Protosphaeroniscus, SCHMALFUSS, 1980

Schmidt, Christian, 2007, Revision of the Neotropical Scleropactidae (Crustacea: Oniscidea), Zoological Journal of the Linnean Society 151, pp. 1-339 : 74

PROTOSPHAERONISCUS SCHMALFUSS, 1980

Type species: Protosphaeroniscus tertiarius Schmalfuss, 1980 .

Diagnosis

Endoantennal conglobation. Hind corners of coxal plate 1 without schisma. Pleotelson shorter than uropod protopodites; exopodites inserted on their inner corner. Apical organ of second antennae longer than apical flagellar article; flagellum three-jointed. Male pereiopod 7 merus with frontal ridge. Apex of male pleopod 1 endopodite bent laterally.

PROTOSPHAERONISCUS TERTIARIUS SCHMALFUSS, 1980

Protosphaeroniscus tertiarius – Schmalfuss (2003).

Description

Approximately 6 × 2.5 mm. Eyes with c. 12 ommatidia. Pleotelson triangular with straight sides.

Distribution

Hispaniola, fossil enclosed in Dominican Amber, age probably 25–30 million years ( Schmalfuss, 1980).

Remark

Schmalfuss (1980) proposed a sister-group relationship between Protosphaeroniscus and a clade composed of Circoniscus , Sphaeroniscus and Spherarmadillo . The published description does not allow determination of the place of P. tertiarius in the phylogenetic hypothesis (cladogram) constructed in the present study. It seems to have had an endoantennal conglobation ability; the first coxal plate has a ridge, but not a schisma, on the inner side. The eyes are well developed, but there is no transverse furrow seen on the drawing ( Schmalfuss, 1980, fig. 4). The latter would exclude P. tertiarius from clade 14 of the present article, if the lack of the furrow is regarded as primary. In the case of Sphaeroniscus pilosus , the lack of the transverse furrow has to be seen as secondary, because the other species of the genus Sphaeroniscus , and all other species of clade 14, which includes Sphaeroniscus , have a transverse furrow. Therefore, a close relationship to Circoniscus and Sphaeroniscus cannot be excluded ( Spherarmadillo belongs to a more distant clade, according to the present analysis).