Let's have a quick look at what the professional arachnologists have to say about this topic.
How about Eugène Simon, who is not only the most illustrious arachnologist ever, but also the person who first described
Linyphia tenuipalpis? According to him, the colouration of
L. tenuipalpis is as in typical
L. triangularis ("Coloration du type"), and the two forms can only be distinguished by the spination of femur I. He considers
tenuipalpis therefore a mere variant, not a separate species.
Or how about Peter van Helsdingen, the author of the authoritative monograph on
Linyphia and related genera, whose work is one of the foundations of modern arachnology? He writes "
L. tenuipalpis resembles
triangularis very closely indeed in coloration, size, and habitat" and "Abdomen. — Strongly resembling triangularis, and as variable..." "The habitat of the present species [
L. tenuipalpis] does not seem to differ from the habitat of
triangularis." He also details the differences in the spination of femur I, despite noting some overlap.
Or perhaps the two most important identification guides might provide some clues: Heimer & Nentwig state that the opisthosoma pattern of
L. tenuipalpis is similar to that of
L. triangularis ("OpS. ähnlich
triangularis"), and Roberts confirms that males and females of the two species are very similar ("Mannetjes en vrouwtjes lijken erg op
L. triangularis...").
Thus, there is consensus in the literature, and the Wiki reflects this expert knowledge. I have seen both species and can confirm that typical specimens are rather distinct, but I would still call them very similar; and they become more so after some time in alcohol. Also, as van Helsdingen writes, both species are very variable, with strikingly aberrant outliers, making it even more important to have a close look at genitals and spination, before jumping to conclusions. That is particularly relevant for
L. triangularis: this species is extremely abundant, and even if only a tiny fraction of specimens show a
tenuipalpis-like habitus, this could result in a large number of misidentifications.
All the information that I refer to here is available for free online, via the
World Spider Catalog. I would suggest that before the next post of this kind, you spend some time reading the relevant literature first. This could help distinguishing between real mistakes and mere misunderstandings. As Pierre and Harald explain, nobody expects the Wiki to be perfect, and constructive criticism is always welcome. But it should have some basis in facts.
Rainer
PS: And reading some of the earlier discussions in the Forum could also be helpful, e.g.
1,
2,
3.
