Rugiloricus sp. 2

Sørensen, Martin V., Herranz, Maria, Grzelak, Katarzyna, Shimabukuro, Mauricio, Kristensen, Reinhardt M. & Zeppilli, Daniela, 2023, Living on the edge - first survey of loriciferans along the Atacama Trench, European Journal of Taxonomy 879 (1), pp. 162-187 : 179-180

Rugiloricus sp. 2

Fig. 10D–F

Material examined

CHILE • 2 Higgins larvae; continental slope off Iquique, and near the Atacama Trench ; st. 9; 20°19.97ʹ S, 70°58.70ʹ W; depth 4050 m; 28 Mar. 2018; R / V Sonne SO261; deep-sea mud; mounted for LM in Fluoromount G on HS slide; NHMD 1177418 to 1177419 • 1 adult of uncertain sex; continental slope off Iquique, and near the Atacama Trench ; st. 9; 20°19.97ʹ S, 70°58.70ʹ W; depth 4050 m; 28 Mar. 2018; R / V Sonne SO261; deep-sea mud; mounted for LM in Fluoromount G on HS slide; see also Table 1 and Fig. 1 ; NHMD 1177420 .

Short description of Higgins larvae and adult

One Higgins larva (NHMD 1177419) was so strongly contracted that it did not offer any significant information. The shape of the toes suggested though, that it is conspecific with the other, stretched and more well-preserved Higgins larva (NHMD 1177418). This larva has a fully protruded head and thin lorica with irregular, longitudinal folds ( Fig. 10E–F ). Body length (exclusive toes) is 140 µm, and maximum width in the anterior part of the trunk is 48 µm. The introvert has five rows of scalids, with clavoscalids in the anterior row and scalids composed of two elongate, articulating units in Rows 2 to 4. Row 5 has short scalids formed by a proximal plate, with a short, flexible distal appendage. A short, hook-shaped scalid is present middorsally, posterior to Row 5. All setae on the lorica are thin, flexible and unbranched. Anterior setae are long (anterolateral seta length = 38 µm; anteroventral seta length = 40 µm), whereas the two posterior pairs are considerably shorter (posterodorsal seta length = 25 µm; posterolateral seta length = 12 µm). Terminal setae are absent. Each toe is 27 µm long and consists of an only slightly tapering proximal part, with a hollow cavity, and a compact distal part that tapers towards its terminal tip.

The adult specimen ( Fig. 10D ) is strongly contracted, which prevents any examination of the head structures. The lorica is 133 µm long and has a maximum width of 114 µm. The lateral and dorsal sides have about 32 plicae, whereas the ventral side has a larger, midventral field with five transverse folds, formed by the fusion of six to eight plicae. Plicae are also fused in the posterior part of the lorica, which seems to have about 12 triangular fields, which all point towards the terminal tip of the lorica.

Figures

Fig. 10. Light micrographs showing overviews of unidentified specimens. A. Pliciloricus sp. Higgins larva from st. 7, lateral view (NHMD 1177415).B. Rugiloricus sp. 1 Higgins larva, ventral view (NHMD 1177416); inset shows close-up of plate-like toe bases with serrated margins. C. Rugiloricus sp. 1 postlarva with developing adult inside, focused medially in specimen (NHMD 1177417). D. Rugiloricus sp. 2 adult, lateral view with dorsal left and ventral right (NHMD 1177420). E. Rugiloricus sp. 2 Higgins larva, dorsal view (NHMD 1177418). F. Same, ventral view.

Fig. 1. Map showing the three stations near the Atacama Trench where loriciferans were collected. Station numbers refer to Grzelak et al. (2021).