Adventures in Spider Misidentification: Spitting Scytodes

Spitting Spider Scytodes cf thoracica (Latreille, 1802)

Finished sweeping yesterday's snow off the walkways, had my coffee, and now it's time to get back to work. Sunday should be, at least in part, a day of rest, even if a deadline is fast approaching. Chapters won't write themselves, of course, but this week looks like working at a computer would be preferable to being outside. Average weather in Edmonton is an oxymoron: Pacific Lows and Arctic Highs push back and forth showering us with extremes. This week looks to be a depressing and Vitamin D-free seesaw of snow, sleet, ice and sunless days. So how about a quick dissemble to a sunnier clime with an ancient photo of a Spitting Spider?

Looks like a week for the snow shovel and ice scrapper

I think this is the cosmopolitan Scytodes thoracica (Latreille, 1802) and, although she inhabited our closet in Brisbane, one might find a similar slowly stalking spitter in many closets in North America. The Spitting Spider spits silk from its chelicerae (fangs) to tie its victims down before eating them. At first this seems strange: silk should come from spinnerets at the other end of the body. But, like most things arthropods do, it is really the jointed limbs that are the key. The fangs are just the first pair of limbs modified for feeding: spinnerets are derived from couple of pairs of more posterior limbs. Arthropods are composed of a series of what were originally very similar segments, each with a pair of limbs and each with the genetic potential to produce silk (silk is, basically, an excretory product). Scytodes are unusual spiders only in that they have turned on the silk producing abilities of the segment bearing their fangs.

More than somewhat alien-looking and silk issues from either end

But in a sense, this is reverting to what most silky arachnids do. Pseudoscorpions and mites, for example, also produce produce silk from their mouthparts and some mites use silk to trap prey (Spinibdella, a genus of snout mites being one such). Pseudoscorpions use their silk to make nests in which to hide away, as do many mites.

Silken cells under bark and some exposed pseudoscorpions

Of course, the gardener's least favourite mites, spider mites, also spin silk, but from their second pair of limbs, the pedipalps. Unfortunately, spider mites feed on plants and not on each other, but use silk much like many arachnids - to make nests and even to disperse on the wind - a method analogous to ballooning in spiderlings.

Two-spotter Spider Mites resting, moulting, and laying eggs in their web 

Come to think of it, we tend to assume what is most common is normal. Spiders are our common experience of silk spinning in arachnids and arthropods in general, but they are the only ones I can think of that produce silk from limb remnants near the middle of their body (over time, the spinnerets have become less limb-like and moved rearward - see the 'living fossil' Mesothelae). Tarantulas were once rumoured to produce silk from their feet, but this hypothesis seems to have come from too much Spiderman and not enough experimental rigour. Even caterpillars produce silk from their mouthparts and the only insect that I know of that has silk producing legs (Embioptera) uses its front feet.

Sticky feet yes, but not silky

Well, enough bludging for a Sunday morning - but not all in vain. I discovered a lapse I'd make yesterday about where silk in sea spiders (Pycnogonida) comes from - and learned that spiders are stranger than I thought.

Bludging with Beetles: Ptinus fur, a spider beetle

Habanera pepper seed & cautious spider beetle

The Anobiidae is a family of beetles with the charming common name of 'Death-watch and Spider Beetles'. Among the thousands of species known worldwide, fewer than a hundred live in Canada and only one, so far as we know, inhabits the Home Bug Garden: Ptinus fur (Linnaeus,1758), the White-marked Spider Beetle. The far more ominous sounding Death-watch Beetle Xestobium rufovillosum (De Geer, 1774) bangs its head against the rafters to attract a mate on calm summer nights (you can watch and hear one here). I suppose if you can't sleep this might sound discomforting, but nowhere near as perturbing as the noises the squirrels make in our attic.

Somewhat battered male Ptinus fur ~3 mm long

Like the Death-watch Beetle, the White-marked Spider Beetle is nocturnal but with a body that is less than half as long. As well as being tiny, these beetles like it chilly - the one above just came out of a 4C refrigerator, but was running around too fast to get a decent picture. No worries, though, there are several excellent pictures on the web, such as this habitus shot at BugGuide and this spectacular stack-image on Flicker. The Flicker picture by John Hallmen consists of 153 separate images, each with a slightly different focus, that were merged into a single high resolution picture.

We find White-marked Spider Beetles in our basement every winter. They have a broad diet, including stored foods, but a long generation time (over a year) and aren't usually considered major pests. As long as we are only finding a few, I don't think I will worry about them, and they count towards the Winter Bug Challenge - over 50 species of arthropods so far.

Family Matters: Primulaceae aka Primroses, Cowslips, Rockjasmines, Shootingstars

A Cowslip or Oxslip - a hardy and typical wild primrose

This Christmas is a working holiday at the Home Bug Garden. When I’m not shoveling snow off the walkways or raking it off the roof, I’m plunked down in front of the computer plugging away at the second edition of a book. Unfortunately, the latter is proving to be more of a chore than expected (a lot of new science has been published in the 13 years since the first edition), and since there is only a skiff of new snow to sweep away this morning, I need something else to do as a break.

