Weberacantha Christiansen, 1951

Potapov, Mikhail, Babenko, Anatoly & Fjellberg, Arne, 2006, Taxonomy of the Proisotoma complex. Redefinition of genera and description of new species of Scutisotoma and Weberacantha (Collembola, Isotomidae), Zootaxa 1382 (1), pp. 1-74 : 57-58

Weberacantha Christiansen, 1951

Type species: Weberacantha octa Christiansen

Diagnosis. Anurophorinae with all abdominal segments clearly separated. Manubrium with distal chaetae on anterior side. Furca stout, with a robust mucro. Tergal sensilla on abdomen in mid-tergal position, all microsensilla present (11/111). B-row on Ti.1–2 complete.

Colour dark, integument with visible granulation. Ocelli 6–8 on each side of head. PAO long and narrow ( Fig. 153 ). Ant.1–3 with full set of bms. Maxillary palp bifurcate with 4 sublobal hairs. Labial papilla E with a full set of guards. Labral chaetotaxy as 4/ 554. Sensillary formula of Th.II–Abd.V as 33/22224. Thorax usually without ventral chaetae. Ventral tube with 3+3 or more laterodistal chaetae and more than 2 posterior chaetae. Macrochaetae differentiated, those on abdominal tip may be thickened or spinelike. Tibiotarsal tenent chaetae (A 1 on Ti.1, A 1 and A 7 on Ti.2–3) differentiated, clavate or pointed. Tibiotarsi without T-chaeta, chaetae x and B 5 on Ti. 3 in males slightly modified. Unguis with or without inner tooth. Anterior chaetae on dens only on its distal part. Mucro robust, about half as long as dens, with 2–3 teeth and no lamellae ( Fig. 152 ).

Discussion. The spine-like chaetae of Weberacantha octa vary in shape and number and have no distinct papillae ( Fig. 154 ). We do not consider these spines as a generic character but rather as an example of a modification of the abdominal tip which is frequent among members of the Proisotoma complex. The low generic value of such modifications is supported by the existence of intermediate forms between “armed” and “unarmed” species like W. echinodermata sp.n. ( Fig. 161 ). Regardless of spines on Abd.V in the type species, Weberacantha shares all significant characters of Scutisotoma and is only weakly separated from the latter by the short furca with a strong mucro and the long, narrow PAO. Nevertheless, five species, included by us in Weberacantha , represent a homogenous species-group which is easily recognized by their general appearance.

Weberacantha in this widened view is probably related to the small Asiatic genus Narynia Martynova, 1967, whose generic status is uncertain. Narynia differs from Weberacantha only by the absence of anterior chaetae on manubrium and presence of a row of straight horizontal macrochaetae on tip of abdomen.

Known species of the genus. Besides the type species, we included in Weberacantha two known species of the complex: Folsomides beckeri Stebaeva and Proisotoma janetscheki Yosii. Two new species of the genus are described below.

Figures

FIGURES 151–155. Weberacantha octa. 151, general distribution of macrochaetae, sensilla and microsensilla on body; 152, dens, lateral view; 153, PAO and ocelli; 154, chaetotaxy of Abd.V (s: sensilla, connected); 155, claw on leg 3.

FIGURES 156–168. Weberacantha echinodermata sp.n. 156, furca posterior; 157–158, dens, anterior (157) and lateral (158); 159, PAO and ocelli; 160, VT; 161, chaetotaxy of Abd.V (s: sensilla, connected); 162, microsensillum; 163, sensillum; 164, macrochaetae on Abd.IV; 165–167, Abd.V, spine-like macrochaetae (165), thick microchaeta (166) and sensillum (167); 168, general distribution of macrochaetae, sensilla and microsensilla on body.