CRISTARMADILLIDIUM ARCANGELI, 1935

Type species: Armadillidium muricatum Budde- Lund, 1885, by original designation. Originally described as a subgenus of Armadillidium (Arcangeli, 1935) .

Diagnosis: According to Arcangeli (1936), Vandel (1954a) and the new species here described, Cristarmadillidium is diagnosed by their Eluma - type head, reduced eye size (from four to six ommatidia in C.myrmecophilum totento 12in C.muricatum),absence of clear sexual dimorphism in pereopod 7, presence ( C. myrmecophilum) or not ( C. muricatum, C. breuili, Cristarmadillidium zaragozai Cifuentes & Prieto, 2020 and Cristarmadillidium alticola Cifuentes, 2021) of a small schisma in pereonite 1 epimera; tubercles developed ( C. muricatum and C. zaragozai), obsolete ( C. breuili and C. myrmecophilum) or absent ( C. alticola); outer margin of pereonite 2 epimera straight; shape of distal part of pereonite 4 epimera narrow and rounded, of pereonite 5 epimera rounded, broader than 4 but narrower than other epimera; large areas of pereon, pleon and epimera, and of telson and uropod exopods, covered by rounded, concave papillae (but see Garcia, 2020); glandular fields in pereonites 2 and 3 epimera transversely elongated, located far from the lateral margin, medially in epimera 2, submedially in epimera 3; and pleopod 2 exopod only slightly longer (1.11–1.30 times) than wide.

Remarks: The tegument microstructures resembling rounded, concave papillae, which are present on large areas of the body surface (Figs 5D, E, 6D, E, 7D, E), resemble those described or illustrated in at least three other Armadillidiidae species: Echinarmadillidium cycladicum Schmalfuss & Sfenthourakis, 1995, Platanosphaera cavernarum (Vandel, 1958) and Eluma praticola Taiti & Rossano, 2015 (Schmalfuss & Sfenthourais, 1995; Schmalfuss et al., 2004; Taiti & Rossano, 2015).