The Mycad (Mycodendron progenitor) is a species of small palm-grass found in the understories of Loxodian rain-pseudoforests. It looks unassuming; on the outside, its only notable feature is its pinnate blades. These fronds, which can be over 250 centimeters long, often droop to the point of touching the ground. The density of this shrub's leaves provides a home to many commensalists and mutualists, but the plant is equally appealing to herbivores and parasites. In this tropical landscape, battles rage daily on and around every mycad. Gone are the days when a single species of arboreal isopod can defend a palm-grass against an equally-homogeneous invading force. While the mycad is among the toughest woodlouse-grasses on Apterra, survival is never guaranteed for it or its inhabitants.
On a shady hillside just two or three miles from the coastline, one particular plant is about to experience the full force of this war. The first sign of trouble is a tiny A. arborealis descendant called the Ranger (Arthrothyreus cursorialis), a single individual of which has just arrived unannounced at the foot of the mycad's trunk. It climbs rapidly, meeting a spiky, well-armored pill bug called a Sheriff (Altipereon spinatus). They touch antennae and the Ranger releases a pheromonal signal that sends the Sheriff into a frenzy. It moves as fast as its little legs can take it (though it's only about a third the speed of its cousin), alerting others of its species. A. spinatus is an incredibly effective wall, but only if all of them get into formation in time. Roughly 200 live on this mycad, and they arrange themselves in a ring around the plant's stem, picking a smooth spot along one of its internodes about halfway up. Each of its body segments has a backward-pointing spine on either side. As they hunker down in their defensive stance, they push back, embedding themselves in the outer layers of the pseudotree. They are just in time, for the first wave of attackers has just reached the mycad.
The Plague (Adversariarthrus pestilentius) is the name for the descendants of Early Muricene grazing woodlice. They are long, low-slung, and possess a trio of spines on their backs that help prevent them from being stepped on. The sides of their exoskeletons are extended into a wide skirt, a trait that allows them to walk with their legs tucked entirely beneath their bodies. Their mouths are sharp and well-adapted to cut even the toughest grasses, making them significantly overpowered against the softer leaves of the mycad. They begin to climb the many leaves they find in contact with the ground, marching single-file along the rachis until they meet an impassable obstacle.
The largest and strongest mycad-defender is the Staghorn Woodlouse (Megaporcellio ejector). Its first body segment has a large, curved, hornlike extension that hangs over the bug's head. Its cephalothorax is strong and well-armored, capable of handling any rival attacking it from the front. It is, however, weak if attacked from the rear, as its pleon is thin and somewhat fragile. This is no problem, though, for the Plague approaches from only one direction. A single staghorn situates itself near the base of each blade. While the short, flat bodies of the invaders pose a formidable defense on flat surfaces, they are vulnerable on the thin fronds of the mycad. As Plague woodlice approach, the Staghorn hooks its thoracic horn underneath their heads, throwing them unceremoniously to the ground one by one. Upon hitting the soil, the Plague begins its second attack.
Hundreds of isopods clamber up the main stem of the mycad, crossing alternating bands of rough leaf scars and smooth internodes. In the former, Flipbugs hide, waiting for an unsuspecting attacker to cross them. These small but strong woodlice in the genus Platyarthrus lie in wait, camouflaging against the tangled mess of old, dead foliage. When trodden on by a member of the Plague, they stand up suddenly, tossing their foes to the ground for a second time. The herbivores who make it through this minefield then come face to face with the wall of sheriffs. In their formation as they currently are, they can repel a force that outnumbers them a dozen to one, but if even a single Plague isopod makes it through, the entire defensive line is in danger.
As the Plague pushes against their Altipereon adversaries, they unknowingly strengthen the wall as the latter's spines are forced deeper into the mycad's flesh. Both sides chew at each other's faces with their heavily-muscled mandibles; if neither can go under or over the other, they'll have to gnaw their way through their enemies. Even when killed, though, the dearly departed Sheriffs remain embedded in the stem. As time goes on, the Plague makes slow progress against the wall of arboreal isopods, progressing a half-millimeter at a time up the plant. The mycad community is not out of tricks, though. As more and more damage is done to the grass, it emits chemical signals into the air. The Gouger (Velociculex megahalterus), a species of mosquito derived from the Early Muricene pansanguinophagus group, is attracted by this scent. This lineage has an extremely strong proboscis, capable of piercing the exoskeletons of Plague woodlice. While other members of its genus feed indiscriminately on all pill bugs, the Gouger has integrated itself into the mutualistic alliance of woodlouse-grass symbionts. In exchange for only attacking the invaders, the arboreal woodlice will allow it to feed freely from the mycad's nectar after the fight is over. Gougers make their living this way, flying from one battlefield to another all day long. As they bleed the Plague dry, another mosquito arrives on the scene, similarly enticed by the scent of the ongoing fight. This one, though, does not fight for the mycad.
