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The World of Protozoa, Rotifera, Nematoda and Oligochaeta

Rhinodrilus

  1. Rhinodrilus lavellei Righi, 1992 (ref. ID; 6019 original paper)
  2. Rhinodrilus lourdesae Righi, 1986 (ref. ID; 6019)
  3. Rhinodrilus pashanasii Righi, 1992 (ref. ID; 6019 original paper)
  4. Rhinodrilus timote Righi, 1989 (ref. ID; 6019)

Rhinodrilus lavellei Righi, 1992 (ref. ID; 6019 original paper)

Descriptions

The single complete worm is 118 mm long and it has 205 segments. The middle-body varies from 5 to 6 mm dia. The dorsal colour is dark bluish-green like No. 428 of Seguy (1936), the ventral side is whitish and the clitellum is dark reddish-brown like No. 112. The prostomium is tentaculiform and the segment I and II have a pair of nephribuccal furrows. The majority of the animals have the prostomium, segment I and 1/2 II invaginated. The setae are arranged in 4 pairs of longitudinal rows. The ventral rows begin in VIII and the lateral ones between XXV and XXVII. The setae b of VIII and IX are dislocated laterally and anterioally. The space ab is reduced from XVII to XXI, increases to XXIV and continues regularly back. The relations among the setae are aa:ab:bc:cd:dd=8.3:1.0:12.0:1.0:24.6 (ab=240 µm) in the middle-body region (segments XL-L) and aa:ab:bc:cd:dd=12.0:1.0:14.4:0.8:29.0 (ab=200 µm) in the posterior region (segments CLXXX-CXC). The common setae are sigmoid with distal nodulus, unicuspidate apex and its subapical portion has 4 alternate rows of wide and shallow semilunar excavations; there are 3-4 excavations per row. The setae length is from 450 to 630 µm (M=534 µm) in the middle-body and from 354 to 459 µm (M=412 µm) in the posterior region. The ventral setae of VIII, IX and XVIII-XXII are transformed into genital setae. There are straight with slight proximal curve and their distal 2/3 has 4 alternate rows of narrow and deep semilunar excavations; there are 14-23 excavations per row. The genital setae are 0.7-1.8 mm (M=1.4 mm) long; the longest and most ornamented setae are in VIII, IX and XVIII-XX. The clitellum extends over the segments XVII-XXV (9); it is very turgid with distinct intersegmental furrows and saddleshaped with unmarked lower margin. Setal papillae contain every ventral setae of VIII, IX and XVIII-XXII. Pairs of egg-shaped puberal papillae surround every couple of ventral setae in XVIII-XX and XXII. One pair of curve puberal furrows lies in XXI, at the side of the setae b and they are associated with 2 pairs of rounded glandular formations projected into the body cavity of XX and XXII. Two pairs of short gutters with thickened borders are aligned with ab in the posterior region of XX and the anterior one of XXI. The septa 6/7-8/9 are very thick, muscular and like long interpenetrated cones, the following ones become successively thin and short up to 15/16, and the remaining ones are thin and quite flat. The anterior oesophagus widens into a thin walled crop immediately before the gizzard. This is globular, large and muscular in VI. Three pairs of calciferous glands depart from the dorsal side of the oesophagus in VII-IX. They are egg-shaped, differently compressed in an anteroposterior direction, with a short duct, no appendix and they are of tubular-panicled structure. The transition oesophagus-intestine lies in 13/14. The typhlosole begins in XXVII. In the cross-section it is a dorsal sigmoid blade as high as the interstinal diameter, its dorsal curve is small and the ventral curve is large, so that its free margin is dorsal. There are no intestinal caeca. Three pairs of slender lateral hearts are in VII-IX and 2 pairs of bulky intestinal hearts in X and XI. The subneural vessel is present. Every segment has one pair of holonephridia. The nephridia of VI and the 3 preceding pairs curl at the sides of the anterior esophagus. Each postclitellar nephridium has a simple preseptal funnel and 3 post-septal loops. The duct connecting the common region of loops I and II with the ventral part of loop III (bladder) is sigmoid and formed by large vesiculated milk-white cells. The mid-ventral end of the bladder is continuous, under the nerve cord, with the bladder of the other side and with those of the contiguous segments. The nephridiopore has strong sphincter and it opens immediately after the intersegmental furrow, aligned with cd. The pairs of testes sacs coalesce ventrally in X and XI; they ascend laterally and surround the hearts. The testes sacs of X coalesce dorsally too. Two pairs of short and cylindrical seminal vesicles are lateral or dorsolateral to the oesophagus in XI and XII. The vesicles of XI are partially surrounded by the testes sacs. The two vas deferens of each side run together on the body wall to XVIII. They are intraparietal in XIX and XX and open side by side in 20/21 at the major glandular invagination of the respective puberal furrow. One pair of fan-shaped ovaries, with radial rows of maturating eggs, lies in XIII, but due to to the funnel-shaped septa it corresponds to the parietal segment XVII. Therefore the short oviducts have the microscopical female opening in 17/18 or frontally in XVIII, immediately at the side of the setae series b, alinged with the male pores. Two pairs of spermathecae are in VIII ad IX and their microscopical pores are in 7/8 and 8/9, at the side of the series b. The spermathecae are similar to each other, but those of the second pair are the largest. In every spermathecae, the intraparietal duct has several seminal chambers full of spermatozoa, and the duct changes gradually into a pyriform flattened ampulla. The ampulla wall is thick, folded, with cylindric epithelium and its cavity is full of secretions. (ref. ID; 6019)

