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The World of Protozoa, Rotifera, Nematoda and Oligochaeta

Monopylephorus

Monopylephorus Levinsen, 1883 (ref. ID; 1257, 3692) or 1884 (ref. ID; 5957, 6649, 6913, 7854), Levinsen, 1884 emend. Baker and Brinkhurst, 1981 (ref. ID; 6972)

Family Tubificidae (ref. ID; 1257, 7854)

Family Tubificidae: Subfamily Rhyacodrilinae (ref. ID; 5857, 5882, 6451, 7824)

Synonym Littodrilus Chen, 1940 (ref. ID; 5957); Postiodrilus Boldt, 1926 (ref. ID; 5957); Rhizodrilus Smith, 1900 sensu Hrabe, 1967 (in part) (ref. ID; 5957); Vermiculus Goodrich, 1892 (ref. ID; 5957)

ref. ID; 1663

Dorsal and ventral setae different. Ventral setae bifurcate, dorsal setae bifurcate or mixture of two or three types. Four bundles of an indeterminate number each per segment. Worm usually reddish. Coelomocytes abundant. Prostomium without ciliated pit. Vasa deferential short, scarcely distinguishable from their tubular atria. Usually among roots of aquatic plants. Several brackish species, one fresh water species. (ref. ID; 1663)

ref. ID; 5957

Tubificid oligochaetes with male ducts having rudimentary or absent vas deferens, ventrolateral sperm funnel leading directly into apical end of narrow tubular prostate-covered atrium leading to short ejaculatory duct, which enters upper end of eversible or protrusible pseudopenes. Spermathecae contain sperm in loose masses; in some species sperm heads may be attached to walls of spermathecal ampullae. Modified genital setae absent; hair setae, when present, thin, spirally twisted. Coelomocytes large and abundant. Salt or brackish water. Cosmopolitan. (ref. ID; 5957)

Remarks

A number of species formerly classified here have now been recognized as belonging to distinct genera, defined below. This leaves a cohesive group consisting of the type species M. rubroniveus (with its cluster of synonyms and related species); M. parvus, a species with one spermatheca; a new species with some simple-pointed setae like the latter but two spermathecae and elongate eversible pseudopenes; and a group of species with thin, spirally twisted, hair setae formerly grouped as M. irroratus. The availability of large numbers of specimens of one of the latter group has enabled the form of the penes to be resolved. Differences thought to be due to degree of maturation (Brinkhurst 1971) are now recognized as the basis for the recognition of five species, all with the same twisted hair setae. The identity of the type species has often been challenged (Hrabe (1967) for example) because of the brevity of the original description. This also applies to the redescription given by Ditlevsen (1904). If the broad definition of the species given here is employed, all of the early species with no hair setae and large median male copulatory bursae are referable to M. rubroniveus, which differs clearly from all other species except limosus and kermadecensis not only by this characteristic but by nature of the setae, number of spermathecae, and nature of pseudopenes. Four of the synonyms of M. rubroniveus were described prior to 1915 in addition to the type, and only one of them has traceable type specimens. None has been confirmed by being collected at a later date. If the differences between them are held to be real and of specific rank, the generic name would not be useable, as the accounts by Levinsen and Ditlevsen would not be distinguished from these various species and the type species would have be declared "species spuria" (Hrabe 1967). In that case the name Postiodrilus Boldt, 1926 would have to be used as Rhizodrilus is no longer available, being used below. The original description of P. sonderi mentions penial setae (emphasized by Hrabe (1967)), but as these setae were described as smaller than the usual ventral setae and are apparently sometimes missing on one side, they sound as though they are simply the ventral setae that are normally shed upon maturation in those species that lack specially modified penial setae, and it is regarded as a synonym of M. irroratus here. (ref. ID; 5957)

Type species

Monopylephorus rubroniveus Levinsen, 1884 (ref. ID; 5957)
  1. Monopylephorus aucklandicus (Benham, 1909) (ref. ID; 5957)
    Syn; Littodrilus aucklandicus (Benham) Chen, 1940 (ref. ID; 5957); Monopylephorus aucklandicus (Benham) Brinkhurst, 1963 (ref. ID; 5957); Rhizodrilus aucklandicus Benham, 1909 (ref. ID; 5957)
  2. Monopylephorus corderoi Marcus, 1952
    See; Monopylephorus rubroniveus (ref. ID; 5957)
  3. Monopylephorus camachoi Rodriguez, 1999 (ref. ID; 6649 original paper)
  4. Monopylephorus cuticulatus Baker & Brinkhurst, 1981 (ref. ID; 5957 original paper)
  5. Monopylephorus evertus Baker & Brinkhurst, 1981 (ref. ID; 5957 original paper)
  6. Monopylephorus glaber Moore, 1905 (in part)
    See; Monopylephorus rubroniveus (ref. ID; 5957)
  7. Monopylephorus helobius Loden, 1980
    See; Monopylephorus rubroniveus (ref. ID; 5957)
  8. Monopylephorus irrorata (Verrill, 1873) (ref. ID; 1257)
    Syn; Postiodrilus sonderi Boldt, 1926 (ref. ID; 1257)
  9. Monopylephorus irroratus (Verrill, 1873) (ref. ID; 5957)
    Syn; Clitellio irrorata Verrill, 1873 (in part) (ref. ID; 5957); Monopylephorus trichochaetus Ditlevsen, 1904 (ref. ID; 5957); Postiodrilus sonderi Boldt, 1926 (ref. ID; 5957); Tubifiex irrorata (Verrill) Moore, 1905 (ref. ID; 5957)
  10. Monopylephorus kermadecensis (Benham, 1915) (ref. ID; 5957)
    Syn; Rhizodrilus kermadecensis Benham, 1915; Hrabe, 1962 (ref. ID; 5957)
  11. Monopylephorus limosus (Hatai, 1888) (ref. ID; 6618) or 1898 (ref. ID; 3692, 5957, 6451, 6972, 7854)
    Syn; Monopylephorus limosus (Hatai). Nomura, 1915; Chen, 1940; Brinkhurst, 1963, 1971 (ref. ID; 5957); Rhizodrils limosus (Hatai). Michaelsen, 1900; Yamaguchi, 1953; Hrabe, 1962 (ref. ID; 5957); Vermiculus limosus Hatai, 1898; Michaelsen, 1900 (ref. ID; 5957)
  12. Monopylephorus longisetosus Brinkhurst & Baker, 1979 (ref. ID; 5945 original paper)
  13. Monopylephorus moleti Brinkhurst & Marchese, 1987 (ref. ID; 6649, 7254 original paper)
  14. Monopylephorus pacificus Brinkhurst & Baker, 1979 (ref. ID; 5945 original paper)
  15. Monopylephorus parvus Ditlevsen, 1904 (ref. ID; 7254) or Ditlevson, 1904 (ref. ID; 1257, 5957, 6972)
  16. Monopylephorus ponticus (ref. ID; 5957)
  17. Monopylephorus rubroniveus Levinsen, 1883 (ref. ID; 1257, 1928) or 1884 (ref. ID; 3692, 5957, 6649, 6972, 7854)
    Syn; Monopylephorus corderoi Marcus, 1952 (ref. ID; 5957); Monopylephorus glaber Moore, 1905 (in part) (ref. ID; 5957); Monopylephorus helobius Loden, 1980 (ref. ID; 5957); Rhizodrilus ponticus Hrabe, 1967; Kasprzak, 1973 (ref. ID; 5957); Vermiculus fluviatilis Ferroniere, 1899(?) (ref. ID; 5957); Vermiculus glotini Ferroniere, 1899 (?) (ref. ID; 5957); Vermiculus pilosus Goodrich, 1892 (ref. ID; 1257, 1928, 3692, 5957)
  18. Monopylephorus rubroniveus iturupi Finogenova, 1982 (ref. ID; 7854)
  19. Monopylephorus trichochaetus Ditlevsen, 1904 (ref. ID; 1257) reported author and year? (ref. ID; 5957)

