Lycodrilides
Lycodrilides Hrabe, 1982 (ref. ID; 7201)
- Lycodrilides grubei (Michaelse, 1905) n. comb. (ref. ID; 7201)
Syn; Lycodrilus grubei Michaelsen, 1905 (ref. ID; 3692)
- Lycodrilides schizochaetus (Michaelsen, 1901) (ref. ID; 7201)
Syn; Limnodrilus schizochaetus (Michaelsen, 1901): Michaelsen, 1926 (ref. ID; 7201); Lycodrilus dybowskii var. schizochaeta Michaelsen, 1901 (ref. ID; 7201); Lycodrilus schizochaetus Michaelsen, 1901: Michaelsen 1903, 1905: Brinkhurst and Jamieson 1971 (ref. ID; 7201)
Lycodrilides grubei (Michaelse, 1905) n. comb. (ref. ID; 7201)
Synonym
Lycodrilus grubei Michaelsen, 1905 (ref. ID; 3692)
Descriptions
Hamburg material: The original labels read L. multispinus, but this was corrected to L. grubei by hand at some date (unknown). The specimens is the head and tail only, and appears to be the remains of the type. (ref. ID; 7201)
New material: Broad worms, cylindrical with little change in width from short, blunt prostomium posteriad. Segments II-IV biannulate, foreign matter in grooves of body, but not markedly developed. Specimens approximately 3-16 mm long, 1 mm wide, up to 75 segments but often ending abruptly in narrow stub of tail (covered in protozoans) suggesting tails recently cropped. Setae stout, simple pointed, tips bent at acute angle to rest of shaft; five per bundle in II, progressively reduced in number to one per "bundle". Unmodified (?) setae present adjacent to spermathecal and male pores in X and XI. Blood vessels obvious in prostomium, II and III, large vessels in VIII and especially IX. Genital pores in setal line. Male duct (paired) with vas deferens bipartite, a proximal part with vacuolated cells and a distal part of more normal appearance. The vas deferens joins the atrium subapically, opposite the entry of the large prostate gland. The atrium is curved posteriad, and the prostate gland is on its posterior face. The atrium narrows slightly before enlarging immediately prior to the modest penis, set in a deep cuticle-lined penis sac. The spermathecae are long and club-shape, without discrete ducts. None of the specimens are mated, so the form of the sperm in the spermathecae remains unknown. The species has not been redescribed since it was first seen over 80 years ago. In the original account most of the salient features noted here were observed, including the presence of setae in the spermathecal pores, though they may be unmodified and should not, therefore, be termed spermathecal setae. (ref. ID; 7201)
Notes
In L. schizochaetus the atria narrow into distinct ejaculatory ducts but this could be exaggerated by the erection of the penes in that material, in contrast to the relaxed setae of the semimature forms of this species. The penes are similar, the prostates are on the posterior faces of the atria, and the atria are curved posteriad in both species. The spermathecae differ, which may be related other degree of maturation. This species has no enlarged setae anteriorly, and has more than two in the first three setal segments and retians setae by the genital pores (again at this stage of maturation). On balance, it seems more sensible to ally this species with L. schizochaetus in the genus Lycodrilides than to separate it. The distinction between Lycodrilus dybowskii and this pair seems geater (according to the description by Hrabe) than the differences between these two species. (ref. ID; 7201)
Type materials
ZMUH (Zoological Museum of the University of Hamburg) V6596. (ref. ID; 7201)
Material examined
ZMUH (Zoological Museum of the University of Hamburg) V6596, one specimen. New collection, four mature, serial sections, two immature whole mounts, two mature specimens in fluid. (ref. ID; 7201)
Synonym
Limnodrilus schizochaetus (Michaelsen, 1901): Michaelsen, 1926 (ref. ID; 7201); Lycodrilus dybowskii var. schizochaeta Michaelsen, 1901 (ref. ID; 7201); Lycodrilus schizochaetus Michaelsen, 1901: Michaelsen 1903, 1905: Brinkhurst and Jamieson 1971 (ref. ID; 7201)
Descriptions
Hamburg material: The specimens from V6595 has the setae characteristic of this species: bifid, with reduced upper teeth and enlarged ventrally in IV-VIII or IX. There are two setae in each bundle of II-III, but one ventrally from IV. The lower tooth in each of the enlarged ventral setae is a good deal longer than those shown in the original illustration, but is closer to those described by Hrabe (1982). The second specimen (from V5601) had even longer lower teeth, and the upper tooth was invisible on some of the largest setae. (ref. ID; 7201)
New material: The dimensions of some of the new specimens range from 20 to 30 mm in the length with 75-88 segments, 0.3-0.8 mm wide. Immature specimens are, naturally, smaller. The proboscis is conical, not usually flattened. The small dorsal setae are usually paired to VII, single posteriorly; the ventrals are single and strongly enlarged in V or VI to IX; many setae are broken and numbers are hard to establish (on one specimen there are three dorsals in a bundle on V, for example). Blood vessels are elaborately coiled in II-VII, to some degree in IX, X, and XI; particularly wide vessels in VI-VII-VIII, especially VIII. Testes and ovaries are in X and XI. Male ducts (paired) with long was deferens, coiled in XI, which enters the ovoid atrium apically. A large prostate gland enters the atrium above the union with the narrow ejaculatory duct, the duct is about twice the length of the atrium. The penis is eversible and has a narrow cuticle-covered distal end on a broader base of about the same length as the distal part. The penes are in the ventral setal line. The spermathecal pores are in the same line or slightly above it. The spermathecal ducts are distinct from the large globular ampullae which are filled with spermatozeugmata. The ducts open to the exterior through small cutcile-lined invaginations of the body wall. Female ducts not observed. This description conforms well to both the original and the recent redescription of the species by Hrabe (1982). The apparent difference in male ducts between Lycodrilus dybowskii and this species (thin crescent-shaped atrium versus glogular to ovoid, long coiled ejaculatory duct versus relatively short duct, distinct penis sheath versus penes with cuticular covering) caused Hrabe to separate these at the generic level despite the great similarity in body form and setae. There are taxa in other families (Haplotaxidae, Phreodrilidae) in which the anterior ventral setae are reduced in number and increased in size in this fashion, so the adaptation may be related to a specific niche related to locomotion and (or) substrate. The presence of protozoan ectoparasites on the tail indicates that the species adopts the characteristic tubificid posture at the mud-water interface. It is not, therefore, necessary to regard the great resemblance in setae between these two species as evidence of generic relationship, but I find it surprising that they have independently evolved this feature. When first described, L. schizochaetus was regarded as a variety of Lycodrilus dybowskii. In my material some of the L. schizochaetus specimens have all but one of the setae worn smooth (though few setae can be seen due to frequent breakage). As I have not examined any material of L. dybowskii in a mature state, I will follow the designation of the new genus in deference to the work of Hrabe, but is would be good to see this independently confirmed. (ref. ID; 7201)
Type materials
ZMUH (Zoological Museum of the University of Hamburg) V5602, two specimens. Also ZMUH V6595. (ref. ID; 7201)
Material examined
One of two specimens ZMUH V6595, also one under L. dybowskii, ZMUH V5601. New collection, three serial sections, four whole mounts, eight in fluid, five of the total being mature. (ref. ID; 7201)