First description by W A & Betty Fitz Maurice in Cactus World Vol. 24 (1) 2006
Body: Forming clusters of up to 10 stems, globose to somewhat columnar, heads to 5 cm in diameter and 10 cm high.
Roots: Fibrous, somewhat thickened.
Sap: With watery sap.
Tubercule: Somewhat angular, tapering toward the obtuse top; 6 - 7 mm long and in diameter. 13 x 21 spirals.
Axil: With varying amounts of tortuous wool., to 1,5 mm long and with up to 15 bristles to 15 mm long.
Radial spine: 16 - 22, subulate, straight, radiating, to 15 mm long, white, occasionally with brown tips.
Central spine: 4 - 8, subulate, straight, somewhat ascending, 1 spine descending and variably hooked, 10 - 20 mm long, light yellow to dark brown with bulbous yellow base.
Flower: Campanulate to funnelform, 15 mm long and 10 - 15 mm in diameter, deep pink with a darker pink midstripe, stigma lobes yellow.
Fruit: Flattened ellipsoidal, with up to 20 seeds, 6 - 13 mm long and 4 - 5 mm wide, white below, pink above.
Seed: Brownish black, 1,0 mm long and 0,8 - 0,9 mm wide
Habitat Substrate: Growing in cracks in vertical stone faces of brown volcanic rock.
Geographic Distribution: Mexico, Jalisco, in Laguna Chapala near Municipio Atarjea. Altitude: 1550 meter.
Comments: Founded by Antonio Machuca in 1995. The only known population consist of about 800 plants. Belongs in the stylothelae crinita group. Bibliography: Cactus World Vol. 24 (1) 2006 p. 7 - 11

In the New Cactus Lexicon, M.manana has been made synonymous with M.fttkaui ssp limonensis (14364, page 165). In the original description (2006) the Fitz Maurice's did compare M.manana with M.fittkaui but concluded that they were seperate species with the following comment '' The plants of the M.fittkaui complex are not shown since their tubercles, always with fully hooked central spines and 8 - 13 spirals, place them well away from M.manana''.
Recently (Jan 2008) I had cause to be in touch with the Fitz Maurice's and they made the following brief comment on M.manana/M.fittkaui '' Indeed, according to us, M.fittkaui is well seperated from M.manana as you quote from our article''. ''Your question asks for clarification of Hunt's declaring that M.manana is synonymous with M.fittkaui ssp limonensis. First, 'M.fittkaui complex' is a misnomer, as we find M.fittkaui to be with no subspecies (note our article Fieldnotes : Mammillaria aff fittkaui Cacti. Suc. Jour. US.64:1, 1992). Secondly, we find M.limonesis to be a valid species well separated from M.fittkaui (note our article Fieldnotes : Mammillaria limonensis Cacti. Suc. Jour. US.65:4, 1993)''.

I must admit that what the Fitz-Maurices say makes a lot of sense to me. M. fittkauii is very distinctive, and as far as my M. limonensis plants are concerned appear to be well different in shape, flower and colour. As for M. manana, again with spine coloration, variability of presence of hooked spines, flower colour and position of where the flowers emerge, I fin dit difficult to merge it with any other of the Stylothelae.