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The World of Protozoa, Rotifera, Nematoda and Oligochaeta

Villiersia

Villiersia Omodeo, 1987 (ref. ID; 6421, 6578 original paper)

Family: Haplotaxidae (ref. ID; 6578)

Synonym Haplolumbriculus Omodeo, 1958 (nom. nud.) (ref. ID; 6578), Pelodrilus partim (P. kraepelini: Hrabe, 1931) (ref. ID; 6578), Eclipidrilus partim (? E. kraepelini: Michaelsen, 1932), Lycodrilus partim (L. kraepelini: Michaelsen, 1914) (ref. ID; 6578)

ref. ID; 6421

Apomorphies include loss of the anterior pair of testes, forward shift of the gonad sequence (shared with Adenodrilus), and presence of genital chaetae (like those of H. dubius), spermathecal pores opening near the mid dorsal line. (ref. ID; 6421)

Type species

Type species by designation Villiersia guanivora Omodeo, 1987 (ref. ID; 6421)

ref. ID; 6578

Diagnosis

Haplotaxids having a pair of testes in X and two pairs of ovaries in XI and XII (or perhaps only XI). Sperm sacs and ovisacs paired, spematecaepaired in VIII-XI (or VII-IX) opening near the dorsomedian line. Setae sigmoid with lumbricine arrangements, genital setae on VI, IX and X, or VIII to X or VIII and X. No gizzard: holonephridia without peritoneal lining. In water or in mud. (ref. ID; 6578)

Etymology

This genus is also dedicated to Dr. A. Villiers. (ref. ID; 6578)

Genotype

Villiersia guanivora (ref. ID; 6578)
  1. Villiersia guanivora (ref. ID; 6578 original paper)
    Syn; Haplolumbriculus insectivorus, nomen nudum, Omodeo, 1958 (ref. ID; 6578)
  2. Villiersia guanivorus Omodeo, 1987 (ref. ID; 6421)

Villiersia guanivora (ref. ID; 6578 original paper)

Synonym

Haplolumbriculus insectivorus, nomen nudum, Omodeo, 1958 (ref. ID; 6578)

Descriptions

  • External characters: Body slightly prismatic, adult specimen 106 x 2.6 mm x 3.6 at the clitellum; 202 to 237 segments, devoid of secondary annulation. No cutaneous pigment. Prostomium large, zygolobic, crescent-shaped. No dorsal pores. Nephridiopores lateral between the setal lines b and c, beginning in XIV or XV. Male pores almost imperceptible in clitellate specimens on XI slightly forward and ventral to the setae a. Female pores very small in the 11/12 and 12/13 on the setal line b. Spermathecal pores in 7/8 and 8/9 on the setal line c or d. Clitellum saddle-shaped on X-XIV, its lateral edges are somewhat dorsal to setal line b. Tubercula pubertatis on XI, encroaching on continuous segments. Setigerous papillae ab on VI, IX and X. Setae lumbricine, very large, sigmoid, ornamented near the tip by transverse incisures; near the middle of the body they are 285 to 316 µm long, with a diameter of 22 µm at the nodulus. Copulatory setae ab of VI, IX and X smooth, arched only near the basis; they become abruptly thinner at their midpoint; their nodulus is proximal. Copulatory setae of VI are 930 µm long, 21 µm thick at the nodulus, 18.5 µm under and above it, and 14 µm distally; copulatory setae of IX-X have the same thickness, but are only 620 µm long. Setal formula aa:ab:bc:cd:dd=4.6:1.1:8.1:1:9.7 (XX). (ref. ID; 6578)
  • Internal organization: Septa begin between segments IV and V: they are thin, and the first ones are funnel-shaped. A small globular gizzard in segment VII; the esophagus passes gradually to middle intestine in XIV; no typhlosole. The peri-intestinal blood sinus is conspicuous in VIII-XI where it is connected with the dorsal vessel by a few short radial commissures. The dorsal and ventral vessels are connected by unbranched lateral commissures that in VI-X are long and sinuous; in XI-XXX these commissures are shorter and show a proximal swelling. Septal glands in II-V. Holonephridia begin in XVII, they have no peritoneal covering. Supraeosphageal ganglia between pro- and peristomium their outline is sketched in Fig.3G. In VI, IX and X, on the inner face of the body wall, there are thick lobated glandular pads ("accessory lobular prostates") on which genital setae ab are implanted. Other glands have not been observed on the body wall. Testes massive, lobated, free in the anterior part of X; in the cavity of X-XI there are free seminal cells. A young specimen showed supllementary testes in IX. Seminiferous funnels in the after part of X at the lower lip of sperm sacs. In adult specimens sperm sacs are long paired tubes, slightly narrowed in correspondence with the septa, that extend for 14-20 segments: they are included in the ovisacs. In preadult specimens many sacs develop from the septa directed either forward or backward, in adult specimens only the sperm sacs emerging from 10/11 subsist. Two pairs of ovaries in the anterior ventral part of XI and XII; ovarian funnels on the ventral lip of ovisacs. Ovisacs envelop the sperm sacs and harbour in their bottom large mesolecithic eggs, orange coloured, measuring 675x550 µm, while the larger ovarian eggs measure 200x250 µm. Spermathecae paired, situated in VIII-IX they have a short duct and a transvserse elongated, rolled ampulla; between the two branches of the ampulla these is often a diverticulum. In adult specimens the spermathecae were filled with sperm. The anterior spermathecae are larger than the posterior ones. (ref. ID; 6578)

    Remarks

    In the coelom of anterior segments small embryonated eggs (49.5x56 µm) have been observed, endowed with a thick, brown, horny shell; they belong to a parasitic nematode. Gregarine cysts are common in the caudal segments: an adult specimen harboured in the front segments and in the sperm sacs hundreds of such cysts. (ref. ID; 6578)

    Systematic position

    The new species is very similar to Lycodrilus kraepelini from Kinshasa, Zaire, described by Michaelsen in 1914; the likeness is such that the two species should be considered congeneric even though there are ovaries in XI only, and an additional pair of spermathecae in VII. Genital setae are reported in slightly different segments. Further, they are undoubtedly related to the haplotaxids because of many characters: form and size of setae, thickness of cuticle, anatomy of vascular apparatus and sperm and ovisacs. The two species have the gonads shifted a segment forward as in Adenodrilus and many lumbriculid genera. They differ from the lumbriculids because the male ducts are plesioporous, they lack atria, they have two pairs of ovaries and the vascular apparatus also is different, even if some details are alike. (ref. ID; 6578)

    Etymology

    The gut of these worms contains chitinous fragments mixed with coarse sand granules. As most fragments belong to fair-sized pigmented coleopterans and to lepidopterans, it is likely that they have been ingested with bat guano: from this type of food derives the specific name. However, some small aquatic arthropods were ingested whole or in pieces by the worm: unpigmented ostracods and amphipods. (ref. ID; 6578)

    Type locality

    Guinea: Segea caves, near Kindia, dark halls, in a brooklet, A. Villiers April 7, 1954. About 20 specimens 'softened', three of which are ovigerous adults. (ref. ID; 6578)