Hi Kim,
This looks like your Ferdinand here: http://www.blackseagr.org/blksea-db/get ... 3&tree=125
Unfortunately, there's not much on his parents or siblings and Catholic records are very difficult unfortunately. But maybe I can get you some more clues.
When I search for Hartmans in Krasna in the Black Sea German database, I see a lot of entries.
The Krasna Koblenz records: http://www.blackseagr.org/blksea-db/sea ... y=contains
EWZ records: http://www.blackseagr.org/blksea-db/sea ... y=contains
Neither of those show Ferdinand, but if you look through them, you might find some clues.
Here's a list of the original settlers of Krasna: https://www.bessarabien.de/upload/krasn ... rliste.pdf
I see a Hartman there, so you are likely descended from him, but this list doesn't show the connections.
Here is some data from the 1850 Krasna census.
23
Karl Harabura 39 - Wife: Katharina 51
Son: Christian 14
Stepsons: Johannes Hartmann 23, Matthias
Hartmann died 1839 age 9
Stepdaughter: Anna Maria Hartmann 24
From this 1850 census data, the only Hartmann that could be the father of Ferdinand would appear to be Johannes, but he's not yet married at the time of the census. I guess he could have gotten married after the census and had a child by January 1851, but that would obviously be pretty quick.
Still, this appears to be the only Hartmann in Krasna near the time Ferdinand was born.The 1835 census has basically the same info, but calls Johannes "the son of the late Johann Hartmann."
Not a definite answer, but hopefully some clues for you!