JIM CONRAD'S
NATURALIST NEWSLETTER
Issued in Río Lagartos, on the northern coast of
Yucatán, MÉXICO
in Ría Lagartos Biosphere Reserve

November 9, 2014

AMERICAN CROCODILE
In last week's Newsletter when we looked at the Morelet's Crocodile commonly seen in the estuary around Río Lagartos, I remarked that so far all the crocodiles I've seen here appeared to be Morelet's. This week while among the vast network of evaporation ponds where salt is commercially harvested near Las Coloradas about 30 kms east of Río Lagartos, my first American Crocodile, CROCODYLUS ACUTUS, turned up. You can see him on salt-encrusted ground beside a ditch filled with saltwater, just across small dunes from waters of the Gulf of Mexico, at http://www.backyardnature.net/n/14/141109cr.jpg.

A close-up of his head is at http://www.backyardnature.net/n/14/141109cs.jpg.

One obvious distinction between the American Crocodile and the Morelet's is that the American's snout is narrower. If you have a picture of the head from above, here's how you can determine mathematically whether the snout is "narrow": Keeping in mind that "maxillary teeth" are those arising in the upper jaw, they're numbered from the front, and that the tenth maxillary tooth coincides with the snout's constriction about midway the snout's length, Jonathan Campbell in Amphibians and Reptiles of Northern Guatemala, the Yucatán, and Belize tells us the following:

The American Crocodile's snout width at the tenth maxillary tooth is less than or equal to 70% of the distance from the base of the tenth maxillary tooth to the tip of the snout. In contrast, the Morelet's snout is wider -- at the tenth maxillary tooth the snout's width is greater than or equal to 75% of the distance from the base of the tenth maxillary tooth to the tip of the snout.

The problem is that in the field normally you don't get a good view from above the head. Still, a side view such as the above photos show also is useful, especially when comparing them with diagrams at the Crocodilian.Com website.

That website's head diagram for the American Crocodile is at http://crocodilian.com/cnhc/cst_cacu_am_head.htm.

The corresponding diagram for the Morelet's Crocodile's head is at http://crocodilian.com/cnhc/cst_cmor_am_head.htm.

Comparing our pictures with those diagrams we can see that the upper jaw of our salt-flat croc lacks a low mound before the eyes. Also, at its end the snout is considerably more slender than the Morelet's. Therefor, this new sighting is a good example of the American Crocodile, CROCODYLUS ACUTUS.

You might also like to compare these American Crocodile pictures with those on our Morelet's page at http://www.backyardnature.net/yucatan/morecroc.htm.

Despite this being my first definite sighting of an American Crocodile, I wasn't too surprised, since the windswept, flat, sun-glaring, salt-encrusted flats next to the Gulf of Mexico constituted a very different habitat from the dark-water ponds, backwaters and slow-moving, mangrove-protected spots where before now I've found nothing but Morelet's Crocodiles.

Maybe the easiest way to distinguish the two species is that on the American Crocodile's belly the scales form regular ranks and files of rectangular scales, while the Morelet's belly scales have smaller scales interspersed among larger ones, disrupting the systematic pattern. In the field, however, you don't see these features.

Yet another feature possibly distinguishing the two crocodile species is that this American Crocodile didn't let us get nearly as close as the Morelet's normally does. Local guides always say that the American is "más bravo" than the Morelet's -- hotter tempered.

All this being said, in my opinion, in the field, during most spottings when mainly you get a side view of just the top of the crocodile emerged, it's hard to tell the two species apart. But if you're in seawater or among the salt ponds, it's almost certainly the American Crocodile.

*****

CARACARAS
In southwestern Texas on the Edwards Plateau's southern slope we were at the northern extreme of the Northern Crested Caracara, CARACARA CHERIWAY. Though Caracaras are members of the Falcon Family, the Falconidae, they behave like members of the Vulture Family, the Cathartidae. Around here caracaras are common. A couple appear atop a tree at http://www.backyardnature.net/n/14/141109cc.jpg.

In that picture the bird at the right is an adult while the one on the left, with pink instead of orange skin at the beak base, and a tan throat instead of a white one, is a juvenile. I'm unsure whether the skin color at the base of the beak is a good indication of age; the Oiseaux-Birds.Com website says that "A patch of bare skin around the eyes can change in colour in few seconds, from pink or red-orange, to yellow when it is excited."

