Sisubiotus hakaiensis, Vecchi & Choong & Calhim, 2022

Vecchi, Matteo, Choong, Henry & Calhim, Sara, 2022, Sisubiotus hakaiensis sp. nov. (Tardigrada, Macrobiotidae), a new tardigrade species from Calvert Island (British Columbia, Canada), European Journal of Taxonomy 823 (1), pp. 64-81 : 69-75

publication ID	https://doi.org/ 10.5852/ejt.2022.823.1815
publication LSID	lsid:zoobank.org:pub:7A993025-6C28-4B38-98C7-683CD96E7885
DOI	https://doi.org/10.5281/zenodo.6640164
persistent identifier	https://treatment.plazi.org/id/837BB60F-E17A-4023-959B-EA6E4169198B
taxon LSID	lsid:zoobank.org:act:837BB60F-E17A-4023-959B-EA6E4169198B
treatment provided by	Felipe
scientific name	Sisubiotus hakaiensis
status	sp. nov.

Treatment

Sisubiotus hakaiensis View in CoL sp. nov.

urn:lsid:zoobank.org:act:837BB60F-E17A-4023-959B-EA6E4169198B

Figs 2–5 View Fig View Fig View Fig View Fig , Tables 2–3 View Table 2 View Table 3

Differential diagnosis

Reliable differences in differentiating the animal morphology between different species of Sisubiotus were not found. By the presence of a labyrinthine layer in the egg processes walls, S. hakaiensis sp. nov. can be easily differentiated from S. spectabilis , S. grandis and S. wuyishanensis (labyrinthine layer absent in these three species). In addition, S. hakaiensis differs from S. wuyishanensis by the presence of granulation on legs (present in S. hakaiensis vs absent in S. wuyishanensis ) and by the shape of the egg processes walls (straight to slightly sigmoidal in S. hakaiensis vs concave in S. wuyishanensis ).

Etymology

This species name refers to the Hakai Institute, which conducts and advances long-term scientific research at remote locations at the coastal margin of British Columbia, Canada, and which includes the Calvert Island Field Station from where the samples were collected.

Material examined

58 animals and 3 embryonated eggs. Specimens mounted on microscope slides in Hoyer’s medium (55 animals + 3 embryonated eggs) and processed for DNA sequencing (3 animals).

Holotype CANADA – British Columbia • Lookout, Calvert Island, British Columbia ; 51°38′54″ N, 128°8′38″ W; 40 m a.s.l.; 29 Jun. 2021; Gillian Sadlier-Brown leg.; moss on rock; JYUt.S1911_SL5_B. GoogleMaps

Paratypes CANADA – British Columbia • 35 animals; Lookout, Calvert Island, British Columbia ; 51°38′54″ N, 128°8′38″ W, 40–50 m a.s.l.; 15 Jun. 2018, 29 Jun. 2021; Henry Choong & Gillian Sadlier-Brown leg.; moss on rock; JYVt.S418_SL2 , JYVt.S1911_SL1 to SL6 GoogleMaps • 19 animals; same collection data as for preceding; RBCM.S1911_SL9 , SL_10 (RBCM 022-00001-002) GoogleMaps • 2 embryonated eggs; same collection data as for preceding; JYVt.S418_SL1 GoogleMaps • 1 embrionated egg; same collection data as for preceding; RBCM.S1910_SL2_A (RBCM 022-00001-001) GoogleMaps .

Voucher specimens are deposited in the Natural history collections of the Jyväskylä University Museum, Ihantolantie 5, Jyväskylä, Finland ( JYV), Survontie 9, 40520 Jyväskylä, Finland (Slides JYVt.S1911_ SL5, JYVt.S418_SL1-2, JYVt.S1911_SL1 to SL6) and in the Invertebrate Zoology Department, Royal BC Museum ( RBCM), 675 Belleville Street, Victoria, BC, Canada ( RBCM.S1910_SL2 ( RBCM 022- 00001-001), RBCM.S1911_SL9, SL10 ( RBCM 022-00001-002)).