Monopylephorus aucklandicus (Benham, 1909) (ref. ID; 5957)

Synonym

Littodrilus aucklandicus (Benham) Chen, 1940 (ref. ID; 5957); Monopylephorus aucklandicus (Benham) Brinkhurst, 1963 (ref. ID; 5957); Rhizodrilus aucklandicus Benham, 1909 (ref. ID; 5957)

Descriptions

Length 29 mm, width 0.5 mm; 80 segments; triannulate anteriorly. Clitellum 1/2 X-1/3 XIII. Dorsally 3-4 bifid setae wtih teeth about equally developed, plus 1-2 thin, twisted hair setae per bundle, fewer posteriorly; ventral setae 3-4 (5) anteriorly falling to 1-2 posteriorly. Genital pores paired in the line of the (absent) ventral setae of X and XI, spermathecal pores at 9/10, male pores in posterior one third of XI. Male ducts (all structures paired) with tubular ciliated atrium covered with diffuse prostate cells, short ciliated ejaculatory duct; eversible pseudopenes with retractor muscles inserted on the roof of XII, pseudopenes with thin cuticular lining. Spermathecae with large ampullae, short bulbous ducts, sperm apparently attached to walls of bulbous ducts. Coelomocytes numerous. Auckland Island, Campbell Island, South Pacific. Sea shores. (ref. ID; 5957)

Remarks

This species has thin, twisted hair setae rather than "long fine hairs ... entangled with the chaetae, which at first examination were mistaken for capillariform chaetae" (Benham 1909). The pseudopenes resemble those of irroratus but lack the small cuticular processes characteristic of that species, and are like those of evertus in that the lining of the distal part of the pseudopenis is quite extensive coiled. The penis lining seems to have a thin cuticular layer, and the species may also be quite similar to the British form termed sp. 2 below. The presence of the twisted hair setae is no longer sufficient to cause this to be synonymised with M. irroratus (as in Brinkhurst (1971)). Benham described the prostate gland cells as forming discrete clumps of cells, much like those of Telmatodrilus. Benham also described the globular sacs of the spermathecae as having the sperm heads imbedded in the epithelial cells. This was obvious in our material although the ampullae did not appear to contain any sperm masses. (ref. ID; 5957)

Material examined

  • Otago Museum (Benham collection): Type series cat. A69.44, whole mount; serial sections A69.42 not labelled type but from type series. (ref. ID; 5957)
  • Zool. Mus. Univ. Hamburg (Michaelsen collection): Rhizodrilus aucklandicus, Campbell Island, 1914, cat. V9418. (ref. ID; 5957)

    Monopylephorus camachoi Rodriguez, 1999 (ref. ID; 6649 original paper)

    Diagnosis

    17 to 51 segments. Diameter of the body at segment VIII, 150-225 µm. Prostomium rounded (67-95 µm long). Nucleate granular coelomocytes ovoid, 7-10 µm longer axis, abundant in some individuals, but scarce in others. Epidermal layer of the body wall up to 4.8 µm thick, on the dorsal side of segment VIII, and up to 6.4 µm on the ventral side. Longitudinal muscular layer up to 4.8 µm on dorsal side, and up to 19 µm on ventral side at segment VIII. Chloragogen cells cover the gut from segment VI, backward. Only bifid setae, 3-5 setae per bundle in anterior segments and down to 2-3 setae per bundle in the posterior part of the body. Anterior setae are 40 µm long in II; 50-59 µm long in the following anterior segments, 58-64 µm long in the median region of the body, and 48-54 µm backwards. Width of somatic setae ca. 2 µm. Teeth in the anterior setae are about the same length in dorsal bundles, the upper tooth being slightly shorter in segment II and longer than the lower in the following ventral bundles. Setal teeth increase in length gradually and get thinner from II to IX. Posterior setae with upper tooth about equal or shorter than lower. In segment X, two enlarged setae in ventral bundles 60 µm long, 2.7 µm thick, with upper tooth about 1.5 times longer and about the same thickness as the lower. Ventral setae absent in segment XI. In three of the examined mature individuals, ventral setae of segment XII are present in a number of one or two per bundle and are like those of segment X. Enlarged setae in segments X and XII are associated with setal glands which are more developed than those of the remaining setal bundles. Clitellum non-prominent (up to 6.4 µm high), from behind setae of segment X to the end of segment XII. Sperm sacs extending forward to IX and backwards to XII. Egg sac up to XIV. One single spermathecal ventral pore that opens on the mid-line of the body, in the anterior part of segment X. One pair of male pores discharge close together into a single median copulatory bursa, that opens on the mid-ventral line of segment XI. One pair of testes in X and one pair of ovaries in XI. One pair male ducts, each consisting of a sperm funnel opening to segment X, situated ventrally on septum X/XI. The male funnel leads to a short vas deferens (about 30 µm long, 11-12 µm diameter) that enters apically the ciliated tubular atrium (167-175 µm long), wider in its ental part (15-17 µm diameter) than in its ectal part (10-13 diameter), covered by a diffuse layer of prostatic cells (up to 31 µm high) and lined by a thin (less than 1 µm) muscular layer. The atrial cells show nuclei in the proximal part of the channel, not clearly seen in the rest of the duct. Ejaculatory duct absent. Atrium discharges laterally into the apical part of muscular ovoid sac containing a protrusible pseudopenis (in the sense of Baker & Brinkhurst 1981), 50-60 µm long and 37-43 µm maximum diameter, formed by ciliated cells lined by circular and longitudinal muscular fibres, surrounded by a peritoneal layer. Finally, the pseudopenial sac separates by a constriction from an elongated penial bursa (125-131 µm long and 52-64 µm maximum diameter), formed by a glandular epithelium lined with fine circular, followed by thick longitudinal, muscular fibres (up to ca. 4 µm thick) and a peritoneal layer. Both penial bursae open into a single median copulatory bursa in the ventral side of segment XI. One unpaired spermatheca is present, usually situated on the left side of segment X, formed by an elongated ampulla (120-160 µm long, and 32-65 µm maximum diameter) and a tripartite spermathecal duct, about 90 µm long, separated from the ampulla by a constriction of circular muscular fibres. Spermathecal duct comprises one ental section (22-32 µm long, 30-40 µm wide) separated by a constriction of a bulbous region (30-37 µm long, 42-50 µm wide), followed by a short narrow ectal duct (20-30 µm long, 12-15 µm wide) that opens to the spermathecal pore. Wall of spermathecal ampulla consisting of an inner epidermal lining (7-11 µm high) and a fine outer muscular layer (ca. 1 µm), covered with peritoneal cells. Lumen of ampulla filled by sperm in a loop-shaped mass. Wall of the spermathecal duct formed by an inner epithelial lining covered by a muscular layer, 1-2 µm thick, thicker in the bulbous part (ca. 2.5 µm). The enternal cuticule of the tegument enters internally by the spermathecal duct as far as the bulbous region. (ref. ID; 6649)

