Macrobiotus annewintersae Vecchi & Stec, 2021

Vecchi, Matteo & Stec, Daniel, 2021, Integrative descriptions of two new Macrobiotus species (Tardigrada, Eutardigrada, Macrobiotidae) from Mississippi (USA) and Crete (Greece), Zoosystematics and Evolution 97 (1), pp. 281-306 : 281

publication ID

publication LSID

persistent identifier

taxon LSID

treatment provided by

Zoosystematics and Evolution by Pensoft

scientific name

Macrobiotus annewintersae Vecchi & Stec

sp. nov.

Macrobiotus annewintersae Vecchi & Stec sp. nov. Tables 3 View Table 3 , 4, Figures 1 View Figure 1 , 2 View Figure 2 , 3 View Figure 3 , 4 View Figure 4 , 5 View Figure 5 , 6 View Figure 6 , 7 View Figure 7 , 8 View Figure 8 , Suppl. material 1


We dedicate this species to MV friend and colleague Dr. Anne Winters, evolutionary ecologist, who collected the sample in which the new species was found.

Material examined.

146 animals and 56 eggs. Specimens mounted on microscope slides in Hoyer’s medium (93 animals + 38 eggs), fixed on SEM stubs (51+18), and processed for DNA sequencing (2+0).

Type locality.

32°21'05"N, 89°56'30"W; 106 m asl: suburban area of Jackson, Mississippi, USA; mixed leaf litter on ground; coll. December 2019 by Anne Winters.

Type depositories.

Holotype ♀ (slide US.084.01 with 10 paratypes) and 63 paratypes (slides: US.084.*, where the asterisk can be substituted by any of the following numbers: 02-05) and 20 eggs (slides US.084.*: 06-08) are deposited at the Institute of Zoology and Biomedical Research, Jagiellonian University (Gronostajowa 9, 30-387, Kraków, Poland). Additional paratypes (71 animals + 29 eggs) (slides: S207_SL*: 1-15; SEM stubs: S207_Stub*:1-4) are deposited at the Department of Biological and Environmental Sciences, University of Jyväskylä (Survontie 9C, 40500, Jyväskylä, Finland).

Description of the new species.

Animals (measurements and statistics in Table 3 View Table 3 ):

In live animals, body translucent in smaller specimens and opaque whitish in larger animals; transparent after fixation in Hoyer’s medium (Figure 1 View Figure 1 ). Eyes present in live animals and after fixation in Hoyer’s medium. Small roundish cuticular pores on the dorsal and lateral cuticle, as well as on the external cuticle of all legs (0.2-0.6 μm in diameter), visible under both PCM and SEM (Figures 1B, C View Figure 1 , 2D View Figure 2 ). On the dorsal surface, pores are absent between cuticle folds and arranged in loose belts (Figure 1C View Figure 1 ). Pores sparse on the ventral surface and visible only under SEM (Figure 8C View Figure 8 ). Patches of fine granulation, on the external surface of legs I-III as well as on the dorsal and dorso-lateral sides of legs IV, visible in PCM (Figure 2A, C View Figure 2 ) and SEM (Figure 2D View Figure 2 ). A pulvinus is present on the internal surface of legs I-III (Figure 2B, E View Figure 2 ).

Claws Y-shaped, of the Macrobiotus hufelandi type. Primary branches with distinct accessory points, a common tract, and an evident stalk connecting the claw to the lunula (Figure 3 View Figure 3 ). The lunulae I-III are smooth (Figure 3A, C View Figure 3 ), whereas lunulae IV are dentate (Figure 3B, D View Figure 3 ). A divided cuticular bar with double muscle attachments are poorly visible under PCM (Figure 3A View Figure 3 ).

