June 28, 2018
AMBERWINGS GALORE
Above the waters of the rancho's cement-lined pond three dragonfly species normally can be seen, by far the most numerous being the Slough Amberwing, PERITHEMIS DOMITIA, nicely portrayed at https://www.backyardnature.net/n/18/180628am.jpg
Slough Amberwings are distributed from Mexico and the Caribbean south through Central America into northern South America. Not much life-history information is available about them, but I can report that they do what dragonflies are famous for doing, which is to streak about above water, grabbing flying insects with their front legs, and returning to things sticking out of the water, and feeding. Also among all the flitters there's a great deal of checking out one another, all done so fast that I can't say what's going on. They must do what they do very well, though, to be so numerous.
One admirable feature about amberwings in general is that as a group they're so easy to identify, with their amber-colored wings and tendency to be smaller than other dragonflies. Knowing that you have an amberwing, it's easy to check on what amberwing species are listed for your area, then compare the species. In dragonfly identification mostly you focus on the intricate network of veins in the wings. The veins form borders of "cells," and cell shape, size, presence or absence tells us which species we have.
Lists on the Internet indicate that in the Yucatan we might expect two amberwing species. Pictures show that the wings of one species are broader than the other, so here we don't even have to consult wing venation. Our Slough Amberwing is the narrow-winged one.
We don't have sloughs here, but that's the way with common names.
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SEED-HARVESTING ANTS IN THE GARDEN
On Sunday the head-tall tobacco plant had looked as healthy as could be, but the next day all its leaves were drooping and already drying up. The plant's base was turning brown with the epidermis peeling off, as shown at https://www.backyardnature.net/n/18/180628ta.jpg
Then I noticed a line of tiny black ants ascending and descending the stalk, as shown at https://www.backyardnature.net/n/18/180628tb.jpg
When I checked in the camera's viewer to see if things were in focus, something interesting turned up. In the above picture, notice that ants descending the stalk are bearing something in their mandibles, but those ascending, aren't. I pushed the camera's macro capabilities a little beyond what the camera was designed for to get a better look at what the ants were carrying. You can see better in the somewhat blurry picture -- and note the ants' curious anatomy, seeming to have more constrictions in its body than normal -- at https://www.backyardnature.net/n/18/180628td.jpg
These were unusually small ants, so the brown, oval items being carried were minuscule. Well, tobacco seeds are minuscule, and my suspicions were confirmed by following the line up to the tobacco's fruiting capsules, which were working with ants as shown at https://www.backyardnature.net/n/18/180628te.jpg
Following the ant line downward, I found it entering an opening in the tobacco plant's tissue near the ground -- maybe an opening excavated by the ants themselves, in the process killing the plant -- as shown at https://www.backyardnature.net/n/18/180628tc.jpg
We've had seed-collecting harvester ants before, up in Texas, so the first step in trying to identify these ants was to check out the taxonomy of harvester ants. It turns out that hundreds of harvester ant species are recognized, and the species are distributed through several genera. Still, we've seen that these ants' anatomy is a bit unusual, with all those constrictions in the abdomen, so maybe an ID was possible.
When pictures of ants in the various harvester-ant genera were consulted, it was noted that two large genera display such anatomy as ours, Aphaenogaster and Pogonomyrmex. I believe ours must be Pogonomyrmex on the grounds that Aphaenogaster ants are described as fairly large, while ours were exceptionally small, plus there's this: Aphaenogaster species have only a single worker caste, but when I checked my photos I found two distinct ant types carrying seeds, as you can verify at https://www.backyardnature.net/n/18/180628tf.jpg
Therefore, though I can find no Pogonomyrmex species listed for the Yucatan, I'm guessing that that's what we have. As of 2014, 69 species of Pogonomyrmex ants were recognized. Most species occur in deserts throughout the Americas, and I have no idea which species ous could be.
If our ants really are Pogonomyrmex, one interesting fact about that is that Pogonomyrmex workers produce the most toxic venom documented in any insect, a toxicity comparable to cobra venom. While taking the ant-covered-fruit-pods picture I was stung several times and found it surprisingly painful for such a small ant. However, the pain quickly passed and left no lingering effect.
Pogonomyrmex ants are described as digging very deep nests with many underground chambers in which seeds are stored as food for the larvae.
