Sphaeroniscus gerstackeri, VANDEL, 1968

Schmidt, Christian, 2007, Revision of the Neotropical Scleropactidae (Crustacea: Oniscidea), Zoological Journal of the Linnean Society 151, pp. 1-339 : 62-63

SPHAERONISCUS GERSTÄCKERI VANDEL, 1968

Sphaeroniscus gerstäckeri Vandel, 1968 – Leistikow & Wägele (1999 *); Schmalfuss (2003 *).

Material examined

Types: ♂, 6 mm, slides with cephalothorax, second antenna, mandible, first maxilla, second maxilla, maxilliped, tergites 1 and 2, pereiopods 1 and 7, pleopods 1 and 2 [ CV 5244-1 to 5244-10 , Ecuador, Prov. Oriente, Archidona , in humus of a tropical forest, altitude 750 m, leg. Leleup, April 1965 (?)] .

Description ( Figs 185–188 )

Male 6 mm, female unknown. Tergites brown with yellow spots. Yellow colour largely extended on the posterior part and on the sides of the head. The four proximal articles of the second antenna are brown, whereas the fifth article and flagellum lack any pigment. Frontal angle of first coxal plate yellow. Pleonepimera 3 and the pleotelson and uropodes unpigmented ( Vandel, 1968). Endoantennal conglobation.

Cephalothorax with frontal shield bearing furrows to hold the antennae. Vandel (1968) described the eyes as relatively small and composed of eight ommatidia, but in the micropreparation of the cephalothorax, prepared by Vandel, only dark pigment below the integument of the frontal corners could be seen. There is no trace of ommatidial lenses, as in Richardsoniscus portoricensis (see below). Coxal plate 1 with a short schisma on hind corner; lower lobe much shorter than the upper lobe. Coxal plate 2 laterally constricted (as common in conglobating species; recognizable noduli laterales not preserved).

First antenna three-jointed, second article very short, apical article bearing two aesthetascs beside the small, acute apex and two (?) on the mesal margin. Second antenna stout, with three-jointed flagellum. Proximal flagellar article is slightly longer than the second, third twice as long as the proximal article. Second and third articles with one (or one row?) of aethetascs, third article bearing antennal cone, which has one short lateral seta and is longer than third and second articles together. Mandibles with four-lobed pars incisiva; left lacinia mobilis with two corners, as broad as the pars incisiva, right lacinia mobilis smaller. Lobe base of the lacinia mobilis covered with spines and one penicil on right mandible and two penicils on left mandible. One penicil between lobe and pars molaris, the latter represented by a tuft of several hairy setae. First maxilla mesal endite with two penicils and laterodistal corner angular, but without a sharp tip. Lateral endite with lateral group of four stout, simple teeth and a triangular lobe and a slender stalk bearing few setules near its apex; inner group of six more slender teeth, five of them cleft, one of these with three tips. No subapical small setae were seen. Distal part of lateral margin with fringe of ‘hairs’ (which might be pectinate scales?). Second maxilla apically bilobate; mesal lobe with scattered sensilla, between both equal-sized lobes with two setae. Maxilliped base only in lateral portion with distinct cuticular scales and with only a few tricorn-like seta. Endite covered with pectinate scales, bearing one stout penicil subapically on frontal face and one seta on caudal face. Palp three-jointed; proximal article with only one large seta (in the same position as the inner seta of most other Oniscidea), second article on mesal margin with distal tuft of setae on a socket, proximal tuft represented only by one small seta, and two small setae beside socket of distal tuft, on lateral margin two different setae. Distal article with apical tuft of setae and two or three setae on lateral margin.

Pereiopod 1 with antennal brush on carpus and propodus; both are composed of both scales with acute tip and scales with fringed apical margin. Merus and carpus with ventral scale-fields. Dactyli on frontal face with large, feathery dactylar seta, ungual seta accompanied by a thin seta of nearly half its length. Ungual seta slightly shorter than outer claw, but more than twice as long as the very small inner claw. One more seta each on frontal and caudal faces. Some more sensilla-like structures and cuticular scales on basal part of dactylus. Pereiopod 7 ischium with shallow distal depression on frontal surface, merus with dorsofrontal triangular lobe on the proximal half. Vestigial scalerows belonging to the water conducting system present on basis and ischium. Genital papilla with long ventral shield exceeded by a lobe; orifices in lateral position near end of lobe. Pleopod 1 exopodite shorter than long, with narrow probable respiratory field and lacking marginal setae; pleopod 2 exopodite long, with a single marginal seta, a hairy stripe along the inner margin, and lacking any trace of a dorsal respiratory field. Endopodite 1 straight, with row of c. 16 small setae; the distalmost four of these are slightly longer and angulate, and bear some setules. Endopodite 2 exceeding the exopodite. Uropod sympodites with obtuse angled corners, small exopodite about one-third as wide as sympodite.

Geographical distribution

Known only from type locality (only one specimen).

Remark

Sphaeroniscus gerstaeckeri differs from the remaining species of Sphaeroniscus by the absence of lenses on the eyes, convex coxal plate 5, and the different position of the rounded lobe on the male pereiopod 7 merus. In the cladistic analysis, it groups together with the other eyeless species, not with the four species of Sphaeroniscus . However, the male pleopod 1 endopodite in the row of setae along the spermatic furrow has the distalmost setae apically cleft into several setules. The same is also found in Sphaeroniscus pilosus and S. quintus , but not in S. flavomaculatus and S. frontalis . Here Sphaeroniscus gerstaeckeri is provisonally retained in the genus Sphaeroniscus , because the hypotheses of a closer relation with the eyeless species forming clade 9 in the cladistic analysis does not appear to be more plausible.

Figures

Figure 185. Sphaeroniscus gerstaeckeri Vandel, 1972: syntype ♂, tergites 3–7, pleon dorsal and ventral, cephalothorax frontal (Ecuador, Oriente Province, Archidona, altitude 750 m, leg. N. Leleup, April 1965, MNHN).

Figure 186. Sphaeroniscus gerstaeckeri Vandel, 1968: holotype ♂, mouthparts, first antenna (Ecuador, Oriente Province, Archidona, altitude 750 m, leg. N. Leleup, April 1965, MNHN).

Figure 187. Sphaeroniscus gerstaeckeri Vandel, 1968: holotype ♂, 6 mm, pereiopods 1 and 7 (Ecuador, Oriente Province, Archidona, altitude 750 m, leg. N. Leleup, April 1965, MNHN).

Figure 188. Sphaeroniscus gerstaeckeri Vandel, 1968: holotype ♂, 6 mm, pleopods 1 and 2, second antenna (Ecuador, Oriente Province, Archidona, altitude 750 m, leg. N. Leleup, April 1965, MNHN).