    Etymology

    The species is affectionately dedicated to Dr Ana Camacho, who has always encouraged me in the study of subterranean aquatic worm. (ref. ID; 6649)

    Habitat characteristics

    M. camachoi is found in clean freshwater, close to the estuary, as a component of a community formed by Odonata, Trichoptera, Ephemeroptera, Plecoptera, and others (Garcia-Valdecasas et al. 1997). Monopylephorus is typically regarded as a genus which inhabits brackish waters; however, it is a recognisable fact that some species are euryhalines and therefore can be also found in freshwater (Marcus 1952), commonly associated with high coductivity due to pollution or salt beds in the watershed (Brinkhurst & Marchese 1987). Thus, M. rubroniveus, M. limosus and M. moleti have been reported in freshwater habitats (e.g., Erseus & Paoletti 1986; Brinkhurst & Marchese 1987; Timm 1997, respectively). The habitat characteristics are unclear for M. kermadecensis (Baker & Brinkhurst, 1981). (ref. ID; 6649)

    Type locality

    River Sata Cruz. Coiba Island, Panama, in the Pacific Ocean. 21 August, 1994. (ref. ID; 6649)

    Type materials

  • Holotype: MNCN16.03/3024, one dissected specimen stained in Ehrlich's haematoxylin, mounted in Canada balsam. (ref. ID; 6649)
  • Paratypes: MNCN16.03/3024, one whole-mounted specimen stained Ehrlich's haematoxylin and mounted in Canada balsam. Two serially sectioned specimens stained in haematoxylin-eosin. All from type locality. (ref. ID; 6649)
  • Other material: Two immature and two mature individuals preserved in ethyl alcohol 70% are deposited in the MNCN. Two mature individuals (one dissected, one preserved in ethyl alcohol 70%) are in author's collection. All from type locality. (ref. ID; 6649)

    Monopylephorus cuticulatus Baker & Brinkhurst, 1981 (ref. ID; 5957 original paper)

    Synonym

    Monopylephorus irroratus Lev. Brinkhurst, 1971 (ref. ID; 5957)

    Descriptions

    Length to 25 mm, up to 86 segments, width at XI to 800 µm (in fixed, slightly compressed specimens). Prostomium rounded, blunt, about as long as broad at peristomium. Clitellum 1/2 X- 1/3 XIII. Dorsal anterior setae 3, 4 bifids and 1 spirally twisted hair setae per bundle, ventral anterior bundles with 3, 4 bifid setae. Posterior dorsal bundles with 2 bifid and 1 spirally twisted hair setae, posterior ventral bundles with 1, 2 (3) bifid setae. All bifid setae with upper tooth thinner and about as long as lower. Setae absent ventrally in XI. Spermathecal pores at 9/10. Male pores posterior in XI. Spermathecal and male pores in setal line. Male ducts (all structures paired): sperm funnel moderate in size, short vas deferens followed by tubular ciliated atrium covered with diffuse prostate cells; atrium leads to short ejaculatory duct which enters eversible pseudopenis apically. Pseudopenis enclosed in muscular sac, pseudopenis not attached to sac except apically; muscular sac with large retractor muscle. Basal 1/3 of pseudopenis with many (20-30) sharply hooked cuticular processes. Spermathecae with large ampullae and thick, somewhat folded ducts. Sperm in random masses. Coelomocytes large, numerous. Coastal. Pacific Northwest of North America (British Columbia to Alaska). (ref. ID; 5957)

    Remarks

    The distinctive cuticular lining to the pseudopenes, which forms a thorny ring around the base once everted, is characteristic of this species and serves to distinguish it form all others that have thin, spirally twisted hair setae. It was once considered to represent fully mature specimens of M. irroratus, but this Pacific species does not seem to go through an irroratus-like phase in its development, nor is irroratus found on this coast. (ref. ID; 5957)

    Type locality

    Port Alice, British Columbia, coll. K. Coates, June 13, 1976. High intertidal (4.11 m) in shale with coarse sand, Enteromorpha on rocks. (ref. ID; 5957)

    Material examined

  • Holotype: U.S.N.M. 61971, a whole mounted specimens. (ref. ID; 5957)
  • Paratypes: U.S.N.M. 61972-61975, whole mounted specimens and sections (from type locality). National Museum of Canada, Ottawa. NMCIC1980-1502a-NMCIC1980c, whole mounted specimens (from type locality). (ref. ID; 5957)
  • Other material:

    Monopylephorus evertus Baker & Brinkhurst, 1981 (ref. ID; 5957 original paper)

