Drepanosticta revisited - a new species after all*

*This entry adjusted August 8, 2018. The new species described below has been published by Dow & Kompier (2018) as Drepanosticta emtrai.

Today, June 27, I had a home day, during my 3 week survey of Northern Vietnam. But of course I could not stay in, so I went for a short trip to Hoa Binh Province, to a touristic site Sebastien introduced to me. Sorry to say, I hated it, but while I was there I noticed a female Coeliccia that was big and had the colors of C. uenoi. That would be a great discovery, so I looked around for the male. I did not find it. But while doing so, I noticed a Drepanosticta. It looked as it was supposed, dark thorax, small rings on dark abdomen, blue abdomen tip. All the works of D. hongkongensis, see the other blog entry on that species. Nevertheless, in hand the appendages appeared different and because it was a new location, I ventured to take it with me. Ba Vi is of course not that far from Hoa Binh, but far enough. When I got home I checked it under the microscope and lo and behold! It showed the same lobe on the superior appendage as the specimen from Ba Vi I took pictures of last year and now, after seeing a great many D. hongkongensis, had sort of dismissed as aberrant (see the first Drepanosticta entry). There are in fact many differences in the appendages, apart from its slightly smaller size, and like I thought of last year's specimen, it has blue markings on the prothorax and also a small blue mark at the base of the second pair of wings. There can be no doubt, this is a different Drepanosticta species and the same as that encountered last year on Ba Vi mountain. Clearly, there are two species in that forest, possibly one appearing earlier (May) and the other later (June/July)!

The two species side by side. On top is Drepanosticta hongkongensis, albeit larger than originally described by Wilson and with pale anterior lobe to the prothorax. In this scan a preserved specimen was used for comparison, so it is slightly duller than in real life. The bottom specimen is the new species from Hoa Binh. It is marginally smaller.

Appendages of D. hongkongensis in dorsal view. Note the blunt tooth to the inferiors.

The same for the new species, note the acute tooth, slanted posteriorly.

Ventral view of appendages of D. hongkongensis. Note the blunt tooth to the inferiors and absence in this view of a process to the superiors (which in fact have a small process, as can be seen in dorsolateral view).

The rather differently shaped appendages of the new species (Drepanosticta emtrai). Dorsum of superiors smoothly rounded and large ventral process at 3/4th of length of superiors.

In dorsolateral view a small process can be seen in D. hongkongensis on the inside of the superior appendages.

This is clearly much more prominent in the new species (Drepanosticta emtrai)

Ventral view of appendages of D. hongkongensis. Note almost straight outer edge of inferiors, that smoothly bend inwards towards the tip.

This is very different in Drepanosticta emtrai. At the halfway point (where the acute tooth can be seen) the appendages make a clear bend outwards and curve almost semicircular back inwards again.

The prothorax shows blue on the lateral lobes and on the anterior lobe.

Here in view of the complete thorax blue can also be seen at the bases of the wings, notably the second pair.

More from Bac Kan

Yesterday I found Merogomphus parvus and in the absolute final light of day many Nihonogomphus thomassoni/lieftincki. Also Gomphidictinus perakensis, Stylurus again, and an as yet unidentified Chlorogomphus (cf. nasutus). Macromia urania was another nice find.

Ba Be and surroundings

Readers!
We are in the field, so no photos. However, here a little news on progress. Ba Be itself, although famous for its lakes, has few streams. The mountains south and north are better. Near Bung Lung we found a great little stream. Interesting finds included Asiagomphus sp. A, Megalogomphus sommeri, Parvogomphus torvus, Stylurus sp., Chlorogomphus (Sinorogomphus) sachiyoae, Lestes cf praemorsus (but larger), Mortonogrion sp, Coeliccia acco, Macromia unca (male), Macromia clio, Macromidia rapida, many Periaeschna magdalena, Matrona basilaris. The target in Ba Be is a new Coeliccia, which we spotted last year. We will keep you posted (literally).

Eventful day at Tay Thien, a few more goodies

This weekend (June 15-16) proved pretty productive at Tay Thien. Apart from the species already described, I encountered about 50 more. Here are a few other highlights

The first was this beautify male Polycanthagyna erythromelas. I saw several females flying about, but this male resting for a short while in a nearby bush was a treat.

