The first member of a tat-puruṣa samāsa preserves its original accent when the second member is the word adhvaryu or kaṣāya denoting a genus.,
Thus प्रा꣡च्याध्वर्युः, कठा꣡ध्वर्युः, कालापाध्व꣡र्युः ॥ These are Appositional compounds denoting 'genus or kind', with a fixed meaning. प्राच्य is formed by यत्, and has accent on the first 6.1.213. कठ is derived by अच् affix 3.1.34, and to it is added the Taddhita affix णिनि 4.3.104, in the sense of कठेन प्रोक्तं 4.3.101, and the affix is then elided by 4.3.107. The word कालाप comes from कलापिन् + अण्, (IV. 3. I08) in the sense of कलापिना प्रोक्तं 4.3.101, and it would have preserved its form without change before this affix 6.4.164 but for a vartika which declares that the इन् of कलापिन् will be elided (See 6.1.144 vartika). Thus कालाप gets accent on the final 3.1.3. So also सर्पिर्मण्ड꣡कषायम्, उमापुष्प꣡कषायम्, दौवारिक꣡कषायम् ॥ These are Genitive compounds. The words सर्पिमण्ड and उमापुष्प are Genitive compounds and have accent on the final 6.1.223. The word दौवारिक is formed by ठक् affix added to द्वार and has acute on the final 6.1.165. Why do we say when meaning a 'genus'? Observe, परमाध्व॒॒र्युः, परमकषा॒॒यः 6.1.223.,