Echiniscus aff. brunus, Dey & Gąsiorek & Michalczyk, 2024

Dey, Pritam K., Gąsiorek, Piotr & Michalczyk, Łukasz, 2024, Convergent evolution of dark, ultraviolet-absorbing cuticular pigmentation in a new Afro-Oriental Echiniscus brunus species complex (Heterotardigrada: Echiniscidae), Zoological Journal of the Linnean Society 200 (1), pp. 34-59 : 46-49

Echiniscus aff. brunus sp. can. 1

( Figs 12 , 13 ) Material examined: Eight individuals (for details, see Table 1 ).

Shortened description: Morphotype almost identical to that of E. brunus , except for the presence of the same type of circular cuticular pores with thick borders on all parts of the dorsal and pedal plates in E. aff. brunus sp. can. 1 ( Figs 12B, D and 13C–D ) vs. pores on dorsal and pedal plates different in E. brunus sp. nov. ( Figs 10B, D and 11C, D ). Molecular phylogenetic analysis suggests it is a closely related sister, potentially cryptic or pseudocryptic, species to E. brunus (see Fig. 2 and genetic distances in the description of E. brunus above).

DNA sequences: A set of five markers was obtained: 18S rRNA (OR520118–9), 28S rRNA (OR520112–3), ITS-1 (OR520104–7), ITS-2 (OR520125–8) and COI (OR506704– 7). Uncorrected pairwise distances to E. brunus can be found in the description of the new species above, whereas genetic p-distances to E. aff. brunus sp. can. 2 are as follows: 18S rRNA, 0.0%; 28S rRNA, 0.4%; ITS-1, 5.1%; ITS-2, 3.7%; and COI, 3.6% (see also Supporting Information, SM.03).

Remarks: Foundwith Echiniscus cf. scabrospinosus , Pseudechiniscus sp. , Milnesium sp. , Dianea sp. , Ramazzottius sp., Diphascon sp. , Minibiotus sp. and Macrobiotus sp. in the sample. Compare Figures 10D , 11D with Figures 12D , 13D for a potential difference in the shape of pedal plate pores between E. brunus and Echiniscus aff. brunus sp. can. 1.

Figures

Figure 2. Phylogenetic position of the new complex in the Bayesian and maximum likelihood tree of the Echiniscus line, with Hypechiniscus excluded (identical topologies; the scale refers to the Bayesian tree and represents substitutions per position; posterior probability values are provided above branches and bootstrap values below branches; *, maximal support; #, support <0.90 in BI and <75 in ML). Diploechiniscus oihonnae and Testechiniscus spitsbergensis constitute an outgroup.Echiniscid clades with convergently evolved dark, UV-absorbing cuticular pigmentation, Viridiscus and the new Echiniscus brunus complex, are marked in green and brown, respectively.The Echiniscus spinulosus group is marked with light blue, and species classified within the E.spinulosus morphogroup are indicated with dark blue.Geographical shapes (Africa, South America and Indian subcontinent) and palm trees (symbolizing the tropics and subtropics) symbolize areas of occurrence of a given lineage, if biogeographically consistent.

Figure 10. Echiniscus brunus sp. nov. seen in PCM. A, dorsolateral view (holotype); the inset shows claws I (paratype). B, cuticular pores, lateral view of intersegmental plates (holotype). C, paired subcephalic plates (holotype).D, pedal plate II (holotype). E, larva, dorsolateral view (paratype); the inset shows claws III. F, armour malformation: median plate 2 fused with the paired segmental plate II (paratype). The flat arrowhead indicates sparsely arranged circular pores, whereas indented arrowheads indicate tightly arranged polygonal pores. The black indented arrowhead with white borders indicates the armour malformation.Scale bars are in micrometres.

Figure 11. Echiniscus brunus sp. nov. seen in SEM. A, dorsal view. B, lateral view.C, cuticular pores in intersegmental plates. D, pedal plate I. The flat arrowhead indicates sparsely arranged circular pores, whereas the indented arrowhead indicates tightly arranged polygonal pores. Scale bars are in micrometres.

Figure 12. Echiniscus aff. brunus sp. can. 1 from India seen in PCM. A, dorsolateral view; the inset shows claws I. B, cuticular pores in intersegmental plates. C, paired subcephalic plates. D, pedal plate II. The flat arrowhead indicates sparsely arranged circular pores. Scale bars are in micrometres.

Figure 13. Echiniscus brunus sp. can. 1 from India seen in SEM. A, dorsal view. B, lateral view.C, cuticular pores in intersegmental plates. D, pedal plate I. The flat arrowhead indicates sparsely arranged circular pores.Scale bars are in micrometres.