic dream, an insect close to the real thing", I can't understand what もさもあろうという means; I tried looking online and on my grammars, but while I found some construction with さも, I'm not sure it's the same thing, and how that construction works.

Answer 1

Yes, さもあろう is can be considered as a variant of さもあらん or さもありなん.

さ (然 in kanji) is an archaic equivalent of そう ("so", "this way") in modern Japanese. も is a particle.

• Meaning of さすれば as a verb

あろう is the "volitional form" of ある. A volitional form can have an inferential meaning, although this usage is becoming old-fashioned.

• がな and ておろうな at the end of sentence parts
• What does the volitional for do in this sentence: 今までリーゼには見せたことの無いであろう優しい目
• Has Japanese syntax changed between the 1950s and today?

  明日は雨が降りましょう。

  This was common in weather forecast until the 1970's, but we never hear this today.

なん in ありなん is explained in this question:

• What's な doing in 絶えなんとする?

All in all, あるだろう, あろう, あらん and ありなん all have a similar meaning.

Practically, さもあらん and さもありなん should be learned by rote as a set phrase without worrying about its archaic grammar. さもあろう is not really a common set phrase, so you have to get used to the inferential usage of the (よ)う-form, which is a little old but still part of the modern grammar.