Origin and Habitat: Chubut, Península Valdés, Argentina.
Altitude: From near sea level to about 400 metres above sea level.
Habitat: It grows among scrubs and stones. Península Valdés has a semi-arid climate characterized by an annual rainfall of 240 millimetres (mm) with significant fluctuations between years and features a peculiar climate because of the effect created by the Atlantic Ocean. During winter there are heavy snows and frosts can occur throughout the year; spring and autumn provide only short transitions between summer and winter. Although it does not rain much in the region on an annual basis, summers are usually mild, and the temperature sometimes gets very hot. The area does get very windy at times. The area of the Peninsula Valdes harbour an interesting succulent flora comprising Austrocactus patagonicusSN|4011]]SN|4011]], Maihuenia patagonicaSN|30848]]SN|30848]] and Tephrocactus darwiniiSN|20945]]SN|20945]].

• Gymnocalycium gibbosum subs. ferox (Labour. ex Rümpler) Papsch
• Echinocactus gibbosus var. ferox Labour. ex Rümpler
• Echinocactus gibbosus f. ferox (Labour. ex Rümpler) Schelle
• Gymnocalycium gibbosum var. ferox (Labour. ex Rümpler) Borg

• Gymnocalycium gibbosum subs. ferox (Labour. ex Rümpler) Papsch
• Echinocactus gibbosus var. ferox Labour. ex Rümpler
• Echinocactus gibbosus f. ferox (Labour. ex Rümpler) Schelle
• Gymnocalycium gibbosum var. ferox (Labour. ex Rümpler) Borg

• Gymnocalycium gibbosum (Haw.) Pfeiff. ex Mittler
• Cactus gibbosus Haw.
• Cereus gibbosus (Haw.) Pfeiff.
• Echinocactus gibbosus (Haw.) DC.
• Gymnocalycium gibbosum var. brachypetalum (Speg.) Papsch
• Echinocactus brachypetalus (Speg.) Werderm. in Backeb.
• Gymnocalycium brachypetalum Speg.
• Gymnocalycium gibbosum f. cerebriformis (Speg.) Papsch
• Echinocactus gibbosus var. cerebriformis Speg.
• Gymnocalycium gibbosum var. chubutense (Speg.) Papsch
• Echinocactus gibbosus var. chubutensis
• Gymnocalycium chubutense (Speg.) Speg.
• Gymnocalycium gibbosum f. cristatum hort.
• Gymnocalycium gibbosum var. gerardii Boed.
• Gymnocalycium gerardii (Boed.) Y.Itô
• Gymnocalycium gibbosum var. leonense (Hildm. ex K.Schum.) Borg
• Echinocactus gibbosus var. leonensis Hildm. ex K.Schum.
• Echinocactus gibbosus f. leonensis (Hildm. ex K.Schum.) Schelle
• Gymnocalycium gibbosum var. leucacanthum (Rümpler) Borg
• Echinocactus gibbosus var. leucacanthus Rümpler
• Echinocactus gibbosus f. leucacanthus (Rümpler) Schelle
• Gymnocalycium gibbosum f. longispinum hort.
• Gymnocalycium gibbosum var. nigrum Backeb.
• Gymnocalycium gibbosum var. nobile (Haw.) Y.Itô
• Cactus nobilis Haw.
• Echinocactus gibbosus var. nobilis (Haw.) K.Schum.
• Echinocactus gibbosus f. nobilis (Haw.) Schelle
• Gymnocalycium gibbosum var. schlumbergeri (Rümpler) Borg
• Echinocactus gibbosus var. schlumbergeri Rümpler
• Echinocactus gibbosus f. schlumbergeri (Rümpler) Schelle

• Gymnocalycium gibbosum subs. borthii (Koop ex H.Till) G.J.Charles
• Gymnocalycium borthii Koop ex H.Till
• Gymnocalycium borthii subs. kokori Halda & Milt
• Gymnocalycium borthii subs. nogolense Neuhuber
• Gymnocalycium borthii var. viridis Neuhuber

