Sisubiotus hakaiensis Vecchi & Choong & Calhim 2022, sp. nov.
Creators: name: Vecchi, Matteo
name: Choong, Henry
name: Calhim, Sara
Publisher: name: Zenodo
Year: 2022
Subjects: Biodiversity
Taxonomy
Animalia
Tardigrada
Eutardigrada
Parachela
Macrobiotidae
Sisubiotus
Sisubiotus hakaiensis

description: Sisubiotus hakaiensis sp. nov.
urn:lsid:zoobank.org:act: 837BB60F-E17A-4023-959B-EA6E4169198B
Figs 2–5, Tables 2–3
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.
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 • 19 animals; same collection data as for preceding; RBCM.S1911_SL9, SL_10 (RBCM 022-00001-002) • 2 embryonated eggs; same collection data as for preceding; JYVt.S418_SL1 • 1 embrionated egg; same collection data as for preceding; RBCM.S1910_SL2_A (RBCM 022-00001-001).
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)
Body whitish; after fixation in Hoyer’s medium body transparent (Fig. 2A). 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) as well as dorsal and dorso lateral of legs IV clearly visible in PCM (Fig. 2D). A pulvinus is present on the internal surface of legs I–III (Fig. 2B). 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). All lunulae smooth (Fig. 3A, D). Single cuticular bar on legs I–III often visible in PCM (Fig. 3C), whereas the horseshoe-shaped structure under claws IV poorly visible only in PCM (Fig. 3D). Mouth antero-ventral. Bucco-pharyngeal apparatus of the Macrobiotus type (Fig. 4A), 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). 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). The oral cavity armature well developed and composed of three bands of teeth, always clearly visible under PCM (Fig. 4D–E). The first band of teeth is composed of numerous small teeth visible in PCM as granules (Fig. 4D–E), 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) 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). 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). 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). Typically-shaped stylet furca, with spherical condyles supported by short branches provided with small apophyses (Fig. 4A).
Eggs (measurements and statistics in Table 3)
Laid freely, white, spherical with large conical processes, areolated (Fig. 5A). 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). The areolae rims are thin and high, and the areolae surface is reticulated (Fig. 5B). The labyrinthine layer between the process walls present and composed by a very fine mesh (Fig. 5C–D). Processes walls straight to slightly sigmoidal, and processes tips usually blunted or flat (Fig. 5C–D).
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 - 6); 28S rRNA (3 sequences: OM523059 -61); COI (2 sequences: OM523181 -2); ITS2 (2 sequences: OM523057 -8).
description: Published as part of Vecchi, Matteo, Choong, Henry & Calhim, Sara, 2022, Sisubiotus hakaiensis sp. nov. (Tardigrada, Macrobiotidae), a new tardigrade species from Calvert Island (British Columbia, Canada), pp. 64-81 in European Journal of Taxonomy 823 (1) on pages 69-75, DOI: 10.5852/ejt.2022.823.1815, http://zenodo.org/record/6639278