Another caracara feeding on something held with a foot while on salt-encrusted ground in the salt flats along the coast about 20kms east of Río Lagartos is shown at http://www.backyardnature.net/n/14/141109cd.jpg.

Around here people call a caracara a Rompe Huesos, which means "bone breaker." They say that caracaras carry bones into the sky, drop them onto hard surfaces, then feed on the marrow when the bones break open. I can't believe that bones fallen from any height will break in a marrow-exposing way, but probably it's true that from time to time you see caracaras dropping bones as they fly away. Usually caracaras turn up feeding on road-kill, competing with ubiquitous Black and Turkey Vultures.

My field guides give the binomial of the Crested Caracara as Caracara plancus instead of the C. cheriway stated above. Lately there's been considerable splitting, lumping and rearranging of this species and its subspecies, and even now the situation doesn't seem settled. Whatever the deal, birds distributed from the US (AZ, FL, LA, NM, TX) south to Panama plus in Cuba now are generally but not always considered Caracara cheriway.

*****

RIGHT- & LEFT-CLAWED FIDDLERS
During my first visit to the Yucatan's northern coast back in 2006 I was fascinated by the fiddler crabs often seen on wet ground along margins of the mangroves. One is shown next to his hole, with the top "movable finger" of his big, "fiddle-like" claw broken off, at http://www.backyardnature.net/n/14/141109fc.jpg.

A side view showing how small the body is compared to the big claw is at http://www.backyardnature.net/n/14/141109fd.jpg.

To give an idea of this fiddler's size, the big claw of this species reaches about 2-½ inches (6.3 cm) in length.

My stories about fiddler crabs gathered back in 2006 are still at http://www.backyardnature.net/yucatan/fidcrab1.htm.

Back then I saw that the males waved their big claws to attract females, who have only small claws, and fought off potential male competitors with them. However, I never solved the mystery of why some males had their big claws on the right side, while others had them on the left. I'd assumed that two species were involved, though they all seemed the same to me. Now I read in a research paper by Backwell and others (Proc Biol Sci. Nov 7, 2007) that among fiddler crabs, "In most species, 50% of males have a major claw on the left and 50% on the right."

Back then, seeing that about a hundred fiddler crab species were recognized, and that their taxonomy was in a mess, I didn't assign a name to our northern Yucatan fiddlers. Since then more literature and pictures have become available on the Internet, so now I'm comfortable to identify our common crab along the margins of mangrove swamps as Mudflat Fiddler Crabs, UCA RAPAX. Mudflat Fiddler Crabs are distributed along the Atlantic and Gulf of Mexico coasts from the Daytona Beach area of Florida in the US to São Paulo, Brazil, and all through the Caribbean Islands.

In my 2006 notes I note how crowded certain muddy areas were with fiddlers. I read that in some Brazilian mangrove forests about 20 individuals can be counted per square meter (per 1.2 square yard).

The Smithsonian Marine Station at Fort Pierce, Florida provides a fine web page all about the Mudflat Fiddler Crab's natural history, including its "fiddle waving," at http://www.sms.si.edu/irlspec/Uca_rapax.htm.

*****

CUDJOE-WOOD
Positioning myself to photograph a small herb in a seasonally flooded but otherwise thin-soiled, dry, low area near the marshes along the coast just east of Río Lagartos, something painfully pricked my back in several places. I was backing into a dense, dark-green, knee-high shrub whose laurel-like leaves were tipped with hard, slender spines. The bush bore clusters of pea-sized, orangish flowers more interesting than what I was about to take a picture of, so you can see the plant that stabbed me in the back at http://www.backyardnature.net/n/14/141109bo.jpg.

A closer look at the clusters of flowers with prickle-tipped leaves below them is at http://www.backyardnature.net/n/14/141109bp.jpg.

The flowers turned out to display the unusual features shown at http://www.backyardnature.net/n/14/141109bq.jpg.

Most striking is that the "ten corolla lobes" seem to alternate in size, the smaller ones with low ridges running their lengths. Are the outer, larger lobes perhaps petal-like calyx lobes? That question was easily answered by examening the flower from the side, as seen at http://www.backyardnature.net/n/14/141109br.jpg.

Here we see the green calyx below the corolla, right where it's supposed to be, its broad, rounded, overlapping sepals fringed with unusually transparent margins, and bearing tiny glands spread across their surfaces. The orange corolla lobes really do alternate in size, and overlap one another, features that are very unusual in the world of corolla anatomy.

