Diaforobiotus svalbardicus, Stec, 2023

Stec, Daniel, 2023, Integrative taxonomy helps to revise systematics and questions the purported cosmopolitan nature of the type species within the genus Diaforobiotus (Eutardigrada: Richtersiusidae), Organisms Diversity & Evolution (New York, N. Y.) 23 (2), pp. 309-328 : 314-318

publication ID	https://doi.org/ 10.1007/s13127-022-00592-6
persistent identifier	https://treatment.plazi.org/id/FE448785-FF8F-856E-FCDF-F934FDB9F92F
treatment provided by	Felipe
scientific name	Diaforobiotus svalbardicus
status	sp. nov.

Treatment

Diaforobiotus svalbardicus sp. nov.

ZooBank: urn:lsid:zoobank.org:act:075186B5-760F-490C-B928-58E3FF071828

Diaforobiotus sp. NO. 386 in Stec et al. (2020c) and in Stec and Morek (2022)

Figs. 6 View Fig , 7 View Fig , 8 View Fig , 9 View Fig , 10 View Fig and 11 View Fig , Tables 4 and 5

Etymology: The name “svalbardicus ” refers to the Svalbard archipelago where the new species has been discovered.

Material examined: 19 animals and 51 eggs: specimens mounted on microscope slides in Hoyer’s medium (10 animals + 40 eggs), fixed on SEM stub (5 + 11), and used for DNA extraction and sequencing (4 + 0; in Stec et al. (2020c)).

Animals (measurements and statistics in Table 4)

When alive, body pale yellow to light orange; after fixation in Hoyer’s medium body transparent ( Fig. 6A View Fig ). Large, black granular eyes present, visible also in specimens mounted in Hoyer’s medium. Body cuticle smooth, without granulation but with circular or elliptical pores sometimes with uneven edges (0.8–2.5 µm in diameter) distributed randomly on the entire body cuticle with the largest pores present in the dorso-caudal cuticle ( Fig. 6B, C View Fig ). Pores on the ventral side of the body more scattered than on the dorsal side ( Fig. 6B, C View Fig ). Granulation on all legs absent. Pulvini present on each leg I–III on the internal leg surface.

Claws slender, of the richtersiusid type, with common tract with a system of internal septa, and with an evident stalk connecting the claw to the lunula ( Fig. 7 View Fig A-D) as described by Lisi et al. (2020). The common tract longer than the half of the entire claw height ( Fig. 7A, D View Fig ). Primary and secondary branches form an acute angle at the

µm] of selected morphological structures of the eggs from the t the neotype population of Diaforobiotus islandicus

( Richters, 1904) mounted in

Hoyer’s medium; N, number of eggs/structures measured,

Range, refers to the smallest and the largest structure among all measured specimens; SD, bifurcation ( Fig. 7 View Fig A-D). Primary branches with prominent accessory points clearly protruding from the branch ( Fig. 7 View Fig A-D). Lunulae, oval or slightly trapezoidal in shape, present on all legs, with lunulae in hind leg being distinctly larger ( Fig. 7 View Fig A-D). Teeth present only in lunulae on hind legs ( Fig. 7 View Fig A-D). A single continuous cuticular bar and paired muscle attachments present proximally to claws on legs I–III ( Figs. 6A View Fig and 7A View Fig ). In PCM, in the leg midsection (lateral perspective on the leg) the cuticular bar is visible as strong and distinct thickening.