    Descriptions

    Length up to 8 mm, up to 45 segments. Prostomium about as long as broad at the base, conical. Clitellum weakly developed from X to XII. Setae bifid with very short teeth, often appearing simple-pointed, upper tooth shorter than the lower, reduced in posterior bundles; anteriorly (2)4-6(7) per bundle, 2-3 per bundle from X, no ventral setae in XI. Spermathecal pores paired in ventral setal line near 9/10 in X; male pores paired in ventral setal line posteriorly in XI. Male ducts (all structures paired) with small sperm funnel, vas deferens short; ciliated atrium elongate, tubular, covered with diffuse prostate cells; atrium terminates in a ciliated elongate ejaculatory duct that runs to the apex of the very long, eversible, nonciliated pseudopenis in which the lining is detached from the muscular wall in the normal manner; male terminalia may penetrate the posterior sperm sacs as far as XII. Total length of male duct up to 1000 µm. Spermathecae with long folded ducts leading to small, ovoid, thick-walled ampullae containing sperm bundles with sperm heads imbedded in the walls. Coelomocytes large and abundant. Intertidal marine, Massachusetts, Delaware, Atlantic U.S.A. (ref. ID; 5957)

    Remarks

    The male terminalia and spermathecae are extremely elongate in this species. It is easily separable from other species in the genus by the absence of spirally twisted hair setae (M. irroratus et al.), the presence of two spermathecae (not as in M. parvus), and eversible pseudopenes (unlike the M. rubroniveus complex). The name reflects the unusual size of the eversible pseudopenes which often contain foreign matter, presumably as a result of prior eversion. In sectioned material is obvious that the heads of the sperm are gathered together in groups and are imbedded within the walls of the spermathecal ampullae. This characteristic appears to be shared with M. aucklandicus but is other wise unique within the Tubificidae. (ref. ID; 5957)

    Type locality

    Prime Hook Creek, near junction with Broadkill River, Lewes, Delaware. 75 degrees 11'33"W, 38 degrees 48'39"N, intertidal in fine grain reducing sediments, various salinities, coll. G.P. Burbanck, various dates 1979. (ref. ID; 5957)

    Material examined

  • Holotype: U.S.N.M. 61976, a whole mounted specimen. (ref. ID; 5957)
  • Paratypes: U.S.N.M. 61977-61980, whole mounted specimens (from type locality). National Museums of Canada, Museum of Natural Scienes, Ottawa. NMCIC1980-1501a - NMCIC1980-1501c, whole mounted specimens (from type locality). (ref. ID; 5957)
  • Other material:

    Monopylephorus irrorata (Verrill, 1873) (ref. ID; 1257)

    Synonym

    Postiodrilus sonderi Boldt, 1926 (ref. ID; 1257)

    Descriptions

    30-35 mm. ca. 90 segments. Anterior dorsal bundles with 0-2 thin hair chaetae with a characteristically twisted distal end, and 3-4 crotchets with short teeth but the upper a little longer than the lower and sometimes a small intermediate spine. Ventral chaetae 3-4 per bundle, similar. Spermathecal and male pores single, mid-ventral. (ref. ID; 1257)

    Monopylephorus irroratus (Verrill, 1873) (ref. ID; 5957)

    Synonym

    Clitellio irrorata Verrill, 1873 (in part) (ref. ID; 5957); Monopylephorus trichochaetus Ditlevsen, 1904 (ref. ID; 5957); Postiodrilus sonderi Boldt, 1926 (ref. ID; 5957); Tubifiex irrorata (Verrill) Moore, 1905 (ref. ID; 5957)

    Descriptions

    Length to 35 mm; up to 90 segments. Bifid setae 2-4 in ventral and dorsal bundles with teeth subequal; dorsal bundles with one or two thin, spirally twisted hair setae, hair setae easily broken leaving stumps in setal sacs thinner than bases of bifid setae; hair setae often accompanied by (?) pectinate setae. Vas deferens rudimentary, atrium ciliated, tubular, covered with diffuse prostate cells. Ejaculatory duct short, distended with sperm at full maturation; walls of ejaculatory duct thin when duct holds sperm, otherwise walls of duct of normal thickness. Ejaculatory duct leads to tall eversible nonciliated pseudopenes with one (rarely two or three) small cuticular processes; pseudopenes may penetrate sperm sacs into XII. Spermathecae with short ducts, ampullae large with sperm in loose masses. Spermathecal pores at 9/10. Coelomocytes large and abundant. Atlantic coasts of North America and Europe. Coastal salt water. (ref. ID; 5957)

    Remarks

    In earlier reviews of the Tubificidae (Brinkhurst 1966, 1971) confusion arose about the form of the pseudopenes in this species. As both M. rubroniveus and M. parvus were held to be cosmopolitan, although with some variation recorded among different populations, it was felt at that time that M. irroratus (often described from similar habitats and localities) constituted another cosmopolitan species, especially as all the material was characterised by unique, thin, spirally twisted, hair setae. The pseudopenes of the few specimens of these available for study were all eversible, with varying degrees of cuticular elaboration of the lining. The form with the most elaborate cuticular lining was taken to be the fully mature form of the species; this was described from a large collection obtained in Alaska. Examination of more material of this form from the Pacific coast of Canada reveals that this form does not go through a stage of development resembling that described above in which the pseudopenes have only one or two small cuticular processes on the linig. The Pacific species is described below as M. cuticulatus. Small cuticular processes have now been observed in T. irroratus specimens described by Moore (1905) (who saw the now-missing Verrill types) as well as in specimens from France. Specimens in the Michaelsen collection labelled Rhizodrilus trissochaetus were donated by Boldt, having been collected at Oldersloe, near Lubeck. Shortly after these were collected, Boldt (1926) described Postiodrilus sonderi from the same habitat. Both these names refer to species that have thin, twisted hair setae, and male ducts of the Monopylephorus type (the name Rhizodrilus being used as an alternate for the genus at that time). The genus Postiodrilus was erected because Boldt considered the folds of the walls of the eversible pseudopenis to constitute a true penis. Neither of these species can be redescribed for certain in the absence of types, but it seems quite possible that the Boldt specimens labelled trissochaetus (lapse pro trichochaetus) are part of the type series of sonderi. The description of sonderi by Boldt (1926) makes no reference to the finding of the similar trichochaetus in the same locality at about the same time as he found P. sonderi, and it is possible that Boldt changed his mind about the identity of his material at some date between the presentation of specimens to Michaelsen and their subsequent description. Monopylephorus trichochaetus was originally described from Denmark by Ditleven (1904), whereas Oldersloe is in the area of Lubeck. There are, therefore, only there confirmed records of M. irroratus, one from Woods Hole, Massachesetts, one from France on the Pas de Calais, and one from the Baltic shores; there is perhaps a record from Denmark. The penes were correctly labelled by Brinkhurst (1965) but were erroneously attributed to M. rubroniveus instead of "partially developed penes of M. irroratus" by Brinkhurst (1971). Specimens attributed to M. irroratus by Brinkhurst (1966, 1971) are now regarded as separable species, but as insufficient material exists they are referred to as sp. 1 and sp. 2 below. Monopylephorus aucklandicus is restored to the status of a distinct species instead of a synonym of M. irroratus, and M. cuticulatus is described as a new species. Hrabe (1967, 1969) suggested that Ilyodrilus asiaticus Chen, 1940 belongs here. However, until a redescription of this species is available we hesitate to place it in Monopylephorus. (ref. ID; 5957)

