Friday, 31 October 2014

A few more goodies from Xuan Son

October 26, in Xuan Son, I had, besides the Calopterygids and Planaeschnids, several other interesting dragonflies. Rhinagrion hainanense is always a great find. Regular at Xuan Son from early spring until autumn, but a wonderful insect. I was also surprised to see a female Merogomphus pavici ovipositing. I had no idea this species flies this late in the year. And two males Lamelligomphus formosanus were another surprise. Of course some Lamelligomphus fly relatively late in the year, but I had not seen L. formosans this late. Boyeria karubei was common, but it is a fine species and a specialty of the park. I also took a few photos of Coeliccia. No less than 6 species were present: C. scutellum, C. pyriformis, C. cyanomelas, C. uenoi, C. sasamotoi and C. poungyi.

Old male Lamelligomphus formosanus, its venter covered in mites.

Pretty Rhinagrion hainanense, male

Female Boyeria karubei

Female Merogomphus pavici, resting after release

Merogomphus pavici, female face

Closer in-hand view. Note the massive hind legs and the spines on it.

Coeliccia poungyi, one of about 12 males

Male Coeliccia sasamotoi

Jewels of forest streams!

Xuan Son National Park is a great place for Calopterygids. October 26 was as good as expected, with many Matrona basilaris, Matrona taoi and Atrocaloperyx coomani. I decided to take pictures of the females. These are all similar in that they have large whitish pterostigmata, but when you know them they are not difficult to identify. Matrona taoi is decidedly reddish brown, which is especially conspicuous in flight. Matrona basilaris is brownish, but if it opens its wings these are dark brown with milky bases, in a pattern similar to the male. Atrocalopteryx coomani has hyaline wing bases.

Female Matrona taoi, with its typical reddish brown wings

Matrona basilaris female with brown wings

And female Atrocalopteryx coomani, showing translucent wings

Wednesday, 29 October 2014

A fourth Planaeschna species from Xuan Son

Sunday October 26 was highly productive for Planaeschnids, with 4 species observed at Xuan Son National Park. This is rather exceptional for me, but I love them. Haomiao Zhang in personal comments stated that this highly speciose genus has at least 50 species with many in southern China. It comes as no surprise that the same goes for northern Vietnam. Indeed, we are only starting to scratch the surface. Partly this is because visiting scholars have been focussing on spring and early summer, whereas many Aeshnids fly in autumn.

After I caught the first "not gressitti" (see earlier posts) I saw another patrolling a square meter of open water on a stream inside the forest. I was able to catch it and although it looked similar, it also clearly was much larger. In fact the "non-gressitti" was 65mm total body length, but this specimen was 75mm. Of course, in detail it is also rather different. For now I need to treat it as yet another species incertae.

Planaeschna species novum / species incertae, male. Note the straight appendages (see below)
The four males caught. Left P. guentherpetersi, middle row P. "not gressitti" and right the present larger species. Note also the variation in the pattern of S2, with 6 marks in the larger species, 5 in P. guentherpetersi and 4 in "not gressitti"

Appendages in dorsal view, robust, straight

But also suddenly expanded in dorso-lateral view

Robust and straight in lateral view

Penile distal segment in ventral view, Angular in outline and with moderate earlobes
In lateral view, earlobes visible

Facial pattern in brown, not black

Two pale-faced Planaeschna species from Xuan Son

October 26 I was working the streams of Xuan Son. This is the place where P. guentherpetersi was described from. I ran into it last year and again this Sunday I bumped into several. Females were flying about and ovipositing in the trees over the water, sometimes at several meters height. But I also noticed them ovipositing on logs floating on the water. Although I saw several, I was only able to catch one female and take pictures of another. Only late in the day, not far from dusk, did I finally catch a male. I also caught another rather similar female, but somewhat smaller, with different ovipositor and different pattern on S2. This somewhat smaller species is different from P. guentherpetersi, but I have as yet not been able to find what it then might be.

Another female Planaeschna guentherpetersi. Note again the characteristic pattern on S2.

Facial pattern of female P. guentherpetersi, largely orange-yellow, but darker anteclypeus.

The male of Planaeschna guentherpetersi.

In dorsal view, the same male. Note the 5-spot mark on the dorsum of S2.

Facial pattern of male P. guentherpetersi, similar to female, but antefrons much darker brownish black towards dorsal half.
Appendages in lateral view of P. guentherpetersi, clear uplift
And in dorsal view. Epiproct looks shorter than it really is through angle (distorted in death)
Penile final segment in ventral view. Not rounded and no "earlobes", very different from the "gressitti" types
In lateral view,  no earlobes

The other pale faced Planeaschna female caught hunting over the stream. Note the very different pattern on S2 and the lack of pale markings between the two greenish yellow lateral stripes.

The face of Planaeschna species incertae, with pale anteclypeus.
The two females in dorsal view. Planaeschna species incertae on top and P. guentherpetersi below.  Apart from the smaller size and reduced amber bases to the wings of the species incertae, note also the very different pattern of S2.
The same in lateral view. Note the different lateral marking on S2 and the different relative length of the paraprocts.

Which becomes obvious here. Much longer and differently shaped paraprocts. Also, the ventral projection of S10 is less pronounced. Female P. guentherpetersi
The same for Planaeschna species incertae. Shorter paraprocts and more pronounced ventral keel. Clearly this is a different species.

