Biology:Psalmopoeus irminia

Short description: Species of spider

Psalmopoeus irminia
Mature female
Metatarus & tarsus of legs I & II
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Arthropoda
Subphylum:	Chelicerata
Class:	Arachnida
Order:	Araneae
Infraorder:	Mygalomorphae
Family:	Theraphosidae
Genus:	Psalmopoeus
Species:	P. irminia
Binomial name
Psalmopoeus irminia Saager, 1994

Psalmopoeus irminia, also known as the Venezuelan suntiger, is a species of tarantula endemic to Venezuela, Guyana and Brazil . They were first described in 1994 by F. Saager.

Description

Psalmopoeus irminia are unique in their striking black coloration paired with vibrant orange chevron and leg markings. Like other Psalmopoeus, this species can often be found in tree cavities at a medium height. Females reach six inches in diagonal leg span on average while males can reach 5 inches. Males are sexually dimorphic, appearing to have much thinner legs as well losing most of their coloration, it can be hard to distinguish them from Psalmopoeus cambridgei mature males. Females can live up to 12 years while males only live to about 4 years.

Taxonomy

Tarantulas fall within the class Arachnida and the order Araneae. They are distinguished from true spiders by their two pairs of book lungs, vertically oriented chelicerae, and urticating setae. However, like all members of Psalmopoeus , P. irminia lack these urticating hairs but make up for it by having stronger venom compared to other New World tarantulas.

Behavior

P. Irminia have a low metabolic rate causing them to spend most of their time burrowed. They are usually content but can become very defensive when disturbed. They will go into a defensive stance where they raise their front legs and show off their fangs. They also have the ability to accelerate from danger very quickly.

Envenomation

P. Irminia do not acquire urticating hairs, so they depend heavily on their fast reflexes and venom to protect themselves. There are very few cases of tarantulas envenoming people, but due to the increase in exotic pets it is most likely to increase. Their venom has been known to cause sweating, vomiting, lightheadedness, and muscle spasms that can last days. However they rarely resort to biting.

Molting

Molting is a very stressful time for a tarantula. Juveniles molt about every three months while adults molt every year or two. Depending on how much they eat can affect how quickly they molt. As P. Irminia goes into premolt, they will begin fasting, seek moisture, shed their abdomen hairs, and their skin will darken.

When they begin to shed, the tarantula will lay on its back and slowly remove its exoskeleton; this process usually happens overnight but can take up to 24 hours. They crawl through the carapace and pull their appendages through. The following days are spent resting and allowing their fangs and exoskeleton to harden.

Diet

P. irminia have a diet that mainly consists of invertebrates such as crickets or cockroaches that are caught at the entrance of their burrow or their immediate surroundings. However, if they grow large enough, they are known to eat small lizards, frogs, rodents, and even birds. These tarantulas are opportunistic feeders that ambush their prey. They use the hair on their legs to sense vibrations, allowing them to catch their prey easier.

Anatomy

Tarantula bodies can be divided into two parts, the cephalothorax (prosoma) and the abdomen (opisthosoma).

Cephalothorax

The cephalothorax is the head and thorax, it holds the stomach, eyes, nervous system, venom, and digestive fluid reservoirs. The carapace is the tarantula’s dorsal shell that is covered in setae. The ventral surface is the central sternum and is the anchor point of the legs and pedipalps.

Tarantulas have a tight cluster of small eyes that lay on their tubercule. Although they have 8 eyes, they have poor eyesight and can only detect contrasts between light and dark, which is why their hairs are so important.

The mouth of the P. Irminia is similar to all tarantulas. They have large chelicerae that have long curved fangs that could reach up to more than 10mm long. Their fangs are hollow and work like needles by taking the venom from glands located in the chelicerae to the tip of their fang. They can also use these appendages as a tool for digging. Located between the chelicerae is the labrum (mouth). This is where digestive fluid is released to break down and take in their liquid food.

Pedipalps, also referred to as ‘palps’, are found on either side of the chelicerae. They are used almost like antennae. They help the tarantula feel the area in front of them but also help them with feeding. Located at the base of the pedipalps are bristles that are used to strain their food. Tarantulas use their pedipalps to help groom themselves, especially after a meal. During reproduction, males use their pedipalps as external reproductive organs. They develop emboli and palpal bulbs on the ends of each palp.