    Material examined

  • Acad. Nat. Sci. Philadelphia: Tubifex irroratus (Verrill) Moore, cat. 2717. Monopylephorus glaber Moore, cat. 2722, many specimens prove to be irroratus with broken hair setae, 12 whole mounts prepared. (ref. ID; 5957)
  • British Museum Natural History: Monopylephorus irroratus (Verrill) Gloucester, Mass., received in London 1880, possibly from Verrill, three specimens on two slides all identifiable as Clitellio arenarius (= C. irrorata Verrill in part), cat. 1880.9.27.54. (ref. ID; 5957)
  • Zoo. Mus. Univ. Hamburg (Michaelsen collection): Rhizodrilus trissochaetus (sic) cat. V9921, coll. Boldt. Oldersloe, 1925-1926, ? types of Postiodrilus sonderi. (ref. ID; 5957)
  • Brinkhurst collection: Wimereux, Pas de Calais, France. Two whole mounts. (ref. ID; 5957)

    Monopylephorus kermadecensis (Benham, 1915) (ref. ID; 5957)

    Synonym

    Rhizodrilus kermadecensis Benham, 1915; Hrabe, 1962 (ref. ID; 5957)

    Descriptions

    Description after Benham (1915). Length up to 40 mm (?) number of segments unknown. Anterior setae bifid 4-6 er bundle, posteriorly 2 setae per bundle; all setae with upper tooth longer and thinner than lower. Vas deferens very short, leads to ciliated tubular atrium covered with diffuse prostate cells; atrium discharges into ciliated ejaculatory duct (= transverse duct; Benham, 1915) which empties via a short constriction into a small nonciliated protrusible (? eversible) pseudopenis (= atrium; Benham 1915). Pseudopenes enter median male bursa posteriorly; median bursa in posterior portion of XI. Spermathecae saccular, opening separately into a median bursa; bursa located near midpoint of X. Coelomocytes abundant. Known only from the Kermadec Islands, "in a waterhole, on Meyer Island 24/4/08" (Benham, 1915) (saline?). (ref. ID; 5957)

    Remarks

    This species differs from others in the genus, and primarily from M. rubroniveus, by details of the male duct (especially the pseudopenis and point of entry of the pseudopenes into the median bursa) and by the position of the spermathecal pores (on a median bursa near the midpoint of X according to the original description) which are at or near 9/10 in other species of this genus and in most rhyacodrilines. (ref. ID; 5957)

    Material examined

    No specimens of this species are available for study. The types are missing according to our correspondence and Reynolds and Cook (1976). (ref. ID; 5957)

    Monopylephorus limosus (Hatai, 1888) (ref. ID; 6618) or 1898 (ref. ID; 3692, 5957, 6451, 6972, 7854)

    Synonym

    Monopylephorus limosus (Hatai). Nomura, 1915; Chen, 1940; Brinkhurst, 1963, 1971 (ref. ID; 5957); Rhizodrils limosus (Hatai). Michaelsen, 1900; Yamaguchi, 1953; Hrabe, 1962 (ref. ID; 5957); Vermiculus limosus Hatai, 1898; Michaelsen, 1900 (ref. ID; 5957)

    Descriptions

    Description after Hatai (1898); Nomura (1915). Length 15-70 mm; up to 130 segments. Anterior setal bundles with 3-5 (6) bifid setae, fewer setae posteriorly; bifid setae with upper tooth shorter and thinner than lower. Ventral setae of II simple pointed. Vas deferens short, leads to tubular ciliated atrium covered with diffuse prostate cells; atrium discharges into short, ciliated ejaculatory duct (= atrial duct portion; Nomura 1915), which opens into a large protrusible (eversible?) nonciliated pseudopenis. Pseudopenes enter median bursa laterally; median bursa in posterior portion of XI. Spermathecae saccular, opening through a common median ventral pore posterior to 9/10; sperm in loose masses. Coelomocytes abundant. Asia, saline gutters and ditches. (ref. ID; 5957)

    Remarks

    This species is similar to M. rubroniveus in that it has only bifid setae and the male pores exit into a median male bursa but it differs in a number of details according to the original description (Hatai 1898). The ventral setae of II as illustrated by Nomura (1915) are larger than the corresponding dorsal setae and appear to be truly simple pointed. The upper tooth of the bifid setae is also shorter and thinner than the lower tooth. The major differences between M. limosus and M. rubroniveus occur in the genital system. In M. limosus the spermathecae open through a common pore ventrally about 1/5 of the length of segment X from 9/10, whereas in M. rubroniveus the spermathecal pores are at 9/10 but usually open separately into a small bursa. Monopylephorus rubroniveus possesses protrusible pseudopenes exiting on a simple bursa while M. limosus possesses protrusible (? eversible) pseudopenes on a complex bursa. (ref. ID; 5957)

    Material examined

    No specimens of this species are available for study. No designated types are known (Reynolds & Cook 1976). (ref. ID; 5957)

    Monopylephorus longisetosus Brinkhurst & Baker, 1979 (ref. ID; 5945 original paper)

    Descriptions

    Length to 4-5 mm; breadth 0.5 mm. About 30 segments. Prostomium longer than broad at the base, rounded. Clitellum 0.5 X-XII. Setae bifid with short teeth, the upper often thinner than the lower, upper teeth reduced posteriorly; mostly three to four per bundle but up to six present or as few as two. Setae 68-72 µm long. Penial setae in ventral bundles of XI, five to eight enlarged bifid setae, progressively diminishing in size from 100 to 65 µm, from the outer (or posterior) seta to the inner (anterior) seta, plus one elongate hair-like seta 220-260 µm long. Male ducts complex, sperm funnels leading directly to atria covered with diffuse prostate gland, succeeded by a narrow, naked tubular section with a wide middle section, terminating in eversible pseudopenes (with accessory glands, not described). Spermathecae elongate, tubular. (ref. ID; 5945)