Primula veris or 'Little First of the Spring'

 It’s too cold (the predicted high today is -23 C) to go looking for winter insects, but cold and snow are good motivators for daydreaming about next spring. The Latin word for spring is ver, from which we get our word ‘vernal’ (as in Vernal Equinox, the next being a very distant 20 March 2013). 

Cowslip is a June bloomer here

Ver is also the root for one of the Home Bug Garden flower species, Primula veris Linnaeus, 1753. The Latin name means more or less ‘little first flower of the spring’, but in the Home Bug Garden early June is when it appears. Also known as Cowslip or Oxslip, veris is the type species on which the genus Primula is based and Primula is the type genus on which the Family Primulaceae is based. 

Garden primroses come from Cowslip, Common Primrose and others

The Cowslip is also the very humble base from which many spectacular horticulture varieties have been bred by crossing with Common Primrose (Primula vulgaris) to produce the 'Polyantha' hybrids.

Auricula hybrid primrose

The Mountain Cowslip (Primula auricula) also seems like a modest beginning for a vast hybrid  swarm of form and colour, but the breeding has been going on for centuries.

Yet another colourful hybrid primrose (possibly Primula x acaulis)

Even without human intervention, Primula is a very successful genus with more than 400 described species worldwide. Only 20 of these species are native to North America, but four of these grow wild in Alberta. Mealy Primrose (Primula incana) is the only one that I have seen – a small, but pretty wildflower that grows in marshy areas throughout much of central Alberta.

Drumstick Primrose (Primula denticulata) more or less hardy here 

Dwarf Canadian Primrose (Primula mistassinica) and Greenland Primrose (Primula egaliksensis) are restricted to marshy spots in the Rockies and Strict Primrose (Primula stricta), although Holarctic, is found here only in the Canadian Shield part of extreme northeastern Alberta.

Siberian or Cortusa Primrose (Primula cortusoides)

Although spectacular, and more or less hardy, the hybrid primroses do tend to be short-lived. We've had better luck with some of the species primroses. Alas not the Orchid Primrose (Primula vialii), it's not quite hardy here and more a biennial than perennial anyway. However, Siberian Primrose (Primula cortusoides) is both hardy and very attractive - much like a wild primrose, but larger.

Siberian Primrose

'Cortusoides' means 'resembling Cortusa',  another of the four genera of Primulaceae in the Home Bug Garden: Primula, Dodecatheon, Androsace, and Cortusa. Apparently the latter was named in honour of a Paduan professor of botany Cortusus. They are commonly called Alpine Bells and I have blogged about them before and have nothing new to add other than the origin of the genus name. 

Alpine Bells another striking wildflower from the Primrose family

I've also blogged briefly about the delightful Pygmyflower Rockjasmine  (Androsace septentrionalis Linnaeus) before, one of three species in the genus that occur in Alberta. 

Pygmyflower Rockjasmine, a Primrose family wildflower and weed

Androsace seems to be from the Greek for 'man + shield', perhaps ‘shield of men’ as Andromeda means ‘ruler of men’. You may have heard of Andromeda from the galaxy, short-lived TV-series, movie and novel (Andromeda Strain) or Andromeda polifolia L. the Bog Rosemary, but the name goes back to Greek Mythology. Since the Greeks (androsakes) and Romans (androsaces) fused this name for the rock-jasmine, though, perhaps we need not delve further.

Eastern Shooting-star Dodecatheon meadia - a primrose in all but name

Amazingly, though, and in spite of my best intentions, I seem to have never taken time to wax prolix about the Home Bug Garden's Shootingstars! Perhaps this is because I'm a bit embarrassed that our species, Dodecatheon meadia (aka Pride of Ohio, Eastern Shootingstar), is not one of the two species native to Alberta: Dodecatheon conjugens (Bonneville Shootingstar) and Dodecatheon pulchellum (Darkthroat Shootingstar). Both species are broadly distributed in, respectively, grasslands and wet meadows or saline flats, in the southern third of the Province. Although mostly North American, Dodecantheon seems to be another of those ancient words for a flower (in this case Greek). 

Russian Blue Potato Flower - not a primrose, but buzz-pollinated

Although not looking much like a primrose, shootingstars are good Primulaceae and closely related to Primula. They have a variety of more humdrum common names such as Mosquito Bill and Mad Violet that refer to their strange inside-out flowers. There is a method to this madness, though. Shootingstars require a special kind of pollination where a bee hangs onto the anthers (the cone in the middle) and buzzes its wings to shake pollen out of the pore at the tip of each anther. Some of our common crops in the Solanaceae such as potato, tomato, and eggplant also are buzz-pollinated and only certain bees (mostly bumblebees and leaf-cutter bees) are smart enough to learn how to buzz. I suspect that having the petals out of the way helps.

Mad Violet, Mosquito Bill or Shootingstar, a Primrose for all of that

In Australian, what I’ve been doing is officially known as ‘bludging’ (evading work), but I prefer to think of it as toning up my botanical skills. In any case, it is Christmas Eve and wishing all my readers Merry Christmas or Happy Whatever Holiday You May Celebrate seems in order. Now, alas, it is time to go back to work.