And in the lower river stretches were several Lamelligomphus formosanus active. Once you know the species, it is not so confusing anymore.

Another species present in good numbers, towards the evening in the open and during the day in dark clearings, was Macromidia rapida. I was lucky with a male that perched nearby.

The female of Sinorogomphus sachiyoae. Very much like the male in appearance. After these shots she happily continued ovipositing.

Another cool female, Heliogomphus scorpio. The male was active nearby as she was ovipositing near the nunnery. Like the male, very pale (white) metepimeron, unlike Heliogomphus sp., which occurred at the same stretch, but is much yellower.

Here a close-up of her pretty face. Note the horn on the occipital ridge.

There was something else I did not expect, Drepanosticta hongkongensis. I noticed a male at 350m asl beyond the nunnery. Under the microscope it is identical to the specimens from Ba Vi. I thought the species there was known only from that location in Vietnam, but when this is D. hongkongensis, well, in that case it is not surprising it occurs elsewhere. Although the caudal appendages are identical, the anterior lobe of the prothorax is all black, as it should be for D. hongkongensis, unlike the specimens from Ba Vi.

The penile organ, identical

As are the caudal appendages

Eventful day at Tay Thien continued - Zyxomma petiolatum

When walking down from the nunnery at Tay Thien late in the afternoon of June 15, I noticed a slender small dragonfly patrolling in the ditch of an almost dry stream, the banks covered in shrubbery. The identification was straightforward. But, it was an addition to my list in Vietnam. Zyxomma petiolatum is a common and widespread species. According to the IUCN website, it also occurs in Vietnam. Maybe because of its largely crepuscular habits that I have not seen it before, or maybe I just do not look in its preferred habitat.
It is an interesting dragonfly, with hugely swollen S1-2, like the Neotropical Brachymesia or Erythemis species.

Zyxomma petiolatum, male. A handsome dresser.

Scan of dorsal side, showing slightly darker wingtips.

An eventful day at Tay Thien - Macromia urania and Macromia unca

To continue with the events of June 15 at Tay Thien, I saw a cool 3 species of Macromia. Macromia pinratani vietnamica is extremely common and normally it is also the only species that I see there. However, today I noticed in the lower part of the stream, on the way to the nunnery, where the water was running over cobblestones and grass, a Macromia flying about to oviposit. It was harassed by a male Sinorogomphus sachiyoae, but kept returning. I decided to try to catch it and was successful. Immediately after I had caught it a second female appeared, which I also caught, but after some photos released again. Because of the clear humeral stripe and facial bar, I thought these could be the females of Macromia clio, of which I found the male a few weeks back near Xuan Son. However, at home checking the pattern, that was clearly different. A little research at home pointed me in the right direction. When I verified the expansion of S7-9 the case was closed: Macromia urania! A species that has been recorded in Northern Vietnam before, and that was originally described from "Tonkin".

Female Macromia urania. Note large yellow marking on S2.

Different female in dorsal view. Note the small paired markings in the abdominal segments and the dark wing bases. The other specimen atypical in that respect.

Face of female Macromia urania

Thorax pattern of the same female

The labium, black, unlike M. clio

The leaf-like lobes on S8-9.

When I descended towards the end of the afternoon I wanted to get to another stream to check for evening flyers. I never made it, because when I crossed the lower part of the stream, I noticed 5-6 large Macromia flying rapidly and erratically over the water, sometimes dipping in it. They were robust and had brownish wings. It was real difficult to catch one to verify, but in hand it was easy. Macromia unca! Only recently discovered in Xuan Son, but swarming here in Tam Dao. Maybe it is not rare, just overlooked (which, given its crepuscular habits and fast flight is not too difficult to understand).

Another female Macromia unca!

