Macrobiotus cf. anderssoni

Roszkowska, Milena, Stec, Daniel, Ciobanu, Daniel Adrian & Kaczmarek, Łukasz, 2016, Tardigrades from Nahuel Huapi National Park (Argentina, South America) with descriptions of two new Macrobiotidae species, Zootaxa 4105 (3), pp. 243-260: 248-249

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Macrobiotus cf. anderssoni


Macrobiotus cf. anderssoni  

( Figs 1–3 View FIGURES 1 – 3 )

Localities and number of specimens. XXVII (5, 2 exuviae and 10 eggs)

Remarks. The eggs found in the present study ( Figs 19–21 View FIGURES 18 – 21 ) correspond perfectly to the original description and the figures published by Richters (1908: p. 17, Fig. 7 View FIGURES 7 – 8 ). The eggs have the same number of processes (15–16) round the circumference, as shown in the original drawings. Moreover, the irregular and jagged apical parts of the processes also correspond to the original drawing. Unfortunately, adult specimens differ significantly by having three instead of two macroplacoids in the pharynx. However, the total length of the first two macroplacoids in the specimens examined correspond well to the length of the first macroplacoid measured by Richters in Mac. anderssoni   (15.9–17.0 µm in found specimens and 15.0 µm in Mac. anderssoni   ) (but we also need to remember that Richters did not report the length of his specimens and it is not possible to compare the length of the macroplacoids in relation to body length). Taking into consideration that the first two macroplacoids can be situated very close one to another it is possible that Richters interpreted two macroplacoids as a single macroplacoid with a deep incision (which is present in the examined specimens). It should be also stressed that Richters did not find any embryonate egg and he could not confirm that the adults and eggs from his sample belonged to the same individuals. Therefore it is possible that his original description was of two separate species. Obviously, further analysis of type material or material from type locality is required to solve this problem. As our specimens do not agree with the original description, but were found close to the type locality of Mac. anderssoni   (Tierra del Fuego in Argentina), we decided to identify them as Mac. cf. anderssoni   . The correct identification will be possible after the re-description of Mac. anderssoni   on type material or on the specimens collected from the type locality.

Macrobiotus anderssoni   has also been reported from Greece and New Zealand ( Horning et al. 1978; Maucci & Durante Pasa 1982). However, New Zealand specimens and eggs were re-examined by Pilato et al. (2006) and attributed to the Mac. hufelandi   group. Greek individuals, based on the eggs with processes ended with a small terminal disc ( Maucci & Durante Pasa 1982), should be also attributed to the hufelandi   group. Thus, both the New Zealand and Greek reports, being so far from the type locality and in different ecozones, are incorrect. Macrobiotus anderssoni   should be probably considered as restricted to Southern Argentina.

Summarizing: the taxonomic position and distribution of Mac. anderssoni   are very unclear and need further, more detailed taxonomic evaluation.