Haplotaxis

Haplotaxis Hoffmeister, 1843 (ref. ID; 3692, 6421, 6913, 6972) or 1845 (ref. ID; 1257)

Family Haplotaxidae (ref. ID; 1257, 5813, 5939, 6421, 6578, 6913, 6972, 7254)

Synonym Phreorcyctes Hoffmeister, 1845 (ref. ID; 6421) or Michaelsen, 1928 (ref. ID; 6578), Phreorcyctes Cernosvitov, 1939 (ref. ID; 6578), Pelodrilus Beddard, 1891 (ref. ID; 6578)

[ref. ID; 1923]
Worms very long and slender (filiform). The genus have only 2 large isolated ventral setae and 2 small dorsal setae per segment; many segments without dorsal setae. (ref. ID; 1923)

[ref. ID; 6421]
This taxon is defined by the apomorphies associated with a predatory habit: replacement of eversible pharynx and septal glands by a massive muscular pharynx, ventral chaetae large, sickle-shaped, dorsals small, straight, single, often lost in many or all segments. (ref. ID; 6421)
Type species; Type species by priority Lumbricus gordioides Hartman, 1821 (ref. ID; 6421)
Species dubia; H. emissarius, H. forbesi, H. ichthyophagus, all seen as potential synonyms of H. gordioides but based on immature material. Other taxa, such as H. heterogyne and H. ascaridoides are also very similar to gordioides. Material is too scarce and fragmentary to allow a proper revision of these species. (ref. ID; 6421)

  1. Haplotaxis aedeochaeta Brinkhurst & Marchese, 1987 (ref. ID; 6421, 7254 original paper)
  2. Haplotaxis africanus (Michaelsen, 1908) (ref. ID; 5813)
  3. Haplotaxis ascaridoides Michaelsen, 1905 (ref. ID; 3692, 5813) reported author and year? (ref. ID; 6421)
  4. Haplotaxis aucklandicus (Benham, 1909) (ref. ID; 5813)
  5. Haplotaxis bipapillatus (Michaelsen, 1924) (ref. ID; 5813)
  6. Haplotaxis brinkhursti (Cook, 1975) (ref. ID; 5813) reported author and year? ref. ID; 5939)
  7. Haplotaxis bureschi (Michaelsen, 1924) (ref. ID; 5813) reported year? (ref. ID; 7254)
  8. Haplotaxis cantabronensis Delay, 1972 (ref. ID; 5813)
  9. Haplotaxis carnivorus Omodeo, 1958 (nom. nud.)
    See; Haplotaxis villiersi Omodeo, 1987 (ref. ID; 6578, 7254)
  10. Haplotaxis corbarensis Delay, 1972 (ref. ID; 5813)
  11. Haplotaxis darlingensis (Michaelsen, 1907) (ref. ID; 5813)
  12. Haplotaxis denticulatus (Cekanovskaja, 1959) (ref. ID; 5813)
  13. Haplotaxis dubius (Hrabe, 1931) (ref. ID; 5813) reported author and year? (ref. ID; 6421)
  14. Haplotaxis forbesi Smith, 1918 (ref. ID; 1923)
  15. Haplotaxis gastrochaetus Yamaguchi, 1953 (ref. ID; 5813, 6421) reported year? (ref. ID; 7098, 7254)
  16. Haplotaxis glandularis (Yamaguchi, 1953) (ref. ID; 5813)
  17. Haplotaxis gordioides (G.L. Hartmann, 1821) (ref. ID; 1257, 1923, 1928, 3692, 5813, 6421, 6578, 6913, 7254) reported year? (ref. ID; 4491)
  18. Haplotaxis gordioides ascaridoides Michaelsen (ref. ID; 7254)
  19. Haplotaxis gordioides dubius (Hrabe) (ref. ID; 7254)
  20. Haplotaxis heterogyne Behham, 1904 (ref. ID; 6421) or Benham, 1904 (ref. ID; 5813) reported year? (ref. ID; 7254)
  21. Haplotaxis hologynus (Michaelsen, 1907) (ref. ID; 5813)
  22. Haplotaxis ichthyophagus Gates, 1971 (ref. ID; 6561, 6651)
  23. Haplotaxis ignatovi (Michaelsen, 1903) (ref. ID; 5813)
  24. Haplotaxis kraepelini (Michaelsen, 1914) (ref. ID; 5813)
  25. Haplotaxis leruthi (Hrabe, 1958) (ref. ID; 5813)
  26. Haplotaxis monticola (Michaelsen, 1908) (ref. ID; 5813)
  27. Haplotaxis novarrensis Delay, 1973 (ref. ID; 5813)
  28. Haplotaxis ornamentus Brinkhurst & Fulton, 1980 (ref. ID; 5813, 6421) or Brinkhurst (ref. ID; 7254)
  29. Haplotaxis smithii (Beddard, 1888) (ref. ID; 5813, 6421)
  30. Haplotaxis tuberculatus (Benham, 1909) (ref. ID; 5813)
  31. Haplotaxis vermivorus (Michaelsen, 1932) (ref. ID; 5813, 6421) reported year? (ref. ID; 7254)
  32. Haplotaxis villiersi Omodeo, 1987 (ref. ID; 6578 original paper, 7254)
    Syn; Haplotaxis carnivorus Omodeo, 1958 (nom. nud.) (ref. ID; 6578, 7254)
  33. Haplotaxis violaceus (Beddard, 1891) (ref. ID; 5813)

