Turbellarian taxonomic database

Proporus lonchitis Notes

[translated from Doerjes 1971]

Description of Proporus lonchitis

type locality: Droebak, Norway; 50-200 m depth, August 1955
material: 1 wholemount, 7 sets serial sections
    no live observations
    holotype a sagittal series, in Naturhist. National Museum, Stockholm
        along with paratype
fixation: sublimat/formol/acetic-acid
    section staining with hematoxylin/eosin
    section thickness 4-5 um

Habitus: roll-shaped body, 1.8 mm long after fixation
    front and  hind ends gently rounded
    circular in cross-section
    whole mount with inbowing of body wall just behind statocysts,
        but this not necessarily a constant character
inner organization
    what stands out in embedded animal:
        nerve complex of brain with statocyst
        pharynx tube behind brain, with mouth
        copulatory organ at posterior tip
        male and female germ tissue
    testes dorso-lateral, in female-mature animal only as small side bands in hind 1/2 body
        converge toward copulatory organ
    female germ cells take up most of posterior 2/3 of body
        conspicuous lack of maturation gradient to eggs: young and mature oocytes and eggs mixed
epidermis of distincts heights:
    front body with insunk, flat epithelium
    hindbody with twice that thickness
        and its epithelial nuclei embedded in granular, weakly vacuolated ground substance
    from body tip posteriorly stepwise from fully insunk to non-insunk
pear-shaped adenal slime glands distributed in peripheral parenchyma
    narrow secretions penetrate body-wall musculature and epidermis, with necks between cilia
    eosinophilous secretion, weakly granular
no frontal gland or rhabdite glands seen
few epidermal-regeneration bodies always in peripheral parenchyma
        ...
musculature like that of other acoels: outer circular, inner longitudinal
    inner musculature only weakly developed
parenchyma:
    peripheral parench spongy, and weakly lamellated in middle of body
        especially well developed in forebody
        in hindbody only as peripheral nucleus-bearing layer,
            between bodywall musculature and inner organs
        border to central parenchyma punctuated with irregular protrusions into it
    central parenchyma granular
        gut space reaches over posterior 2/3 of body,
        narrowed by voluminous ovaries and copulatory organ
        begins at tubular pharynx at level of first 1/4 body
mouth at transition between first and second 1/4 body
    from it, pharynx reaching in dorso-caudal direction
    pharynx of simplex type
        = simple invagination of ventral epidermis
        circular and longi muscles over whole length
        numerous long-necked insunk glands penetrate this musculature
            secretions slightly eosinophilic
            proximal opening of pharynx with obvious musculature that could be fixators or dilators
            beginnings of weak fibers in transitional zone between pharynx and gut seen at high mag.
nervous system
    visible only in forebody
    brain mass insunk, encompasses statocyst completely
    2 clear nerves toward frontal end, 2 toward lateral body wall
        not easily followed in these sections
    2 pairs lateral nerves to body periphery that branch tree-like at level of body-wall muscles,
        lost into peripheral parenchyma
male reproductive organs
    male germ tissue shortly behind midbody, reaches in 2 dorsolateral fields, narrowed by ovaries
    spermatogonia go from peripheral tissue band of peripheral parenchyma
        and come together in formation place to ball-like follicles where spermatogenesis occurs
        narrow club-shaped sperm grow and differentiate toward vesicula seminalis
    copulatory organ simple invagination of body wall like pharynx
        terminal pore connects inwards to a spacious ciliated antrum tube
            antrum can widen as ring-shaped fold in front of muscular ves. sem.
        numerous long-necked accessory glands insunk in atrial musculature, penetrate epithel.
            eosinophilic secretions into antrum lumen
        proximal sperm vesicle of weak musculature, with cellular structure at entrance part
female reproductive organs
    no female helping organs
    unpaired ovary reaches over posterior 2/3 of body, filling whole body width
    formation zone is exceptional: no local fixed body position,
        rather in whole ventral side of posterior 2/3 body
        oogonia differentiate out of peripheral layer of peripheral parenchyma, move dorsally
        therefore get young and mature eggs together
    oocytes more or less rounded in all stages of development, no lobopodia

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