Turbellarian taxonomic database

Proporus minimus Notes

Proporus minimus (An der Lan, 1936) (citation)
  Steinbock O 1935 (citation)- mentions this species as Archiproporus - compares with 
  	his Protomacrostomum groenlandicum - says he brought this back from Groenlad and it was
  	found among his acoels.
  An der Lan, 1936 (citation)- describes as Archiproporus minimus.	
  Westblad E 1945 (citation)- moves from Archiproporus to include in Proporus.
  Westblad E 1948 (citation)- p 33, notes simple reproductive organs.
  Steinbock O 1966 (citation)- mentions p 134, 135 calls it Archiproporus and discusses.
  Dorjes J 1968 (citation)- lists as good species.  p 370 - see note on this species as treated by 
  	Westblad- he disagrees.
  Dorjes J 1971 (citation)- lists as (An der Lan, 1936) - described by An der Lan as Archiproporus minimus-
  	describes and illustrates- p 117-121.  Diagnosis p 133.
  Karling TG 1974 (citation)- says this should be a separate genus-	
  Dorjes J, Karling TG 1975 (citation)-	Greenland and North Sea- SMNH.
  Smith JPS 1981 (citation)- mentions Dorjes description of epithelium in digestive tract.

[translated from Doerjes 1971]

Proporus minimus (An der Lan 1936)
    Archiproporus minimus An der Lan 1936
    Proporus minimus Westblad 1945, 1948
    Pr. m.  Dorjes 1968
    Diskobay, southern Godhavn, 250 (-300) m deep on muddy bottom (Steinbock Aug 1926)
    Droebak, Norway, depth ?, sediment ? (E Westblad July 1935)
sections of Westblad in Natural History Museum Stockholm, wrongly labeled as Haploposthia viridis.

because Westblad based his placing this species into Proporus solely on literature,
Doerjes adds this account of the sections:

epidermis thickly condensed, insunk in front end;
    reaches twice thickness in mid-body
    gradually reduces to original thickness in posterior
    from insunk anteriorly to intraepithelial posteriorly
mucous glands eosinophilous and finely granulated
    no distinct arrangement; An der Lan wrote of regular distribution
    glands into peripheral parenchyma with voluminous gland body
    open with fine necks between cilia
    no rhabdite glands
    frontal organ only weakly developed
body-wall musculature forms inner border to epid.
    layering typical of acoels (inner longitudinal)
inner-body musculature exceptionally well developed
    strong longitudinal fibers, weak dorsoventral fibers with distinctive functions
    2 retractors insert on front end and
        run in diagonal direction to ventral and dorsal body-wall musculature
    2 other longi- bands reach into body
    ventral longitudinal end at level of inner pharynx opening w/o tying w/ pharynx muscles
    dorsal longitudinal muscles reach far into inner body
        and surround what An der Lan (1936) called a gut-like space, corresponding gut lumen
    in hind portions, these fan horse-tail-like and protrude into gut epithelium
    besides these powerful muscle bands,
        numerous circular surround gut lumen and
        fixators run from gut musculature to body-wall muscles
    large number of muscles insert into brain, dispersing shortly into parenchyma
nervous system
    brain cross-form, sunk into body, ensheaths statocyst
    nerves: two clear frontal- and two lateral-nerves to front body pole
        and to lateral body periphery
        longi nerves in body are followed by the powerful inner longitudal muscles
    peripheral parenchyma is exceptionally spongy
        vacuolated consistency is thicker in front than posteriorly
        appears lamellate through distinct muscle fibers through it
        round nuclei relatively small, strongly cyanophilic
            and frequently in peripheral layers of the tissue
        reminiscent of gastrodermis of other (non-acoel) turbellarians:
            peculiar structure in delimiting region between marginal parenchyma and gut lumen
            basal layer is set off by numerous circular and longitudinal muscles
                which form a special gut musculature
                that is linked to body-wall muscles by cross-fibers
        gut musculature sits proximal to epithelial binding tissue
            which is overlain by numerous villi in central lumen
        no digestive glands or ciliation like those in Nemertoderma and Meara
        digestion apparently by form of holocrine secretion
        numerous cell groups loose from epithelium in central digestive cavity
        supports An der Lan's statement that "regular spaces corresond to true gut lumen"
        Doerjes skeptical about lack of limit betwen peripheral parenchyma and gut
            because of clear membranous & muscular layer
mouth opening ventral between first and second body fifths
    pharynx tube ciliated, projects inward from mouth dorsally and slightly posteriorly
    = simplex type, simple inturning of epidermis inward
    weak longi- and circular muscles over its entire length
        continue at inner end partly as gut musculature, partly as dilators toward bodywall musc.
    pharyngeal glands finely granulated, insunk in peripheral parenchyma
        not regularly distributed over length of pharynx, more at mouth and inner end 
male reproductive organs
    germ cells in unpaired testes in peripheral layers of peripheral parenchyma 
        in region from first to second body third
        into small, few-celled follicles
        formation center not visible (An der Lan described as behind brain)
        dorsal testicular string widens posteriorly, reaches body wall at its end 
        here, the follicles are tightly appressed, borders not clear
        sperm club-shaped, no synchronous dev't 
            sperm, sermatogonia, and spermatids mixed together, reaching right to copulatory organ
    copulatory organ unremarkable
        opens with very short antrum masculinum on hind body pole
        consists of outer glandular vesicle [vesicula granulorum] covered with muscles +
            inner vesicula seminalis into which the short muscular cirrus is invaginated;
            ciliated atrial portion narrows toward body to an unciliated ductus ejaculatorius
            in front of whose proximal end lie additional eosinophilous gland cells
            these glands are different from those of glandular vesicle in distal part of ves. sem.
            secretions of these glands stop off the lumen of the penis
        mature sperm penetrate through canal that binds sperm vesicle with endbranch of testes string
            and into vesic. sem.
female reproductive organs
    no female accessory organs
    medial ventral egg string, with no hint of pairing in fully mature animal
        (so differs from observations of An der Lan who studied younger animals)
    oogonia formed in wide area in front portion of middle third of body
        at first are united as thickly granulated oogonia
        climb toward midbody and come together to a compact egg field
    mature eggs reach diameter of 3/4 of body height
        protrude into gut space by end of their development
        uptake of nutrients by osmosis [pinocytosis] (no lobopodia seen)

Notes from synonyms

Notes for Archiproporus minimus

An der Lan H 1936 (citation)- p 322-3 describes and illustrates, figure 4 and 16.  
  Westblad E 1945 (citation)- p 43 says Archiproporus minimus = Proporus minimus.
  Westblad E 1948 (citation)- p 58 says he has eliminated this genus.
  Dorjes J 1971 (citation)- also places minimus in Proporus.
  Karling TG 1974 (citation)- says Dorjes considers this a valid genus.
  Dorjes J, Karling TG 1975 (citation)- lists.

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