Kristenseniscus

Gąsiorek, Piotr & Michalczyk, Łukasz, 2025, Novel integrative data for Indomalayan echiniscids (Heterotardigrada): new species and old problems, Organisms Diversity & Evolution 25 (1), pp. 81-116 : 106

Diphyly of Kristenseniscus

The evident non-monophyly of Kristenseniscus (Fig. 2) should be solved by an erection of a new genus for K. limai . Despite an overall similarity, this species consistently differs from K. tessellatus and the K. walteri complex in two important characters: (1) the presence of three pairs of intersegmental platelets inserted between the segmental (scapular, paired segmental and caudal) plates, instead of two pairs in the latter, as clearly the third pair, positioned between the second paired segmental plate and caudal plate, is absent in Kristenseniscus s.s. ( Fig. 21 ); and (2) the subdivision of plates into false subplates is limited to the scapular and caudal plates, but it is ancestrally present in all segmental plates in Kristenseniscus s.s. ( Fig. 21 ). The intersegmental platelets of K. tessellatus were drawn in the original description ( Murray, 1910), and later shown based on the material from Hawaii ( Dastych, 1997a). Their relatively strong sclerotisation may have caused the effect of “nimbus” described for empty exuviae ( Murray, 1910). The abovementioned new genus is not established due to nomenclatorial problems with its probable type species (see below) and a need for sequencing some enigmatic echiniscid taxa, such as Zealandiscus palmai ( Dastych, 1997b) , which is similar to K. limai in the development of large epicuticular granules on the dorsal plates ( Gąsiorek et al., 2021c), potentially signifying a close phylogenetic affinity of the two species.

Figures

Fig. 21 Schematic illustration depicting major differences in morphology between: A Kristenseniscus s.s. (K. tessella- tus+the K. walteri complex); B. Kristenseniscus limai. Lateral intersegmental platelets marked in red