Question: What year did the genre of opera in which Josef Mysliveček contributed to eventually end?

Context paragraphs:
Josef Mysliveček: Josef Mysliveček (9 March 1737 – 4 February 1781) was a Czech composer who contributed to the formation of late eighteenth-century classicism in music.  Mysliveček provided his younger friend Wolfgang Amadeus Mozart with significant compositional models in the genres of symphony, Italian serious opera, and violin concerto; both Wolfgang and his father Leopold Mozart considered him an intimate friend from the time of their first meetings in Bologna in 1770 until he betrayed their trust over the promise of an operatic commission for Wolfgang to be arranged with the management of the Teatro San Carlo in Naples.  He was close to the Mozart family, and there are frequent references to him in the Mozart correspondence.

Demetrio (1779): Demetrio is an eighteenth-century Italian opera in 3 acts by the Czech composer Josef Mysliveček.  It was the composer's second setting of a libretto by the Italian poet Metastasio that was first performed in 1731, one of the most popular of the Metastasian librettos in Mysliveček's day.  For a performance in the 1770s, it would only be expected that a libretto of such age would be abbreviated and altered to suit contemporary operatic taste.  The cuts and changes in the text made for the 1779 performance of Mysliveček's opera are not attributable.  All of Mysliveček's operas are of the serious type in Italian language referred to as opera seria.

Ezio (Mysliveček) (1777): Ezio is an eighteenth-century Italian opera in 3 acts by the Czech composer Josef Mysliveček.  It was the composer's second setting of a libretto by the Italian poet Metastasio that was first performed in 1728, one of the most popular of the Metastasian librettos in Mysliveček's day.  The story is based on incidents from the lives of the 5th-century Roman emperor Valentinian III and his general Aetius.  For a performance in the 1770s, it would only be expected that a libretto of such age would be abbreviated and altered to suit contemporary operatic taste.  The cuts and changes in the text made for the 1777 performance of Mysliveček's opera are not attributable.  All of Mysliveček's operas are of the serious type in Italian language referred to as opera seria.

La clemenza di Tito (Mysliveček): La clemenza di Tito ("The Clemency of Titus") is an 18th-century Italian opera in 3 acts by the Czech composer Josef Mysliveček.  It was composed to a libretto by the Italian poet Metastasio that was first performed in 1734 with music of Antonio Caldara.  For a performance in the 1770s, it would only be expected that a libretto of such age would be abbreviated and altered to suit contemporary operatic taste (similar to the setting of the same text by Wolfgang Amadeus Mozart).  The cuts and changes in the text made for the 1774 performance of Mysliveček's opera are not attributable.  All of Mysliveček's operas are of the serious type in Italian language referred to as opera seria.

Opera seria: Opera seria (] ; plural: "opere serie"; usually called "dramma per musica" or "melodramma serio") is an Italian musical term which refers to the noble and "serious" style of Italian opera that predominated in Europe from the 1710s to c. 1770.  The term itself was rarely used at the time and only attained common usage once "opera seria" was becoming unfashionable and beginning to be viewed as a historical genre.  The popular rival to "opera seria" was "opera buffa," the 'comic' opera that took its cue from the improvisatory commedia dell'arte.

Romolo ed Ersilia: Romolo ed Ersilia ("Romulus and Ersilia") is an 18th-century Italian opera in 3 acts by the Czech composer Josef Mysliveček composed to a libretto by the Italian poet Metastasio first produced in Innsbruck in 1765 with music by Johann Adolf Hasse.  The drama was one of Metastasio's last, shortest, and least popular.  Mysliveček's setting of 1773 was the only other one known to have been produced during the remainder of the eighteenth cebtury.  It includes significant alterations, in particular the introduction of new arias that augment the importance of certain characters and the re-ordering of existing arias.  The alterations are not attributable.  This opera (and all the rest of Mysliveček's operas) belong to the serious type in Italian language referred to as "opera seria".  In Mysliveček's day, the opening aria, "Questa è la bella face," the duet that concludes the first act, and the quartet that concludes the second act were famed for their brilliance.

La Nitteti: La Nitteti is an 18th-century Italian opera in 3 acts by the Czech composer Josef Mysliveček.  It was composed to a libretto by the Italian poet Metastasio that was first performed in 1756, one of the newer (and less popular) of the Metastasian librettos in Mysliveček's day.  For a performance in the 1770s, it would only be expected that a libretto of such age would be abbreviated and altered to suit contemporary operatic taste.  This opera contains more substitutions of original aria texts than any other Mysliveček setting of a Metastasian libretto.  The cuts and changes in the text made for the 1770 performance of Mysliveček's opera are not attributable.  All of Mysliveček's operas are of the serious type in Italian language referred to as opera seria.

Ezio (Mysliveček) (1775): Ezio is an eighteenth-century Italian opera in 3 acts by the Czech composer Josef Mysliveček.  It was the composer's first setting of a libretto by the Italian poet Metastasio that was first performed with music by Pietro Auletta in 1728, one of the most popular of the Metastasian librettos in Mysliveček's day.  The story is based on incidents from the lives of the 5th-century Roman emperor Valentinian III and his general Aetius.  For a performance in the 1770s, it would only be expected that a libretto of such age would be abbreviated and altered to suit contemporary operatic taste.  The cuts and changes in the text made for the 1775 performance of Mysliveček's opera are not attributable.  All of Mysliveček's operas are of the serious type in Italian language referred to as opera seria.

Antigono: Antigono is an 18th-century Italian opera in 3 acts by the Czech composer Josef Mysliveček composed to a libretto by the Italian poet Metastasio first produced in 1744 with music of Johann Adolf Hasse.  This opera (and all the rest of Mysliveček's operas) belong to the serious type in Italian language referred to as "opera seria".  For a performance in the 1780s, it would only be expected that a libretto by Metastasio would be abbreviated and altered to suit contemporary operatic taste.  The cuts and changes in the text made for the performance of Mysliveček's version are not attributable.

Demetrio (1773): Demetrio is an eighteenth-century Italian opera in 3 acts by the Czech composer Josef Mysliveček.  It was the composer's first setting of a libretto by the Italian poet Metastasio that was first performed in 1731, one of the most popular of the Metastasian librettos in Mysliveček's day.  For a performance in the 1770s, it would only be expected that a libretto of such age would be abbreviated and altered to suit contemporary operatic taste.  The cuts and changes in the text made for the 1773 performance of Mysliveček's opera are not attributable.  All of Mysliveček's operas are of the serious type in Italian language referred to as opera seria.

Supporting paragraphs: Josef Mysliveček Opera seria
Answer: 1770