Testechiniscus meridionalis ( Murray, 1906 )

Gąsiorek, Piotr, Stec, Daniel, Zawierucha, Krzysztof, Kristensen, Reinhardt Møbjerg & Michalczyk, Łukasz, 2018, Revision of Testechiniscus Kristensen, 1987 (Heterotardigrada: Echiniscidae) refutes the polar-temperate distribution of the genus, Zootaxa 4472 (2), pp. 261-297 : 285

Autapomorphies of Testechiniscus meridionalis ( Murray, 1906) and T. macronyx ( Richters, 1907)

(measurements and statistics of juveniles and adult specimens of both sexes of T. meridionalis in Tables 10–12)

Both species assigned to the genus Testechiniscus by Kristensen (1987) and McInnes (1994a), respectively, exhibit unique phenotypic traits. Given that works on their systematic position are in progress (McInnes, personal communication), we do not designate them as new genera, but, instead, we present their autapomorphies, which exclude their affiliation within the revised Testechiniscus . Both species have brown lipoid or red eyes and are dioecious whereas Testechiniscus s.s. exhibits black crystalline eyes and parthenogenetic reproduction (although the presence of males was suggested in T. laterculus by Kathman & Dastych (1990)).

Moreover, T. meridionalis resembles Testechiniscus s.s. in having eight rows of ventral plates, however it differs from Testechiniscus s.s. by: a smaller body size, i.e. with adults not exceeding 200 µm (compare Figs 1A–B , 6A–B , 10A–C and 12A–B , see Tables 10–11), whereas adults of Testechiniscus spp. are typically 300–450 µm long; smaller ventral plates ( Figs 12C–D ) with minute cuticular pillars that are more like in the Bryodelphax weglarskae group (see Dastych 1984, Kaczmarek et al. 2012) rather than in Testechiniscus spp.; the dorsal sculpture consisting solely of granules ( Fig. 14E ) and never polygonal pores typical for Testechiniscus (e.g. Fig. 14A ); evident sexual dimorphism, i.e. cephalic papillae and primary clavae are significantly longer in males than in females (one-tailed Welch t -test for: cephalic papillae: t 3=4.07, p=0.013, and primary clavae: t 3=4.14, p=0.013, compare also Figs 12A, D , arrowheads).

Finally, T. macronyx differs from the revised Testechiniscus by: a smaller body size (i.e. below 200 µm); the presence of only lateral, exceptionally long cirri A ( Fig. 13A ); nine (instead of eight) rows of small ventral plates (configuration IX:2-5-5-2-4-4-4-1-2, Fig. 13B ); dorsal sculpture in the form of an irregular reticulum/pseudopores (see McInnes 1994a), that look like dark margins of minute bright depressions on the cuticle surface ( Fig. 14F ); and by considerably longer claws, curved slightly only in their terminal parts.

Figures

FIGURE 1. Testechiniscus spitsbergensis spitsbergensis (Scourfield, 1897), habitus under PCM: A—adult female with short cirri (dorsal view, neotype); B—adult female with typically developed ventral plates (ventrolateral view, neoparatype); Cadult female with long cirri from Scotland (Echiniscus spinuloides sensu Murray 1907, dorsal view, the arrowhead indicates an aberrant cirrus in position B d); D—adult female with weakly developed ventral plates; E—sexually immature female with welldeveloped ventral plates (neoparatype); F—sexually immature female (neoparatype, Roman numerals indicate rows of ventral plates); G—larva (dorsolateral view, neoparatype); H—larva (ventrolateral view, neoparatype). All but C–D from Spitsbergen. Scale bars in micrometres.

FIGURE 6. Testechiniscus spitsbergensis tropicalis ssp. nov., habitus under PCM: A—adult female (dorsolateral view, holotype); B—larva (dorsolateral view, paratype). All from Ethiopia. Scale bars in micrometres.

FIGURE 10. Testechiniscus laterculus (Schuster et al., 1980), paratype habitus under PCM: A—dorsal view; B—lateral view; C—ventral view (Roman numerals signify rows of ventral plates); D—anterior body part (Roman numerals signify rows of ventral plates, arrowheads indicate dim pulvini at the leg bases, and the empty arrowhead indicates spine I). All from the USA. Scale bars in micrometres.

FIGURE 12. Testechiniscus meridionalis (Murray, 1906), habitus under PCM: A—female, dorsal view (arrowheads indicate cephalic papillae, and empty arrowheads indicate primary clavae); B—female, ventral view (Roman numerals signify rows of ventral plates); C—female, anterior body part (Roman numerals signify rows of ventral plates and arrowheads indicate cephalic papillae); D—male, ventral view (arrowheads indicate prominent cephalic papillae, and empty arrowheads indicate prominent primary clavae). All from the Antarctic. Scale bars in micrometres.

FIGURE 13. Testechiniscus macronyx (Richters, 1907), general habitus (from McInnes 1994a): A—dorsal view; B—ventral view.

FIGURE 14. Sculpture types within the genus Testechiniscus sensu lato, scapular plates under PCM: A—spitsbergensis subtype (polygons); B—spitsbergensis subtype at a different focusing level; C—laterculus subtype (polygons); D—laterculus subtype at a different focusing level; E—meridionalis subtype (granules); F—macronyx subtype (irregular reticulum/ pseudopores, DIC). Scale bars in micrometres.