Polystoma africanum Szidat 1932
Creators: name: Aisien, Martins S. O.
name: Du, Louis H.
Publisher: name: Zenodo
Year: 2009
Subjects: Biodiversity
Taxonomy
Animalia
Platyhelminthes
Monogenea
Polystomatidea
Polystomatidae
Polystoma
Polystoma africanum

description: Polystoma africanum Szidat, 1932
(Figs. 1–4)
Specimens studied: Four specimens (LPRM2-0710-8a-d) deposited in the Invertebrate Collection of the Professor A.B.M. Egborge Museum, University of Benin, Benin City, Nigeria and six specimens (NHM 2008.11.18.1-6) in the Parasitic Worm Collection of the Natural History Museum London; remaining specimens in the collection of the senior author.
Levels of infection: Numbers of hosts and parasites collected are presented in Table 1. For the total sample of 443 toads examined the prevalence was 18.7% and the mean intensity (average number of parasites per infected host) was 4.6. The maximum number of parasites recovered from a single host was 20.
06/2002 6 /44 13.6 3.0 07/2002 20 /97 20.6 2.5 08/2002 0/18 0 0 09/2002 11 /63 11.5 5.7 Total 37/222 16.7 2.9 Ogbonna
06/2002- 09/2003 1 /114 0.90 4.0 Agbede
08/2007 11 /21 52.4 4.9 09/2007 19 /23 82.6 5.9 10/2007 7 /20 35.0 6.9 11/2007 1 /10 10.0 1.0 12/2007 6 /18 33.3 7.2 01/2008 1 /15 6.7 11 Total 45/107 42.1 6.0 Grand total 83/443 18.7 4.6
Description: Based on egg-producing adults (n = 20). Larval sclerite characters based on oncomiracidia (n = 13) hatched from eggs released by specimens collected.
Adult: General characteristics of mature, egg-producing parasite (Figure 1) typical of Polystoma. Body elongate, total length 6,015 (5,162–7,481), greatest width 2,219 (1,835–2,586), haptor length 1,572 (1,352- 1,887), width 2,245 (1,908–2,713); haptor length to body length ratio 0,26 (0,22–0,28); haptoral suckers 6, mean diameter 407 (315–491); hamulus length 388 (335–452); hamulus hook (Figure 4 A) 85 (72–93). Mouth subterminal, ventral. False oral sucker 431 (288–577) wide, pharynx length 244 (204–300), width 232 (194–325). Intestine bifurcate with lobed lateral diverticula averaging 45 (31–53) in number per parasite and large intensely branched medial diverticula numbering 15.3 (12–20) per parasite. In 9.2% of specimens two neighboring medial diverticula on one side join to form loop (Figure 2 F&G). Of 65 specimens examined (for frequency of intercaecal anastomoses only) 41 (63%) have intercaecal anastomoses (37% with 0, 34% with 1, 21.5% with 2; 6% with 3 and 1.5% with 4). Posterior pre-haptoral medial anastomosis spanning position of joining two intestinal caeca (Figure 2 A-D) is present in 22% of specimens examined. Caeca confluent posteriorly, extending into haptor. Haptoral caecal diverticula present. Variation in gut arrangement shown in Figure 3.
Testis follicular, ventral, medial and posterior to ovary (Figure 2). Seminal vesicle prominent, packed with sperm. Genital atrium median, ventral, posterior to intestinal bifurcation; genital bulb with 7–8 spines, 34 (28 – 38) long. Ovary sinistral, 23% from anterior end, ovary length 628 (447 – 766), width 273 (154 – 371). Tubular uterus confined to area anterior to ovary, 90% of time holding single egg (but up to three eggs observed); egg capsule length 185 (174 – 197), width142 (132 – 147). No indication of intrauterine development, eggs operculated. Vitellaria throughout most of body. Genito-intestinal canal prominent, on same side as ovary, joining intestinal caecum posterior to ovary (Figure 2).
Oncomiracidium: Ciliated larva 313 (275-358) with narrow cylindrical body and circular cup-shaped opisthaptor bearing 16 marginal hooklets. Marginal hooklet C1 36.6 (33.3–38.6), marginal hooklet C2 – 7 18.6 (17.0–21.0), marginal hooklet C8 34.9 (31.8–38.0); hamulus primordia 9.8 (9.4 – 10.2) (Figure 4).
description: Published as part of Aisien, Martins S. O. & Du, Louis H., 2009, A redescription of Polystoma africanum Szidat, 1932 (Monogenea: Polystomatidae), pp. 37-46 in Zootaxa 2095 on pages 38-40, DOI: 10.5281/zenodo.187616