Mouth antero-ventral. Bucco-pharyngeal apparatus of the Macrobiotus type (Figure 4 View Figure 4 ) with ventral lamina and ten peribuccal lamellae. The stylet furcae typically-shaped, the basal portion is enlarged and has two caudal branches with thickened, swollen, rounded apices. Under PCM, the oral cavity armature is of the patagonicus type, i.e., with only the second and third bands of teeth visible (Figure 4B, C View Figure 4 ). However, under SEM the first band of teeth is visible and composed of one row of very small cones situated anteriorly in the oral cavity, just behind the bases of the peribuccal lamellae (Figure 5 View Figure 5 ). The second band of teeth is situated between the ring fold and the third band of teeth and composed of 3-4 rows of teeth visible in PCM as granules (Figure 4B, C View Figure 4 ). The third band of teeth is divided into a dorsal (Figure 4B View Figure 4 ) and a ventral portion (Figure 4C View Figure 4 ). Under PCM, the dorsal teeth are seen as three distinct transverse ridges whereas the ventral teeth appear as two separate lateral transverse ridges between which one big tooth (sometimes circular in PCM) is visible (Figure 4B, C View Figure 4 ).

Pharyngeal bulb spherical, with triangular apophyses, two rod-shaped macroplacoids and a drop-shaped microplacoid (Figure 4A, D, E View Figure 4 ). The macroplacoid length sequence is 2<1. The first and the second macroplacoid have a central and a subterminal constriction, respectively (Figure 4D, E View Figure 4 ).

Eggs (measurements and statistics in Table 4 View Table 4 ):

The surface between processes is of the Macrobiotus persimilis type, i.e., with a continuous smooth chorion, never with pores or reticulum (Figures 6 View Figure 6 , 7 View Figure 7 ). Under PCM the surface between the processes is covered with wrinkles that appear as dark thickenings/striae, whereas under SEM the surface appears clearly wrinkled (Figures 6 View Figure 6 , 7 View Figure 7 ). Processes are of a modified Macrobiotus hufelandi type (Figures 6 View Figure 6 , 7 View Figure 7 ). The proper terminal disc is absent and instead 2-8 thick tentacular arms (typically 5-6) are present in the distal part of the process (Figures 6 View Figure 6 , 7 View Figure 7 ). The tentacular arms present bubble-like structures (visible in PCM). Under SEM, each tentacular arm is distally divided into many irregular digitations that are sometime covered with micro-granulation (Figure 7C-F View Figure 7 ). Also, under SEM micro-pores can be seen on the egg surface between the processes and around the process bases (Figure 7C, E View Figure 7 ).

Reproduction / Sexual dimorphism. The species is dioecious. Spermathecae in females as well as testis in males, clearly visible under PCM up to 24 hours after mounting in Hoyer’s medium, have been found to be filled with spermatozoa (Figure 8A, B View Figure 8 ). The species exhibits secondary sexual dimorphism in the form of clearly visible lateral gibbosities on the hind legs in males (Figure 8B, C View Figure 8 ).

DNA sequences.

18S rRNA: GenBank: MW588024-MW588025; 659 and 664 bp long.

28S rRNA: GenBank: MW588030-MW588031; 679 and 703 bp long.

ITS-2: GenBank: MW588018-MW588019; 298 bp long.

COI: GenBank: MW593927-MW593928; 532 and 535 bp long.

Phenotypic differential diagnosis. By having an egg chorion of the Macrobiotus persimilis type (smooth or wrinkled chorion) and by having thick tentacular arms instead of a proper terminal disc on the distal part of egg processes, M. annewintersae sp. nov. resembles only one species: Macrobiotus anemone Meyer, Domingue & Hinton, 2014 from USA. However, the new species differs specifically from:

• M. anemone by having eyes (absent in M. anemone), by the presence of granulation on all legs (absent in M. anemone), by having the oral cavity armature (OCA) of the patagonicus type (maculatus type - only the third band of teeth visible under light microscope - in M. anemone), by the presence of dentate lunulae in legs IV (smooth lunulae in legs IV in M. anemone), by having the thick tentacular arms in the distal part of the processes filled with bubble-like structures (tentacular arms solid in M. anemone, Figure 17) and by lacking a cavity between the process trunk and tentacular arms that appears in PCM as a clearly refracting dot (the cavity present in M. anemone, Figure 17).