Austeruseus balduri

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 : 49-52

Austeruseus balduri nov. sp.

( Figures 9–15 )

Type material. The holotype (slide FO15-004 [ZMUC-TAR-1073]), 4 paratypes and 7 eggs (slides FO15-001a, - 001b, -002c, -003a, -003b, -005a, -005b and -019 [ZMUC-TAR-1074 to ZMUC-TAR-1078]). The slides are deposited in the Zoological Museum, the Natural History Museum of Denmark, University of Copenhagen, Copenhagen, Denmark.

Type locality. “Úti á Trøð”, Vágoy, Faroe Islands. The sample was a moss cushion growing on rock. GPS: 62°02.775’N, 7°07.996’W. Altitude 110 m a.s.l. Date: 10 March 2002. Coll.: Birna V. Trygvadóttir.

Additional material. Two specimens (FO1A-001a and -001b [ZMUC-TAR-1079]) found at Sornfelli mountain, Streymoy, Faroe Islands. Moss cushion. GPS: 62°04.757’N, 6°57.843’W. Altitude 640 m a.s.l. Date: 6 July 2001. Coll.: Birna V. Trygvadóttir & Reinhardt M. Kristensen.

Etymology. A. balduri is named after BVT’s eldest son Baldur.

Specific diagnosis. Small animals with two macroplacoids (the first broken in the middle) and microplacoid. Eyes present. Body broadest at the third pair of legs, tapering to rostral and caudal extremities. Ventral strengthening bar absent. Two lateral hook-shaped appendages present on the buccal tube. Small eohypsibiid type claws. Cuticular bars on legs I–III. Able to extend and retract the buccal/pharyngeal apparatus telescopically.

Description. Holotype (young female) ( Fig. 9 ): Body length, 326.5 µm (length of paratypes, 236.0–376.5 µm). Eyes present. Body broadest at the level of the third pair of legs tapering to anterior and caudal extremities. Cuticle with transverse bands of minute dots. Ventral strengthening bar absent. Two lateral hook-shaped appendages for insertion of the stylet muscles. Buccal tube, 28.8 µm long and 2.4 µm wide. Mouth opening with 14 peribuccal lamellae. Two bands of teeth in the buccal cavity. First band of infrabuccal teeth, immediately behind the lamellae, comprised of five rows of small teeth (juveniles may have only three rows). Second band of infrabuccal teeth comprise a single row of teeth which forms an arch (viewed ventrally or dorsally) across the bottom of the buccal cavity ( Figs. 10 & 12 ). Third band of infrabuccal teeth absent. Stylet sheaths are visible even in polyvinyl lactophenol mounted specimens. Stylets are robust, straight, only bent caudally. Stylet supports are inserted on the buccal tube at 20.9 µm. Pharyngeal apophyses, two macroplacoids and a microplacoid present in the pharynx. First macroplacoid, 6.1 µm long and broken c. 60% of its length. Second macroplacoid, 3.6 µm long. Microplacoid, circular, 2.0 µm long. Pharyngeal bulb pear shaped.

This species is capable of extending and retracting the buccal apparatus, so the mouth opening protrudes forwards with a tube-like extension ( Figs. 14 D–F & 15A), while the rest of the apparatus is drawn forward, such that the pharyngeal bulb lies in front of the eyes (the normal position of the bulb would be behind the eyes).

The claws are of the Eohypsibiidae type with smooth lunules. The external claw larger than the internal, with the largest on the fourth pair of legs ( Fig. 11 B). Two accessory points present on primary branches. Cuticular bars present on legs I–III

Several eggs were found that do not belong to any other described species, and can probably be attributed to this species ( Figs. 11 C, 13B). None of the eggs were embryonate, so this needs to be confirmed. Eggs deposited free. Egg diameter between 68.6–92.5 µm without processes, process length 7.8–12.5 µm. Processes mammiform, with tips comprising 4–6 small cells. Base of the processes surrounded by a ring of small circles, with smooth surface between processes. The process tips exhibit a more regular number of cells (compartments) and therefore the length of the processes were more regular than the egg belonging to A. faeroensis .

Figures

FIGURE 9. Austeruseus balduri, nov. gen. et nov. sp., holotype (female), habitus in ventral view (scale bar 100 μm). Abbreviations: b: brain, c: cloaca, cg: claw gland, co: coelomocytes, cu: cuticular bars, e: eye spot, g: gonad, mg: midgut, mt: malphigian tubules, sg: salivary gland. Drawing by Stine Elle.

FIGURE 10. Austeruseus balduri, nov. gen. et nov. sp. Lateral view of bucco-pharyngeal apparatus (scale bar 10 μm). Abbreviations: a: apophyses and cuticular rod, bt: buccal tube, f: furca, h: hook-shaped appendage, l: peribuccal lamellae, m 1: first macroplacoid, m 2: second macroplacoid, mi: microplacoid, p: muscular sucking pharynx, r 1: first row of teeth, r 2: second row of teeth, ss: stylet sheath, su: stylet support. Drawings by Stine Elle.

FIGURE 11. Austeruseus balduri, nov. gen. et nov. sp. A: claws from leg I with cuticular bars and B: claws from leg IV (scale bar 20 μm). C: egg (scale bar 50 μm). Drawings by Stine Elle.

FIGURE 12. Austeruseus balduri, nov. gen. et nov. sp., holotype. Ventral view of bucco-pharyngeal apparatus (scale bar 10 μm). Drawing by Stine Elle.

FIGURE 13. Austeruseus balduri, nov. gen. et nov. sp. (LM). A: habitus, holotype (scale bar 100 µm). B: egg with mammiform processes. C: ventral view of bucco-pharyngeal apparatus, paratype. D: Eohypsibiidae-type claws from legs II and III, paratype (B – D scale bars 50 µm).

FIGURE 14. Austeruseus balduri, nov. gen. et nov. sp., live paratype (LM). A: habitus. B: large coelomocytes visible (A – B scale bars 100 µm). C: claws on leg IV and cuticle “ dots ”. D: ventral view of bucco-pharyngeal apparatus, normal position. E – F: extended buccal tube (C – F scale bars 50 µm).

FIGURE 15. Austeruseus balduri, nov. gen. et nov. sp. (SEM micrographs). A: overview, adult. Specimen infected by bacteria and shrinked. Note also the extended buccal tube (scale bar 100 µm). B: mouth opening with 13 lammelae, the 14 th is damaged (*) (scale bar 1 µm). C: claws of leg II, l: lunule, ac: accessory points, pc: primary branch, sc: secondary branch (scale bar 1 µm). D: claws and legs IV (scale bar 10 µm).