Two new tardigrade species (Echiniscidae and Doryphoribiidae) from the Salta province (Argentina)

Abstract

Tardigrades from Argentina are poorly known. Two new species from the Salta province are described in the present contribution: Pseudechiniscus saltensis sp. nov., and Doryphoribius cephalogibbosus sp. nov. The former species belongs to the novaezeelandiae group and, apart from the nominal species of the group, it is similar to nine congeneric species by the following characters: the absence of spines on legs I and lateral papillae, the scapular plate with a transversal fold, the presence of projections at the posterior margin of the pseudosegmental plate, caudal plate not faceted, and cuticular ornamentation in the form of heads (capituli) of endocuticular pillars, protruding through epicuticle and joined by striae. However, the new species differs from all of them in important qualitative (e.g. colour, different division of plates, details of cuticular ornamentation, claws etc.) and morphometric characters. The new species exhibits a unique morphology of gonopore and anus. Doryphoribius cephalogibbosus sp. nov., by the presence of two macroplacoids, dorsal gibbosities, and inhabiting terrestrial environment, belongs to the flavus group and differs from all members of the group in having ten, instead of nine, rows of gibbosities (X:2-4-6- 6-6-6-6-4-2-2+2[LI–III]), with as a peculiar exclusive character, the presence of the two cephalic gibbosities, never reported in other Doryphoribius species. Moreover, the new species differs from the other species of the group by morphometric and more detailed morphological characters. The new species description also gave an occasion to discuss the issue of gibbosity arrangement in other species and address the morphology of claw accessory points.

Phylogeography and morphological evolution of Pseudechiniscus (Heterotardigrada: Echiniscidae)

“…saltensis , divided into two putative species in the Bayesian implementation of the Poisson Tree Processes (bPTP), although with weak support (0.50). However, we classified populations AR.251 and 266 as morphologically homogeneous and largely corresponding with the original description 31 . Consequently, the number of Pseudechiniscus species utilised in our phylogenetic reconstruction was determined as 25.…”

Two new Bryodelphax Thulin, 1928 species (Heterotardigrada: Echiniscidae) from the Republic of Ireland with comments on the ‘weglarskae group’ and other heterotardigrade taxa, including the controversial genus Bryochoerus Marcus,1936

“…Guidetti et al (2014) included an anus focused SEM micrograph of Mopsechiniscus franciscae Guidetti, Rebecchi, Cesari and McInnes, 2014 but analysis of the anal structures was not included in the description. Rocha et al (2020) noted visible perianal structures in their species description of Pse. saltensis Rocha, Doma, Gonzalez Reyes and Lisi, 2020, but were not able to investigate further without SEM.…”