The word putra coming after a Masculine noun in a tat-puruṣa samāsa has a acute accent (udātta) on the first syllable.,
Thus कौनटिपु꣡त्रः, दामकपु꣡त्रः, माहिषपु꣡त्रः ॥ Why do we say 'a पुत्र'? Observe कौनटिमातुलः ॥ Why do we say 'after a masculine word'? Observe गार्गीपुत्रः, वात्सीपुत्रः ॥,