Diphascon (Diphascon)

Fontoura, Paulo, Pilato, Giovanni & Lisi, Oscar, 2010, First record of Tardigrada from São Tomé (Gulf of Guinea, Western Equatorial Africa) and description of Pseudechiniscus santomensis sp. nov. (Heterotardigrada: Echiniscidae), Zootaxa 2564, pp. 31-42 : 38-39

Diphascon (Diphascon) sp.

Material examined: One specimen (slide CII93), deposited in the collection of P. Fontoura at the Department of Biology, Faculty of Sciences, University of Porto, Portugal.

Description: The examined specimen clearly belongs to the ‘ pingue group’ characterised by having smooth cuticle; pharyngeal bulb with apophyses, three macroplacoids, microplacoid and septulum; lunules and other cuticular thickenings on the legs absent; claw bases without indentations. According to several authors (e.g. Pilato & Binda, 1997 /98; 1998; 1999; Fontoura & Pilato, 2007) the species belonging to this group are very difficult to separate from one another, differing in some quantitative characters and in only a few cases in qualitative characters.

The only specimen collected in São Tomé, 173 µm long, is not perfectly oriented to measure all the structures necessary to ensure a correct specific diagnosis. As a consequence the measurements indicated here have to be considered approximate. Buccal tube 13.8 µm long and 1.6 µm wide externally (ptd = 11.6), its length is about 35.3 % of the total length of the bucco-pharyngeal tube; stylet supports inserted on the buccal tube at about 71.0 % of its length; pharyngeal bulb with apophyses, three rod-shaped macroplacoids, microplacoid and septulum; entire row of placoids (microplacoid and septulum included) 10.0 µm long (ptd = 72.5); line of the macroplacoids 8.2 µm long (ptd = 59.4); first, second and third macroplacoid 2.7 µm long (ptd = 19.2), 2.4 µm long (ptd = 17.7) and 3.6 µm long (ptd = 25.7) respectively; microplacoid 0.7 µm long (ptd = 5.1); septulum 1.4 µm long (ptd = 10.1).

The claws, of ‘ Hypsibius type’, are well developed and with accessory points on the main branches; external and internal claws of the second and third pairs of legs 7.3 µm long (ptd = 52.9) and 5.2 µm long (ptd = 37.7) respectively; anterior and posterior claws of the hind legs 5.5 µm long (ptd = 39.9) and 7.8 µm long (ptd = 56.5) respectively.

For some characters the specimen collected in São Tomé is similar to Diphascon (D.) claxtonae Pilato & Binda, 1998 and Diphascon (D.) faialense Fontoura & Pilato, 2007 but some metric characters are clearly different (the buccal tube is wider; the stylet supports are inserted in a more posterior position and the ptd values of the claws length are higher). Due to the poor orientation of the specimen, we prefer not to attribute it to any known species of the ‘ pingue group’, nor do we think it opportune to describe a new species.

Paramacrobiotus gerlachae ( Pilato, Binda & Lisi, 2004) + Paramacrobiotus richtersi ( Murray, 1911) + + + Isohypsibius schaudinni ( Richters, 1909) + Isohypsibius tetradactyloides ( Richters, 1907) + Diphascon (Adropion) scoticum Murray, 1905 +

Diphascon (Adropion) scoticum ssp ommatophorum +

( Thulin, 1911)

Diphascon (Diphascon) sp. + Fractonotus caelatus ( Marcus, 1928) +