Three South African Monhystera species, described by Joubert &amp; Heyns (1980) (M. magnacephala, M. gabaza and M. taaiboschiensis) are redeseribed and two of them figured in more detail, incorporating newer information about the morphology of the Monhysteridae

Coomans, A

Heyns, J

Jacobs, L.J.

English

AJOL - African Journals Online

62 S.·Afr. Tydskr. Dieck. 1994,29(1) Redescription of three South African Monhystera species (Nematoda)* L.J.Jacobs, J. Heyns** and A Coomans*** Department of Zoology, Rand Afrikaans Univers~y, Johannesburg Received 13 January 1993: accepled 22 July 1993 Three South African Monhystera species, described by Joubert & Heyns (1980) (M. magnacephala, M. gabaza and M. taaiboschiens;s) are redescribed and two of them figured in more detail, incorporating newer information about the morphology of the Monhysteridae. Drie Suid·Afrikaanse Monhystera spesies wat deur Joubert & Heyns (1980) beskryf is, nl. M. magnacephala, M. gabaza en M. taaiboschiensis, word herbeskryf en twee van hulle meer volledig ge'illustreer in die lig van nuwere Qegewens omtrent die morfologie van die Monhysteridae . • Adapted from a D.Se. thesis submitted to the State University of Ghent. Belgium. by the senior author •• To whom correspondence should be addressed at: Department of Zoology, Rand Afrikaans University, P.O. Box 524, Auckland Park, 2006 Republic of South Africa ••• Rijksuniversiteit Gent. Ledeganckstraat 35, B-9000 Gent. Belgium During the course of a monographic study of the Monhysteridae de Man, 1876 by the senior author (Jacobs 1988),. the types and the other specimens of three South African Monhystera species described by Joubert & Heyns (1980) were re-examined and redescribed in more detail in the light of newer knowledge about the morphology of this group. The present paper presents these rcdescriptions and more detailed illustrations of two of the species. Monhyslera magnacephala Joubert & Heyns, 1980 (Figures I and 2) Female: L = 1,15 (1,08-1,28) mm; a = 25,5 (22-28); b = 5,46 (5,2-5,8);c = 7,15 (6,67-7,58); V = 67,4 (66,2-68,6); c' = 6,05 (5,5-6,7); V' 78,4 (77,5-79,5); vulva-anus distance/tail 1,32 (1,25-1,47); tail = 161 (142-174) Jlm; egg 45 x 31 Jlm. Male: L = 1,12 (1,07-1,26) mm; a = 22,7 (20-27); b = 5,49 (5,1-5,8); c = 7,63 (7,00-7,96); c' = 5,07 (3,9-5,4); spicules = 95 (90,5-99) Jlm; tail = 147 (134-165) Jlm; tail/ spicule = 1,54 (1,4-1,7); spicule/anal body diameter = 3,Z7 (2,8-4,0). Anterior end of body not set off, but distinctly broadened between fovea and labial setae. Oral opening about 10 Jlm wide, surrounded by peri-oral platelets. Cephalic setae shorter than labial setae, the latter 19-23% and 23-26% of the head diameter in females and males respectively. With a large number of short somatic setae distributed over the entire body, the most anterior of these situated at about one half head diameter posterior to fovea. Lateral chord field extending to just anterior of fovea. Fovea diameter 16-23% and 22-30% of corresponding body diameter in females and males respectively. Anterior rim of fovea 0,61-D,93 and 0,66-0,83 times the head diameter from anterior end in females and males respectively. Buccal' cavity not more strongly scleroti7.cd than lumen of pharynx. Stoma can be open bell·shaped so that outlet of dorsal pharyngeal gland lies in the base of the opened mouth cavity. Nucleus of dorsal pharyngeal gland situated halfway between nerve ring and base of pharynx; nuclei of two ventrosublateral pharyn-geal gfands near base of pharynx, at about the same level, with a large conspicuous sac·like cell body just anterior to the nuclei, filled with secretion and containing a centrally situated, refractive, nucleus-shaped structure/inclusion of unknown nature. Outlets of posterior ventro-sublateral glands at level of nerve ring. Just posterior to nerve ring a second pair of