Mediorhynchus limpopoensis, Smales & Halajian & Rampedi, 2021

Smales, Lesley, Halajian, Ali & Rampedi, Kgethedi Michael, 2021, A new species of Mediorhynchus Van Cleave, 1916 (Acanthocephala: Gigantorhynchidae) from Burhinus capensis (Aves: Charadriiformes) and a report of Mediorhynchus africanus Amin et al. 2013 from Guttera edouardi (Aves: Galliformes) from South Africa, Zootaxa 5005 (3), pp. 395-400 : 396-399

Mediorhynchus limpopoensis , n. sp.

( Figs 1 –14)

Diagnosis. With characters of the genus Mediorhynchus . Males smaller than females. Body elongate, pseudo-segmented, laterally flattened except for more or less cylindrical anterior and posterior ends. Anterior end of trunk asymmetrical, dorsal body wall thicker than ventral body wall, bent ventrally, retracted forming cup shaped space containing proboscis. Proboscis in 2 parts; anterior proboscis cylindrical with large hooks; posterior proboscis divided into anterior region reflected anteriorly within the cup shaped space, with irregular rows of 3–4 larger spines, posterior region forming collar surrounding anterior proboscis with irregular rows of 2–3 smaller spines. Proboscis armature similar in both sexes: anterior proboscis with 22 longitudinal rows of 4 hooks, 88 in total (determined by dissection) and posterior proboscis with about 35–45 irregular rows of 5–7 spines. Hook blades difficult to observe, largest blades 25–35 long, shorter than roots. Hook roots markedly longer than blades, simple, directed posteriorly; posterior ends of roots rounded with ornamented edges without lateral ornamented wings, largest roots 60–80 long. Spine blades not seen. Proboscis receptacle single walled with the characters of the genus. Cephalic ganglion near middle of proboscis receptacle, adjacent to retractor muscles. Lemnisci long, digitiform, slightly unequal, 6–14% body length. Male reproductive system in posterior quarter of trunk. Testes large, ovoid, short distance apart; cement glands 8, ovoid, each with single large giant nucleus, clustered together: gonopore terminal. Female reproductive system relatively short with marked curvature of uterus, connected to body wall with filaments; gonopore sub ventral. Eggs ovoid with posterior pole pointed. The new species differs from its congeners on the basis of the form of the prosoma, asymmetrical with dorsal wall thicker, the shape of the proboscis, posterior region forming spinous collar, and a proboscis armature of 22 rows of 4 hooks anteriorly, root bases with ornamentation, without accessory lateral ribbed wings, 35–45 irregular rows of 5–8 spines posteriorly.

Description ( Table 1).

Host. Spotted thick-knee, Burhinus capensis (Lichtenstein) ( Charadriiformes : Burhinidae )

Site of infection. intestine.

Prevalence and Intensity of infection. 1 of 4 birds, 25%, 57 worms.

Etymology. The species name refers to the province where the acanthocephalans were collected.

Remarks. None of the specimens were alive or in good condition when collected from their host and consequently their preparation for examination was not ideal. The probosces could not be extended by placing them in tap water overnight and the fixation of the worms was poor. Sufficient morphological data could be collected, however, to characterise the new species. Mediorhynchus limpopoensis n. sp. resembles most closely those species found in Africa with a pseudosegmented trunk and can be distinguished from them as discussed below.

Mediorhynchus africanus from galliform birds from south and east Africa is the most similar species to M. limpopoensis in morphometrics but differs from it in being a larger worm with a shorter cylindrical anterior end that has neither an asymmetrical body wall, nor ventral flexion, nor is retracted, forming a cup shaped space within which the proboscis lies. Moreover, the hooks and spines of the proboscis armature of M. africanus are embedded in dome shaped cuticular swellings, the anterior proboscis has longitudinal rows of 4–6 hooks with the hook blades as long as the roots, the hook roots each with 1 pair of prominent accessory lateral ribbed wings and the posterior proboscis conical not forming a spiny collar. The lemnisci of M. africanus are markedly unequal, the testes are broader and rectangular in shape and the eggs are ovoid but more pointed at both poles ( Amin et al. 2013). Measurements for this species are given in Table 1.