Mouth antero-ventral. Relatively short bucco-pharyngeal apparatus ( Fig. 8A View Fig ) with ten peribuccal lamellae, rigid buccal tube, bent anteriorly, with ventral lamina. Based on PCM observations, the oral cavity armature is well developed and composed of three bands of teeth ( Fig. 8B, C View Fig ). The first band is composed of very small granular teeth positioned posteriorly to peri-buccal lamellae ( Fig. 9A, B View Fig ) visible as faint granulation in PCM ( Fig. 8B, C View Fig ). The second band of teeth is composed of several rows of granular teeth (larger than teeth of the first band), of which the most posterior row comprises the larger teeth ( Figs. 8B, C View Fig and 9A, B View Fig ). The teeth of the third band are located within the posterior portion of the oral cavity, anteriorly to the buccal tube opening ( Figs. 8B, C View Fig and 9A, B View Fig ). The third band of teeth is divided into the dorsal and the ventral portion ( Figs. 8B, C View Fig and 9A, B View Fig ). The dorsal portion is composed of three large teeth ( Figs. 8B View Fig and 9A View Fig ). The two lateral teeth are (visible as lateral circular granules in PCM) positioned just before buccal tube opening whereas the medial tooth (circular granule in PCM) is positioned further towards the pharynx in the buccal tube ( Figs. 8B View Fig and 9A View Fig ). The ventral portion of the third band of teeth is fainter compared to the dorsal portion ( Figs. 8C View Fig and 9B View Fig ). The ventral portion is composed of two small indistinct lateral teeth (in PCM faintly visible as granular) and a medial tooth (in PCM circular; Fig. 8C View Fig ). In SEM and all teeth in the ventral portion of the third band are clearly conical with the median tooth being distinctly larger than laterar teeth ( Fig. 9B View Fig ). Pharynx spherical, with triangular apophyses, three anterior cuticular spikes (typically only two are visible in any given plane) and two rod-shaped macroplacoids (2<1) ( Fig. 9A, D, E View Fig ). The first macroplacoid is anteriorly narrowed and constricted in the middle, whereas the second has a subterminal constriction ( Fig. 9D, E View Fig ). Microplacoid absent. Remarks: Residual of the additional thickening of ventral lamina reported for Diaforobiotus by Lisi et al. (2020) not visible in the examined specimens. Most probably the difference in visibility of this structure is caused by the usage of different mounting media (Hoyer’s medium in this study and polyvinyl-lacto-phenol in Lisi et al. (2020)).

Eggs (measurements and statistics in Table 5)

Laid freely, strongly orange, spherical with stout conical processes (base diameter constitute more than half of the process height) and smooth egg surface without areolation or reticulation ( Figs. 10 View Fig A-I and 11A-F). In PCM only, the egg surface between processes has densely and evenly distributed, faintly visible, minute light refracting dots, resembling extremely delicate reticulation ( Fig. 10C, F, H, I View Fig ). Dark thickenings/projections around egg processes bases absent. Ring of several small pores surrounding egg processes absent. Only sometimes in SEM singular, isolated micropores are present on the egg surface between process ( Figs. 11B, D, F View Fig ). The process apices not projected at the top ( Figs. 10 View Fig A-I and 11A-F). Nearly entire process surface (excluding the most basal portion) is covered by granulation: dark dots of rough/ jagged wall in the process midsection ( PCM)/ clear nodular granules ( SEM) ( Figs. 10 View Fig A-I and 11A-F).

Reproduction: The new species is dioecious: both males with testes and females with ovaries were recorded within the new species population. Other secondary sexual phenotypic characters, e.g. gibbosities on the hind legs in males, absent.

DNA sequences: The DNA sequences of four molecular markers (18S rRNA, 28S rRNA, ITS-2 and COI) associated with this population have been previously published by Stec et al. (2020c). All markers were represented by the same haplotype, hence only one sequence per marker was uploaded in GenBank. The respective GenBank accession numbers are given in Table 1.

Locality: 78° 44′ 02' 'N, 16° 36′ 12" E; Norway, Svalbard, Ragnardalen ; moss from tundra; coll. 11.07.2017 by Michala Tůmová .

Type depositories: The holotype (slide NO.386.01 with 2 paratypes), as well as 4 paratypes (slide: NO.386.02) and 35 eggs (slides: NO.386.* 04–07) are deposited at the at the Institute of Systematics and Evolution of Animals , Polish Academy of Sciences , Sławkowska 17, 31–016, Kraków, Poland . A further 3 paratypes (slide NO.386.03) and 9 eggs (slide: NO.386.08) are deposited at the Department of Animal Taxonomy and Ecology , Institute of Environmental Biology , Adam Mickiewicz University in Poznań , Uniwersytetu Poznańskiego 6, 61–614 Poznań, Poland .