Mopsa, a stupid country wench in Sidney's Arcadia, is such a delightful comic creation that one is curious to know more about her origin and function. William Ringler suggests that the name is ‘probably from Mopsus, a shepherd in Virgil's Eclogues.’ In the Fifth Eclogue one of the two shepherds in the singing contest is named Mopsus. In the Eighth Eclogue the embittered shepherd Damon laments the loss of Nysa, mentioning that she has married Mopsus. Since Sidney uses other names from the Eclogues (Dametas, Menalcas) and since Mopsa is the daughter of a shepherd, Professor Ringler's suggestion has merit.
Virgil is probably not the only source of Mopsa's name, however; I suggest that Sidney is making a kind of pun, humorously combining the name's Virgilian associations with those surrounding the Dutch word mops and its playfully Latinized form Mopsus or, feminine, Mopsa. Mops means ‘pug dog’ and, formerly, by extension, meant ‘countrylout' also; Mopsa in the Arcadia is in a sense ‘doggy’ and is clearly a country lout.