Haplotaxis aedeochaeta Brinkhurst & Marchese, 1987 (ref. ID; 6421, 7254 original paper)

Descriptions

Length at least 4 cm (preserved), width (slide mounts) 0.16 mm anteriorly, 0.11 posteriorly. Many segments, anterior end in front of mouth (prostomium and ?segment I) 2-ringed, mouth large immediately in front of first chaetae. Segments V and VI 2-ringed, VII, VIII, and to a lesser extent to segment X, 3-ringed. Ventral chaetae single, longer proximally than distally, nodulate with curved distal end. No dorsal chaetae. No ornamention observed. External gonopores invisible on whole mounts. The mouth leads into a capacious crop, which extends back to near the posterior end of V. No eversible pharyngeal pad or septal glands. The crop wall consists of two separate layers. Muscular-walled so-called gizzard (using traditional terminology for this structure in Haplotaxis) begins in V, in V and VI the walls are thick and unfolded and the lumen is narrow, straight, and lined with cuticle. In VII the "gizzard" lumen is large, and the wall more folded than before, and there are strong muscle bands between this and the body wall. Intestine from VIII. Anterior blood vascular system with a median vessel that divides at the anteriormost end to form two lateral, these uniting in II to form the second longitudinal median vessels in each segment (dorsoventral orientation uncertain). Spermathecae paired 2-part structures, the inner ampullae small in these unmated specimens, the outer thick-walled ducts opening dorsolaterally in VIII-X (nonmated specimens only). Testes (GII, i.e., the second of a presumptive four pairs of gonads; see Brinkhurst 1982) and male funnels in XI. Ovaries (GIII) and male genital chaetae in XII, the latter very long, hair-like, in muscular sacs that may protrude into XI, normal chaetae missing in XII. Sperm sac in X and posterior to XVIII, egg sac to XXI. Brain large, heart-shaped in front of the mouth, nerve cord broad. Paired stained bodies ventrolateral in II-IV(V), other bodies (perhaps nephridia but indeterminable on this material) from XXX. (ref. ID; 7254)

