Doryphoribius maasaimarensis Fontoura, Lisi & Pilato, 2013, sp. nov.
Creators: name: Fontoura, Paulo
name: Lisi, Oscar
name: Pilato, Giovanni
Publisher: name: Zenodo
Year: 2013
Subjects: Biodiversity
Taxonomy
Animalia
Tardigrada
Eutardigrada
Parachela
Hypsibiidae
Doryphoribius
Doryphoribius maasaimarensis

description: Doryphoribius maasaimarensis sp. nov.
Figs. 1, 2; Tab. 1.
Material examined. Holotype and 13 paratypes extracted from an unidentified moss growing on a tree trunk. Locality: Sarova Mara Game Camp (1º 31ʹ 46.49ʹ S; 35º 19ʹ 0 4.84ʹ E; 1780 meters a.s.l.), in the rolling plains of the savannah at the Masai Mara Game Reserve, Kenya. Date: August 2010. Collector: Cristina Cruz (University of Porto).
Type repository. The holotype (slide No. 5485) and 4 paratypes (slide Nos. 5486-5488) are deposited in the collection of Binda & Pilato (Museum of the Department of Animal Biology “Marcello La Greca”, University of Catania, Italy). The other 9 paratypes (slide Nos. CV-22 to CV-30) are deposited in the collection of P. Fontoura at the Department of Biology, Faculty of Sciences, University of Porto, Portugal.
Specific diagnosis. Body orange-pink (colourless after slide mounting); eye spots present; dorsal and lateral cuticle with a faint, irregular reticular design with obvious tubercles at crossings; a similar ornamentation present on the legs; nine transverse rows of dorsal and dorso-lateral gibbosities (configuration IX:4-6-4-6-4-6-4-4-2). Bucco-pharyngeal apparatus of the Doryphoribius type; oral cavity with two fine ventral and two dorsal transverse ridges; a small medio-dorsal tooth probably present but difficult to observe (other ridges or teeth not visible under light microscope); buccal tube narrow with a long ventral lamina; pharyngeal bulb with apophyses, two macroplacoids and without microplacoid or septulum. Robust claws of the Isohypsibius type with short and thin accessory points and very small, smooth, lunules.
Description of the holotype. Body length 270 µm (Fig. 1A); colour orange-pink (colourless after slide mounting); eye spots present; dorsal and lateral cuticle sculptured with small variously shaped tubercles; these are interconnected via short irregular bars forming a rough reticular design with the tubercles at the interconnection points of the mesh (Fig. 1B). The circular tubercles are more evident on the posterior portion of the body, up to 2.2 µm in diameter, but many are smaller or have an elongate shape. A similar, but less visible, ornamentation is present on the legs. In addition, nine transverse rows of dorsal and dorso-lateral gibbosities are present with the following configuration: IX:4-6-4-6-4-6-4-4-2 (according to the configuration system introduced by Michalczyk & Kaczmarek, 2010). Rows II, IV and VI placed in line with legs I, II and III. The most lateral gibbosities in rows I, VII, VIII are placed in a more posterior position relatively to the central gibbosities; gibbosities in the first row slightly smaller than the others. Ventral cuticle smooth.
Bucco-pharyngeal apparatus of the Doryphoribius type (Figs. 1C, D; 2A, B); mouth antero-ventral with six peribuccal papulae; oral cavity armature similar to that of many eutardigrades, i.e. with the usual transverse ridges, two fine dorsal (Fig. 1C) and two ventral (Fig. 1 D); a small medio-dorsal tooth probably present (but difficult to observe) (Fig. 1C); other teeth not visible under light microscope (Fig. 1C, D).
Buccal tube narrow with a single, gradual curvature (Fig. 2A, B), 33.6 µm long and with an external diameter of 3.0 µm (pt = 8.9) at level of the stylet supports insertion; cephalic portion slightly narrower; stylet supports inserted at 69.9 % of the buccal tube length (pt = 69.9); the ventral lamina is obvious throughout its length and the caudal end almost reaches the level at which the stylet supports are inserted on the buccal tube (Fig. 2B). Pharyngeal bulb with large apophyses, two rod-shaped macroplacoids and without microplacoid or septulum (Fig. 2A). Placoid row 10.1 µm long (pt = 30.1). The first macroplacoid, very slightly constricted in the middle, is 4.9 µm long (pt = 14.6); second macroplacoid 3.3 µm long (pt = 9.8) and without constriction.
Claws of the Isohypsibius type, robust (Fig. 2C, D); distal portions of the branches taper gradually (Fig. 2D); main branches with short and very thin accessory points (Fig. 2D); small, smooth lunules present under all claws (Fig. 2D); cuticular bars on legs absent. The measurements of the claws and other structures of the three best measurable specimens are reported in Table 1. The assessment of some statistical parameters of the best measurable specimens is given on Table 2.
*Measurements from Claxton et al. (2010).
Remarks. Eggs unknown. The paratypes are similar to the holotype in both qualitative and metric characters (Table 1). However, some of the gibbosities are poorly defined and therefore difficult to count in some paratypes. To have a clear image of the configuration of the gibbosities it may be necessary to examine several specimens.
Etymology. The name maasaimarensis refers to the locus typicus, maasaimarensis = inhabiting Masai Mara.