Having such fine field marks to work with when I "did the botany," the pretty little bush revealed itself as BONELLIA MACROCARPA ssp. MACROCARPA, which is so rarely documented that it has no decent English name, though some web pages have settled on calling it Cudjoe-wood. The term "Cudjoe" is a name given at birth to a black child in certain creole-speaking cultures, indicating the child's sex and the fact that the child was born on a Monday. What our plant has to do with that practice can only be imagined.

Anyway, Cudjoe-wood occurs in Mexico and Central America, where often it's a component of "thorn scrub," which is one designation of our local vegetation. In Florida and Cuba, Cudjoe-wood has escaped from plantings into the wild, where it lives on spoil deposits and the fringes of mangrove forests.

Experts say that the smaller, petal-like structures between the larger corolla lobes are "staminodes," which are stamens modified to look like corolla lobes. Technical descriptions insist that Cudjoe-wood's flowers have only five corolla lobes, though it certainly looks like they have ten. Then there are five fertile stamens, and five staminodes that look like corolla lobes.

Maya in the Yucatán traditionally use Cudjoe-wood medicinally for skin problems.

Another very similar Cudjoe-wood species, Bonellia flammea, is listed for the Ría Lagartos Biosphere Reserve. Its flower stems, or pedicels, appear more slender and somewhat longer than our Bonellia macrocarpa.

Taxonomists have problems deciding where to put Cudjoe-wood on the Phylogenetic Tree of Life. For years Cudjoe-wood resided in the genus Jacquinia as Jacquinia macrocarpa, and many web pages still use that name. Though the online Flora of North America recognizes the genus Bonellia, it retains the species in the small, seldom heard-of Theophrastus Family, the Theophrastaceae, even though gene sequencing data has caused many experts to lump the genus into the Primrose Family, the Primulaceae.

Whatever our little shrub's affiliations, I was glad it caught my attention by stabbing me in the back.

*****

SWEET MANGROVE
A lot of the plants and animals in the Río Lagartos area are new to me. Still, normally I can recognize what family a new-to-me flowering plant belongs to, and often even the genus, which helps a lot during the identification process. However, sometimes something comes along that simply throws me for a loop, maybe by mingling features that I'd thought were to be found only in different plant families. That was the case with a certain belly-high, evergreen shrub growing in salt-saturated sand of what might have been an ancient dune along the coast just east of Río Lagartos, shown being photographed by my friend Jim Legault at http://www.backyardnature.net/n/14/141109ma.jpg.

The sand's high salt content manifested itself in the bush's growth form, for the bush's stems and leaves were fairly succulent, succulence being a water-retaining feature of many plants adapted for very dry and/or salty conditions -- plants that are "halophytes." The chewed leaves had a definite salty taste. A branch of the plant is shown at http://www.backyardnature.net/n/14/141109mb.jpg.

A picture of the unusual, green flowers, with some kind of glistening exudation -- probably nectar -- beaded atop a doughnut-like disk surrounding the base of the plump ovary is shown at http://www.backyardnature.net/n/14/141109mc.jpg.

The bush bore pea-sized, capsule-type fruits about to turn red, shown at http://www.backyardnature.net/n/14/141109md.jpg.

Some branches bore remains of capsules that earlier had split open, allowing the seeds to escape, and remained on the stems looking like tiny, brown flowers, as shown at http://www.backyardnature.net/n/14/141109me.jpg.

Still, the strange blossoms interested me most, for they reminded me of flowers seen last year in southwestern Texas on a Hog Plum tree belonging to the Buckthorn Family, the Rhamnaceae and the genus Colubrina. You can compare our flower photo with a Hog Plum flower in Texas at http://www.backyardnature.net/n/13/130519rj.jpg.

The most obvious difference between the two flowers is that the Hog Plum blossom in Texas bears tiny, green petals, but our Río Lagartos plant's flowers have none, just petal-like calyx sepals. That difference didn't keep me from assuming that we had a member of the Buckthorn Family, though. The problem was that no plant in the Buckthorn Family listed for the Yucatan bears such flowers on a shrub with succulent twigs and leaves.