ventrosublateral nuclei can be seen, optically similar to the posteriorly located pair of gland. nuclei. Pharynx subeylindroid, slightly broadening posteriorly, enveloping the stoma anteriorly. Pseudococl not seen in neck region. Cardia mushroom-shaped. Hyaline, pericardial cells present. Without ocelli. Veniial gland situated subven· trally· just posterior to progaster. Position of excretory pore uncertain. First intestinal cells with Oap-like protrusions into intestinal lumen. Vaginal suspensor, vulva dilator and large vaginal sphinc· ter distinct. Postvaginal gland? cell present. Ovary reaching to progaster area, accompanied anteriorly by one 'or two large, ovoid coclomocytes.· Numerous spermatozoa in uterus. Uterus with two posteriorly situated, ventrolateral accompanying cells (coclomocytes?). Oviparous, Spicules long, slender, evenly curved; spicule diameter 2,8-4, I % of thc spicufe length; capitulum small, distinctly offset from corpus. Gubernaculum well developed, the apo-deme appearing yellowish, siiongly sclerotized and hook-shaped (horse-hcad·shaped), the dorsal apophysis longer than the gubernaculum, hyaline and sometimes indistinctly demarcated. Two pairs of large ejaculatory glands, with two accompanying cells (coclomocytes?) between both glands. Several dorsal cloacal gland cells open into cloaca. Rectum 86- 103% the anal body diameter, with dorsal rectal gland cell. Tail of female stubby, elongate-conoid, with the terminal \6-y, filiform and ventrally or dorsally bent; with large, spindle-shaped spinneret. Tail of male more sfender, sig-moid·shaped with the elongate-conoid part ventrally and the filiform part dorsally bent; spinneret spindle·shaped but with the base of the spinneret narrower in relation to the maxi-mum diameter of the spinneret than in the female. Distribution: Benthic, Vaal River System. Endemic in South Africa, Reproduced by Sabinet Gateway under licence granted by the Publisher (dated 2009).S.Afr. J. Zool. 1994,29(1) F B c co \ H \ E .. ~ N 63 .Flgure 1 Monhystera magMcephala. Type population. female. A: entire hOOy; B & C: head region: D: dorso-ventra! view of head! E: basal pan of pharynx and cardia; F: vagina! region. G: vUlva-anusregion and tail; H: somatic setae on tail. Reproduced by Sabinet Gateway under licence granted by the Publisher (dated 2009).64 A c (!) I UJ B S.-AFr. Tydskr. Dierk. 1994,29(1) Figure 2 Monhyslera magnacephala. Type population. male. A & B: head region; C: basal part of pharynx and· cardia; D: somatic setae on tail; E: spicule, gubernaculum, ejaculatory glands and coelomocytes; F: spicule, gubernaculum and associated muscles; G: spicule and gubernaculum; H: entire body; I: tail with spicule and gubernaculum. Reproduced by Sabinet Gateway under licence granted by the Publisher (dated 2009).S. Afr. J. Zoo!. 1994,29(1) Monhystero gabaza Joubert & Heyns, 1980 Female: L = 0,91 (0,71-1,00) mm; a = 24,3 (20,1-29,7); b = 6,0 (5,5..{i,6); c = 5,8 (4,9..{i,3); V = 62 (6()...<;4); c' = 7,9 (6,8-9,0); vulva-anus distance/tail = 1,20 and 1,32; tail = 157 ILm. Male: L = 0,75 (O,74~,77) mm; a = 21,2 {I 6,5-27,2); b = 5,85 (5,8-5,9); c = 6,4 (6,0-7,0); c' = 4,4 and 4,1; spicules = 70 (60-80) ILm; tail = 117 (106-125) ILm; tail/spicule = 1,71 and 1,77; spicule/anal body diameter 2,4 and 3,0. Anterior end of body conoid, not set off. Cephalic setae shorter than or as long as labial setae, 2,0-2,5 ILm in female, 2,0-3,0 ILm in male, Le. 19-25% of head diameter. Fovea diameter 3,0-3,5 ILm and 4,Q..