Kovács I. (szerk.): A Magyar Természettudományi Múzeum évkönyve 78. (Budapest 1986)

Taiti, S., Ferrara, F. ; Schmalfuss, H.: Chileoniscus marmoratus gen. et sp. n. from Chile (Oniscidea, Scleropactidae)

ANNALES HISTORICO-NATURALES MUSEI NATIONALES HUNGARICI Tomus 78. Budapest, 1986 p. 63-69. Chileoniscus marmoratus gen. et sp. n. from Chile I (Oniscidea, Scleropactidae) by S. TAITI (Firenze), F. FERRARA (Firenze) & H. SCHMALFUSS (Stuttgart) Abstract — A new genus and species of the terrestrial isopod family Scleropactidae, Chileoniscus marmoratus, is described and figured, constituting the first record of this family from Chile. In the light of the new findings the phylogenetic relationships within the family Scleropactidae are re-considered. With 19 figures. The Isopod material collected in Chile by the expedition from the Hungarian Natural History Museum, Budapest, contains several specimens of a hitherto undescribed species of Scleropactidae (= Sphaeroniscidae, compare HOLDICH et al. 1984), a family which up to now had not been reported from Chile. Further specimens of the same species are deposited in the Isopod collection of the Natural History Museum, Stuttgart. We consider this species to represent a new genus characterized by the unusual structure of the cephalon and the uropods. Chileoniscus gen. n. Type-species : Chileoniscus marmoratus sp. n. Diagnosis — Animals with very convex back and ability of eusphaeric conglobation. Dorsum with evident scale-spines. Cephalon with frontal margin interrupted in the middle. Frons with a triangular shield ventrally limited by the antennái grooves. Distinct antennái lobes protruding frontally. Pereon-epimera I with lateral margin slightly thickened and externally grooved, and with a "notch" (but not a true schisma) on the ventral surface. Epimera of pereon-segment II ventrally with a very slight transverse thickening. Telson broader than long, roughly trapezoidal, distinctly shorter than tips of pleon-epimera V. Antenna with 2-jointed flagellum. Mandible with molar penicil constituted of several plumose setae each arising separately. Maxillule: outer branch with all teeth simple, inner branch with two penicils. Endite of maxüliped without a penicil. Only pleopod-exopodite I with a weakly developed respiratory area. Uropod with protopodite flattened, in situ slightly surpassing tip of telson and distinctly shorter than pleon-epimera V; exopodites and endopodites lamellar, occupying the space between telson, uropod-protopodites and pleon-epimera V, thus forming a closed outline of the pleon; exopodite inserted terminally; endopodite inserted proximally to exopodite. Remarks — The characters distinguishing Chileoniscus from all other members of the family Scleropactidae are the structure of the cephalon and of the uropods. The presence of antennary sockets is in fact a unique feature because in all the other genera of this family no special structures exist that form a fitting shelter for the antennae during conglobation; in these genera the antennae simply rest upon the plain frontal shield as in most Armadillidae and Eubelidae. In the new genus, however, the development of the antennái lobes creates a deep groove in which the peduncle of the antennae is inserted. The structure of the cephalon is therefore similar to that in the family Armadillidiidae

, especially to the so-called Eluma-type. Still more characteristic for the new genus is the structure of the uropods. In contrast to all the other Scleropactidae the space between the fifth pleonepimera is occupied by the uropod-exopodites and the endopodites, while in the other scleropactid genera this gap is filled by the enlarged protopodites. In other conglobating families of terrestrial isopods, different strategies have been developed to arrive at a closed