Morphology of the presoma of Corynosoma hamanni (Acanthocephala: Polymorphidae)

Abstract

A morphological study of the presoma of adult Corynosoma hamanni (Linstow, 1892) was undertaken in a n effort to clarify some problems encountered during analysis of a large collection of juveniles of this species assembled from fishes of McMurdo Sound. This study is based on approximately 600 adult specimens recovered from four Weddell seals, Leptonychotes weddelli, collected at McMurdo Sound.Morphologically the proboscis armature is more varied than previously reported and consists of 18 to 23 longitudinal rows each with 11 to 15 hooks of two distinct types. At the apex of the proboscis is an undivided, bi-nucleated apical organ unlike that described for species of Neoechinorhynchus. In the basal third of the proboscis is a thin-walled vesicle which extends into the anterior quarter of the proboscis receptacle. The more posterior of two external folds on the presoma is a cuticular invagination permitting recognition of the neck-trunk border of C. hamanni. Lemnisci originate between the two folds and extend into the trunk cavity between the body wall and extensive neck retractor muscles. Contrary to Linstow's original description, each lemniscus is a single structure.Several limitations in material prevent speculation at this time about the limits of intraspecific variation in C. hamanni.

On the occurrence of juvenile acanthocephalans of the genus Corynosoma Lühe, 1904 in fishes off South Georgia and south Shetland Islands (the Antarctic)

“…Remarks. The material examined is morphologically identical with the very detailed description of Chamanni given by Nickol and Holloway (1968) and as well as with the description of Cpacifica Nikol'sky, 1974. The two species differ in sizes of their eggs, 0.088-0.120 mR1 and 0.192-0.208 mm in C.hamanni according to Holloway and Nickol and in C. pacifica after Nikol'sky .…”

“…The latter was found to occur in fishes and in seals as definite hosts at a number of Antarctic and Sub-Antarctic localities, but no final zoogeographical conclusions can be drawn at the present stage owing to the lack of quantitative data. At any rate, mass occurrence of the species was recorded in the proximity of the Antarctic continent (Nickol and Holloway, 1968). Off South Georgia, the species had been noted in seals and fishes (Linstow, 1892;Baylis, 1929) as well as in fishes off South Shetlands (Baylis,19.29).…”

5. Acanthocephala: functional morphology

“…The detection of an apical organ in a few palaeacanthocephalans by Nickol & Holloway (1968) was doubted by Herlyn et al (2001). But then, lateral sensory pits resembling those of eoacanthocephalans and archiacanthocephalans were described from a few species.…”

The musculature of the praesoma in Macracanthorhynchus hirudinaceus (Acanthocephala, Archiacanthocephala): re-examination and phylogenetic significance

“…Derived from the "circular and longitudinal muscle Rüsselmuskulatur (Hamann 1891), Sarkolemmaring longitudinal layer of the proboscis" Nickol and Holloway (1968) der Rüsselscheide (Kaiser 1893), musculature of the described in Corynosoma hamanni (Linstow, 1892); erstes Muskelsegment der Körperwand (Meyer 1933) praesoma (pc, pl) note: the longitudinal subtegumental muscle layer of the proboscis described in several Palaeacanthocephala and Eoacanthocephala species probably refers to the outer tube of the complex proboscis retractor (see Taraschewski (Meyer 1933), circular muscle layer (of the musculature of the (1967) in Acanthocephalus ranae (Schrank, 1788) proboscis) (Hyman 1951), subtegumental musculature trunk (tc, tl) (of the metasoma) (Taraschewski 2000) Medulla (me) Anterior non-contractile part of the receptacle; Markraum der Rüsselscheide (Kaiser 1893), derived from Dunagan and Miller (1974), Markbeutel des Receptaculi proboscidis (Kilian 1932), who described a "medullary fluid" in its inside in Receptaculum-Plasma (Meyer 1933), cytoplasmic part Macracanthorhynchus hirudinaceus of the proboscis receptacle wall (Taraschewski 2000) Midventral Adopted from Hyman (1951) (Kilian 1932), vorderer und muscle (ml) hinterer (ventraler) Rinnenmuskel (Meyer 1933), midventral receptacle muscle (Hyman 1951), primary ventral protrusors and longitudinal band (Schmidt 1972), ventral receptacle muscle of proboscis receptacle (Wanson and Nickol 1975) Muscle plate (mp) Derived from Haffner (1943) who described a Ringmuskelplatte (Kaiser 1893), muskulöse Platte "Muskelplatte" in Oligacanthorhynchus thumbi (Kilian 1932) Muscle sac (ms) Posterior contractile part of the receptacle; term that Innere Rüsselscheidenwandung (Hamann 1891), comprises the probable homologous tissues inner wall innere Rüsselscheide (Kaiser 1893), Receptaculum-(e.g. Taraschewski 2000 in species with a doubleMuskelschicht (Meyer 1933), muscular wall walled receptacle and receptacle wall muscle (Schmidt 1972), receptacle wall (Hyman 1951, (Dunagan andMiller 1974) illustration of Acanthocephalus; in the present proboscidis (Kaiser 1893;…”