{j,O ILm in female and male respectively, or 37-38% and 57% of the corresponding body diameter respectively. Anterior rim of fovea 0,28-0,45 and 0,75 times the head diameter from anterior end in fe-male and male respectively. Peri-<lral plates present. Cheilo-stome cylindroid. Buccal ring at 33% of the head diameter from anterior end. Stoma V -shaped with what appelIT' as small sclerotizations at its base; dorsal pharyngeal gland opening at base of stoma. Nucleus of dorsal pharyngeal gland halfway between nerve ring and base of pharynx. Nuclei of venlTosublateral glands 0,5 times pharynx diame-ter from base of pharynx. A second pair of smaller ventro-sublateral nuclei can be seen at the level of the nerve ring similar to posterior pair of gland nuclei, but it is not clear whether they are gland nucleL Pharynx subcylindroid, slightly broadened posteriorly. Cardia mushroom-shaped. Two subdorsal ocelli, one behind the other, situated at 3-5 times the body diameter from the anterior end. VenlTal gland about one corresponding body diameter long, situated posterior to progaster. Excretory pore halfway between nerve ring and anterior end of body. Vagina about one body diameter long, with a dorsal gland cell opening into lumen of vagina at about one thiRl its length from the vulva. No postvaginal gland cell. Ovary not reaching progaster area. Uterus small. always with two large, ovoid hyaline accompanying cells posteriorly. on the right hand side. Oviparous. Spicules evenly curved. slender. their diameter 3% of their length. Capitulum rectangular. weakly differentiated. Gubernaculum with well developed. yellowish apodeme and large hyaline dorsal apophysis. longer than gubernaculum and 50-77% of the anal body diameter. Gubernaculum 18-20% of the length of the spicules. With one pair of ejaculatory glands. Rectum length about equal to anal body diameter. Rectum with large dorsal gland cells. Elongate-conoid part of tail about halF tail length in female. about two thirds tail length in male. In the male the filiform pan of the tail is always dorsally bent or recurved. Spinneret spindle-shaped. Distribution: Benthic in reedbcds. Taaiboschspruil, Vaal . River System. Endemic in South AFrica. '. 65 Monhystera taaiboschiensis Joubert & Heyns, 1980 (Figures 3-5) Female: L = 1.11 (0.79-1.30) mm; a = 18.5 (16-22); b = 6,4 (5.5-7.3); c = 5,8 (5.3..{i.2); V = 64 (61..{j6); c'= 8.0 (7.1-9.1); V' = 77.6 (74~0); vulva-anus distance/tail = 1.05 (I.O-I.ll); tail = 1931Lm. Male: L = 0.95 (0.81-1.04) mm; a = 22.6 (17.1-28.6); b = 6,1 (5.4..{j.5); c = 5.6 (5.3-5.9); c' = 6,9 (6.0-8.3); spicule = 85,4 (79-90) ILm; tail 168 ILm; tail/spicule = 1.98 (1.6-2.2); spicule/anal body diameter = 3.58 (3.2-4.3). Anterior end connuent with body. sometimes slightly broadened, but not set off by constriction. Female about 15% longer than male. With about 15 striae per 10 IJ.nl on cuticle. Cephalic setae shoner than labial setae. the lauer 3, I ILm. or 21 % the head diameter. A large number of somatic setae scattered over the body. but more concentrated in the neck and tail regions. Diameter of fovea 4.8 (4,0-5,4) ILm, or 26,5 (21-36)% of the corresponding body diameter in the female. In the male the respective figures are: 4.5 (4,2-4,9) ILm and 28,6 (26-33)%. Anterior rim of fovea 0,46 (0,4-0,6) and 0,56 (0,4~,7) times the corresponding body diameter from the anterior end. Oral opening about 3,5..{i,5 ILm wide. Peri-oral plateS present. Buccal ring well deve-loped, about 8,5 ILm wide. or 60% of the head diameter. Stoma V-shaped, with the pharyngeal lumen behind the stoma slightly broadened. Pore of dorsal pharyngeal gland sclerotized, located in dorsal sector of base of stoma, with similar sclerotil.ations in the ventro-sublateral sectors. Nuclei of ventro-sublateral pharyngeal glands near base of pharynx; dorsal nucleus situated loi-'A the distance between nerve ring and base of pharynx; two funher ventro-subla-teral nuclei visible at level of nerve ring. smaller but similar to the pair of posteriorly situated gland nuclei. Pharynx subcylindroid. markedly broadened posteriorly. Cardia mushroom-shaped, surrounded by six large. hyaline pericar-dial cells. First intestinal cells with thin. valve-like extensions into lumen. Two