Fortunately as I was banging my head against this plant's elusive identity I happened to be in communication with botanists at CICY, the Centro de Investigación Científica de Yucatán, in Mérida -- the Center for Scientific Study of Yucatán. An expert there was kind enough to identify our Río Lagartos bush as MAYTENUS PHYLLANTHOIDES, known as Sweet Mangrove, Mangle Dulce, Mayten, Florida Mayten, Gutta-percha Mayten, Leatherleaf and by other names. It's a member of the Staff-Tree or Bittersweet Family, the Celastraceae, which also includes the Hearts-a-bustin' or Strawberry Bush, Euonymus americanus, we had back in Mississippi. The Hearts-a-bustin' green flowers also had a doughnut-like disk at the base of the flower's ovary, and  no petals, as shown at http://www.backyardnature.net/n/09/090406ev.jpg.

That picture shows that blossoms of Hearts-a-bustin' and Sweet Mangrove are very similar structurally. I should have recognized the similarities, but I just didn't. If you want to see the Hearts-a-bustin' plant, which you'll probably recognize when you see it, it's profiled at http://www.backyardnature.net/n/w/euonymus.htm.

Sweet Mangrove isn't common enough to be considered one of the four species thought of as constituting the Yucatan's mangrove ecosystem. The bush is distributed along the coasts of Florida and southern Texas, but mostly it's a Mexican plant, occurring on both the Pacific and Gulf coasts. The online Atlas de las Plantas de la Medicina Tradicional Mexicana reports that besides living in the vicinity of mangrove swamps, Sweet Mangrove can be found in a variety of dry soil situations, including oak forests.

The Atlas also says that leaves, roots and bark of Sweet Mangrove have been used in traditional medicine against "rhumatism," which probably is arthritis. Boil the leaves and stems for about an hour, let the resulting tea cool off, add a little alcohol, and massage the liquid onto painful joints. Add some cinnamon and it's also good for the kidneys.

*****

NECKLACEPOD
In the dense, waist-high tangle of scrub stabilizing salt-saturated dunes along the coast just east of Río Lagartos a compact shrub draws attention to itself nowadays with the handsome racemes of fair-sized, yellow flowers shown at http://www.backyardnature.net/n/14/141109so.jpg.

With its reclining habit and large, pinnately compound leaves, except for the flowers' color, this could be a Wisteria. Notice that immature, slender, green-bean-type legumes emerge from calyxes at the bottom of the raceme where old flowers have lost their corollas, just like Wisteria. Both this plant and Wisteria belong to the Bean Family, the Fabaceae, so the similarities are not incidental. A close-up of a flower is shown at http://www.backyardnature.net/n/14/141109sp.jpg.

That's a classic Bean-Family type flower, one that's "papilionaceous," which means that the corolla consists of five petals, of which the top one is enlarged and rises above the others, there are two side petals called "wings," and the two lower petals are fused along their common border to form a scoop-like structure called the "keel." An important difference between this flower and those of Wisterias is that the stem-like filaments of this flower's ten stamens are separate from one another, while in Wisteria blossoms the filaments of nine stamens are joined together, with the tenth stamen separate. Among botanists, such differences in flower structure are monumental, so, despite the superficial similarities, Wisterias and this plant don't even belong to the same tribe within the Bean Family.

This handsome, salt-tolerant, dune-loving bush can be found on many of the world's tropical and subtropical coasts, so it's known by many English names, including Yellow Necklacepod, Yellow Sophora, Necklace Pod, Silverbush, Seaside Pigeon Pea and Tambalisa. It's SOPHORA TOMENTOSA, which in the US occurs only on the coasts of Texas and Florida. The "necklace" part of some of its names refers to the long legumes that for much of the season dangle from stems, the legumes constricted between the beans, looking like beads on a string.

This is such a tough, pretty bush with flowers that attract hummingbirds that it's often sold in plant nurseries up north, though it's freeze intolerant.

Often the plant is employed in traditional medicine, for problems ranging from cholera, food poisoning and breast cancer to venereal diseases, depending on the culture. There might be something to some of the uses because the seeds are regarded as poisonous due to the presence of a cystisine called sophorine, and other compounds related to nicotine. In fact, all parts of the plant contain some poisonous alkaloids. Its juice is used as fish poison in East Africa, and as an insecticide in Fiji.