Description: Gymnocalycium gibbosumSN|8057]]SN|8057]] subs. ferox (Labour. ex Rümpler) Papsch is a local or morphological form of the very variable Gymnocalycium gibbosumSN|8057]]SN|8057]] that, as the name states, is characterized by very robust, ferocious white/brownish radial spines and usually no centrals. Moreover it has more slender, 4 angled tubercles. It is often considered just a spinier form of Gymnocalycium gibbosumSN|8057]]SN|8057]] v. chubutense because the two species or populations exist in the same geographic area and thus regularly encounter one another. It is also similar to Gymnocalycium gibbosumSN|8057]]SN|8057]] var. nobile.
Stem: Deep glaucous-green, olive green, brown to grey-black, discoidal that became elonged with time 10-25 cm tall, up to 12 cm in diameter, the apex is slightly woolly.
Ribs: 10-16 straight, divided in well distinct angular ribs.
Areoles: Whitish-grey, elonged.
Radial spines: 5-7 (-9) 20-65 mm long slightly bent against the plants body, whitish to clear brown with a darker base when young, becoming whitish-grey with a black base as they age.
Central spines: Usually absent or if any very similar to the radials.
Flowers: Infundibuliform in the nearest periphery just around the apex 45-60 mm long, 60-65 in diameter. Tepals ivory white with a brownish mid rib or occasionally reddish, throat greenish with a basal reddish area. Style white-greenish, stigma white. Anthers cream coloured.
Fruits: Globate or fusiform, 20-40 mm long green with white bordered scales.
Remarks: Seems to be a pretty variable plant you might get some other names which are effectively the same plant.... and also not sure all plants identified as this are really this.

Bibliography: Major references and further lectures
1) William Taylor Marshall, Nathaniel Lord Britton “Cactaceae: with illustrated keys of all tribes, sub-tribes and genera” Abbey garden press, 1941 – 227
2) Edward Anderson “The Cactus family” Timber Press, Incorporated, 2001
3) David R Hunt; Nigel P Taylor; Graham Charles; International Cactaceae Systematics Group. "The New Cactus Lexicon" dh books, 2006
4) James Cullen, Sabina G. Knees, H. Suzanne Cubey "The European Garden Flora Flowering Plants: A Manual for the Identification of Plants Cultivated in Europe, Both Out-of-Doors and Under Glass" Cambridge University Press, 11/Aug/2011

Cultivation and Propagation: Gymnocalycium gibbosumSN|8057]]SN|8057]] subs. ferox is a summer grower species that is easy to cultivate.
Growth rate: It is a relatively rapidly growing and easily flowering species that will make clumps given the best conditions.
Soils: It likes very porous standard cactus mix soil. Prefer a low pH compost, avoid substrata rich in limestone; otherwise growth will stop altogether.
Repotting: This plant needs plenty of space for its roots, repotting should be done every other year or when the it has outgrown its pot. Use pot with good drainage.
Watering: During cold weather periods keep rather dry, but it can handle excessive water to little water, keep dry in winter at a minimum temperature of 0°C. Make sure that soil gets the chance to dry out in between waterings.
Fertilization: Feed with a high potassium fertilizer in summer.
Frost Tolerance: Reputedly resistant to frost if kept on the dry side prior to, and during, cold weather (Hardy down to -12° to -32° C), but for safe cultivation it is best to avoid severe freezing temperatures.
Exposition: The plant tolerates extremely bright situations but enjoys filtered sunlight or afternoon shade, inside it needs bright light, and some direct sun. Tends to bronze in strong light, which encourages flowering and heavy spine production, but is likely to suffer from sun scorch or stunted growth if over exposed to direct sunlight during the hottest part of the day in summer.
Uses: It is an excellent plant for container growing. It always looks good and stays small. It look fine in a cold greenhouse and frame or outdoor in a rockery.
Pests & diseases: It may be attractive to a variety of insects, but plants in good condition should be nearly pest-free, particularly if they are grown in a mineral potting-mix, with good exposure and ventilation. Nonetheless, there are several pests to watch for:
- Red spiders: Red spiders may be effectively rubbed up by watering the plants from above.
- Mealy bugs: Mealy bugs occasionally develop aerial into the new growth among the wool with disfiguring results, but the worst types develop underground on the roots and are invisible except by their effects.
- Scales: Scales are rarely a problem.
- Rot: This species is particularly easy and accommodating, seldom suffer of cryptogamic diseases. Rot it is only a minor problem with gymnocalyciums if the plants are watered and “aired” correctly. If they are not, fungicides won't help all that much.
Propagation: Mainly through seeds. Seeds germinate in 7-14 days at 21-27° C in spring, remove gradually the glass cover as soon the plants will be well rooted (ca 1-2 weeks) and keep ventilated, no full sun for young plants!
Seed Collecting: Permit fruit to ripen, fruit must be significantly overripe before harvesting seed; clean and dry seeds.