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FISHING SPIDER IN THE POND
While sitting beside the rancho's cement-lined pond waiting for something to happen, a fair-sized green spider skated across the water's surface and took up position on a floating leaflet, as shown at https://www.backyardnature.net/n/18/180628sp.jpg
Back in Texas we've seen an aquatic spider with similar shape, white lines along the front part (the cephalothorax), and white spots along the top of the abdomen at the rear, but it wasn't green. You can compare our Yucatan spider with the Texas one at https://www.backyardnature.net/n/a/fishspid.htm
The Texas one was identified as the Six-spotted Fishing Spider, Dolomedes triton, and is commonly found throughout much of North America, plus it's known to occur in Mexico, though I can't find mention of the species in the Yucatan. Also, they're not green.
The North American ones and our Yucatan ones are so similar structurally that I can't imagine that they belong to different genera. However, I can't find any Dolomedes species looking like ours listed for the Yucatan. So here's another instance of "maybe we have something new."
Whatever the case, our picture and this information is being filed on the Internet under "Dolomedes aff. triton, the "aff." meaning "affinity," which admits uncertainty about the name, and we'll just wait for a specialist to let us know what the deal is.
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SILKY ANOLE VARIATIONS
Two weeks ago we looked at the Silky Anole who visits the hut's patio, shown at https://www.backyardnature.net/q/s-anole.htm
This week two more pictures were made, either of the same individual who'd changed colors, or a different one. It's important to be familiar with the variations, so the first picture, showing one perched on the near-vertical side of the deep pit below the porch, is at https://www.backyardnature.net/n/18/180628an.jpg
Jonathan Campbell in his Amphibians and Reptiles of Northern Guatemala, the Yucatán, and Belize speaks of some individuals showing a "pale dorsolateral line extending from behind the eye onto the body," which seems to appear in that picture. Also he mentions indistinct spotting over the body, and that the labial area (lips) and venter (bottom) are whitish or cream, shown in the second view at https://www.backyardnature.net/n/18/180628ao.jpg
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QUEEN-OF-THE-NIGHT CACTUS
Right beside the rancho entry gate, which I pass each day, this week for the first time ever I noticed a slender little cactus growing along a tree's trunk, shown at https://www.backyardnature.net/n/18/180628cc.jpg
Though it was neither flowering nor fruiting, I knew it might be easy to identify because its spines were so unusual, as you can see at https://www.backyardnature.net/n/18/180628cd.jpg
These are such unusual spines that I took the close-up shown at https://www.backyardnature.net/n/18/180628ce.jpg
The spines are so soft and weak that eventually they're deciduous, plus they're mixed with long, whitish hairs adding to the droopy image.
And with such spines, it was indeed easy to get a name: It's what's sometimes called Queen-of-the-night, SELENICEREUS GRANDIFLORA, distributed in much of Mexico south to Nicaragua, and the Caribbean area. Taxonomy of the genus Selenicereus is notoriously confused and understudied, so the species name grandiflora has to be seen as a placeholder until the group is better understood.
The grand name Queen-of-the-night is earned by the species' spectacular white flowers, up to a foot long (30cm). In fact, sometimes the species also is known as Night-blooming Cereus, though that name is shared by several species with big, white blossoms.
Despite the cactus looking like it's been in place for a long time, I'm uncertain as to whether our individual beside the gate grew there naturally, or whether years ago someone put it there. Theoretically the species can occur naturally here, but I've not seen it before in the Yucatan.
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CACTUS BESIDE THE TENT DOOR
Several weeks ago, on April 5th, in the mountains east of Saltillo, Coahuila, northeastern Mexico, I started out hiking on a valley floor, and climbed a small limestone mountain that was grassy and scrubby at its base, but forested on top. At the top, at ±7000 feet in elevation (2100m), the forest was composed of widely spaced, low growing, somewhat gnarly pines and junipers, between which grew clumpgrasses, low shrubs, a few giant yuccas and other things, and, especially, a nice selection of cactus species.
This time we're looking at a pricklypear species that occurred right outside my tent's door, as you can see at https://www.backyardnature.net/n/18/180628c5.jpg
That's a Pinyon Pine in the background, and up front the spiky plants are Lechuguilla Agave. And notice how the pricklypears were scattered all around the tent. There are many pricklypear, or Opuntia, species, but this one did something spectacular I'd never seen before, shown at https://www.backyardnature.net/n/18/180628c6.jpg
The orangish-red items aren't flowers or flower buds, and their presence is extraordinary. A closer look at them mostly arising along a pad's margins, but with a few emerging from the pad's face, is at https://www.backyardnature.net/n/18/180628c7.jpg
You can see one of the orangish-red items after it's grown a little, revealing what we're looking at, at https://www.backyardnature.net/n/18/180628c9.jpg
So, the orangish-red things are immature cactus pads, and the sharp-pointed, conical items causing the immature cactus pads to be so brightly colored are... the cactus' vestigial leaves. For, the first cacti -- as well as some primitive genera still existing -- had leaves. The vast majority of cactus kinds, however, finding that leaves lost too much water, evolved with their stems containing chlorophyll, and taking on the photosynthesizing job usually handled by green leaves. These vestigial leaves are like the human appendix, something inherited from our distant ancestors, but really of no use. The pricklypear's vestigial leaves simply fall off as the pads grow larger. Normally the leaves are green and people don't notice them.
