ENTER A NEW YEAR

JANUARY 2019

The new year is here and summer is in full swing with 186mm rain recorded at the Central area in January, so far. Everything is green and everything is growing.

I read a really interesting article in PlantLife SA (volume 46:3 December 2018) regarding the relationship between flowers and pollinators. Now, the more specific the pollinator is for the plant, the more chance the flower's pollen will reach another flower of the same species and therefore be productive. In other words, if a yellow daisy, of which there are many species, attaches it's pollen to a common Honey Bee who is attracted to all yellow flowers, the chances are not so good that the Bee will fly to another daisy of the same species without visiting many other yellow flowers on the way, minimizing the chances for that pollen to be deposited on the correct flower species. But if a flower is designed to accommodate a very limited amount of specialized pollinating insects by, for example, storing the nectar (which the insect is attracted to for food) at the end of a long spur (as is the case with many orchids), then only insects with long enough mouthparts that are able to reach the nectar will visit the flower and collect pollen on it's body to transfer to the next flower of the same design (read species).

This article involved two plant species found here at Finsbury and their associated insect pollinators. These plants form the Milkweed Family (Apocynaceae), Pachycarpus campanulatus and P. concolor are so intricately designed that only a very few pollinators can reach their nectar, the food they are seeking. These are the Spider-hunting wasps of the Pompilidae family and the Chafer beetle, Atrichelaphinis tigrina, respectively.

Pachycarpus flowers are noticeable because it is difficult to identify the flowering parts when comparing them to other flowers. The male and female whorls are fused into a structure called the gynostegium which form the central pillar of the flower. Radiating out from these are the grooved corona lobes. So the female parts are now inside the gynostegium and the male parts form pairs of flattened, hardened structures, forming the sides of gynostegium, termed "guide rails". Beneath the slit in the guide rails are stored the pollinaria, two sacks of pollen attached by a thread, resembling a minute saddle. 

The nectar is produced and stored in the corona lobes which are designed to allow only suitable pollinators to reach it, and then only awkwardly! While the insect is manipulating it's body to reach this yummy nectar, one of it's legs invariable get caught in the flaired groove of one of the opposing corona lobes where it gets caught. The insect then panics and struggles to free its limb which slides up the groove of the lobe and is forced into the slit in the guide rail. The insect then pulls the leg out of the guide rail, and in doing so, the limb slides past the pollinaria and snags the joining membrane so that, when the leg is finally freed, it has the pair of pollinaria attached to it.

The insect now has to approach another flower and experience the same trauma of it's limb getting caught in the flayed groove of the corona lobes. As it enters the guide rail, the opening is too small to allow the pollinaria sacks in so, through frantic tugging, the joining membrane breaks and the pollinaria remain behind in the lobes as the limb enters the guide rails once again. From here they grow through the pillar wall and pollination is complete!

Fairy-bell Pachycarpus, P. campanulatus, showing the flayed corona lobes (cream colour) radiating out from the central pillar (green) with the guide rails (brown) attached to the sides.

A poor shot of a Spider-hunting wasp (they move too fast!) from the Pompilidae, the specific pollinator of the above Fairy-bell Pachycarpus.

A beautiful Pachycarpus concolor. This species utilizes a species of Chafer beetle for pollination. The beetle gets a leg caught in the flayed part of the corona lobe and, as it panics and struggles to free it's leg, the leg slides up the groove and enters the guide rail, where it snags a pair of pollinaria on it's way to freedom.

The Chafer beetle, Atrichelaphinis tigrine, responsible for pollinating Pachycarpus concolor above. This one was photographed on the flower head of a Xysmalobium, also in the Milkweed family, high up near Mount Prospect.

I have managed to capture many other exciting things while working in this incredible environment over the last month. Here are some of them:

An endemic Spotted Dwarf Gecko, Lygodactylus ocellatus, helping me control the ants on my stoep. Well designed hunting machines: all toes, except the rudimentary inner toe, are equipped with a retractable claw and adhesive scansor pads. The tail also has modified adhesive scales at the tip, allowing it to act as a fifth foot! When this 40mm long reptile is not inhabiting human establishments, it (if it is male) establishes a territory, a large boulder, into which it allows females and juveniles. Once mated, the females lay two hard-shelled eggs in a communal nest together with the other females under a nearby rock. Their main food is ants and termites (note the silly ant approaching his back leg).

