This question arrived in my mailbox this morning and I decided to respond here so that we might encourage a wider community to take this excellent question farther. Here's the question...
A quick one about <special>
The researcher has identified a potential connection between the words <special> and <species>, presumably through an etymological reference such as this information on <special> from my Mactionary:
ORIGIN Middle English : shortening of Old French especial ‘especial’ or Latin specialis, from species ‘appearance’ (see species).
The researcher then recognizes the need for proper tools/reference material to guide their inquiry. This is excellent becasue this signals to me that they are not only thinking about how to resolve this question, but how to resolve any similar question. Let me start by sharing the reference chart that I like to use to guide any spelling investigation:
Following this trail of questions we should start by working through how the connotations of the words <special> and <species> echo the underlying denotation from their root, which from this reference seems to be "appearance". I just took a quick peak at Etymology On-Line and found this more detailed reference that may help us understand this connection better.
The nub of the quesstion, however, is to determin whether or not these two wrods are morphologically related. As the researcher apparently knows, this question must be addressed with a word sum, but she has not yet found one that works.
To start this part of the investigation, let's collect our data:
A useful way to begin a morphological analysis question like this is to look for the highest common factor (HST) between the words with a hypothesized connection. We can make provisional word sums based on this mechanical pattern seeking process that will give us a concrete representation of a hypothesis that can then be analysed further. With these two words the HST are is the letter sequence <speci>. Treating that as a potential morphological structure linking these to words, we end up with these potential word sums:
speci + es --> species
speci + al --> special
I'll leave my contribution to this question here. Perhaps the questioner or other classroom language labs out there can build on this start. I will add, however, if we treat this excellent question as a jumping off point for wider systemic learning, we don't stop our investigation when we thing we have a conclusion to the specific question "how are these words related?" Instead, if researchers out there follow the road maps in the chart above, and investigate the questions about relatives to look for a wider family, and also consider the grapheme-phoneme correspondences within key words encountered along the way, our ability to investigate other questions in the future will improve!
I look forward to seeing where the trail leads us!