Chaetonotus acanthocephalus - Kisielewski (1981; 1991:54, Figs 65-68, Tab. 22) ; Hummon (2007: 5) ; Balsamo et al. (2009: 12, Appendix 1) .
Água Limpa: 2 specimens, Soberbo: 1 specimens, Preto River: 5 specimens.
The description is based on an adult specimen, 236 μm in total length. Head with three lobes and a one pair of ciliary tufts. Five peculiar cephalic scales with long spines present on the head. Two ventral plates at the sides of the hypostomion. Pharynx 65 μm in length from the posterior edge of the mouth to the pharyngo-intestinal junction that is at U27. The general long-spine distribution pattern shows two pairs of conspicuous lateral neck spines. Two pairs of long lateral spines at the furcal base.
Features Range N Literature data from Brazil Literature data from Europe Body length 169-236 µm 2 123-175 µm 100-148 µm Length of adhesive tube 27.5-28 µm 2 11-17 µm 14-16 µm Pharynx length 62.5-65 µm 2 34-54 µm 37-49 µm Diameter of mouth ring 8-8.75 µm 2 5 µm 6.5-8 µm Cephalion length 20 µm 1 - - Length of neck scales 7 µm 1 6-7 µm 4-7 µm Length of trunk scales 10 µm 1 5.5-9.5 µm 5.5-8 µm Maximum length of the neck spines 24-27 µm 2 7.5-19.5 µm 11-15 µm Maximum length of the trunk spines 30-35 µm 2 12.5-28 µm 16.5-22 µm Length of terminal spines 19-31.25 µm 2 8-19.5 µm - Number of scales in a single longitudinal row 17 2 17 16-18
Kisielewski (1991) reported three distinct morphotypes of Chaetonotus acanthocephalus in Brazilian inland waters:two of them were collected in São Carlos city and one in Juréia Reserve. Our specimens appear to be close to one of the morphotypes found in São Carlos due to the presence of two pairs of long spines at the furcal base, and the peculiar transversal row of trunk spines ( Kisielewski 1991:54, Figs 65-66 ). However, the body length, width and the posterior spines of the Diamantina specimens are larger than those observed from São Carlos (Table 3).
Brazil: Diamantina (Minas Gerais State); São Carlos ( São Paulo State), Juréia Reserve ( São Paulo State), Corumbá (Mato Grosso do Sul State); Poland: Lake Piaseczno; Germany; Bulgaria.
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