subdorsal ocelli situated about twice the head diameter from the anterior end; colour of pigment unknown but in fixed material visible as large black granules. Ventral gland small, about 0,8 times the corres-ponding body diameter, at level of progaster. Excretory pore not seen. Vaginal sphincter large; postvaginal, V-shaped gland(s?) yellowish, with large granules consistently present. Ovaries of young females long, extending to progaster area, in gravid females compressed to convoluted, meandriform or renexed and reaching only 10% of length of reproductive system; oviduct short, subdorsal of uterus; uterus long, in gravid females containing up to seven eggs and five juveniles. Posterior pan of uterus always accompanied by two large. hyaline cells. situated on right hand side. Spicules long and slender. ventrally curved, the spicule diameter 3,2 (2,8-3.6)% its length. Capitulum small, spheri-cal. Gubernaculum well developed with a hook-shaped, yellowish. refractive apodeme and a hyaline. thumb-shaped Reproduced by Sabinet Gateway under licence granted by the Publisher (dated 2009).66 .~ :.~:: ~~. ....• , .... ~, A .... '.~ B -f-·::·:: :: .. :' ___ • ,i, E ( H c F E .. • " '" I I Ll.. I « J S.-Afr. Tydskr. Dierk.1994, 29(1) o K E .. ~ Figure 3 Monhystera laaiboschiensis. Type population. female. A & B: head region; C: dorso-ventral view of head; 0: basal part of pharynx and cardia; E: ventral view of vulva; F: vaginal region; G: somatic setae on tail; H & I: oviduct region of young female with respectively receptaculum se~inis and oviduct filled with spermatoloa; J: ventral view of anus; K: anterior pan of intra-uterine juvenile. Reproduced by Sabinet Gateway under licence granted by the Publisher (dated 2009).'5. AfT. J. Zoo\. 1994,29(1) A E § E ~ o 2 F I I UJ G 67 H D Figure 4 Monhyslera laaiboschiensis. Type population A-D female. A: entire body; B&C: reproductive system with eggs (8), and developing eggs and juveniles (C). in uterus; 0: vulva-anus region and tail. E: genital primordium in intra-uterine juvenile. F-H male. F&G: head r~gion; H: basal part of pharynx and cardia. Reproduced by Sabinet Gateway under licence granted by the Publisher (dated 2009).68 S.·Afr. Tydskr. Dierk. 1994, 29(1) Figure 5 Monhystera taaiboschiensis. Type population. male~ A: entire body; B: spicule; gubernaculum and ejaculatory glands; C: spicule. gubernaculum, associated muscles. and caudal glands; D & E: spicule and gubernaculum; F: somatic setae on tail region; G & H: Tail with spicule and gubernaculum. Reproduced by Sabinet Gateway under licence granted by the Publisher (dated 2009).S. AfT. J. Zoo!. 1994.29(1) dorsal apophysis. Two pairs of ejaculatory glands presen~ opening close to anterior end of cloaca: cloacal gland cells opening dorsally into the cloaca. Basal two thirds of tail elongate-<:onoid. distal one third filiform. Elongate-conoid part. especially in the male. ventrally curved. and the distal filiform part always dorsally curved. Spinneret spindle-shaped. Distribution: Benthic in the Vaal River System: Taaibosch-spruit and Loch Vaal. Endemic in South Africa. Acknowledgement We thank Dr. Esther van den Berg of the Plant Protection Research Institute. Pretoria for the loan of specimens. References JACOBS. LJ. 1988. Monografische studie van de Monhysteridae de Man. 1876 (Nematoda). Doctoral thesis. State University of Ghen~ Belgium. Pan 1. pp. 1-370. JOUBERT. A.P. & HEYNS. J. 1980. Freshwater nematodes from South AfTica. 4. The genus MonhySlera Bastian. 1865. S. Afr. J. Zool. 15: 190-197. Reproduced by Sabinet Gateway under licence granted by the Publisher (dated 2009).

Redescription of three South African Monhystera species (Nematoda)

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Redescription of three South African Monhystera species (Nematoda)

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