A mating pair of Swamp Bluet Damselflies, Africallagma glaucum, photographed on the island in K33. DBI 1 (refer previous blog). The blue male transfers his sperm from his primary genitalia, towards the end of his abdomen, to his secondary genitalia, a special sperm storage pouch just behind his thorax. He then clasps the drab female behind her head with claspers on the end of his abdomen. She then twists her abdomen forward under her and locks it onto his second genitalia, forming a heart shape with their bodies, where sperm transfer is completed. The male then guards the female as she flies over the surface of the water, dipping her "tail" as she deposits the eggs singly into the water where they sink to the bottom. The egg hatches into a carnivorous nymph who sheds as it grows. Once the final instar is reached, the nymph crawls up a vertical stem in the water and emerges into the dry air. It forces it's way out of it's final nymphal casing and stretches out into an adult. It spends the next few weeks of adulthood voraciously feeding on other flying insects and seeking out mating opportunities.

This S/he was slowly on it's way along the cycle path between Loop road and the KLF road. S/he is an Achatina fulica, Giant Land Snail. You will mostly know them as the huge long dead snail shells that you may have encountered on the Estate. This is because the living ones bury themselves in soil or thick tufts during the day and only emerge in the night or on rainy days like this one was. I call it a S/he because, like all snails, they are hermaphrodites, meaning each individual has testes and ovaries, and when they mate they usually transfer sperm to each other's ovaries. Sperm is stored for up to two years (there's no rush anywhere here!) and they lay batches of up to 200 eggs six times a year. In bad times, though, they can remain sealed in their shells, underground, aestivating for 3 years. In a survival situation for us, the snail is a delicacy, escargot, bon apetit!

Wow! How's this one? Caught on the underside of a Pyjama flower, Colchium melanthoides, right near the summit of Mount Anderson, this Small Crab Spider, Thomisus sp. was enjoying her meal before I exposed her. I identified her to the genus by the large tubercles on which her eyes are imbedded, fer-eaky! These spiders are special because they can slowly change colour, like a chameleon, to the colour of the flower they have chosen as their ambush site. Once settled amongst the flowering parts where the attractive nectar is, they lie in wait, camouflaged, until an unsuspecting pollinator comes along, whence they will snatch them up with those oversized front legs!. They have powerful venom and will subdue a much larger insect like a Bee in a few seconds. They then suck the juices from their victims and discard the empty exoskeletons.  

This is a lovely, small (only 50mm) frog that I remember fondly from the Lowveld. Fondly because of the melodic bubble-popping boip call that they loudly emit. It is a Bubbling Kassina, Kassina senegalensis, that I have heard rarely from the manager's house area since being here at Finsbury. I visited Ian and Johnny at Finsbury House recently and while we were enjoying a drink and a chat on the verandah, this frog started calling. They told me that it had called loudly from a spot just outside the porch, every afternoon while they were there. I followed it's sound and managed to find it hiding in the garden bed, under a thick bush. He posed nicely for the photos. He is a male who starts calling, quite far from the water, in the afternoon. After no response from a female, who is attracted to the call, he moves closer to the water, all the time calling out with his distinctive call, the single-syllabled boip that is repeated only a few times a minute. By the time he reaches the water he has, hopefully, attracted a female with his song. If so, they will pair in amplexus and sink to the bottom of the pond while she lays batches off eggs that adhere to the muddy bottom and vegetation. The tadpoles are easily recognizable with their brightly reddish fins. They are voracious plant eaters. 

I hiked to the summit of Mount Anderson quite frequently in the last month or so, and while I have always encountered special flowers up there, on my last trip I found a treasure trove of five fine orchid species! Here they are with their SANBI Red Data status:

Disa amoena, a near endemic with four colour forms ONLY found in our area. Red Data status: Vulnerable.

Schizochilus cecilii ssp. transvaalensis, tiny and delicate. Red Data status: Least Concern.

Disa stachyoides, common but captivating. Red Data status: Least Concern.

The recently described, ONLY from this summit, Disa sterkeriana, mind-blowingly beautiful! Red Data status: Critically Endangered!

Satyrium longicauda, Common in grassland in Mpumalanga and KZN. Red Data status: Least Concern.

February begins and the rains keep coming. Just had another heavy rainfall this afternoon that interrupted this blog. With the rains comes life! We are a water catchment reserve here at Finsbury, with exceptional fly-fishing opportunities right now. Come and enjoy it!