Description

Animals (measurements and statistics in Table 2 View Table 2 )

Body whitish; after fixation in Hoyer’s medium body transparent ( Fig. 2A View Fig ). Eyes present in animals before and after fixation in Hoyer’s medium. Cuticle poreless. Patches of fine granulation on the internal and external surfaces of legs I–III ( Fig. 2B–C View Fig ) as well as dorsal and dorso lateral of legs IV clearly visible in PCM ( Fig. 2D View Fig ). A pulvinus is present on the internal surface of legs I–III ( Fig. 2B View Fig ). Claws slender, of the hufelandi type. Primary branches with distinct accessory points, a long common tract, and with an evident stalk connecting the claw to the lunula ( Fig. 3 View Fig ). All lunulae smooth ( Fig. 3A, D View Fig ). Single cuticular bar on legs I–III often visible in PCM ( Fig. 3C View Fig ), whereas the horseshoe-shaped structure under claws IV poorly visible only in PCM ( Fig. 3D View Fig ). Mouth antero-ventral. Bucco-pharyngeal apparatus of the Macrobiotus type ( Fig. 4A View Fig ), with the ventral lamina and ten peribuccal lamellae. Pharyngeal bulb spherical, with trapezoidal apophyses with a median constriction, two rod-shaped macroplacoids and a large microplacoid positioned close to them; Fig. 4B–C View Fig ). The macroplacoid length sequence is 2<1. The first macroplacoid is anteriorly narrowed and constricted in the middle whereas the second has a sub-terminal constriction ( Fig. 4B–C View Fig ). The oral cavity armature well developed and composed of three bands of teeth, always clearly visible under PCM ( Fig. 4D–E View Fig ). The first band of teeth is composed of numerous small teeth visible in PCM as granules ( Fig. 4D–E View Fig ), arranged in several rows, situated anteriorly in the oral cavity, which start behind the bases of the peribuccal lamellae and extend on the lamellae bases. The second band of teeth is situated between the ring fold and the third band of teeth and comprised of 3–4 rows of teeth visible in PCM as granules ( Fig. 4D–E View Fig ) larger than those in the first band. The most anterior row of teeth within the second band comprises larger and longitudinally elongated teeth than the subsequent posterior rows ( Fig. 4D–E View Fig ). The teeth of the third band are located within the posterior portion of the oral cavity, between the second band of teeth and the buccal tube anterior ending ( Fig. 4D–E View Fig ). The third band of teeth is divided into the dorsal and the ventral portion. Under PCM, both bands are divided into three distinct transverse ridges, with the medio-dorsal larger than the medio-ventral one. In some specimens, additional mucrones can occur behind the medio-ventral ridge ( Fig. 4E View Fig ). Typically-shaped stylet furca, with spherical condyles supported by short branches provided with small apophyses ( Fig. 4A View Fig ).

Eggs (measurements and statistics in Table 3 View Table 3 )

Laid freely, white, spherical with large conical processes, areolated ( Fig. 5A View Fig ). About ten processes on the circumference. Each process is surrounded by usually eight to twelve deep areolae. Usually, two rows of areolae are present between the neighboring processes ( Fig. 5A View Fig ). The areolae rims are thin and high, and the areolae surface is reticulated ( Fig. 5B View Fig ). The labyrinthine layer between the process walls present and composed by a very fine mesh ( Fig. 5C–D View Fig ). Processes walls straight to slightly sigmoidal, and processes tips usually blunted or flat ( Fig. 5C–D View Fig ).

Reproduction

The examination of animals freshly mounted in Hoyer’s medium revealed the presence of testis filled with sperm, so this species can be considered gonochoric.

DNA sequences

Sequences from 3 individuals from sample S1911 were obtained. 18S rRNA (3 sequences: OM523054 View Materials - 6); 28S rRNA (3 sequences: OM523059 View Materials -61); COI (2 sequences: OM523181 View Materials -2); ITS2 (2 sequences: OM523057 View Materials -8).