    Remarks

    This species is very small for a Monopylephorus and is unique in the possession of two sorts of penial setae. The male ducts are very similar to those of M. frigidus Br. with the glandular atrium following directly behind the sperm funnel with no naked vas deferens (as seen in M. pacificus for example) but a long naked duct beyond the glandular section with a dilated region in the middle. The homologies of the various portions of the male ducts in this genus require elucidation. C. Erseus pointed out to us small additional glands attached to the pseudopenes near the pores. Similar glands were indicated in dissections of partially mature M. frigidus but have not been observed in other species where sections have been examined. They may be analogous to the glands associated with spermathecal setae in M. pacificus, although none were seen in association with the penil setae of the latter. Hrabe (1967) still prefers to regard the type species (M. rubroniveus Lev.) as a species spuria, using the name Rhizodrils Smith, and recognizes most of the species described in the literature as valid, whereas the senior author has grouped the various taxa into seven species plus the two described above (Brinkhurst and Jamieson 1971). Hrabe (1967) also includes Ilyodrilus asiaticus Chen this assemblages. (ref. ID; 5945)

    Etymology

    Reference to long seta as the species is characterized by an elongate hair-like penial seta. (ref. ID; 5945)

    Monopylephorus moleti Brinkhurst & Marchese, 1987 (ref. ID; 6649, 7254 original paper)

    Descriptions

    Very slender worms, fragments 1.5x0.01-0.02 cm, up to 83 segments. Chaetae all bifid, anteriorly up to 5 per bundle, 3 per bundle from VIII, but only 2 from XX rearward. Anteriorly the upper teeth are a little thinner and shorter than the lower but posteriorly the upper tooth is distinctly shorter; up to 4 simple-pointed penial chaetae per bundle. Male ducts with cup-shaped funnel (?, presumably in VII) followed by a short naked vas deferens (? in VIII). Atria tubular, with diffuse prostate on at least one side, second section naked with thick muscular layer and with cuticular lining where it joins upper extension of a median common copulatory bursa. Penial chaetae enter posterior edge of the bursa on each side. Single tubular spermatheca present on left side (? in VII) with a complex histology, outer surface covered in peritoneal epithelum (?). Spermathecal pore ventrolateral (?). Coelomocytes abundant. (ref. ID; 7254)

    Remarks

    The quantity and quality of the material does not permit much more detailed analysis, but sections of the holotype clearly indicate the affinity with Monopylephorus. The median male pore, structure of the atria, and reduction of the spermathecal number indicate the relationship, but the penial chaetae are limited to this species (they are present in a number of related genera comprising species originally attributed to Monopylephorus). The species was at first considered to belong to Epirodrilus but the presence of the prostate gland and median male pore caused rejection of that concept. While most Monopylephorus species are estuarine, several are found in inland site where there is elevated conductivily due to pollution or salt beds in the watershed. This species is closely related to the widespread but scarce Monopylephorus parvus Ditlevsen, 1904 which also has a single spermatheca, no hair chaetae, and a median copulatory bursa, but the new species has penial chaetae. The presence or absence of genital chaetae is troublesome elsewhere but this form also differs from M. parvus in the forward location of the genital segments, again a somewhat variable character. (ref. ID; 7254)

    Etymology

    Named for Mr. Ulices Molet who greatly assisted M. Marchese with the field collection of material used in this study. (ref. ID; 7254)

    Type locality

    Mendieta River, Sante Fe Province, Argentina, January 1984, coll. M. Marchese and U. Molet. (ref. ID; 7254)

    Type materials

  • Holotype: USNM102739, a sectioned specimen. (ref. ID; 7254)
  • Paratypes: USNM102740-1, two whole-mounted specimens from the type locality. (ref. ID; 7254)

    Monopylephorus pacificus Brinkhurst & Baker, 1979 (ref. ID; 5945 original paper)

    Descriptions

    Length to 15 mm; breadth 1 mm; up to 100 segments. Prostomium conical, prominent. Dorsal and ventral anterior setae one to three per bundle, one or two posteriorly, all with long thick upper teeth, setae on raised prominances, distal nodulus. Setae increase in length from II (68 µm) to VI-VII (100 µm) and decrease posteriorly. Spermathecal setae single in X, with hollow tips. Penial setae up to 9 per bundle in XI, short beyond the nodulus, bifid with short teeth, bifid tips close together. Male ducts with non-grandular vasa deferentia about as long as the atria, entering the latter subapically. Atria long tubes surrounded by prostatic tissue followed by narrow naked sections leading to eversible pseudopenes, distal portions of which bear slightly thickened cuticle. Male pores in close proximity to each other, but obviously separate. Spermathecae with large glandular spermathecal setal sacs, pores fairly close together bur separate, sperm traps in short thick ducts leading to thin-walled ampullae. This species differs from all other in the genus in having modified genital setae in both X and XI. The freshwater M. lacteus has them in IX and XI, rarely in IX, X and XI but they are different in form and number. (ref. ID; 5945)

    Etymology

    A Pacific species. (ref. ID; 5945)

    Monopylephorus parvus Ditlevsen, 1904 (ref. ID; 7254) or Ditlevson, 1904 (ref. ID; 1257, 5957, 6972)

    Descriptions

    Length 8-15 mm; up to 64 segments. Anterior setal bundles with 3-4 or 5 bifid setae with the upper tooth about as thick and as long as the lower but variable; simple-pointed setae replacing one or both setae in some ventral and (or) dorsal median and posterior bundles; those posterior setae that are bifid have short, thin, upper teeth. Male pores open separately or combined into a large median bursa; spermathecal or combined into a large median bursa; spermathecal pore single, median. Male funnel ventrolateral, leading to ciliated tubular, prostate-covered atrium running diagonally across XI to open through a short, nonciliated ejaculatory duct into the upright protrusible pseudopenis. Spermatheca single, on left side, with short duct and elongate, twisted ampulla containing sperm in masses. Coelomocytes large and abundant. Cosmopolitan (Atlantic and Gulf coasts of United States, India, South Africa, Brazil, Denmark, British Columbia, Canada). Littoral and estuarine sites. (ref. ID; 5957)

    Remarks

    Marcus (1965) discussed variations in the distribution of setae and the degree of union of the pseudopenes in his own material and that of Ditlevsen (1904), Moore (1905) and Stephenson (1917), but dismissed them as insignificant. As variations of this type have been used in the past to delineate species within what we regard as the M. rubroniveus group this dismissal of variations within M. parvus (which is closely related to M. rubroniveus) has a significant bearing on the debate over the specific limits of M. rubroniveus. The specimens from British Columbia agrees well with the description of the species. (ref. ID; 5957)

