Echiniscidae Thulin, 1928

Family: Echiniscidae Thulin, 1928 View in CoL

Genus: Echiniscus C.A.S. Schultze, 1840 (amended by Gąsiorek et al., 2017)

Species: Echiniscus quasiporus sp. nov.

( Table 3; Figs. 1 View Fig , 2 View Fig , 3 View Fig , 4 View Fig , 5 View Fig , and 6)

ZooBank registration: https://zoobank.org/ 4F7CFD71- CCE6-46FC-BC50-019F4E13AAF1

Type locality: 10°08′23″N, 77°05′53″E, 1 915 m asl: Asia, India, Western Ghats, Kannan Devan Hills , Kerala and Tamil Nadu, Nilgiris , Ooty ; moss on soil (see also Table 1) GoogleMaps .

Females: Barrel-shaped body. Yellow to dark orange body colour with red granulate eyes when alive ( Fig. 1A View Fig ). The pigment dissolves in a few days in Hoyer’s medium and animals become colourless and transparent ( Fig. 1B View Fig ). Primary and secondary clavae of a typical Echiniscus - type. Peribuccal cirri embedded in bulbous cirrophores ( Fig. 1B–C View Fig ). Cirrus A short (cirrus A /body length ratio <20%) and with an evident, conical cirrophore ( Figs. 1B–C View Fig and 2A View Fig ). Body appendage configuration A-(B)-(B) d -C-C d -D-D d -E ( Fig. 1B–C View Fig ). Asymmetries frequent, and rarely, some appendages absent.

Dorsal plate sculpture ( Figs. 2 View Fig , 3 View Fig , and 4) superficially similar to the Echiniscus blumi-canadensis type. However, an SEM examination of dorsal plate sections ( Fig. 4 View Fig ) revealed that in contrast to the blumi-canadensis sculpturing, the new species does not exhibit true pores (i.e. holes in the exocuticle that penetrate down to the surface of endocuticle and connect the environment with the mesocuticular cavity network, i.e. spaces between mesocuticular pillars), but deep cavities in exocuticle which are indistinguishable from pores under LCM and regular SEM observations of cuticle surface, but which do not connect the environment with the mesocuticular cavity network. To account for this new type of cuticular sculpturing, we name these epicuticular cavities as quasipores (see section Types of cuticular puncturing in Echiniscidae below for more details). When focusing down from the cuticle surface to mesocuticle in PCM ( Fig. 3A–G View Fig ), quasipores appear as bright spots (indistinguishable from true pores) connected with faint dark striae ( Fig. 3A View Fig ). Then, striae disappear and a polygonal dark rim around each quasipore becomes prominent ( Fig. 3B–C View Fig ). The polygonal rims are separated with a brighter strip ( Fig. 3C View Fig ). Focusing further down, dark rims separate into a polygonal outline composed of multiple dark spots ( Fig. 3D–E View Fig ). Finally, these dark spots disappear, and the rim of the quasipores becomes fainter, but in a centre of each quasipores, a conspicuous dark dot appears ( Fig. 3F–G View Fig ). In NCM ( Fig. 3H–N View Fig ), the sculpture appears similar as in PCM, except the striae are not detectable ( Fig. 3H View Fig ) and dark polygonal rims are visible as a polygonal network ( Fig. 4I–J View Fig ). In SEM ( Fig. 4A View Fig ), cuticle surface is smooth (no epicuticular granulation or other sculpturing), with regularly distributed roundish-polygonal holes of varying size and with sharp edges (indistinguishable from true pores). Based on SEM observations of dorsal plate sections ( Fig. 4 View Fig ), we interpret the dark polygonal rims and their bright outlines ( Fig. 3B–C View Fig ) as areas of more and less cuticular matrix, respectively. Furthermore, multiple dark dots forming the dark rims ( Fig. 3D–E View Fig ) are probably areas of denser cuticular microfilaments/microfibers which form the cuticular matrix ( Fig. 4B–C View Fig ). Finally, the dark dot in the centre of a quasipore ( Fig. 3F–G View Fig ) is a large mesocuticular pillar situated under the quasipore.

Roundish-polygonal quasipores are larger in the centres of the plates and gradually decrease in diameter towards plate edges and become large dark dots which are mesocuticular pillars without a quasipore above and hence are visible only in PCM ( Fig. 2 View Fig ) and in SEM cross-sections ( Fig. 4D View Fig ). Cephalic plate consists of two halves with an anterior chalice-like incision. The cervical plate appears as a belt with mesocuticular pillars clearly visible as dark dots only in PCM ( Fig. 2A View Fig ) and rarely with minute quasipores visible only in SEM in some specimens ( Figs. 1C View Fig and 2B View Fig ). Scapular plate non-facetted with the hinged rectangular lateral shoulder platelets ( Figs. 1C View Fig and 2A–B View Fig ). Three median plates; m1 and m3 unipartite, plate m2 bipartite ( Figs. 1C View Fig and 2C–F View Fig ); sculpture well developed with larger quasipores in the m1 and in the posterior portion of the m2. Sculpture is reduced with smaller quasipores and less prominent darker polygonal rim on the anterior portions plate. E–F Caudal plate. The flat arrowhead indicates the large quasiporus, whereas the indented arrowhead indicates mesocuticular pillars not terminated with quasipores. Scale bars: in μm

of the m2 and the m3 ( Fig. 2C–F View Fig ). The view of the third median plate sometimes reduced to a narrow strip due to the overlapping of the posterior part of the second pair of paired segmental plates and the anterior part of the caudal plate. Two pairs of large segmental plates, with their narrower anterior portions having two thin belts (or only one belt arrowhead with white borders indicates a dark polygonal rim around a quasipore, the white flat arrowhead with black borders indicates the dark dots of polygonal rims (probably represented by denser cuticular filaments/fibres), and white indented arrowheads with black borders indicates the large mesocuticular pillars under the quasipores. Scale bars: in μm (all photographs are at the same scale)

in some specimens) devoid of sculpture ( Figs. 1B–C View Fig and 2C–D View Fig ). The caudal (terminal) plate with evident incisions ( Figs. 1B–C View Fig and 2E–F View Fig ) and often facetted ( Figs. 1B–C View Fig and 2E–F View Fig ). Ventral plates present, not always well visible under PCM especially in well-stretched specimens but clearly visible under the SEM ( Fig. 5C View Fig ). Subcephalic and genital plates are more developed than other plates ( Fig. 5C View Fig ). Ventral cuticle densely granulated with minute mesocuticular pillars, very well visible in the subcephalic and gonopore region ( Fig. 5C View Fig ). Pulvini present on legs I–III ( Figs. 1B–C View Fig and 5A–B View Fig ). Legs I with a minute spine ( Figs. 1B–C View Fig and 5A–B View Fig ), legs IV with a small papilla, both clearly visible in PCM and SEM ( Figs. 1B–C View Fig and 5A–B View Fig ). Pedal plates I–III C Cross section of quasipores (lateral view). D Cross section of dorsal cuticle without quasipores. White flat arrowheads with black borders indicate mesocuticular pillars. Scale bars: in μm

very weakly outlined and without pores (barely visible in PCM, better in SEM), but well developed with pores and a fringe composed of 8–12 large teeth on legs IV ( Fig. 5A–B View Fig ). Claws isometric, with spurs present on the internal claws of all legs (spur/claw branch length ratio at 20–31%) ( Fig. 5 View Fig ).