Neoechiniscoides MOBJERG, JORGENSEN & KRISTENSEN 2020, GEN. NOV.
Creators: name: Møbjerg, Nadja
name: Jørgensen, Aslak
name: Kristensen, Reinhardt M.
Publisher: name: Zenodo
Year: 2019
Subjects: Biodiversity
Taxonomy
Animalia
Tardigrada
Heterotardigrada
Echiniscoidea
Echiniscoididae
Neoechiniscoides

description: GENUS NEOECHINISCOIDES MØBJERG, JØRGENSEN & KRISTENSEN GEN. NOV.
(FIGS 2–7)
urn:lsid:zoobank.org:act:8FA86B31-39B9-4523- AFAF-E0DB7DE91562:
Diagnosis: Primarily interstitial Echiniscoidinae, with seven to eight, occasionally six or nine, anisonych claws (generally more than six claws on each leg in adults). Epicuticular pillars absent. The dorsal cuticle is strongly sculptured. Cirri Aand Eare present and relatively short in both sexes. First and second leg sensory structures are small and dome shaped. The third leg sensory structure is a seta, and the fourth leg sensory structure is papillar, as is the primary clava. Secondary clavae (cephalic papilla) are more distinct and appear relatively larger in males than in females. Cephalic papillae may be subdivided into secondary and tertiary clavae. Seminal receptacles are lacking. The anal system appears large, with two wings associated with the lateral lobes. The distance between the anus and the gonopore is larger in females than in males. Asmall ventral cuticular plate is present in front of the female gonopore (not observed in N. pollocki).
Etymology: From the Greek νέος, neos (new or young) combined with the generic name Echiniscoides.
Type species: Neoechiniscoides aski; described below.
Other members of the genus: Neoechiniscoides horningi (Miller & Kristensen, 1999) comb. nov. (basionym: Echinsicoides horningi Miller & Kristensen, 1999), sub-Antarctic (Macquarie Island), collected from the lichen Caloplaca sp. on rock in lower supralittoral zone. Neoechiniscoides pollocki (Hallas & Kristensen, 1982) comb. nov. (basionym: Echiniscoides pollocki Hallas & Kristensen, 1982), Rhode Island, USA, found interstitially, from tidal sediments.
Differential diagnosis of the genus: Neoechiniscoides leg sense organs are of the Echiniscoides sigismundi type, i.e. p1 and p2 are dome shaped, p3 is a short setae, and p4 is similar to the primary clava, consisting of a small papilla with a spiny tip. Cirri (internal, external, Aand E) are shorter in Neoechiniscoides (range unadjusted for body size 3.0–8.7, 3.0–7.6, 10.0– 17.0 and 10.0–18.0 µm, respectively) compared with Isoechiniscoides (range unadjusted for body size 7.3– 12.0, 6.6–9.7, 14.5–21.0 and 24.0–33.0 µm, respectively), but generally longer than cirri of Echiniscoides. Specifically, cirri are longer in N. aski and N. pollocki than in Echiniscoides, but N. horningi falls within the range of Echiniscoides, which has an internal, external, Aand Ecirri length unadjusted for body length of 3.1– 4.8, 2.2–3.8, 8.3–13.0 and 7.5–12.0 µm, respectively, according to Kristensen & Hallas (1980). The anal system (Fig. 6) of Neoechiniscoides differs from that of Echiniscoides and Isoechiniscoides, specifically in the paired wings associated with the lateral lobes of the anus (wl in Figs 2, 4). Using light microscopy, the lateral anal lobes thus appear as a double structure. In scanning electron microscopy, these anal lobes appear as a double swollen structure, which can be observed when viewed dorsocaudally. Interestingly, during sampling we observed that the movements of the new interstitial Neoechiniscoides species were more similar to slowly moving eutardigrades than to other members of Echiniscoididae. Notably, specimens of the new species, N. aski, were highly responsive to freshwater shocking, which resulted in a fast gain of body water and associated swelling.
Generic discussion: The molecular phylogenetic investigation of Echiniscoididae reveals several possibly undescribed taxa. Here, we establish the new genus Neoechiniscoides, with its members morphologically clearly distinguishable from the other taxa in Echiniscoididae. The wing structure of the lateral anal lobes is not present in other heterotardigrades. We acknowledge that a cautious approach should be taken to morphological structures with regard to their significance at a specific taxonomic level at this early stage of echiniscoidid revision. Hence, characteristics of the anal system might, in the future, have significance at a higher taxonomic level.
description: Published as part of Møbjerg, Nadja, Jørgensen, Aslak & Kristensen, Reinhardt M., 2020, Ongoing revision of Echiniscoididae (Heterotardigrada: Echiniscoidea), with the description of a new interstitial species and genus with unique anal structures, pp. 663-680 in Zoological Journal of the Linnean Society 188 (3) on pages 668-669, DOI: 10.1093/zoolinnean/zlz122, http://zenodo.org/record/4623663