Via the Missouri Ethics Commission – there are two additional Democratic Party candidates vying for the open seat in the 19th Legislative District:

C161013: Friends Of Manny Abarca For Missouri

Committee Type: Candidate
Po Box 6591 Party Affiliation: Democrat
Kansas City Mo 64124 Established Date: 01/21/2016
[….]

Candidate [….]
Manny Abarca

[….]

Election History
Election Year Primary Outcome General Outcome Political Office
2016 State Representative District 19

Committee History
Scan Title Scan Date Report Year
Statement of Committee Organization 01/22/2016 2016

[emphasis added]

And, today:

C161017: Mcmurray For Missouri

Committee Type: Candidate
201 North Gladstone Blvd Party Affiliation: Democrat
Kansas City Mo 64123 Established Date: 01/26/2016
[….]

Candidate [….]
Clifford Mcmurray
[….]

Election History
Election Year Primary Outcome General Outcome Political Office
2016 State Representative District 19

[emphasis added]

John Rizzo, who currently holds the seat in the 19th Legislative District, is a candidate [pdf] (among others) for the open seat in 11th Senate District.

Previously:

Ingrid Burnett (D) in the 19th Legislative District (January 22, 2016)