Tuesday, September 2, 2014

A Well Known Spider

A friend brought me this impressively large female spider – a good 25 mm in length – for identification, he said his porch was literally crawling with them. I had never seen anything like it before and after several fruitless Internet searches was none the wiser as to its identity.

The eye pattern is definitely Araneus.

Ventral aspect of the chelicerae


The photos of the spider were uploaded to BugGuide.Net and the mystery arachnid was quickly pegged as a Barn Spider (Araneus cavaticus). I'm reliably informed by many other people that this spider is by no means rare, in fact, it's very common on and under porches, in barns and other rural outbuildings – and yet my submission to BugGuide.Net is the first data point for Ontario.

In fact this spider is not only ubiquitous but has no small claim to fame – this is Charlotte A. Cavatica in the children's book Charlotte's Web, written by E.B. White.

Saffron-winged Meadowhawk (Sympetrum costiferum)

Attaining a length of up to 35 mm (± 2 mm), the Saffron-winged Meadowhawk appears larger in the field than the average Sympetrum spp, approaching the size of a Blue Dasher. This meadowhawk's behaviour also quite different from that of its cousins, it's wary and extremely difficult to approach, staying on the wing for long periods, and preferring to rest on the vegetation over the water rather than the shoreline plants.

The Saffron-winged Meadowhawk is reputed to be local and uncommon, and I had always considered it to be rare as it's seldom encountered in this neck of the woods, my last (and to date, only!) sighting was at Stoco Lake in early August, 2009.

But perhaps it isn't so uncommon after all, maybe successful "dragonhunting" is a matter of finding suitable habitat first and then looking for the dragonfly. Dry Lake, south of Marlbank near the intersection of Hog's Back Road and Moneymore Road (44.419895°, -77.107758°), is quite unlike other local wetlands – it's shallow and very calcerous, with a slimy, limy bottom, and several fen indicator plant species were present along the shoreline.

As often as not, different water conditions and plant life generally mean a different suite of dragonflies ... and on the afternoon of August 24, I lucked out and sighted two Saffron-winged Meadowhawks.

The sides of the Saffron-winged Meadowhawk's thorax are a rusty brown color, giving the insect a distinctly darker aspect in the field than other meadowhawks (we're talking about the mature male in these photos, females and young males are yellow-orange). According to the books the legs have fine yellow stripes, a feature lacking in this individual, but perhaps (this is guesswork on my part) this is an older insect and the marks on the legs have faded with age.

The veins along the front edges of the wings are saffron (this fades with increasing age), and the sides of the abdomen bear relatively thin black lateral markings rather than the large triangles of most of our other local Sympetrum species.

S8 and S9 usually have small black dorsal marks.

A mug shot.

The long pterostigmata are reddish-orange.

A ventral view of the abdomen and a closeup of the epiporoct.

Upland White Aster (Solidago ptarmicoides)

Formerly grouped with the asters and named Aster ptarmicoides, the taxonomical powers that be decided that this plant's flower structure is more akin to that of the goldenrods and moved it to the genus Solidago (which are themselves members of the family Asteraceae, so when all is said and done, this is still an "aster").

Sunny, dry areas in alvars and calcerous fens are a good place to look for the Upland White Aster; these photos were taken in mid-August at the Menzel Centennial Provincial Nature Reserve, and Dry Lake south of Marlbank. In fact, at Dry Lake it was growing with other plants associated with the Stoco Fen, such as Shrubby Cinquefoil and Grass of Parnassus.

A look at the involucral bracts or phyllaries.

The stems and leaves.

This showy little wildflower grows to a height of 30 cm to 50 cm, and, as further proof of its genetic kinship with the goldenrods, the Upland White Aster is known to hybridize with other species of Solidago.

Wednesday, August 20, 2014

Difficult to distinguish Darners

Yes, even after seven years of "dragonhunting" there are some species that prove to be my nemesis (or should that be nemeses?) when it comes to separating them in the field, namely, the females of Black-tipped and Lance-tipped Darners.

Male dragonflies are never a problem, they are easily distinguished by their terminalia, such as, for example, this male Black-tipped Darner (Aeshna tuberculifera). The inset shows the claspers and the "black-tip" – the all black S10, although in some individuals this segment may bear tiny blue spots.

The female Black-tipped Darner (Aeshna tuberculifera) is very similar to the male in terms of color and patterning. So far so good ...

Lance-tipped Darner (Aeshna constricta), male ... the inset illustrates the "lance-tipped" cerci, also note the blue spots on the upper surface of S10.

