Xyroptila observations in iNaturalist and elsewhere

I have attempted to summarise the descriptive information in the most recent treatments of species in the genus Xyroptila in another post.

There is much that is unsatisfactory about the descriptions provided by Kovtunovich and Ustjuzhanin's 2006 paper. For a number of the species described, no photograph or painting of any kind is provided. For the rest, reproduction is poor (very dark) and only for a few species is the abdomen illustrated. The descriptions for each species are limited in detail (compared e.g. to the historical descriptions by Meyrick and Fletcher) and seem in a number of respects to be misleading.

For many species, the descriptions state that the termens of the first, the second or both forewing lobes are concave. At best, this categorisation leaves several possibilities unstated. Some forewing lobes on some of these species have a straight termen, while others are rather narrow and have little or no obvious termen. More importantly, the photographs included of several of the species do not agree with the information in this description on this point. As an example, for X. marmarias, Meyrick wrote, "first segment rather narrow, second posteriorly dilated, its apex produced, termen concave, oblique," while Kovtunovich and Ustjuzhanin write (of the lectotype), "outer margin of both lobes concave". Photographs are included of two of Meyrick's specimens and these show a concave termen for the first lobe for the lectotype and a more acute lobe for the syntype. This seems therefore to be a character which cannot readily be used to distinguish live individuals.

Additionally, for many of the species, Kovtunivich and Ustjuzhanin write of the dorsal fringe of the forewing that it includes "patches of dark hair at the base, in the centre and at the apex." The natural reading of this wording would be to interpret this as a series of positions along the wing. However, the actual positions of these patches in the species do not seem to include any at the base of the wing. More correctly, they include patches around the middle of the wing, below the base of the cleft (i.e., around 60-65% of the way along the wing), and near the tornus (i.e., around 95%). This seems to be the only possible interpretation of this description.

For two of the species, we have enough information in Meyrick's descriptions and other material to know their appearance.

X. marmarias is well illustrated by this Papuan specimen and the individual represented in this photograph from Queensland (actually a modified image to give bilateral symmetry - I believe that the whitish prothorax is a lighting artefact). These individuals match the syntype for X. marmarias, which is illustrated (with abdomen attached) by Kovtunovich & Ustjuzhanin. Note the abdominal pattern on these individuals, mostly golden yellow, but white at the base and between the 2nd and 3rd segments and ferruginous on the 3rd segment and apical region.

X. peltastes is shown in this photograph from Queensland. The appearance matches Meyrick's original description. Note the abdominal pattern with a bronzy fuscous coloration with a whitish metathorax and basal segment and whitish edges or spots on subsequent segments.

The current Xyroptila observations on iNaturalist can be separated into two groups: 1) Two apparently matching individuals from Hong Kong (here and here), and 2) One individual from West Bengal, India (here).

It is clear that the two iNaturalist forms do not match either X. marmarias or X. peltastes.

The Indian observation is somewhat close to X. marmarias but the colouration is much more orange and the abdominal pattern is only whitish at the base (very extensively). As discussed on the observation page, the moth in the photograph is a perfect match for X. oksana as illustrated by Kovtunovich & Ustjuzhanin.

The Hong Kong moths have presented me with more difficulties. The abdominal pattern is very distinctive in comparison with the other species for which live observations are available. The basal segment shows brilliant white edges, leaving a ferruginous triangle, completely different from the whitish basal segments on the other three species. Of the remaining Indo-Australian species, 1) X. soma is described as dark brown on the head and thorax and different in most other visible characters, although the forewing description is self-contradictory; 2) X. vaughani is described by Fletcher and has the first two abdominal segments pale yellow; 3) X. dohertyi has dark forewings with hardly any pale scales; 4) X. colluceo is illustrated and completely different; 5) X. falciformis is apparently brown and yellow, with a different pattern in the forewing dorsum; 6) X. maklaia, 7) X. variegata, 8) X. aenea and 9)X. siami again apparently have a different pattern in the forewing dorsum; 10) X. kuranda has a violet iridescence on the forewings and a different pattern in the dorsum; and 11) X. uluru apparently has light brown forewings with grey spots.

This leaves just two candidate species: 12) X. oenophanes, the type species of the genus and one of the most widely recorded, including Taiwan and Guangxi province, China; and 13) X. elegans from the Moluccas, Sulawesi, New Guinea and Australia. The descriptions provided for both of these species by Kovtunovich & Ustjuzhanin could fit these Hong Kong individuals. However the supplied photograph of a specimen of X. elegans shows much more extensive pale mottling on the forewings, whereas the best image of X. oenophanes shows a pattern very close to these iNaturalist observations. Moreover, the syntype of X. oenophanes is illustrated - the picture is very dark, but clearly shows the same pattern as the Hong Kong specimens in the white at the base of the abdomen.

Returning to Meyrick's original description of X. oenophanes, the description of the forewings in particular is a good match for these observations: "Fore-wings with apex of second segment produced, acute, termen concave ; dark ferruginous-fuscous, somewhat sprinkled with whitish ; a whitish bar parallel to termen crossing both segments before their middle : cilia pale ochreous tinged with crimson, with a black bar at apex, and blackish-grey posterior patches on lower margin of first segment and both margins of second." Interestingly, the "crimson" colouration can be seen in some of these Hong Kong images.

I therefore conclude that, based on geography and appearance, the Hong Kong individuals are X. oenophanes.

Note: following writing this post, I discovered that I had earlier identified this Xyroptila from Singapore as X. oenophanes. There is some difference in the extent of the pale patches on the forewing (which corresponds with at least one of the specimens photographed by Kovtunovich & Ustjuzhanin) but again I can see no reason to identify this as anything else.

Posted on 11 de dezembro de 2016, 07:55 PM by dhobern dhobern


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