*****

BOLLS OF WILD COTTON
Last week we looked at the narrowly endemic, genetically diverse, woody stemmed wild ancestors of much-planted Upland Cotton growing among dunes of the Yucatan's northern coast. At that time I couldn't find mature fruits and seeds but this week I did. You can see an open capsular boll with white cotton fiber tumbling out, covering hard, spherical, blackish seeds, at http://www.backyardnature.net/n/14/141109gp.jpg.

Another shot showing a black seed (upper right) and a split-open capsule is at http://www.backyardnature.net/n/14/141109go.jpg.

Here you can see that these seeds are fairly large compared to the small size of the capsule producing them.

*****

LUFFA THE VEGETABLE SPONGE
Down the street a house has been torn down leaving an open space with some trees at the back of the lot absolutely smothered in vines, as shown at http://www.backyardnature.net/n/14/141109lu.jpg.

Up in Mississippi this is how Kudzu grows over things, but this isn't Kudzu. The vine produces fair-sized yellow flowers, one of which is shown at http://www.backyardnature.net/n/14/141109lv.jpg.

Just with the plant's viney nature and the large, yellow flowers, already we're thinking in terms of this being a member of the Squash/Gourd/Cucumber Family, the Cucurbitaceae. However, that's a big, complex family, so to know exactly what this is we need to pay attention to field marks. Two important features to notice in the last picture are that the corolla is divided into five very deeply divided lobes, unlike the flowers of garden squashes and gourds, plus several flower buds arise from the same stem as the open blossom. You might remember that in most other members of the family there's just one blossom per flower stem.

At http://www.backyardnature.net/n/14/141109lw.jpg we see the flower's face, which doesn't tell us much , until we take a closer look at the bundle of yellow items in the blossom's center, shown at http://www.backyardnature.net/n/14/141109lx.jpg.

That's a cluster of stamens doing funny, frilly things with their pollen-producing anthers. Mainly, the anthers are "sigmoid," an amazing term meaning "curved like a C," or "crescent-shaped." Also they're flexible, so normally in botanical literature they're described as "sigmoid-flexuous." Maybe the most important point to notice about the stamens, however, is that this blossom contains no female parts. This is a unisexual male flower, for members of the Squash/Gourd/Cucumber Family always produce unisexual flowers.

Unlike the leaves of common squash and cucumber vines, this vine's leaves are somewhat star-shaped, as shown at http://www.backyardnature.net/n/14/141109ly.jpg.

And while I was rearranging stems for the above picture something heavy bumped against me, the thing shown in my hand (dirty from gardening) shown at http://www.backyardnature.net/n/14/141109lz.jpg.

So, now we've seen all we need to know what we have. When the fruit shown in the last picture matures, it can be broken open, its contents removed, cleaned and dried, and then you'll have something like a sponge, or at least a nice, scratchy rag. This vine and its fruit are often called Vegetable Sponge, Dishcloth Gourd, Dishrag Gourd, Rag Gourd, Sponge Gourd and a host of other names. It's LUFFA CYLINDRICA.

Vegetable Sponge has served humanity for so long, and has been spread across the warmer parts of the entire world so effectively, that it's hard to say where the wild ancestor lived, though it's assumed to have been in Africa or Asia. A similar species of the same genus and with many of the same features sometimes is encountered, Luffa acutangula, but its long fruits are more distinctly ribbed and angled than our Río Lagartos one.

Not only can you make a good washrag from the mature fruit's fibrous interior -- its "endocarp," in botanical terms -- but also the young fruit can be eaten fresh or cooked as a vegetable, especially in countries where cultivars have been developed with eating in mind. The roasted seeds are edible and contain an oil that is both edible and serviceable in the manufacture of soap. Goats crave the fruits and leaves, and bees feed on the flowers.

To top it off, it's medicinal. Root preparations are taken for the treatment of constipation and as a diuretic, and in Gabon it's used for nose cancer. In Tanzania a root decoction and the leaf sap are drunk to reduce the danger of abortion. Well, such uses just go on and on.

For a long time in human history Luffa gourd has been a cherished neighbor around people's homes and it's a shame it's not grown more nowadays, if only in gratitude.

*****

FEATURED ESSAYS FROM THE PAST:

"Wander Birds" from the June 27, 2009 Newsletter, at http://www.backyardnature.net/n/p/090627.htm

"Wasting Food" from the October 10, 2010 Newsletter, at http://www.backyardnature.net/n/p/101010.htm

*****

Best wishes to all Newsletter readers,

Jim

All previous Newsletters are archived at http://www.backyardnature.net/n/.