The Reaper (V. herbicisor) is a cousin of the Gouger. It uses its sharp mouthparts to slice away at the base of each frond, hoping to cut it from the plant. Once separated from the main defending force, the stranded Staghorns will make a tasty meal for the Reaper. This species is also useful to the Plague because the arboreal woodlice won't protect detached blades, allowing the grazers to feed on these leaves even if they end up failing to conquer the whole palm-grass.
With the tide of battle turning, one final group of defenders steps up to the front line, stepping cautiously over the corpses of the Sheriffs. These are the Snatchers (Brachiarthrus lacerator), a tall and sure-footed species that walks seemingly on tiptoes, holding its body off the ground on its second and third pairs of legs. Its front limbs, on the other hand, are long and tipped with a sharp barb. As it meets the Plague, it slips a claw beneath an enemy exoskeleton. Holding fast in its quadrupedal stance, it lifts the attacker into the air with one arm. It hooks the other between its prey's cephalothorax and first body segment, pulls with all its might, and rips the Plague woodlouse's head off in one swift movement. The whole process, from selecting a target to decapitation, takes about three seconds. In a matter of minutes, a few dozen Snatchers tear through the Plague, sending the survivors scattering into the surrounding pseudoforest.
With that, the battle is won. Mycads, being the best-defended of all woodlouse-grasses, survive assaults by the Plague and their allies almost every time. In the aftermath, though, less-aggressive assailants will take advantage of the plant's weakened state. Flitflies, a type of mosquito in the genus Saccharophilus, love to mooch on the sugary nectar of mycads and other palm-grasses. They do not, however, help the mycad reproduce, as this species still utilizes wind pollination. As such, they are not tolerated by the arboreal community, being regular targets of the Snatcher. In their weakened state, though, the local Brachiarthrus often miss their marks, allowing the Flitflies to feed freely for a few days. Another opportunist is the isopod Sacchararthrus, a genus commonly known as Leechbugs. These latch onto the mycad's stalk, feeding on its sap without providing any defensive function to the plant. They are, however, descendants of arboreal forms, and as such are not always recognized by their cousins as a threat. Perhaps in a month or so they'll notice and reject the parasites. For now, though, the Leechbugs run amok, drinking their fill and reproducing with alarming speed.
The mutualists rebuild their numbers almost as quickly. The few surviving Sheriffs repopulate their home in a few weeks, while the Ranger leaves to follow the Plague. He'll trail behind wherever they go, sounding the alarm every time they get too close to another palm-grass. One day, he'll cross paths with a female, who'll temporarily settle down on a mycad to give birth in another month or so. Male Staghorns will battle for breeding rights, attempting to toss each other from the mycad. The many losers will disperse to other plants to try their luck elsewhere, while the victor will gain access to every female in his territory. The Snatchers will bury the hundreds of woodlouse carcasses after eating their fill, helping to fertilize the mycad in the process. They are obligate carnivores, having changed their diet to avoid competition with their fellow mycad residents. During the periods between battles, they help the arboreal community remain sanitary by eating the corpses and shed exoskeletons of their cousins.
As both mycad and Plague recover, life returns to normal. This particular plant is lucky enough to be host to a type of mutualistic mushroom called Poamyces, whose hyphae crisscross the pseudotree's trunk and release enzymes that hasten the production of a new whorl of fronds, accelerating the mycad's return to full health. Where the dead Sheriffs have left thousands of tiny cuts and scars on the stalk of the grass, the fungus also induces new tissue production to cover the wounds, resulting in a rejuvenated (if also slightly widened) ring of repaired culm.
Long after the battle ends, footsteps can be heard far away. The quiet sound of a bird trotting along gradually approaches, and a meter-tall kiwi sizes up the mycad. It pecks at a Leechbug, finding it sweet to the taste as a result of its diet. It then grasps the base of a frond in its beak and pulls back, tearing off a few dozen leaflets as it goes. After a few more bites, it appears satisfied and continues on its way. This is a Raspbird (Phyllapteryx pappillingus), a descendant of A. furtivus. It uses its rough, sandpaper-like tongue to grind the mycad blades against the roof of its mouth, swallowing them to be further processed in its gizzard. It finally makes it back to its herd, spotting another male sitting on the group's communal nest. After greeting the six females, he chirps at his brother, signaling that he's ready to take a turn incubating the half-dozen eggs hidden in the thicket. While this species feeds on palm-grasses readily, it never takes much from any individual plant. It benefits from the mycad winning its battles, as a weakened Plague means more food for the herd.