Abstract
A collection of 94 pentastomid specimens, comprising four species (three belonging to the genus Sebekia Sambon, 1922 and one (?)belonging to the genus Alofia Giglioli, 1922), were recovered from the lungs of a single Nile crocodile Crocodylus niloticus taken in the Okavango swamps, Botswana. On the basis of external morphology only, two specimens out of the entire assemblage were immediately distinctive, by virtue of their being comparatively long and slender. After clearing in Hoyer's medium and examination of the chitinised structures of these two specimens (hooks, fulcra, oral armature, male copulatory spicule and egg size) a new species, Sebekia okavangoensis, was described. It proved necessary to clear and slide-mount virtually all of the remaining specimens in the collection before any further progress towards specific diagnosis was possible. When this was done, two additional (damaged) specimens belonging to the above new species were discovered. Furthermore, it was postulated that two other female Sebekia specimens, described earlier under the binomial Sebekia cesarisi Giglioli in Sambon, 1922 by Riley, Spratt & Winch (1990), also belonged to this taxon. Seven females and one male in the present collection were assigned to S. cesarisi, primarily on the basis of the distinctive morphology of the oral cadre. Uniquely this cadre possessed a pair of prominent anterior flanges which line the front part of the buccal cavity. Stylised drawings of these structures are the only features of diagnostic significance contained within the perfunctory type description of S. cesarisi. The majority of the present collection (a total of 75 specimens, 72 of which were slide-mounted) comprised a single species, S. wedli Giglioli in Sambon, 1922, and we were able to confirm the usual variation in the key parameters of all of the chitinous structures measured: this seems to be a hallmark of pentastomid morphometrics. Nonetheless, despite this problem, all of the present Sebekia spp. can be discriminated by appropriate combinations of characters, and there is no confusion between these and the remaining eight well characterised species in the taxon (Riley et al., 1990). Finally, a new species of Alofia, A. nilotici, based on two females and two males, possesses hooks that are intermediate between Sebekia and the other known Alofia spp., although the distinctive copulatory spicules leave no doubt as to its generic status. The hooks of this new species carry a dorsal patch of minute spines which suggests a rather close relationship between the two genera, as initially proposed by Heymons (1941) and later by Self & Rego (1985). Six specimens, deemed by eye to be the best preserved, were examined solely by SEM. Three were identified as S. wedli, one as S. okavangoensis n. sp., one as S. cesarisi and the remaining Alofia specimen possessed hooks without spines; we remain uncertain about the specific status of this particular specimen.
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Riley, J., Huchzermeyer, F.W. Descriptions of four species of pentastomid parasites belonging to the genera Alofia Giglioli, 1922 and Sebekia Sambon, 1922, from a single Nile crocodile Crocodylus niloticus from Botswana. Syst Parasitol 31, 221–238 (1995). https://doi.org/10.1007/BF00009120
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DOI: https://doi.org/10.1007/BF00009120