Differential diagnosis. Only four species of Doryphoribius are known having cuticle patterned with an irregular, reticular mesh design that forms small tubercles where the mesh crosses, nine transverse rows of dorsal gibbosities and pharyngeal bulb with two macroplacoids: D. huangguoshuensis, D. dawkinsi, D. barbarae and D. zyxiglobus. The new species differs from D. huangguoshuensis, D. dawkinsi and D. barbarae in having a different configuration of dorsal gibbosities (i.e. a different number of gibbosities in the transverse rows (configurations): IX:4-6-4-6-4-6-4-4- 2 in the new species; IX:4-4-4-4-4-4-4-2- 2 in D. huangguoshuensis; IX:6-6-4-6-4-6-4-4- 2+2[L IV] in D. dawkinsi; IX:2-4-4-4-4-6-4-4- 2 in D. barbarae). In addition, it differs from D. huangguoshuensis in having cuticle with a more irregular reticular design and slightly less developed accessory points; from D. dawkinsi in having eye spots, lacking gibbosities on the hind legs and having lunules; and from D. barbarae in having eye spots and lunules.
The new species is very similar to Doryphoribius zyxiglobus with the same configuration of gibbosities but differs in having slightly less close cuticular tubercles; the buccal tube is slightly longer with respect to the body length (in the new species is ca. 11.8–15.1% and in D. zyxiglobus is 9.8–11.2%) and, as a consequence, the pt values between D. zyxiglobus and D. maasaimarensis sp. nov. for structures which have slightly different lengths may appear similar (e.g. the claws, which are slightly longer in the new species while the pt values are similar) (see: Table 1); for the same reason structures of similar dimensions have slightly different pt index values as is the case of the external buccal tube width (Table 2). The new species has pt index values relative to the ventral lamina of the buccal tube sightly higher (Table 2). D. maasaimarensis sp. nov, has a gradually bent anterior third of the buccal tube compared with D. zyxiglobus where the buccal tube has a marked bend immediately behind the oral cavity (Figs. 2B and 3A, B, arrow). Significant qualitative differences can be noted regarding the claw shape. In D. maasaimarensis sp. nov. the main branch of both external and internal claws has uniform width and the distal portion tapers gradually (Fig. 2D); in D. zyxiglobus instead, the proximal portion is wider and tapers abruptly at about half length (Fig. 3D); as a consequence the claws of D. maasaimarensis sp. nov. appear more slender. On the contrary, in the new species the terminal portion of the secondary branches are stouter (Figs. 2D and 3D). In D. maasaimarensis sp. nov. the accessory points are clearly thinner (Figs. 2D and 3C, D).
Claxton et al. (2010) also attributed to Doryphoribius zyxiglobus a specimen from South Africa (Natal Museum, slide No. 29). However, some of the metric characters differ from both Doryphoribius zyxiglobus and Doryphoribius maasaimarensis sp. nov., which would make it opportune to search for more South African specimens to clarify this situation.
Four species groups within the genus Doryphoribius were defined by Michalczyk & Kaczmarek (2010), characterized by the number of placoids and the presence or absence of cuticular gibbosities; they wrote on page 48: “At the moment it cannot be stated whether these groups reflect the phylogenetic relationships within the genus […] However, even if they do not, the groups are useful for purely practical reasons”. Those four species groups appear to us artificial and we wish to stress that known species from other genera demonstrate variation for the characters used by those authors to institute those groups. For example, in species with gibbosities, the number of gibbosity rows in some cases is variable, and sometimes even specimens without gibbosities can be found, e.g. in Isohypsibius elegans Binda & Pilato, 1971 according to Pilato, 1975; in some species, individuals may be observed with or without cuticular ornamentation, or in which the juvenile cuticle is smooth while the adults are ornamented (e.g. Ramazzottius oberhaeuseri (Doyère, 1840) and Isohypsibius granulifer Thulin, 1928 according to Ramazzotti & Maucci, 1983, and also Ramazzottius semisculptus Pilato & Rebecchi, 1992). Similarly, there are species with a marked incision in the first macroplacoid that can in some individuals appear subdivided into two distinct (sub)placoids (e.g. Macrobiotus persimilis Binda & Pilato, 1972, Macrobiotus echinogenitus Murray, 1911, Murrayon hastatus (Murray, 1907), Murrayon nocentiniae (Ramazzotti, 1961), Murrayon pullari (Murray, 1907)); in Pseudobiotus megalonyx (Thulin, 1928) the adults have two macroplacoids but some populations of new-borns have been observed with three macroplacoids (Bertolani, 1982). One could hypothesize that the above mentioned individual variability is mistaken and actually represents sibling species, but even if this were the case we do not think that sibling species can be attributed to different species groups. A “species group” is not a true taxonomic category, but we think that assigning species to a “species group” is only justifiable if there is supporting phylogenetic evidence. For these reasons, we do not attribute the new species to any of the four groups indicated by Michalczyk & Kaczmarek (2010).
description: Published as part of Fontoura, Paulo, Lisi, Oscar & Pilato, Giovanni, 2013, A new tardigrade Doryphoribius maasaimarensis sp. nov. (Eutardigrada: Hypsibiidae) from Kenya, pp. 359-368 in Zootaxa 3630 (2) on pages 360-366, DOI: 10.11646/zootaxa.3630.2.10, http://zenodo.org/record/220179