Finding the number of chromosomes of an organism
Answer

An comprehensive online database of the chromosome numbers of all living species most likely doesn't exist. This Wikipedia article is the best and most complete reference comprising animals that I can personally find on the internet.

This source in Spanish, which I've translated with Google Translate reads:


  Canedo Delgado (1999) performed the karyotype description of the three species of the genus Pygoscelis , noting that there is a high homology both numerically and morphologically: Pygoscelis antarctica presented 2n = 92, Pygoscelis papua 2n = 94 and Pygoscelis adeliae 2n = 95 in females and 2n = 96 in males.


Also, note that chromosome number cannot be "guessed" or "assumed" for closely-related species. As shown above, the three Pygoscelis species have a high homology, but have very different chromosome numbers.

The other chromosome number you found for the species (38) is actually that of the Emperor penguin, as a simple Google search shows.



References


Ledesma, Mario A., T. R. O. Freitas, J. Da Silva, Fernanda Da Silva, and R. J. Gunski. “Descripción Cariotípica De Spheniscus Magellanicus (Spheniscidae).” El Hornero 18, no. 1 (August 2003): 61–64.