    Material examined

    Baker collection: Intertidal, Prime Hook Creek, Lewes, Delaware, U.S.A., coll. G.P. Burbanck, 1979, 4 whole mounts; East Point, Saturna Island, British Columbia, coll. H.R. Baker, 1979, 1 whole mount. Other material not seen during this review but examined by R.O. Brinkhurst earlier includes specimens described by Stephenson (1917) from a coastal lagoon system in India (British Museum Natural History 1933, 5.26.666-5.26.671), specimens from Woods Hole deposited by Moore in the Philadelphia Academy of Natural Sciences (cat. 2728) not traceable (apart from two specimens still in the R.O. Brinkhurst collection (now returned), which are assigned to M. evertus q.v.) and specimens described from South Africa by Brinkhurst (1966) in the collection of the National Institute for Water Research, Pretoria. Material described by Marcus (1965) we suppose to be in Sao Paulo, Brazil. (ref. ID; 5957)

    Monopylephorus rubroniveus Levinsen, 1883 (ref. ID; 1257, 1928) or 1884 (ref. ID; 3692, 5957, 6649, 6972, 7854)

    Synonym

    Monopylephorus corderoi Marcus, 1952 (ref. ID; 5957); Monopylephorus glaber Moore, 1905 (in part) (ref. ID; 5957); Monopylephorus helobius Loden, 1980 (ref. ID; 5957); Rhizodrilus ponticus Hrabe, 1967; Kasprzak, 1973 (ref. ID; 5957); Vermiculus fluviatilis Ferroniere, 1899(?) (ref. ID; 5957); Vermiculus glotini Ferroniere, 1899 (?) (ref. ID; 5957); Vermiculus pilosus Goodrich, 1892 (ref. ID; 1257, 1928, 3692, 5957)

    Descriptions

    25-40 mm. 65-74 segments. Dorsal and ventral bundles with 3-5 (rarely 2-6) simple bifid crotchets per bundle, the upper tooth being longer and thinner than the lower. Some posterior segments with simple-pointed chaetae?. Spermathecal and male pores each open to a median ventral bursa. (ref. ID; 1257)

    Length 10-60 mm; up to 86 segments. Setae two to six per bundle anteriorly, usually fewer posteriorly. Setae bifid with teeth of variable proportions. Male pores open into capacious median copulatory bursa in posterior portion of XI; spermathecal pores close together or more or less united midventrally at 9/10. Male funnel ventrolateral in front of 10/11; vas deferens short, leading directly to narrow tubular atrium covered with diffuse prostate cells; atrium ascends diagonally across XI where it discharges into a short naked ejaculatory duct which opens into the tall protrusible pseudopenis. Vas deferens and atrium (? ejaculatory duct) ciliated. Walls of ejaculatory duct thin when holding sperm, otherwise walls of normal width. Pseudopenes nonciliated, enter median bursal laterally. Spermathecae small, ovoid, containing sperm in masses. Coelomocytes large and abundant. Cosmopolitan. Littoral, estuarine or salt-polluted inland sites. (ref. ID; 5957)

    Scarce intact specimens were up to 17 mm long and consisted of 49 segments. Some bigger but tailless pieces measuring up to 28 mm, had at least 71 segments. Forebody 0.6-0.8 mm wide under the cover glass, clitellar region 0.8-1.2 mm, tail gradually tapering down to 0.3 mm. Anterior end bluntly conical, prostomium zygolobic. Intersegmental furrows weakly expressed. All chaetae bifid, with distal nodulus, tapering from 5 to 4 µm near their distal end, 3-6 per bundle and 120-150 µm long in anteclitellar segments; 2-4 per bundle and 110-140 µm long posteriorly. Teeth sharp, either equally long or upper one longer in new chaetae, whereas in older chaetae both teeth can be worn down. In the mature individuals, clitellum covers XI, XII, and a part of X. Unpaired, ventromedian male pore in XI, unpaired spermathecal pore in 9/10. Body wall epidermis 16-18 µm thick (30-80 µm in clitellum), circular muscle layer 4-8 µm, longitudinal musculature 16-32 µm. Brain anteriorly bifid, posteriorly rounded; ventral nerver chain thin. Pharynx in III, in the posterior half of the segment, with thick and muscular roof. Three cylindrical appendages (pharyngeal glands), 100-120 µm long and 60-70 µm thick, attached dorsally to posterior wall of pharynx, and one or two more, laterally. From IV on, digestive tube narrow, thick-walled and interiorly ciliated; in VI sparse chloragogen cover begins. No distinct transition from oesophagus to intestine; the latter dilates gradually only after egg sacs. Sparse masses of chromophilous cells in IV-VI. Dorsal blood vessel lies freely in coelome, mostly beside intestine. No coelomocytes were observed in whole mounts. In section, oval, 12-15 µm long coelomocytes appeared to be stuck together as a dense mass in the dorsal portion of coelome in forebody. Nephridia were observed at 6/7, 7/8, and 8/9. No tests were seen but free sperm cells occurred in X. Unpaired anterior sperm sac bulged into IX, posterior one, many segments backwards. Ovaria as compact strings in XI. Egg sac can reach XVI-XX. Egg funnels not seen. Male funnels in X, of a different shape, up to 190 µm in diameter, with epithelium 14-18 µm thick, bearing abundant spermatozoa. Vasa deferentia rudimentary, up to 40 µm long and 40-60 µm wide. Penetrating 10/11 under ovaria, they immediately change into long tubular atria consisting of three different portions. (1) Within irregular, up to 630 µm long and 80-380 µm wide (tapering distally) mass of strongly staining glandular (prostatic) tissue, 45-60 µm wide epithelial tube, covered with 2 µm of muscular layer, passes back- and upwards. Some grandular content (spermatozoa?) can be visible in sections of this tube. 2) Shorter midpiece (100-380 µm in different individuals) in dorsal and posterior regions of XI, devoid of gland cells. It is tapering gradually from 60-100 to 35-60 µm, while lumen decreases from 30-40 to 12-15 µm. Epithelium is uniformly 10-20 µm thick but external muscular layer increases from 5-10 to 15-20 µm, with prominent ectal muscle bundles in its distal part. (3) The widest (90-190 µm, widening gradually), up to 1000 µm long, externally smooth portion descending to male pore. Its wall consists of 20-50 µm thick layer of irregular, weakly staining epithelium covered with 2-6 µm of muscular layer. 30-60 µm wide lumen is either empty or contains some granular matter. Ectal ends of atria taper to 12 µm and fall, close together, into unpaired copulatory sac under nerve chain. Sometimes up to 50 µm long papillae (pseudopenes?) occur around their apertures. Copulatory sac is an about 200 µm wide inversion of body wall, lined with thinner epithelium (10 µm). A mightly system of muscles connects it to proper body wall. A pair of spermathecae in X are more or less erect and pear-shaped, up to 760 µm long. Their ampulla is roundish, 200-390 µm wide, wall consisting of 8-14 µm thick epithelium and up to 2 µm thick external muscle layer. Ampulla is tightly filled with spermatozoa arranged with their heads towards wall. In sections, the mass of spermatozoa seems to be surrounded by thin capsula (maybe detached inner cuticule of spermatheca?). Duct is externally not distinctly separated from ampulla, but is only tapering and bearing some transversal folds. However, their internal difference is large, as duct has very narrow lumen and thick wall consisting mainly of epithelium covered with about 10 µm thick muscle layer. Both ducts fall, close together, into small unpaired median chamber under nerve cord at 9/10. This chamber is, like copulatory sac, an invagination of body wall. (ref. ID; 7854)

