Rugiloricus sp. 1

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

Rugiloricus sp. 1

Fig. 10B–C

Material examined

CHILE • 1 Higgins larva; abyssal plain, on the west side of the Atacama Trench ; st. 7; 22°56.22ʹ S, 71°37.08ʹ W; depth 5500 m; 20 Mar. 2018; R / V Sonne SO261; deep-sea mud; mounted for LM in Fluoromount G on HS slide; NHMD 1177416 • 1 postlarva containing a developing adult; abyssal plain, on the west side of the Atacama Trench ; st. 7; 22°56.22ʹ S, 71°37.08ʹ W; depth 5500 m; 20 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 1177417 .

Short description of Higgins larva and postlarva

The Higgins larva ( Fig. 10B ) is strongly contracted (length =136 µm and width =97 µm). The lorica has longitudinal folds, but the exact number of folds could not be determined. Anterolateral setae are thin and unbranched (length=56 µm); anteroventral setae were not observed. Posterior setae are also thin, flexible and unbranched, with long posterodorsal setae (length=34 µm) and much shorter posterolateral ones (length= 12 µm). Terminal setae are not present. The toes are the most remarkable trait in the larva. Each toe consists of a cylindrical proximal part (length =14 µm) and a gradually tapering distal part (length=21 µm). The toes reach their maximum width in the transition point from cylindrical to tapering, and these medial thickenings give the toes their peculiar appearance ( Fig. 10B ). The entire cylindrical proximal part and half of the tapering part are hollow, and likely to contain some glandular tissue; the distal tips are compact. Ventrally, the toe bases are supported by plate-like extensions with serrated posterior margins ( Fig. 10B inset).

The postlarva ( Fig. 10C ) is made up by a simple cuticle without any visible structures or ornamentation (length =188 µm and width= 118 µm). It contains an adult at a very early developmental stage. The adult trunk is nearly globular (diameter =100 µm) and contains mostly undifferentiated cells. The scalids of the introvert appear more developed and extend into the anterior part of the postlarval cuticle. They are long and slender, with the typical appearance of adult scalids, stressing that the specimen in the postlarval cuticle is not another larval stage.

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).