Remarks

In the most recent review of the whole family (Brinkhurst 1966) it was suggested that all of the known species be grouped in the single genus Haplotaxis, type species Haplotaxis gordioides (Hartman, 1821). This was meant to be a provisional action pending clarification of homologies of the various structures termed pharynx and gizzard, among other things. The two major genera, Haplotaxis and Pelodrilus, seemed to overlap in the sense that one poorly known species described from immature material from Sumatra, Haplotaxis vermivorus Michaelsen, had many of the characteristics of Haplotaxis s.str. (furrowed prostomium, highly modified chaetae, no septal glands) but Brinkhurst (1966) may have misinterpreted the original description of the gut (in German). Michaelsen (1932) is clearly describing a large crop and a muscular gizzard in IV and part of V, very much like that of H. gordioides. Michaelsen compared the crop with the eversible pharyngeal roof of the Enchytraeidae because at that time this structure was supposedly limited to that family. It has since become recognized as a general attribute of microdrile oligochaetes. It is always associated with septal (or pharyngeal) glands which constitute the cell bodies of secretory cells of the pharynx roof. The lack of septal glands in H. vermivorus further indicates the similarity of this species to H. gordioides. It is now possible to recognize a group of species, by inspecting the data and by cluster analyses (Jaccard, average linkage, performed independently by R.O. Brinkhurst and by Coates (1987)) which represents Haplotaxis s.str; phylogenetic analyses by Coates do not quite correspond with these, however. Haplotaxis aedeochaeta clearly belongs to the group (which includes the type species) consisting of H. gastrochaetus Yamaguchi, H. heterogyne Benham, H. gordioides, and its associated subspecies H. gordioides dubius (Hrabe) and H. gordioides ascaridoides Michaelsen as well as its supposed synonyms. Haplotaxis vermivorus clearly belongs here if we interpret the confusion about its gizzard as stated above. Indeed, it becomes difficult to separate from H. gordioides which is, in fact, also vermivorous in habit, as noted below. We can separate H. aedeochaeta from these species as follows. The presence of worm carcasses (the tubificid Limnodrilus) in the intestines of some Haplotaxis ?gordioides specimens from North America observed by R.O. Brinkhurst suggests a carnivorous habit that may be the function basis for the varying degree of modification of the foregut observed in these forms. The specific term vermivorus used by Michaelsen reflects the presence of oligochaete chaetae in the gut of that taxon as well. A recently described taxon, Haplotaxis villiersi Omodeo, 1987 (formerly Haplotaxis carnivorus Omodeo nom. nud.) has highly modified dorsal chaetae, but the smaller ventral chaetae are paired throughout. While there is no gizzard, the nature of the pharynx and septal glands that we might therefore assume to be present is, unfortunately, not reported, perhaps because the norm was not considered to be significant. This taxon is unique in terms of chaetae but its classification in any restricted Haplotaxis is unlikely. The species was found in an African bat cave along with another species which contained fragments of chintious insect parts that may have been derived from the bat guano (Omodeo 1987). This second taxon was named Villiersia guanivora Omodeo, 1987 (= Haplolumbriculus insectivorus Omodeo nom.nud.). The chaetae of this species are paired and lumbricine, and while there are genital chaetae in VI, IX, and X, they are elongate distally but not hair-like. The gizzard is globular in VII but there are septal glands in II-V and a normal eversible pharynx. All other species, currently or formally assigned to the genera (Pelodrilus, Tiguassu, Metataxis etc.; see Brinkhurst 1966; Omodeo 1987), are separable as a group from Haplotaxis s.str. by the presence of such normal pharyngeal structures and lumbricine chaetae and the lack of a genital chaetae at least, plus other specialized characteristics such as the proboscis of Tiguassu. One further point of interest in relation to any future analysis of the family is that Omodeo (1987) noticed ornamentation on the chaetae of H. gordioides specimens from Turkey. Until now this feature was thought to the characteristic of a small group of species related to Haplotaxis bureschi Michaelsen, all cave-dwelling European species, but ornamentation was then noticed on a rather different form, Haplotaxis ornamentus Brinkhurst from Tasmania (Brinkhurst and Wetzel 1984). Reexamination of chaetal preparations now reveals similar ornamentation on material resembling H. gordioides from Lake Tahoe (Nevada, U.S.A.) and Britain and H. vermivorus type material. (ref. ID; 7254)

Etymology

From aidoio, Greek, a euphemism for genital, and chaite, Greek, long hair, for the elongate, hair-like genital chaetae. (ref. ID; 7254)

Type locality

Center of the main channel of the Middle Parana River, Corrientes, Entre Rios and Santa Fe Provinces, Argentina, in sand, 1977-1978, coll. U. Molet, R. Regner, M. Marchese, and E. Varela. (ref. ID; 7254)

Type material


Haplotaxis bureschi (Michaelsen, 1924) (ref. ID; 5813) reported year? (ref. ID; 7254)

Descriptions

See the remarks of H. aedeochaeta. (ref. ID; 7254)