Remarks

The new species is near to Rhinodrilus lourdesae Righi, 1986, known in Brazil, State of Rondonia, and to R. timote Righi, 1989 known in Venezuela, State of Aragua. The main characters to distinguish these species from R. lavellei are summarized below. (ref. ID; 6019)

Etymology

The name of the new species is in homage to Dr. Patrick Lavelle. (ref. ID; 6019)

Type locality

The worms were collected manually from the soil in Peru, Department of Loreto' Yurimaguas (5 degrees 54'S-76 degrees 05'W) in 1987 and preserved in 10% formalin. The study was made by dissections, pieces mounted in glycerine-water (1:1) and serial histological sections (10 µm) stained by Mallory's triple method (Pantin 1964). (ref. ID; 6019)

Examined material

Eight clitellate worms (7 without a posterior portion) and one mature aclitellate worms (ZU-1235A holotype, ZU-1235B paratypes). (ref. ID; 6019)

Type deposited

The material is deposited in the Department of Zoology, University of Sao Paulo, Brazil. (ref. ID; 6019)

Rhinodrilus pashanasii Righi, 1992 (ref. ID; 6019 original paper)

Descriptions

Length 140-155 mm, mid-body region 2.9-3.5 mm dia. Number of segments 198-222. The tentaculiform prostomium and the reduced segments I and II are invaginated in the majority of the animals. Only one worm has segments I and II evaginated and they have a pair of nephribuccal furrows. The dorsal colour is pale reddish-brown like No, 135 of Seguy (1936), the clitellum is dark and the ventral side whitish. There are 4 pairs of setae per segment arranged in regular longitudinal series. The ventral series begins in VII and the lateral ones between XI and XXV. The common setae are elongated sigmoid, the bad-marked nodulus is distal, the apex is unicuspidate and the subapical region has 4 pairs of alternate rows of shallow semicircular excavations; there are 2-3 excavations per row. The setae length varies in the mid-body from 283 to 379 µm (M=331 µm) and in the posterior region from 334 to 476 µm (M=400 µm). The setal relations are aa:ab:bc:cd:dd=4.3:1.0:6.0:0.7:14.3 (ab=240 µm) in the mid-body (segments LVI-LXVI) and aa:ab:bc:cd:dd=3.0:1.0:4.1:0.7:9.1 (ab=280 µm) in the posterior region (segments CXCV-CCV). The setae a and b of VII-IX and XIX-XXIII are transformed into genital setae. They are straight with a slight proximal curve and their distal half has 4 alternate rows of deep semicircular excavations. In VII-IX the length of the genital setae increases from 964 µm in VII-1151 µm in IX (M=1080 µm) and they have 12-15 (M=13) excavations per row. In XIX-XXIII the length of the genital setae decreases more or less regularly from 1311 µm in XIX - 1016 µm in XXIII (M=1125 µm) and they have 10-12 excavations per row. The saddle-shaped clitellum occupies segments XVI-XXV (10), but it is most tumid in XVII-XXIV and the lower margin is gradual in bc. Small crateriform papillae surround every genital setae. The ventral surface of VII-IX is turgid. One pair of bent puberal furrows lies in XXI laterally to setae b. Two pairs of short gutters are in the posterior half of XX and in the anterior half of XXII at each side of the midventral line. The gutter are convex to one another and they have differentiate margins. The area with the gutter in XX is salient mainly in contracted animals, which have the midventral region of XXI depressed. Pairs of puberal papillae are constant in XXII and XXIII, generally they occur in XIX and XX and seldom in XXI. The papillae are milk-white, circular or egg-shaped, sometimes confluente and they contain the couple of setae a and b. The septa 6/7-17/18 are conic and interpenetrated; the following septa are flat. 6/7-8/9 are very thick and muscular; the following ones become successively thinner up to 17/18, which is similar to the remainder. The septa 9/10 is fastened dorsally in the intersegmental furrow 10/11 and ventrally in 9/10. The pharyngeal bulb extends to the parietal 1/2 VII. The thich and very muscular gizzard is in the cavity of VI, but due to the elongation of the septa it corresponds to parietal