Now let's look at a couple of Lance-tipped Darner (Aeshna constricta) blue form females – as noted in field guides the styli are long and quite visible, but the styli of the Black-tipped Darner are noticeable as well, and lengths can be difficult to judge in the field. Unlike the male's last abdominal segment, the female Lance-tipped Darner's S10 doesn't bear any blue spots, so that doesn't help.

With a length of 71 mm to 78 mm the Black-tipped Darner is theoretically larger than the Lance-tipped Darner, which weighs in at 65 mm to 72 mm. But length is also tough to guesstimate in the great outdoors, and who bothers to cart a ruler around with them on a nature hike?

Lance-tipped Darner female #1

Lance-tipped Darner female #2

The following study of the differences between the females of these two species is based both on the material found in field guides and my own observations. Markings can vary according to the individual insect and by region so I'm not sure how reliable my observations are in the context of the big picture, but they work for me.

Lance-tipped Darner (Aeshna constricta), female:
– The lateral thoracic stripes are relatively narrow and notched.
– The dark lines separating the lateral blue abdominal spots are very straight and quite narrow.
– The blue line on S2 is continuous, and there is generally more blue than dark in this area.
The last two factors conspire to give the Lance-tipped Darner's abdomen a bluer overall aspect than the abdomen of the Black-tipped Darner.

Comparing the female Black-tipped Darner (Aeshna tuberculifera):
– The lateral thoracic stripes are broad and pale, sometimes almost white, and when the dragonfly is perched in a shady place they almost seem to glow.
– The dark lines separating the lateral blue abdominal spots are somewhat irregular, and larger than in the Lance-tipped Darner.
– The blue line on S2 is broken, there is more dark than blue on this part of the dragonfly.
– The face usually bears a thin brown cross-stripe.

Although not common, green and yellow form females occur more frequently among Lance-tipped Darners than Black-tipped Darners. There were a total of about fifty of these striking insects foraging high in the air and perching on the shrubs and this was the only green female encountered.

Note that although the colors are different in the next two examples, the patterning is still consistent with the blue form Lance-tipped Darner females studied above.

Two yellow form females were flying but I was only able to capture one of them.

Before sending this beauty on her way I had to capture an image of those awesome eyes ...

A green form female Lance-tipped Darner in a more natural pose, hiding in plain sight despite its size and eye-catching markings. The complex patterning breaks up the dragonfly's profile and makes it difficult to espy when it's perching among the tangle of background vegetation.

Christmas in mid-August

And why not Christmas in August? In my opinion any day a person discovers a cool plant or animal new to them feels like Christmas.

On this particular day I was searching for odonate naiads in a a sand-bottomed woodland stream near the intersection of the trans-Canada Trail and Sulphide Road (44.494167°, -77.285556°). I happened to look up, and growing on a shaded rocky bank covered with thin soil was a luxuriant patch of (what else?) Polystichum acrostichoides, better known as Christmas Fern.

A lower and upper surfaces of a fertile frond – only the pinnae toward the tip produce spores. The two lowest pinnae are angled downward.

A closer look at the dense clusters of sori.

The pinnae (note the bristly margins) have upward pointing lobes near their bases, think of the toe on a Christmas stocking.

The stipe and rachis are scaly.

The dark green glossy leaves – both the sterile fronds and non-reproductive parts of the fertile fronds – persist throughout the winter, always a welcome break from the monotonous white of a winter's day. Although there are other fern species with evergreen fronds, for whatever reason this one earned the name Christmas Fern.

Tuesday, August 12, 2014

A Forcipate Emerald at the Stoco Fen

Reputed to be rare and local, perhaps the Forcipate Emerald is more common than generally thought and is merely secretive, with a preference for habitats that are inaccessible to the average person, such as bogs and alder swamps – or the Stoco Fen.

Somatochlora forcipata is a medium sized dragonfly with a length of 45 mm to 50 mm. It flies from early June until mid-August and this male, encountered on August 11th, is beginning to show its age and its few yellow markings are obscured.

One thing time doesn't fade in an Emerald are its eyes. In fact, they start out life as rather dull orbs, and acquire the luminous green that seems to glow with an inner light only with increasing maturity.

The abdomen is relatively slender.

Many Somatochlora spp – especially older dragonflies with dulled colors – resemble one another closely even when perching and have to be identified in the hand. Even so care must be taken because the terminalia of the Forcipate, Incurvate, Kennedy's and Delicate Emeralds look superficially similar to one another. Here's series of images making a 180° "walk-around" the claspers.

A few other unidentified Emeralds (including a possible Brush-tipped Emerald)and Darners were sighted at the fen, and it is currently host to a robust community of Band-winged Meadowhawks (Sympetrum semicinctum). Who knows what other odonate surprises might be lurking out there in this unique little corner of the world?