So, what species is this? In cactus identification the size and disposition of spines is very important, so a close-up of this cactus's spine clusters is shown at https://www.backyardnature.net/n/18/180628c8.jpg
Each cluster is composed of three or so larger spines, with a few smaller ones at their bases. Spine color can be important, and these are somewhat reddish to white. An important feature is that many of the spines bend downward.
Despite the exotic-looking vestigial leaves, this turns out to one of the most common -- and some ranchers would say pestilential -- of all cacti. In Texas we called it by its usual name up there, the Texas Pricklypear, but deep inside Mexico that name won't do. The cactus's technical name is Opuntia engelmannii, so here another frequently-used name for the species, Engelmann's Pricklypear, seems most appropriate.
The online Flora of North America speaks of five varieties of this species, and treats them all, but our plants don't quite fit any of them. The closest fit, because of their chalky white older spines , seems to be variety engelmannii. The species is variable. Maybe here at the species' southernmost boundary we seeing something new.
You might enjoy comparing our mountaintop plants with the Texas ones presented at https://www.backyardnature.net/n/h/tx-prick.htm
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SUMMER SOLSTICE FEELING
Last week on June 21st the Summer Solstice marked the moment at which days in the Northern Hemisphere begin to shorten, while in the Southern Hemisphere they grow longer. During certain parts of the year it seems I can sense the changes taking changing each day, but not now. The Summer Solstice feeling is as strong today as it was a week ago.
At dawn and dusk a certain kind of dwarf cicada calls, setting the stage for the Summer Solstice feeling. Its call isn't raucous and penetrating like that of big ones, but rather it's a prolonged, subdued ringing that's echoic, watery, ethereal. The Turquoise-browed Motmot at this time also might issue low, ghostly, whoow-whoow calls.
At breakfast, the Sun rising across the papaya field below the hut is a weakly defined, silvery luminescence in the morning's light fog. But even in this tentative light, curves and margins of dew-wet leaves and stems of dark vegetation all around are highlighted with random-shaped puddles, speckles and arcs of muted colorlessness that change shape, and come and go as the Sun rises diagonally. It's as if the Sun at this season, self-conscious about changing it's course so drastically, unsettles all it touches with auras of impermanence.
As soon as the Sun rises higher and burns off the mist, though, then suddenly the feeling becomes the opposite of what it's been so far, unrelentingly stinging exposed skin and flooding everywhere with such brilliance that you can't look at it. Now the surrounding vegetation is all hard greenness and black shadows. This quick changing from extreme to extreme also is the Summer Solstice feeling, the feeling of mingling extremes.
But, of course, this whole matter of there being a Summer Solstice feeling is purely an invention of my bicameral human brain, one side coming up with stories and explanations for the other side's jumbled harvest of sensory stimuli. Beyond the framework of existing in one Earthly hemisphere instead of the other, and thinking about it and forming impressions about it that go no further than my own head, there really is no Summer Solstice feeling, nothing.
So, the Summer Solstice feeling -- which for seventy years has meant a great deal to me -- is all in my own head. And yet, I'm sitting here wondering whether what's going on with me might be an echo of what the Universal Creative Impulse does all the time, if it's true that She's created the Universe so that She may know Herself, which I like to believe.
If so, then instead of limiting Herself to either the Northern or Southern Hemisphere of the little planet Earth circling an unexceptional star in one of untold billions of galaxies, I'm betting She's populated the Universe with all forms of mentality from which to experience all forms of being.
In this context, I feature myself with these thoughts, feelings and insights about the Summer Solstice feeling as reporting for duty in the service of the Universal Creative Impulse. I am Her loyal nerve ending, stationed exactly here and now, doing my best to sharpen my perceptions, and by experiencing, feeling and thinking, faithfully reporting back to Headquarters.
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Best wishes to all Newsletter readers,
Jim
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