Mediorhynchus kuntzi , parasite of Burhinus senegalensis (Swainson) from Egypt differs from the present species by having a smaller body without anterior asymmetry or ventral flexion, the anterior proboscis has a total of 72–136 hooks and roots without ornamentation and the posterior proboscis not forming a spined collar ( Ward 1960).

Mediorhynchus leptis , parasite of Falco tinnunculus (Linnaeus) from Egypt differs from the present species in having a much smaller body without anterior asymmetry or ventral flexion, the anterior proboscis with 108 hooks in total, longer hook blades and hook roots without ornamentation and the posterior proboscis with irregular rows of about 11 spines not forming spiny collar ( Ward 1966).

Mediorhynchus mattei parasite of Tockus erythrorhynchus (Temminck) from Senegal differs from the present species in having a smaller body and although the anterior end is bent ventrally with asymmetry it does not form a cup shaped space containing the proboscis; the anterior proboscis is armed with 15 longitudinal rows of 4 hooks and the posterior proboscis, not forming spiny collar, with 10 –12 rows of 6–8 spines ( Marchand & Vassiliades 1982).

Mediorhynchus taeniatus parasite of hosts including Numida meleagris Linnaeus from south eastern Africa and Tockus leucomelas Lichtenstein from Limpopo Province, South Africa differs from the present species in having neither anterior asymmetry nor ventral flexion and a proboscis armature of 10 longitudinal rows of 3 hooks and about 22 longitudinal rows of about 8 spines ( Ward 1966).

Neither M. meringi from Corvus capensis Lichtenstein from the Eastern Province of South Africa, nor M. numidae from N. meleagris reported as N. ptilorhyncha (Perlhun) from south west Africa, nor M. mokgalongi from Turdus smithi Bonaparte from Limpopo Province, the other species of Mediorhynchus reported from southern Africa, have pseudo-segmentation. ( Meyer 1933; Bisseru 1960; Smales et al. 2018).

Mediorhynchus africanus , M. mokgalongi , M. taeniatus and now M. limpopoensis have all been reported from Limpopo Province. Each of these species differs morphologically as described above. Furthermore, each of these species utilises different families of birds as hosts: M. africanus occurs in Numididae and Phasianidae (Galliformes) , M. mokgalongi in Turdidae (Passeriformes) , M. taeniatus in Bucerotidae (Bucerotiformes) , Burhinidae (Charadriiformes) , Numididae (Galliformes) and Otididae (Otidiformes) , and M. limpopoensis is found in Burhinidae (Charadriiformes) ( Junker & Boomker 2006, 2007; Davies et al. 2008; Junker et al. 2008; Amin et al. 2013; Smales et al. 2018).

The helminth community of the helmeted guineafowl, Numida meleagris (Linnaeus) , including M. africanus , has been studied extensively in Limpopo Province (see for example Junker et al. 2008). The host range (galliform birds) and geographic range (sub-Saharan Africa) of M. africanus has been delineated by Amin et al. (2013). Finding M. africanus in a crested guineafowl, G. edouardi , in this study is, therefore, consistent with the previous reports of this acanthocephalan

Roadkilled birds were collected under Limpopo Department of Economic Development, Environment & Tourism permit number ZA/ LP/87586 . Thanks to Prof WJ Luus-Powell (DSI-NRF SARChI Research Chair (Ecosystem Health), Department of Biodiversity , University of Limpopo) for allowing use of her lab for part of this study and also to those who assisted AH in the lab, volunteers Matheogela Moloto for the Guineafowl and Connie Manganyi and Seskie Kana Maringa for the thick-knee .

Figures

FIGURES 1–10. Mediorhynchus limpopoensis n. sp. 1. Male, showing shape of un segmented cylindrical anterior end; 2. Male, proboscis and proboscis receptacle; 3. Male, proboscis retracted, showing internal structures of prosoma; 4. Anterior proboscis, dissected from prosoma; 5. Female, mid body segments; 6. Hooks; 7. Male, posterior end; 8. Egg; 9. Female posterior end showing ovejector; 10. Female, posterior body shape. Abbreviations: cg = cephalic ganglion, o = ornamentation, s = spine. Scale bars: 1, 1.0 mm; 2, 9, 200 µm; 3, 5, 10, 500 µm; 4, 100 µm; 6, 8, 25 µm; 7, 400 µm.