Eriocaulon robustobrownianum

Eriocaulon robustobrownianum Ruhland, Pflanzenr. IV, 30: 77 1903. (syn: Eriocaulon mysorense Fyson; Eriocaulon rhodae Fyson);

SW. India, Sri Lanka, Myanmar as per WCSP;
Eriocaulon robustobrownianum Ruhland ... Eriocaulaceae
along Kumta Sirsi Road on December 17, 2012 ... thanks to ... for ID 

I could not find any clue to what the epithet robustobrownianum in context of Eriocaulon robustobrownianum Ruhland stands for.
Hopefully someone helps with the etymology.
I was able to trace back to the original publication by Engler in 1903 (see attached). Although there is no direct mention of etymology of the specific epithet in the protologue, we can infer something. First of all, the specific epithet is originally hyphenated (robusto-Brownianum). And, there is another species called Eriocaulon brownianum (the first letter of specific names derived from name of a person or place was usually capitalized in the past). I assume that this plant, E. robusto-brownianum, is morphologically somewhat similar to E. brownianum but comparatively more ''robust'' in its habit, i.e. the peduncles could be more in number and/or stouter than those of E. brownianum. This is just a hypothesis, though!
Attachments (1)- Eriocaulon robusto-brownianum.pdf
Thank you very much ...; your analysis is convincing, and etymology should be so. I too was thinking that robusto could be a descriptive prefix, when I saw few instances of the hyphenated epithet, as in Herbarium JCB, IISc, ... but did not know of another species E. brownianum. Thank you very much.
I agree with ...  although in the protologue it mentions SUBROBUST, but such terms are usually in comparison with another existing species, eg. Balanopsis and Cyclobalanopsis. Sometimes names are even in parts or just to sound like an existing name or just opposite of the wording of an existing name:
Thismia : Thomas Smith, some say it is opposite of SMITH.
Sedirea: Opposite of another orchid Aerides because flower looks like it but obviously not same genus.
Thanks and regards

This the first post in efi so far for this species.
So pl. post more images so that these are incorporated in efi site.
Oh sure, ... Will do it tonight or so.