The typical facial pattern

An eventful day at Tay Thien - Ophiogomphus sinicus

June 15 I went to Tay Thien again. It was partially cloudy and I was not too happy with that, but it was warmer than yesterday and there eventually were good spells of sun. I ran into several cool species. The first I want to share is another Onychogomphid. Last year, when we were discussing the possibility of several Lamelligomphus species in Vietnam, Sebastien showed a photo of a Gomphid with huge pincers as appendages. Clearly it was not Lamelligomphus, but we did not know what the alternative was. I decided today to first look at the stream where he had seen it. I did not see a lot going up the stream, but on the way back all of a sudden I saw it, sitting on a stone in midstream. I was able to first take some pictures and then to catch it for in hand shots. The stream where I caught it is a low elevation, really bordering the plains, and runs through a relatively open area, although the hills are covered in degraded forest. But later in the day, when I walked the path to the nunnery at Tay Thien (a different stream) I saw two more right next to the nunnery, so in the middle of the forest on the stream at 350m altitude.
Anyway, it is Ophiogomphus sinicus. A rather weird Ophiogomphus at that. It was first included in Onychogomphus as Onychogomphus sinicus, but after studies were done on the larval stages, it was transferred. Well, I guess there are good reasons to do so, but it sure as hell does not look like regular Ophiogomphus species. It is known from a large part of Southern China, although locations are scarce, for instance Guangdong and Guangxi. Not too surprising it occurs in Northern Vietnam.

Ophiogomphus sinicus, male, perched on rock in stream

In hand, the same male

Face of O. sinicus. There is not much difference with Lamelligomphus, really

Appendages in dorsal view

And in ventral view. Note the dorsal tooth at 1/3rd of superior and inferior appendages

And to be complete, ventral view

The shape of the anterior and posterior hamuli

Idionyx thailandica

June 14 I caught a male Idionyx thailandica near Tay Thien. I had also caught several in Huu Lien on May 25, but to my dismay I forgot to publish them. Hamalainen described I. thailandica in 1985. In 1991 he also described I. victor from Hongkong. I am a little confused by these species. The descriptions do not really give an answer as to why these are different species. Hamalainen states that the lateral expansion of S7-9 is distinctly  wider in I. thailandica than in I. victor. The appendages are (almost?) identical. Based on the lateral expansion criterium my specimens are all I. thailandica.

Idionyx thailandica, male, Huu Lien, May 25

The same male, different angle

A different male on the same day, same location

Young male I. thailandica, Tay Thien (Tam Dao), June 14

Face of young Tay Thien male

Appendages in dorsal view of Tay Thien male

Same in lateral view

And in ventral view

Huu Lien male appendages in lateral view

Tetrathemis platyptera and Rhinagrion hainanense

On June 8 I was oding in Xuan Son. On the verge of the reserve I first visited the large stream and in some ponds bordering it I found a small dragonfly I had been looking for for quite some time. Last year in Ba Be I saw it from the corner of my eye, but although Sebastien saw them several times at Xuan Son (see his blog), I missed out. But there it was. And although I could only get some shots from a distance, I was happy.

Later, inside the reserve, I twice bumped into beautiful Rhinagrion hainanense. First a fresh female, just emerged from the stream along the dam and later a male along one of the minor streams flanking the large stream with the bridges. I featured it before in the blog, but this is a species you can never see enough of.

Cute, small, Tetrathemis platyptera, male. Yes, I know, calling a dragonfly cute is degrading to the insect, but hey, it is pretty.

Freshly emerged Rhinagrion hainanense, female

And yet another handsome fella. Rhinagrion hainanense, male

Philosina buchi

On June 7 on the way to Mau Son I could not help to check some streams in the general area where one upon a time Echo maxima had been collected. The stream along QL 1A is pretty polluted, but just north of QL279 there is a feeder stream that runs into it that is really not bad at all, even if it runs from a village somewhat further upstream. Maybe there are even better stretches past that village. We checked the stream and apart from a nice Nihonogomphus thomassoni / lieftincki (I now lean towards thomassoni, but if it is one and the same species, who cares) saw at least 15 Philosina buchi, sometimes 3-4 together. I also noticed interesting interaction between males. One male flew towards another and perched close to it, after which both at regular intervals raised their wings somewhat up in one short jerky motion. This lasted for a few minutes, until the original intruder flew off again. The remaining male thereafter sat still.

Philosina buchi, nice male

Two males in close proximity, the lower one had flown in just before and both were at regular intervals raising their wings somewhat in an apparent intimidation display.