    Remarks

    The differences between the various taxa included within this specific description are presented in outline in Table 1. The distinctive hairly covering of the body described in Goodrich (1892, 1895) has not been subsequently observed in preserved whole mounts but is normal in live worms. Worms fixed for electron microsocpy show this hairly covering distinctly (H.R. Baker, personal observation). Hatai (1898) claimed that V. limosus had such hairs posteriorly but the body wall of the same species was described as naked by Nomura (1915). Moore (1905) described a ring of sensory hairs on M. glaber's segments, but these are not visible on the types or on recent material mounted by our methods. Setal differences between the various synonyms involve variations in the proportions of the setal teeth (all more or less close to equally long and thick). The male ducts of the various species have not been well described in the literature. The major variation described is the degree of elaboration of the short naked ejaculatory duct. Our observations show, for the first time, that this may be distended with sperm in mature individuals, but that it is usually inconspicuous. All of the entities considered here have protrusible pseudopenes opening into median male pores and paired spermathecae unlike all other species in the genus. The spermathecal pores vary in position but such variation has been noted within populations as well as between populations from different sites (Goodrich 1895). Vermiculus pilosus (Weymouth, England) has been regarded as a synonym of M. rubroniveus by Ditlevsen (1904), Michaelsen (1913), Chen (1940), and Marcus (1952). The two species described by Ferroniere (1899) (Atlantic France) are uncertain at best. Vermiculus fluviatilis is supposed to have simple-pointed setae posteriorly and may be partly ascribable to M. parvus. Chen (1940) believed V. glotini had hair setae as he discussed it in relation to M. trichochaetus and M. irroratus, but he synonymized V. fluviatilis with M. rubroniveus. The types of M. glaber (Atlantic U.S.A.) have been stored in close proximity to specimens of Tubifex (= Monopylephorus) irroratus Verrill collected by J.P. Moore and deposited at the Academy of Natural Sciences in Philadelphia. It appears that at some time in the past these two collections have been mixed as the tubes labelled M. glaber were found to contain glaber (with a large median male bursa, no hair setae, and simple protrusible pseudopenes) and specimens of irroratus with most of the hair setae broken off (leaving distinctive thin stumps within the setal sac). This was partly the cause of some confusion in labelling earlier illustrations of the penes of M. rubroniveus. The eversible pseudopenes illustrated by Brinkhurst (1971) under that name are, in fact, those of M. irroratus sensu strictu. Monopylephorus corderoi (South America), M. ponticus (Black Sea, Baltic Sea), and M. helobius (Gulf of Mexico) are all similar in somatic and genital characteristics and appear to be indistinguishable from rubroniveus. Although the setae of M. helobius differ somewhat from those of the rubroniveus group (upper tooth shorter than lower), the male system appears to be identical. In the light of the newly established species separation of the irroratus group considerable cautions about the acceptance of the widest definition of rubroniveus should be voiced. However, the finding of rubroniveus in the Pacific tends to support the conclusion that this is a truly cosmopolitan species. (ref. ID; 5957)

    The basically marine littoral and brackish water genus Monopylephorus Levinsen, 1884 was last revised by Baker and Brinkhurst (1981) and Finogenova (1982). The only freshwater species, M. limosus (Hatai, 1898), lives mainly in polluted rivers and canals of China and Japan (recently found also into Italy, according to Paoletti, 1987) but differs from our worm by the shorter upper tooth in its chaetae, simple-pointed vental chaetae in II, and distally joint spermathecal ducts opening in a common pore backwards of 9/10 (Baker and Brinkhurst 1981). The discribed worm obviously belongs to the cosmopolitan, variable brackish-water species M. rubroniveus Levinsen, 1884. This has repeatedly been described from different continents under different names treated as subspecies by Finogenova (1982), but as synonyms by Baker and Brinkhurst (1981). M. rubroniveus iturupi Finogenova, 1982, described from seas of the Far East, is not separable from the nominate form either, according to Erseus et al. (1990). The present form corresponds well to the descriptions of M. rubroniveus iturupi and of the European Rhizodrilus ponticus Hrabe, 1967, which is a synonym of M. rubroniveus in the broad sense, it is only slightly larger; consequently, its chaetae and internal organs are larger too, and the maximum number of chaetae per bundle is highr. The orientation of spermatozoa in tightly filled spermathecal ampulla, with their heads against the wall, has so far been depicted in a related species, M. aucklandicus (Benham, 1909) by Baker and Brinkhurst (1981, fig.7). The freshwater population of M. rubroniveus in the urban rivers of Ussurijsk is the only one known in the whole world. High abundance and large size are an evidence of a favourable environment. The species inhabits a limited are here (with a distance of about 600 m between two known localities) sharing this with a diverse community of pelophilous, pollution-tolerant tubificids; Tubifex tubifex, Limnodrilus hoffmeisteri, L. udekemianus etc. Bottom sediment was a thick layer of clayey mud in the Rakovka River, whereas in the Komarovka, where current velocity reached 0.8 m sec-1, cobbles were covered with a silted mat of cyanobacteria. Some local pollution with mineral salts in these sites is possible but not proved. (ref. ID; 7854)

    Material examined

  • Brinkhurst collection: R. Tame, from Birmingham to R. Trent, U.K. coll. R.W. Martin, 1973, whole mounts, dissections, and sections; R. Weaver, U.K. coll. R.O. Brinkhurst, 1961, many; Prince Rupert, Powell River, Port Alice, all Britisch Columbia, coll. K. Coates, 1978, many. (ref. ID; 5957)
  • Baker collection: Patricia Bay and Nuchatlitz Inlet, British Columbia, coll. H.R. Baker, 1978, many. (ref. ID; 5957)
  • Acad. Nat. Sci. Philadelphia: Syntypes of M. glaber Moore, cat. 2722, many. (ref. ID; 5957)

    195 specimens, mostly mature but damaged, in two samples from the lower course of Rakovka and Komarovka Rivers, 03.06.1996. Eight of them sectioned, two dissected, the rest studied as whole mounts. (ref. ID; 7854)