Thelocactus nidulans is a species of cactus native to Mexico. Here's a description:

Description: Thelocactus nidulans is a small to medium-sized cactus with globular or cylindrical stems that can reach up to 10-15 centimeters in height and 5-10 centimeters in diameter. The stems are usually solitary or slowly clustering, with numerous ribs bearing distinctive tubercles. The tubercles often have woolly areoles from which spines emerge. The spines are typically short, straight, and radial, with a central spine that can be slightly longer and more robust than the radial ones. The coloration of the stems can vary from green to bluish-green, often with darker green markings or a reddish tinge. During the flowering season, which typically occurs in spring or early summer, Thelocactus nidulans produces funnel-shaped flowers that emerge from the apex of the stem. The flowers are usually pink, magenta, or purple, with darker stripes or markings on the petals.

Cultivation: Thelocactus nidulans is relatively easy to cultivate and is well-suited to cultivation in containers or rock gardens. Here are some cultivation tips:

• Light: Provide ample sunlight, preferably in a location where the plant receives direct sunlight for several hours each day.
• Soil: Plant Thelocactus nidulans in a well-draining cactus mix, such as a combination of potting soil, sand, and perlite.
• Watering: Water sparingly, allowing the soil to dry out between waterings, especially during the winter months when the plant is dormant.
• Temperature: Keep the plant in a warm environment, with temperatures above 10°C (50°F). Protect it from frost and freezing temperatures.
• Fertilization: Fertilize sparingly during the growing season with a balanced fertilizer diluted to half strength.
• Potting: Repot the plant as needed, using a pot with drainage holes to prevent waterlogging.

With proper care and cultivation, Thelocactus nidulans can thrive and reward growers with its charming appearance and occasional beautiful blooms.