segments XI-XIII. Three pairs of calciferous glands depart from the dorsal oesophageal wall in the cavity of segments VII-IX. Each gland is egg-shaped, peduncled, without an appendix and of panicled-tubular structure. The transition oesophagus-intestine lies in 24/25. The intestine widens suddenly in XXV and continues uniformly backwards. The typhlosole begins in XXVI. In the cross-section it is sigmoid and is as high as 1/3-1/2 of the diameter of the intestine. There are no intestinal caeca. Three pairs of slender lateral hearts are in VII-IX and 4 pairs of bulky intestinal hearts in X-XIII. The subneural vessel is present. There is one pair of holonephridia per segment. The postclitellar nephridia have a small preseptal funnel and 3 postseptal loops. The duct between the loops I and II and the mid-ventral end of loop III (bladder) is thin, not glandular. The nephridiopore has a small sphincter and it opens in the intersegmental furrow, space cd. The nephridia of VI and the previous ones are intermingled at each side of the anterior oesophagus. Two pairs of testes sacs are in X and XI and two pairs of small seminal vesicles are in XI and XII. Each pair of testes sacs coalesces ventrally. They grow upwards and forwards following the slope of the septa; therefore they cover the oesophagus, calciferous glands and hearts like two pairs of valves. The testes sacs of XI cover the first pair of seminal vesicles too. One pair of compacted glandular structures (prostatoid glands) is fastened to the ventral body wall in XX-XXI sometimes right to XXII and they project at the sides of the oesophagus. The two vas deferens of each side open anterolaterally in the glandular cavity. The cavity of each gland is central along the horizontal axis, branching out little. The walls are composed of the juxtaposed neck of the long calviform glandular cells and it is continuous with the surface epithelium in 21/22, at the posterior end of the corresponding puberal furrow. One pair of ovaries and female funnels are ventral in the cavity of segment XIII, but due to the infundibuliform shape of the septa they correspond to the parietal segment XVII. The microscopic female pores are in 18/19, line b. Two pairs of spermathecae lie in VIII and IX; they open in 7/8 and 8/9 at the sides of the mid-ventral line, sometimes inside a fusiform transverse depression common to each pair. The spermathecae of the second pair are the greatest. In each spermatheca the duct present an ental dilation with several intraparietal seminal chambers, the tubular ampulla has thick gandular walls. Groups of ravelled up spermatozoa fill up the seminal chambers and small groups are among the secretion mass fulfilling the ampulla. (ref. ID; 6019)

Remarks

Having in mind the great variation of size associated with food, the variation of colour associated with the environment and its fading in preserved animals, as well as the similarity of the male genital field, I first interpreted R. pashanasii as a variety of R. lavellei. However, detailed examination of anatomical characters led me to separate the two species as follows. R. pashanasii is distinguished from R. lavellei by diameter, colour, puberal papillae, setal ratio, position and ornamentation of the genital setae, number of hearts, morphology, of the postclitellar nephridia and male pores. (ref. ID; 6019)

Etymology

The name of the new species is in homage to Mr. Beto Pashanasi. (ref. ID; 6019)

Type locality

The worms were collected manually from the soil in Peru, Department of Loreto' Yurimaguas (5 degrees 54'S-76 degrees 05'W) in 1987 and preserved in 10% formalin. The study was made by dissections, pieces mounted in glycerine-water (1:1) and serial histological sections (10 µm) stained by Mallory's triple method (Pantin 1964). (ref. ID; 6019)

Examined material

Nine clitellate, 10 mature aclitellate and young worms (ZU-1237A holotype, ZU-1237B paratypes). (ref. ID; 6019)

Type deposited

The material is deposited in the Department of Zoology, University of Sao Paulo, Brazil. (ref. ID; 6019)