Diphasconinae Dastych, 1992

Gąsiorek, Piotr, Blagden, Brian, Morek, Witold & Michalczyk, Łukasz, 2024, What is a ‘ strong’ synapomorphy? Redescriptions of Murray’s type species and descriptions of new taxa challenge the systematics of Hypsibiidae (Eutardigrada: Parachela), Zoological Journal of the Linnean Society 202 (1), pp. 1-63 : 5

Subfamily Diphasconinae Dastych, 1992

The phylogenetic position of Diphascon greveni Dastych, 1984 among the Diphasconinae ( Fig. 2 ) further undermines the diagnosis of this group, which had previously been challenged by the inclusion of taxa lacking a DABT ( Tumanov and Tsvetkova 2023, Zawierucha et al. 2023). Diphascon should group species with an apodeme according to its last broad diagnosis (Pilato 1987, Bertolani et al. 2014), although its morphology is diversified among species currently classified within this genus ( Fig. 3 ). The type species of Diphascon , Diphascon chilenense Plate, 1888 , and members of the Diphascon pingue group ( Pilato and Binda 1997 /8, 1999) have a disparate pharyngeal apparatus (short, rodshaped, or granular macroplacoids; Fig. 4 ) and claw morphology (minute claws with smooth bases and no bars) with respect to D. greveni , thus highlighting the artificial nature of the current definition of Diphascon Plate, 1888 ( Tumanov and Tsvetkova 2023).

Figures

Figure 2. Phylogenetic relationships within Hypsibiidae in the Bayesian and maximum likelihood analyses (identical topologies; the scale refers to the Bayesian tree and represents substitutions per position; posterior probability values are provided above the nodes, whereas bootstrap values can be found below the nodes; *, maximal support; #, no support).Calohypsibius ornatus constitutes an outgroup. Newly added species and populations are in bold.

Figure 3. Various Diphasconinae, morphology of the DABT (SEM): A, Diphascon higginsi Binda, 1971 (dorsal view); B, Diphascon higginsi (lateral view); C, Diphascon pingue (Marcus, 1936) (lateral view); D, Diphascon pinguiforme Pilato & Binda, 1997/8 (dorsolateral view). Scale bars: 1 μm.

Figure 4. The Diphascon pingue group, morphology of pharyngeal structures (SEM): A, Diphascon pingue; B, C, Diphascon pinguiforme. Scale bars: 2 μm.