Turbellarian taxonomic database

Convolutidae Haplodiscus Notes

Weldon WFR 1889 (citation)-
Bohmig L 1895 (citation)- lists of 7 species described here.  Long description of anatomy and histology
	in the genus- definition p 35, key p 35, 37.  Also p 39, 43, and 45.

Graff L v 1904 (citation)- definition of
Graff L v 1905 (citation)-

"Proporidae without a bursa seminalis.  The mouth usually lies on the ventral side or behind this,
the pharynx is very short or completely wanting.  Body flattened, plate shaped.  the frontal gland
is a little more strongly developed than in other Acoela and openings lie scattered on the anterior
end in such a way that no frontal organ is formed.  Moreover the arrangement of this latter
appears to be of specific significance.  In one alleged instance (H. piger) one finds also a
statocyst which lies on the dorsal side of the brain, while eyes appear to be lacking.  The 
genital opening occurs ventrally shortly before the posterior end of the body.  The testicular 
follicles are scattered thickly dorsally either in a single median egg-shaped mass or
(H. obtusus) in two longitudinal rows.  Neither the testes nor the two ventral ovaries possess a
membrane.  All species contain xooxanthellae.  The flattened body (described many times as naked
in preserved specimens) has a circular to oval or leaf shaped outline.  0.8-2.5 mm."  Pelagic only
one species parasitic.
						Teirreich - Graff 1905, p 6.  

Bohmig L 1908 (citation)- p 3 lists in family Proporidae, mentions p 6.
Lohner L 1910 (citation)- comment on type of digestive parenchyma in a species of this genus.
Wilhelmi J 1913 (citation)- mentions p 36, 67, 103, 113 lists p 12 in Family Proporidae.
Westblad E 1948 (citation)- p. 12- comment on epithelium in, p 56- in key.
Hyman LH 1951 (citation) -vol 2, p 129- notes these are pelagic and habits poorly known.
Steinbock O 1966 (citation)- mentions testes in p 85, 138.
Dorjes J 1968 (citation)- lists this way in literature review- places in family Convolutidae
	p 85- definition and description of species- 7 species
		     Haplodiscus piger Weldon 1888
		     Haplodiscus acuminatus Bohmig 1895
		     Haplodiscus obtusus Bohmig 1895
		     Haplodiscus orbicularis Bohmig 1895
		     Haplodiscus ovatus Bohmig 1895
		     Haplodiscus weldoni Bohmig 1895
		     Haplodiscus ussowi Sabussow 1896
Dorjes J 1970 (citation)- description of new species Haplodiscus bocki and summary of genus.  Long
	description and literature review p 261-265.  Lists species as above but H. orbicularis
	is uncertain, also H. scutiformis and H. ussowi.  Also, p 255, 257, 259, 261-5, and diagnosis
	p 265.

Yamasu T, Okazaki A 1987 (citation)- Haplodiscus sp in faunal list.

from Doerjes (1970) (citation) Haploplodiscus bocki spec. nov.,....

all Haplodiscus species are pelagic
    Lebensform characters with this life-style: 
        broad-bodied, often disc-shaped
        numerous symbiotic algal cells
    (but body form of certain species and absence of statocyst in H. piger should be discussed:)

H. piger absence of statocyst
    Weldon (1899) described H. piger as a neotenic cestode or trematode larva
        so no statocyst described
    Bohmig doubted this, but had communication from Weldon that was actual absence
    Graff (1904-08) speculated that statocyst easily overlooked in Weldon's material
    Doerjes had difficulty finding statocyst in H. bocki, so overlooking in H. piger understandable
    other acoels without statocyst:
        Amphiscolops sargassi Hyman (1939)
        A. evelinae Marcus (1947)
    but Bohmig (1895: 37) right in synonymyzing H piger with H orbicularis

    H piger is the only species to have been studied alive (by Weldon)
        therefore, whether body form described for others, studied only in fixed
        preps, is applicable to live animal, is in question
    same applies to length and breadth measurements

data from sections provides only vague results:
    insunk brain
    simple mouth opening (even in H ovatus--i.e., not pharynx simplex here)
    penis tube terminal, invaginated in a muscular bell
    ovaries paired
    epidermis partially or wholly insunk
    parenchyma strongly spongy, vacuole-rich

    ovary position distinctive
        in second body third
            (except in H. bocki, where are in forebody back to second body third;
            and H. ussowi, where are in third body third)
        ovary fields 
            hang together in H. ussowi, H. scutiformis, H obtusus
            but eggs separated by broad interspace in H. piger, H. acuminatus, H bocki
            unknown in incompletely mature specimens of H ovatus, H. orbicularis
                which is certainly true of H. weldoni
    bursa seminalis
        known only in H. bocki
        simply built, probably overlooked in other species
            (e.g., Sabussow (1896) mentions unpaired sperm mass between copulatory organ and ovary)
            (for this reason Doerjes did not establish separate genus for H. bocki)
    testes unpaired except in H. bocki and H. obtusus
        germ center in dorsal peripheral parenchyma in middle body third
    copulatory organ similar in all spp
        ventro-caudal body wall invaginated into tube into body
            bounded by more or less loose or bell-shaped muscle tissue 
        both organ parts tightly bound together
        lengths appear not to be significant (contrary to Bohmig (1895))
            because judged so far only in fixed material
        Bohmig (1895) distinguished 2 groups:
            with or without an antrum masculinum
            but certain only for H. ovatus (w/o) and H. acuminatus (with)
        muscle sheath of copulatory organ functions as sperm reservoir
            i.e., serves as sem. ves.
            this applies as well to H. ussowi, H. bocki
            H. piger, according to Weldon 1889, with sperm assembling in peripheral parenchyma
                proof of a sem. ves. lacking for this species
    brain insunk in all species
        5 prs of longitudinal nerves at most
        large number of frontal and marginal nerves and around statocyst
            but apparently lacking in H. piger
        no nerve connection between brain and statocyst/sense-cell complex
            in H. bocki; embedded in a circle of finely granular cells
            (this sensory complex is in position Bohmig and Sabussow described 
             a postcerebral cell concentration, though this appears more like 
             germ-cell center, according to Doerjes)

key to species of Haplodiscus difficult because of uncertainty of characters

    H bocki with
        ovary beginning in front end
        bursal organ
        mouth opening in hind body third
    H obtusus
        paired testes
    H piger
        lack of statocyst
        length/breadth relationship unique
        otherwise identical to H orbicularis
    H. orbicularis / H. ussowi difficult to distinguish

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