Gymnocalycium sanluisense Neuhuber spec. nov.
Neuhuber, G. (2018): Gymnocalycium sanluisense. - Kaktus Klub (2): p. 14-17.
Type: Argentina, Province San Luis, north of La Carolina, Peñon Colorado, 1530 m s.m., leg. G. Neuhuber GN11-1564/4737, 17.11.2011.
Holotype: CORD: GN11-1564/4737, Flower in alcohol Nr. 3856.
Paratypes WU: GN11-1564/4737, Flower in alcohol Nr. 4085, GN11-1564/4737, Dry fruit Nr. 3573.

Gymnocalycium cabreraense Schädlich, Bercht & Melojer species nova
Schädlich, V.; Bercht, L.; Melojer, M. (2018): A sensational discovery from the utmost northwest of Paraguay – Gymnocalycium cabreraense spec. nov. - Schütziana 9(2): p. 3-16.
Abstract: Michael Melojer made a sensational new discovery in 2010 in a remote location in the Gran Chaco in Paraguay, at the foot of Cerro Cabrera, in the very northwest of the country. To gather further information about the new species, Volker Schädlich and Ludwig Bercht and other companions made several trips to the inselberg. Due to adverse circumstances, however, the site could only be reached again in 2016. After years of detailed study of the plants in culture and habitat, the first description of Gymnocalycium cabreraense is presented here.

Type: Cultivated plants grown from seeds collected in the habitat. The plants are growing on rocky hill slopes of the Cerro Cabrera, Province Alto Paraguay, Paraguay under shrubs and low trees, altitude 482 m. First discovery October 24th, 2010.
Holotype: Melojer MJ 2010-13 (Herbarium WU 4039).

Etymology: The species has been named after the mountain Cerro Cabrera in the utmost northwest of Paraguay. Directly west of the massive there is the border with Bolivia

Gymnocalycium friedrichii subsp. tumaemulticostatum I. Milt subsp. nov.
Milt, I. (2018): Gymnocalycium friedrichii subsp. tumaemulticostatum Ivan Milt subsp nova. - Cactaceae etc. 28(1): p. 7-9
Holotyp: The material of the Holotype deposited in the Regional Muzeum in Olomouc with the number B 171.826. The type culture in the collection of Ivan Milt, the original collect VoS 03-64 (Volker Schädlich).
Etymology: Taxon named in the honour of Mr. Ing. Pavel Tuma, gymno grower from Prague and the second part of the name means "many ribs".

Gymnocalycium x momo Gapon et Schelkunova nothospec. nov.
Gapon, V. & Schelkunova, N. (2018): Die Arthybride Gymnocalycium x momo Gapon et Schelkunova. - Cactus-Club 2018 (1): p. 71-76
Abstract: In 2010 in the foothills of the Sierra Grande in the Argentinean province of Cordoba, to the south of Villa Icho Cruz the authors found a very interesting gymnocalycium that was clearly distinct from G. monvillei. Thorough inspection of the surrounding area led to discovery of five more specimens of these plants, all within 5 meters from the first find. Scanty quantity of similar plants around, underdeveloped generative organs, fruits and seeds, also morphological characters of that find give the authors ample reasons to presume that the newly found plants are natural hybrids between G. monvillei (Lemaire) Britton & Rose and G. mostii (Guerke) Britton & Rose, both native to this area. The authors submit here protologue of nothotaxon and compare the characters of the find with those of the assumed parents and G. schuetzianum H. Till & Schatzl. They also beg the readers to be lenient to their choice of the epithet… The authors are sincerely grateful to Gert Neuhuber and Walter Till (Austria) for their valuable advices and help in depositing of herbarium materials.
Typus: Argentina, province of Cόrdoba, south of Villa Icho Cruz, 1113 m above sea level. Holotypus: WU, inventory No. 3202, dry plant VG11-1159a/5075 leg. V. Gapon 24 December 2011; Paratypi: WU (inventory No. 3086-3087, flowers VG10-1159a/4787 in alcoholic preserving liquor).
Diagnosis: differs from G. monvillei (Lemaire) Britton & Rose in the same place by stronger red-brown spines. Differs from G. mostii (Guerke) Britton & Rose in the same place by greater number of radial spines, their color, flowers morphology, light color of the throat. Differs from G. schuetzianum H. Till & Schatzl by greater number of ribs, more elliptical areolas, greater number of radial spines and their colour, flowers morphology and their color.

Gymnocalycium sutterianum subsp. tetraploideum Řepka subsp. nov.
Řepka, R. (2018): Gymnocalycium sutterianum subsp. tetraploideum Řepka, eine neue Unterart aus der argentinischen Provinz Córdoba. - Gymnocalycium 31(1): 1263-1270.
Type: Argentina, north-central, Córdoba Prov., Dept. Calamuchita, San Antonio Arroyo Corto, in dry pasture with protruding flat rocks, 5,6 km WNW of the town of La Cruz, 32°17'02.1'' S, 64°32'33.0'' W, 552 m s.m., 27. November 2016, coll. R. Řepka (RER 798, Herbarium Jardin Botánico de la Fucultad de Ciencias Forestales, Univeridad Nacional de Santiago del Estero no. 2097, holo).