Tuesday, 28 October 2014

Planaeschna - just when it started to make sense

Planaeshnids are beautiful, generally slender and brightly patterned Aeshnids. They are also notoriously difficult to separate. What is more, some characteristics are difficult to ascertain. As I tried to point out, drawings of the penile organs depend on the state of the specimen. That is not to say the shape is of no meaning. Far from it. There are also subtle differences in markings between similar species. Then there are small differences in the appendages, but it seems that many species have largely similar appendages. Thus a combination of minor differences may point the way to specific identification. Then there are many species and maybe many more awaiting description, but also there may well be several names that are synonyms referring to the same species. It does not help that many species are described based on just one of a few types and rarely recorded. Good photographs are generally lacking and with the slight differences in patterning and shape the quality of drawings is of great influence. And thus with 4 species bagged this Sunday in Xuan Son I knew there would be no end to my troubles. Today I will start with the easy species. Planaeschna gressitti. After Sebastien found it this spring on Mau Son in Lang Son Province I have also found it at Pia Oac. There are hardly any differences between specimens of the two locations. I already noted that it is somewhat worrying that very similar P. tamdaoensis was recorded from the same altitude somewhere in between these locations. Going back to the literature I found that P. suichangensis was in fact also extremely similar. Wilson (2005) points out that differences between P. tamdaoensis and P. suichangensis are slight and that the former may be a junior synonym of the latter. Problem is that although Wilson gives good drawings of both the dorsal view and patterning of the abdomen and lateral of the first few segments, this is not so in Asahina (1996) or Karube (2002). This somewhat complicates comparison. Now, the patterning on S1-3 is a close match especially with P. suichangensis as depicted in Wilson. The pale line on the dorsum of S3 or the dorsal patterning of S1-2 and the lateral patterning on these same segments is identical. The dorsal or ventral view of the appendages is somewhat paddle shaped, clearly broadened in the apical half. This is also a good match, but this is the same for P. tamdaoensis or P. gressitti. The angle of the superior appendages in lateral view is the largest difference between these species, with P. gressitti being the straightest and P. tamdaoensis the most sinuous. The facial patterning of all these species is depicted as characterized by an all black antefrons.
Now, the specimens from Pia Oac and Mau Son are similar in these respects, but also characterized by a clear yellow lower border to the antefrons. The sides are also yellow and this moves up high towards the apex. They share the pale line of the dorsum of S3, have slim lines almost touching centrally on S2 forming a cross, and paddle shaped appendages. In these respects they are very similar, but they differ from the drawings of all three species concerned in the yellow lower border to the antefrons.
Now let's consider the very similar species of Xuan Son, a location much lower (450m asl). My first impression was that this too is M. gressitti (if that is what the others are). But they do not have a lower yellow margin to the black antefrons. Also, the labrum is bordered by an even blacker anteclypeus and has not only black borders, but the yellow is split in the center into two distinct yellow spots. The yellow on the sides of the antefrons also does not extend as far towards the apex. The appendages are not as paddle shaped at all. And the pattern on S1-3 is different too. The cross on S1-2 is more robust, but also more separated, and S3 misses the dorsal line. It is possible that these are regional differences and little is known about the variation, either geographically or within populations, but the two males I caught at Xuan Son are highly similar to each other and so where the different specimens of Pia Oac and Mau Son, but of course not to those from Xuan Son.

Male Planaeschna with black and yellow face from Xuan Son No. 1

Male No. 2
Male No. 1 face. As you can see the yellow area on the labrum is heavily bordered black and split in the middle by a black line. The anteclypeus is very dark blackish brown and the antefrons has no lower yellow border and the yellow sides do not extend towards the antennae. See the posts on P. gressitti for the facial view of the species.
Male No. 2 face, very similar, but even dark on anteclypeus

Dorsal view of specimen from Mau Son. Note the dorsal line on S3 and the cross on S2.

Dorsal view of specimen from Pia Oac. Very similar

Dorsal view of No. 1 male from Xuan Son, note lack of dorsal line and robust but open cross on S2

Dorsal view of No. 2 male, very similar
The appendages of the Mau Son specimen in dorsal view

The same in lateral view

No. 1 from Xuan Son, undulating and not as paddle shaped

In lateral view one smooth broad curve, not sinuous

No. 2 male exactly the same differences

Indeed, smooth broad curve of male No. 2
Although extremely similar in patterning, it is clear from the shape of the appendages and the facial pattern that this is most likely a different species. But the undulating outline of the appendages in dorsal view is different from P. tamdaoensis, P. gressitti and P. suichangensis. So what is it?

Monday, 27 October 2014

Huu Lien - still a treasure trove*

*Updated after publication of Paracercion ambiguum

On October 19 I was all day at Huu Lien and as we know I ran into beautiful Coeliccia galbina. Thus it was a memorable day. Most other goodies were there too. On the gomphid front Labrogomhus torvus was still flying. Not surprising, as we saw it into December last year. Ceriagrion nipponicum, Vestalaria miao, Atrocalopteryx atrocyana and A. auco (the newly described endemic), Paracercion ambiguum, Prodasineura croconota, Gynacantha japonica and many more. Here are a few additional photos.

Price for rarity is likely deserved by Atrocalopteryx auco. Although its brother A. atrocyana is common all over Huu Lien, I saw only a single male of this species.

But what I did not expect was a great many Prodasineura croconota still flying. Last year I had not seen them and only discovered them in spring this year. But apparently I just overlooked them last autumn. Quite a few tandems were active. This is of course a female.

And this a tandem, with the exquisite male easily identified

Just like last year, Gynacantha japonica was active at dusk, hawking over the paddies. Until now I have not found this species anywhere else. This is a male.
These are the distinctive appendages in ventral view, about 4 times the length of the epiproct

Recognizable by the almost absent lower appendages and the brown crescent along the wing tips: male Vestalaria miao.
And there he is! The Paracercion ambiguum. As usual common along the stream from the reservoir.