Austeruseus faeroensis

Trygvadóttir, Birna Vár & Kristensen, Reinhardt Møbjerg, 2011, Eohypsibiidae (Eutardigrada, Tardigrada) from the Faroe Islands with the description of a new genus containing three new species, Zootaxa 2886, pp. 39-62 : 45-46

Austeruseus faeroensis nov. sp.

( Figures 4–8 )

Type material. The holotype (slide FO30-005 [ZMUC-TAR 1068]), 2 paratypes (slides FO30-010c and FO30- 011-012b [ZMUC-TAR 1069 and ZMUC-TAR 1071]) and one embryonated egg (slide FO30-011b [ZMUC-TAR 1070]). The slides are deposited in the Zoological Museum, the Natural History Museum of Denmark, University of Copenhagen, Copenhagen, Denmark.

Type locality. Summit of Vaðhorn mountain, Eysturoy, Faroe Islands ( Fig. 1 B). The sample was a large moss cushion with underlying soil. GPS: 62°16.909’N, 7°00.349’W. Altitude 726 m a.s.l. Date: 20 November 2003. Coll.: Regin Árting.

Additional material. One specimen (F036-011 [ZMUC-TAR-1072]) was found at “Hvannhagi”, Suðuroy, Faroe Islands. The sample was a large moss cushion. GPS: 61°34.375’N, 6°49.576’W. Altitude 200 m a.s.l. Date: 24 September 2004. Coll.: Uni Árting.

Etymology. A. faeroensis is named after the type locality on Faroe Islands.

Specific diagnosis. Medium sized animals with two macroplacoids (the first broken in the middle) and microplacoid. Large black eyes present. Ventral strengthening bar absent; however, a complex of three cuticular elements and two thin filaments are attached ventral to the buccal tube. Two hook-shaped appendages for insertion of the stylet muscles attached laterally on the buccal tube. Two rows of teeth in the buccal cavity. Cuticular bars present on legs I–III (at least the first bar appears dotted). Lunules on fourth pair, dentate.

Description. Holotype (adult male) ( Fig. 4 ): Body length, 411.7 µm (body length for paratypes range from 254.8–329.5 µm). Eyes present. The cuticule smooth. The buccal tube without ventral strengthening bar and 34.4 µm long and 4.0 µm wide. A complex of three small lens-shaped cuticular elements and two filaments replace the ventral strengthening bar ( Fig. 5 A). The two filaments (which may be of a cuticular origin) run parallel with the stylets. The buccal tube with two lateral hook-shaped appendages. Mouth opening with 14 peribuccal lamellae, and two bands of teeth in the buccal cavity. First band of infrabuccal teeth comprised of three irregular rows of small teeth (mucrones) (one paratype with 5 irregular rows in the first row). Second band of infrabuccal teeth comprise a single row of large indented teeth, with the two largest in the middle. Third band of infrabuccal teeth absent. Stylet supports are inserted on the buccal tube at 26.7 µm of its length. Stylets are robust, straight, only bent at the caudal end (immediately before the furcae). Pharyngeal bulb oval. Triangular pharyngeal apophyses present (in one paratype the apophyses can be seen constricted near the caudal-most point, with the appearance of an uvula). Two macroplacoids and a microplacoid present. First macroplacoid, the longest (9.5 µm), was broken in the middle, second macroplacoid, 4.7 µm long. Microplacoid circular in shape, 2.1 µm long.

Claws of the Eohypsibiidae type with two accessory points on the primary branches. Claws on the fourth pair of legs were the largest. Large smooth lunules at the base of all claws on legs I–III; lunules weakly dentate on the fourth pair of legs. Cuticular bars present on legs I–III and at least on the first pair the bars appeared pitted.

A single egg with an embryo inside, deposited free, was found and is attributed to this species ( Figs. 6 & 7 D– E). Egg diameter, 76.1 µm without the processes. Egg processes very variable in length, with mean length of the processes c. 8.2 µm (see illustration, Figs. 6 A–B). Egg processes are mammiform with separate cells (from one to six) forming long tails. Base of the processes surrounded by a ring of small circles, more or less irregular in size and number. Egg surface between the processes, smooth.

Figures

FIGURE 4. Austeruseus faeroensis, nov. gen. et nov. sp, holotype (male), habitus in ventral view (scale bar 100 μm). Abbreviations: b: brain, c: cloaca, cg: claw gland, co: coelomocytes, e: eyespot, mg: midgut, mt: malphigian tubules, sg: salivary gland, t: testis. Drawing by Stine Elle.

FIGURE 5. Austeruseus faeroensis, nov. gen. et nov. sp. A: ventral view of bucco-pharyngeal apparatus. B: claws on leg I. C: claws on leg IV. Abbreviations: a: apophyses for insertion of the stylet muscles, ap: bulb apophyses, bt: buccal tube, cu: cuticular bar, f: furca, l: peribuccal lamellae, m 1: first macroplacoid, m 2: second macroplacoid, mi: microplacoid, r 1: first row of teeth, r 2: second row of teeth, s: stylet, sh: stylet sheath, ss: stylet support. Scale bars 10 μm. Drawings by Birgitte Rubaek.

FIGURE 6. Austeruseus faeroensis, nov. gen. et nov. sp. A: egg ornamentation. B: embryo inside of egg. Scale bars 20 μm. Drawings by Birgitte

FIGURE 7. Austeruseus faeroensis, nov. gen. et nov. sp., paratypes (LM). A: habitus (scale bar 100 µm). B: Eohypsibiidae-type claws from leg I and II (scale bar 50 µm). C: bucco-pharyngeal apparatus (scale bar 20 µm). D: egg with mammiform processes (scale bar 50 µm). E: embryo visible inside egg (photo-reconstruction by Birgitte Rubaek, scale bar 20 µm).

FIGURE 8. Austeruseus faeroensis, nov. gen. et nov. sp., live male holotype (LM). A – B: habitus (scale bar 200 μm and 100 μm respectivly). C – D: different phocal planes of bucco-pharyngeal apparatus, ventral view. E: claws of legs III, t: testis. F: claws on legs IV, arrows: malphigian tubules (C – F scale bars 50 μm).

FIGURE 1. A: Map overview of the Faroe Islands with the sampled stations (black triangles). B: Vaðhorn, to the right, type locality of Austeruseus faeroensis, nov. sp. and type species for the new genus (photo courtesy: KT Depilin). C: Sornfelli mountain on Streymoy, type locality of Austeruseus rokuri nov. sp. (white squares indicate the sample sites) (photo courtesy: the Faroese Earth & Energy Directorate).