Haplotaxis forbesi Smith, 1918 (ref. ID; 1923)

Descriptions

With 1 pair of testes in segment 10, ovaries in segments 15 and 16, length 100-150 mm, diameter 0.6-0.7 mm. (ref. ID; 1923)

Haplotaxis gastrochaetus Yamaguchi, 1953 (ref. ID; 5813, 6421) reported year? (ref. ID; 7098, 7254)

Descriptions

See the remarks of H. aedeochaeta. (ref. ID; 7254)

Haplotaxis gordioides (G.L. Hartmann, 1821) (ref. ID; 1257, 1923, 1928, 3692, 5813, 6421, 6578, 6913, 7254) reported year? (ref. ID; 4491)

Descriptions

With 2 pairs of testes in segments 10 and 11, ovaries in segments 12 and 13, length 150-200 mm, diameter scarcely 1 mm. (ref. ID; 1923)
See the remarks of H. aedeochaeta. (ref. ID; 7254)

Remarks

The ventral setae are similar in size and form to those described by Yamaguchi for Japanese specimens (1953) but they are ornamented by minute depressions, unlike the dorsal setae. This has not been reported for this species before. Holonephridia begin in XIV. The supraesophageal ganglion is situated between the prostomium and peristomium, its form is shown in Fig. 1B. The gizzard occupies most of IV and V. The lateral commissures connecting dorsal with the ventral vessel are moderately developed in cephalic segments. H. gordioides is a holarctic species, it is new for Turkey. It lives in the sapropel and in the gyttia, it is common in caves and has been found in phreatic waters. (ref. ID; 6578)

Type locality

Narlikakoy cave, Antakya Turkey. K. Kosswig leg. (1946, 1 juvenile). (ref. ID; 6578)

Haplotaxis gordioides ascaridoides Michaelsen (ref. ID; 7254)

Descriptions

See the remarks of H. aedeochaeta. (ref. ID; 7254)

Haplotaxis gordioides dubius (Hrabe) (ref. ID; 7254)

Descriptions

See the remarks of H. aedeochaeta. (ref. ID; 7254)

Haplotaxis heterogyne Behham, 1904 (ref. ID; 6421) or Benham, 1904 (ref. ID; 5813) reported year? (ref. ID; 7254)

Descriptions

See the remarks of H. aedeochaeta. (ref. ID; 7254)

Haplotaxis ornamentus Brinkhurst & Fulton, 1980 (ref. ID; 5813, 6421) or Brinkhurst (ref. ID; 7254)

Descriptions

See the remarks of H. aedeochaeta. (ref. ID; 7254)

Haplotaxis vermivorus (Michaelsen, 1932) (ref. ID; 5813, 6421) reported year? (ref. ID; 7254)

Descriptions

See the remarks of H. aedeochaeta. (ref. ID; 7254)

Haplotaxis villiersi Omodeo, 1987 (ref. ID; 6578 original paper, 7254)

Synonym

Haplotaxis carnivorus Omodeo, 1958 (nom. nud.) (ref. ID; 6578, 7254)

Descriptions

See the remarks of H. aedeochaeta. (ref. ID; 7254)

Remarks

The great development of the vessels that in the anterior segments adhere to, and upholster the inner face of the thin body wall, suggests that gas exchanges in this worm occur there. As these vessels do not branch into smaller vessels, and as no capillaries have been seen in histological preparations, one is tempted to conclude that Haplotaxidae have a primitive circulatory apparatus, but this point needs more investigation. (ref. ID; 6578)

Systematic position

The species here described is surely new for science, because neither the special distribution of the setae, nor the exaggerated development of transverse commissural vessels have ever been described for any Oligochaete. Unfortunately, only young specimens were available. As few oligochaetes other than members of the genus Haplotaxis (sensu Brinkhurst) have gonads in X-XIII, this species is tentatively attributed to it. (ref. ID; 6578)

Etymology

This species is dedicated to Dr. A. Villiers who collected the material studied here. (ref. ID; 6578)

Type locality

Cave of Sigea, near Kindia, Guinea, in a brook; water pH 5.0, temperature 26 degrees C, Dr. A. Villiers leg. April 7, 1954. Three young specimens well preserved. (ref. ID; 6578)