Cyriocosmus

The dwarf tarantula genus Cyriocosmus was established by French arachnologist Eugène Simon in 1903. He created the genus to house two small Neotropical species he had originally described in 1889 as Hapalopus sellatus and Hapalopus elegans; these became Cyriocosmus sellatus (the type species) and Cyriocosmus elegans respectively. These spiders are part of the subfamily Theraphosinae and are characterized by compact bodies, often with striking abdominal patterns and a simple, oval carapace.

Through the early and mid-1900s, South American workers such as Mello-Leitão added several species under Cyriocosmus and closely related genera. Later studies showed that two supposedly separate genera, Erythropoicila (Fischel, 1927) and Pseudhomoeomma (Mello-Leitão, 1930), were not distinct after all; both were formally synonymized with Cyriocosmus, effectively folding their species into Simon’s genus.

Modern understanding of Cyriocosmus really took shape in the late 20th century. In 1998, Pérez-Miles published a full revision and phylogenetic analysis of the genus, clarifying species limits and relationships and providing modern diagnoses. A second major revision in 2005 (Zootaxa 846) re-examined type material across South America and nearby islands, described new species, and revalidated C. fasciatus, which had previously been treated as a synonym of C. elegans. Subsequent work, especially by Kaderka and co-authors, has continued to add new species from Peru, Brazil, Venezuela and neighboring regions.

Today, Cyriocosmus includes over twenty described species spread across the tropical regions of northern and central South America, as well as Trinidad and Tobago. They occupy a variety of microhabitats but are best known in the hobby as colorful, fast-growing dwarf tarantulas. Distinctive reproductive structures (a unique paraembolic process in males and spiral spermathecae in females), along with characteristic urticating hairs, clearly separate Cyriocosmus from other tarantula genera.

Source: Fukushima 2005

Source: Kaderka 2019

Cyriocosmus ritae

C. ritae can be found in the forests of Peru and Brazil. This is a dwarf species but fast-growing. They have beautiful black and white colorations with unique abdominal patterns. Considered fossorial but may climb as well.

Habitat: native to tropical rainforests with dense vegetation and humid environments. This is considered a fossorial species and will burrow under fallen logs, leaf litter, or crevices.

Husbandry Notes:

Given name: Cortado

Sex: Male

Life stage: Adult

Size: Approximately 1.25 inches

Growth: Molted recently

Disposition: Sling behavior and twitchy

Eating habits: Strong feeding response

Misc: Generally visible

Genus and species: Cyriocosmus perezmilesi

Common name: Bolivian Dwarf Beauty

Given name: Bean

C. perezmilesi is a fossorial dwarf species found in Bolivia. They have black heart-shaped patch in the middle of their abdomen. Their coloration is copper and black. They have an aggressive feeding response. Adults grow to approximately 2 inches, but tend to grow quickly to this length. The species name perezmilesi honors Dr. Fernando Pérez-Miles, a renowned Uruguayan arachnologist.

Habitat: native to tropical areas of Bolivia near the Beni River. They burrow but are commonly visible.

Husbandry Notes:

Enclosure: 4x3x2.5

Flora: Substrate

Sex: Undetermined

Life stage: Sling

Size: Approximately 0.5 inches

Growth: Steady growth, has not molted

Disposition: Sling behavior

Eating habits: Strong feeding response

Misc: Always visible and will take down larger prey