Tarantulas have 8 legs and each foot ends with a cluster of bristles called scopulae and a pair of tarsal claws. These parts allow the tarantula to climb most surfaces and capture their prey. Mature male’s have a tibial hook on their second pair of legs.

Abdomen

The abdomen is covered in long hairs and is where the heart, intestines, liver, respiratory system, primary reproductive organs, and silk manufacturing system reside. Two pairs of book lungs are present on the ventral surface.

Spinnerets are located on the abdomen and are the external parts of the silk machine. Tarantulas have four total spinnerets with the posterior being the largest. Due to P. Irminia being arboreal, they are known to produce large amounts of web.

The hairs on the tarantula are the most vital sensory feature. They act like receivers for vibrations through both the air and substrate. They are able to detect the size and direction of any incoming prey or predator.

Although P. Irminia are sexually dimorphic, it is difficult to determine the gender of an immature spiderling. The only way you can determine is by examining their molt. For male’s, there is a simple slit on the epigastric furrow. The females have two pockets in order to store sperm.

Reproduction

Tarantulas are known to be polygamous creatures. Females can accept more than one male throughout the breeding season, which takes place between late September and early October. However, once inseminated, any other males that try to seduce her will be eaten. If the males are able to live after insemination, they will redo the process with another female.

Males become sexually mature earlier than females do in order to avoid inbreeding. When a male spots a female during the breeding season, they will create a sperm web. A sperm web is a web that deposits seminal fluid into a special silk patch located on the web’s roof. The male will then climb out of the web equipped with his new palpal bulbs (genital organs), suck the fluid into both palps from the top of the web and proceed to destroy it. After that the male tarantula is ready to mate.

Once ready, the male will drum his forelegs and waive his palps around. If she approves she will move towards him and sometimes signal the same way. The female’s way of accepting the male is by dropping her fangs. The male will proceed by forcing the female’s body upward and locking her fangs together with his tibial spurs. The male will insert one palp in the epigastric furrow and the other in the epigyne and deposit his sperm. Once finished, he will immediately release and run away to avoid being killed. Once inseminated the female will produce an egg sac. Each sac usually holds between 50 - 200 eggs. Females are also able to produce a double egg sac without needing to breed again. The fertile eggs in the second egg sac will be around 80 eggs.

References

Peer Reviewed

1. Bertani, Rogério, et al. “ First Record of the Genus Psalmopoeus (Araneae: Theraphosidae) in Brazil.” Biotaxa.Org, 2016, www.biotaxa.org/cl/article/view/12.2.1860/19757.
2. Simon, Mark, and Christopher Hoyte. “A Case Report of Venezuelan Suntiger Tarantula (Psalmopoeus Irminia) Envenomation and Review of Tarantula Exposures.” Science Direct, 2023, www.sciencedirect.com/science/article/pii/S0736467923003207.
3. Psaila, Nathan. “Husbandry Manual for Exotic Tarantulas.” Nswfmpa.Org, 2005, www.yumpu.com/en/document/view/36334919/husbandry-manual-for-exotic-tarantulas-nswfmpaorg.
4. Foley, Saoirse, et al. “Tarantula Phylogenomics: A Robust Phylogeny of Multiple Tarantula Lineages Inferred from Transcriptome Data Sheds Light on the Prickly Issue of Urticating Setae Evolution.” bioRxiv, Cold Spring Harbor Laboratory, 1 Jan. 2019, www.biorxiv.org/content/10.1101/501262v3.abstract.

Not Peer Reviewed

1. “Venezuelan Suntiger (Psalmopoeus Irminia) Care.” The Tarantula Collective, www.thetarantulacollective.com/caresheets/psalmopoeus-irminia. Accessed 29 Nov. 2023.
2. Ian. “Venezuelan Suntiger.” Tarantula Friendly, 5 May 2021, tarantulafriendly.com/venezuelan-suntiger/.

Wikidata ☰ Q135055 entry