Ultrastructure of the integument of the sea spider Pycnogonum littorale (Ström) (Pycnogonida)
Compère, P.; Thiry, P.; Bussers, J.-C.; Goffinet, G. (1993). Ultrastructure of the integument of the sea spider Pycnogonum littorale (Ström) (Pycnogonida), in: Chardon, M. et al. Third Belgian Congress of Zoology, 5-6 November 1993. Belgian Journal of Zoology, 123(Suppl. 1): pp. 11-12
In: Chardon, M.; Goffinet, G. (Ed.) (1993). Third Belgian Congress of Zoology, 5-6 November 1993. Belgian Journal of Zoology, 123(Suppl. 1). University of Liège: Liège. 109 pp., more
In: Belgian Journal of Zoology. Koninklijke Belgische Vereniging voor Dierkunde = Société royale zoologique de Belgique: Gent. ISSN 0777-6276; e-ISSN 2295-0451, more
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Document type: Summary
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| Authors | | Top |
- Compère, P., more
- Thiry, P.
- Bussers, J.-C., more
- Goffinet, G., more
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| Abstract |
Recent studies suggest that all arthropod cuticles are structured according to the same basic pattern but have undergone major adaptives changes, keeping with the integument physiology and to the habitat of each species. In this respect, pycnogonids appear as a very original and interesting group to study, being commonly considered to form a class among the chelicerates and believed to descend from an early line of marine arthropods that never became terrestrial. Althought their phylogenetical connectton with terrestrial arachnids remains unclear, pycnogonid are quite remote from Mandibulata, some of which have independantly colonised terrestrial habitats. As to the ultrastructure of their integument, no information is available. In this preliminary study of the leg and cephalic cuticle of the coastal sea spider Pycnogonum littorale, we show that the cuticle presents the same basic organisation as marine benthic crustaceans, but also original features, confirming that this group is in many respects aberrant. Overlying a classical simple epidermis, the cuticle includes two main layers: a thin surface epicuticle and a much thicker lamellated procuticle. The epicuticle seems to consist of three layers closely resembling those observed in marine decapod crustaceans (1): an outer surface coat, the cuticulin layer, which is assumed to be a primitive, general feature of the arthropod cuticle, and a thin inner epicuticle. The procuticle is not mineralised and shows neither any obvious horizontal subdivision (i.e. exo- and endocuticle) nor pore canals. Owing to the relatively important thickness of its lamellae, decreasing gradually toward the epidermis, its appearance fits the benthic structural pattern defined in crustaceans (2). The most unusual features of the pycnogonid integument is the presence of large dermal glands within the cuticle, opening at the cuticle surface through short, epicuticle-lined ducts. On the basis of these and previous observations, we conclude that the adaptative modifications of the arthropod cuticle result in showing greater differences between closely related marine and terrestrial species than between distant taxa living in the same environment. (1) Ph. COMPERE and G. GOFFINET (1992). Mém. Soc. r. beige Ent..35: 715- 720.(2) K. PUTZ and F. BUCHHOLZ (1991). Mar. Biol., 110: 49-58. |
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