Colomboscia, VANDEL, 1972

Schmidt, Christian, 2007, Revision of the Neotropical Scleropactidae (Crustacea: Oniscidea), Zoological Journal of the Linnean Society 151, pp. 1-339 : 31-32

COLOMBOSCIA VANDEL, 1972

Type species: Colomboscia cordillerae Vandel, 1972 (by monotypy).

Diagnosis

Conglobating or not conglobating. Small noduli laterales inserted on the posterior margin of the pereionites. Strongly convex, protruding eyes. Cephalothorax with distinct lateral lobes, median lobe present or absent. Linea supraantennalis present. Profrons with a median obtuse longitudinal carina; frontal region separated from vertex by a deep groove that continues along the inner margin of eyes. This groove is evenly curved (except for Colomboscia parva ). All coxal plates simple. No interruption in the body outline between pereion and pleon. Pleotelson distally rounded or triangular, distinctly shorter than pleon-epimera 5 and uropodal protopodite. First antenna of three articles, third article conical, bearing a tuft of aesthetascs on the mesal face and two aesthetascs on the apex. Second antenna short, when bent backwards, slightly surpassing the posterior margin of tergite 1. Flagellum of three articles, the apical cone as long as the flagellum (unknown in C. bituberculata ). Pars molaris of mandible consisting of a tuft of hairy setae. First maxilla mesal endite with two penicils, lateral endite with outer group of five stout teeth (or four teeth and a basal lobe?) and a slender seta, which is apically hairy, and inner group of six slender teeth, five of which are apically cleft. Maxilliped with hairy endite bearing a penicil on its frontal face. Maxilliped palp with basal article bearing one large seta near the mesal margin. Medial article with basal tuft of several small setae, distal tuft of setae on a socket. Pereiopods with a long hairy dactylar seta. Male pereiopod 7 with a triangular process on the frontal surface. Pleopod exopodites without dorsal respiratory structures. Uropod protopodite flattened, rectangular. Exopodite inserting on the posteromedial corner. Endopodites laterally flattened and distinctly exceeding the pleotelson and the protopodites. [Based on the diagnosis given by Taiti et al. (1995).]

Remarks

Vandel (1972) described Colomboscia cordillerae as a species of Bathytropidae , without any argument supporting this placement and obviously because of a superficial similarity of the habitus. Taiti et al. (1995) redescribed the species, described a new species, and transferred the genus to the Scleropactidae . Their arguments for the inclusion in the latter family are

1. ability to roll up

2. cephalic groove similar to that in species of Scleropactes

3. telson distinctly shorter than uropod protopodite 4. antenna with very long apical organ

5. outer branch of the first maxilla with a setose stalk among the outer group of teeth

6. dactylar seta very similar to that of Scleropactes 7. uropod protopodite flattened, exopod inserting in a notch on posteromedial corner, endopodite projecting beyond tip of telson

Characters (3) and (5), and probably also (6), are plesiomorphic. The telson is shorter than the uropod protopodite in Olibrinus , Scyphacidae , Actaecia , some ‘Philosciidae’, and Ligia . In consequence, this has to be regarded as a character that was been present in the groundpatterns of the Crinocheta and Oniscidea. The conglobational ability (1) should be regarded with caution. On the one hand, conglobation ability evolved many times independently, e.g. in the Armadillidae , Tylidae , and Armadillidiidae , some species of the Porcellionidae and Eubelidae , some species of Armadilloniscus , Actaecia , Buddelundiella , and the Tendosphaeridae , and even some taxa outside the Oniscidea or the Isopoda . On the other hand, within the Scleropactidae , two modes of conglobation are found, the exoantennal in Colomboscia and Scleropactes and the endoantennal in the remaining species. Also, conglobational species usually have coxal plates 2 and 3 or 2–4 somewhat laterally constricted, which is not the case for Colomboscia . Despite the assumption of Taiti et al. (1995) that Colomboscia spp. have exoantennal conglobation ability, the morphology of the body and coxal plates is clearly of the ‘creeper type’ ( Schmalfuss, 1984).

Character (2) could be regarded as a synapomorphy with Scleropactes .

The cephalic transverse groove as a putative synapomorphy justifies the inclusion of Colomboscia in the Scleropactidae .

The presence of distinct cephalic lobes is a plesiomorphy compared with the lamina frontalis of most of the Scleropactidae . The same is true regarding the three-jointed flagellum with the long apical organ.

The present study suggests that the two named and one unnamed species previously included in Colomboscia form a monophylum characterized by the clinger habitus, which evolved secondarily from a conglobating habitus. Furthermore, the species andinus and gaigei , formerly included in the genus Scleropactes , and one new species, are successively related to that monophylum. In order to avoid paraphyletic genera, these three species are here included in the genus Colomboscia . The alternative would have been the introduction of three new genus names for the latter three species.

One of the characters reported by Taiti et al. (1995) can be regarded as an autapomorphy of Colomboscia : ♂ pereiopod 7 merus on the frontal face with a triangular process; the base of this process occupies the basal half of the merus.

The genus Colomboscia includes four named and one unnamed species.