Weberacantha echinodermata, Potapov & Babenko & Fjellberg, 2006

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 : 59-62

Weberacantha echinodermata sp.n.

Figs. 156–168

Material. Holotype: ♀, Russia, Yakutia , Suntar-Khayata Mt.Range (63 o 13’N 139 o 36’E), 1450 m alt., eastern slope, under Pinus pumila (pit-traps), 09–30.vii.2002, leg. O. Makarova. Paratypes: 1 ♂, same sample. 2 ♀♀, 2 ♂♂, same region, from 1450 m alt., southern slope, herbaceous association with Dryas sp. (pit-traps), 10–30.vii.2002, leg. O. Makarova ( MSPU) .

Description. Size about 1.5 mm. Colour dark, blue-violet, extremities paler. Cuticle finely reticulated. Ocelli 8+8, subequal ( Fig. 159 ). PAO narrow, with indistinct constriction, 1.1–1.3 as long as U 3. Maxillary outer lobe with 4 sublobal hairs and bifurcate palp. Maxillary head with short, unmodified lamellae. Labral chaetotaxy as 4/ 554. Labium with 3 proximal and 4 basomedian chaetae, papilla E with full set of guards. Ventral side of head with 4+4 postlabial chaetae. Ant.1 with 2 basal microsensilla (bms) and 2 sensilla (s), Ant.2 with 3 bms and 1 s, Ant.3 with 1 bms and (5)6 distal s (one of the lateral sensilla can be absent). Male “spurs” on Ant.2–3 present. Sensilla on Ant.4 hardly differentiated, subapical organite small.

Dorsal axial chaetom of Th.II–Abd.III as 8–9,5–7/555–6. Thorax usually without ventral axial chaetae but one of the paratypes has 1+1 ventral chaetae on Th.III. Macrochaetae clearly differentiated ( Fig. 161, 168 ). Abd.V with 8 straight and thickened dorsal macrochaetae ( Fig. 161 ), about 0.6 as long as tergite. Abd.IV with 4 macrochaetae on each side, dorsal and anterior ones are subequal with lateral and dorsolateral ( Fig. 168 ). Sensilla on tergites clearly differentiated, significantly shorter and thinner than ordinary chaetae, microsensilla almost of the same size as sensilla ( Fig. 162, 163 ). Sensillar formula 33/22224 (s), 11/111 (ms) ( Fig. 168 ). Sensilla on Abd.I–III in mid-tergal position. Medial and lateral pairs of sensilla on Abd.V similar in size and set in a line ( Fig. 161 ).

Unguis curved, without inner tooth. Ti.1–3 with a basic set of chaetae (21-21-25). Brow on Ti.1–2 with 7 chaetae. Chaetae x and B 5 on Ti. 3 in males slightly thinner and shorter than other chaetae. Tibiotarsal tenent chaetae (1-2-2 on Ti.1–3) clavate, about 1.3–1.6 as long as U 3. Ventral tube with 6+6 laterodistal and 7–10 posterior chaetae ( Fig. 160 ). Tenaculum with 4+4 teeth and a chaeta. Anterior furcal subcoxa with 7–10, posterior one with 5–6 chaetae. Furca rather short. Anterior side of manubrium with a pair of distal chaetae. Posterior side with 10–13+10–13 on the main part and 3+3 chaetae on laterobasal lobes ( Fig. 156 ). Dens anteriorly with 3 distal chaetae ( Fig. 157 ). Posterior side almost smooth, with 4–5 chaetae. Mucro massive with two strong teeth, subapical largest, lamellae not differentiated ( Fig. 158 ). Ratio of manubrium: dens: mucro = 3,8–4,6: 1,7–2,0: 1. Each of the anal lobes with 3 tiny chaetae along distal edge.

Affinity. The general appearance, long and narrow PAO and short furca with strong mucro without lamellae indicate a position of echinodermata within Weberacantha . It is distinguished from the known species of the genus by the increased number of chaetae on VT. The thick posterior macrochaetae on Abd. V in echinodermata correspond to the posterior spines in the type species of the genus.

Distribution. Known only from the type locality.

Name derivation. The new species is named after erect macrochaetae resembling quills of Echinodermata.

Weberacantha magnomucrella sp.n.

Figs. 169–176

Material. Holotype: ♀, Mongolia, Somon Khankh , East Sayan Mts. Range, Munku- Sardyk Mt. (51 o 44’N 100 o 20’E), 2800 m alt., lichen mountain tundra, 14.vii.1982, leg. A. Druk. Paratypes: 4 ♀♀, 1 ♂, 1 juv., same sample ( MSPU) .

Description. Size up to 1.4 mm. Colour dark, blue-violet, sometimes almost black, extremities paler. Cuticle with visible primary granulation. Ocelli 8+8, G and H strongly reduced ( Figs. 172, 173 ). PAO narrow, usually constricted, 1.3–2.0 as long as inner edge of U 3 and almost as long as width of Ant.1 ( Fig. 172 ). Maxillary outer lobe with 4 sublobal hairs and bifurcate palp. Maxillary head with short, unmodified lamellae. Labral chaetotaxy as 4/554. Labium with 3 proximal and 4 basomedian chaetae and a complete set of papillae and guards. Ventral side of head with 4+4(5) postlabial chaetae. Ant.1 with 2 basal microsensilla (bms, dorsal and ventral), and 2 ventral sensilla (s). Ant.2 with 3 bms and 1 laterodistal s. Ant.3 with 1 bms and 6 distal s (one of the lateral sensilla can be absent in young specimens). Male “spurs” on Ant.2–3 present. Sensilla on Ant.4 hardly differentiated, subapical organite small.

Dorsal axial chaetom of Th.II–Abd.III as 8–9,5–7/555–6. Thorax without ventral chaetae. Macrochaetae differentiated laterally on Th.II–III and on abdominal tip. Medial macrochaetae on Abd.V 0.4–0.5 as long as tergite. Abd.IV with 4 macrochaetae on each side. Dorsal and anterior macrochaetae are 2/3 as long as the lateral and dorsolateral ( Fig. 176 ). Sensilla on tergites clearly differentiated, significantly shorter and thinner than ordinary chaetae. Microsensilla almost of the same size as sensilla. Sensillar formula 33/ 22224 (s), 11/111 (ms) ( Fig. 176 ). Sensilla on Abd.I–III in mid-tergal position. Medial pair of sensilla (accp1 and accp2) on Abd.V clearly longer than lateral one (accp3 and accp4) ( Fig. 174 ).

Unguis curved, with clear inner tooth ( Fig. 175 ). Ti.1–3 with a basic set of chaetae (21-21-25). B-row on Ti.1–2 with 7 chaetae. Chaetae x and B 5 on Ti. 3 in males slightly thinner and shorter than other chaetae. Tibiotarsal tenent chaetae on Ti.1–3 (1-2-2) weakly clavate, about 1.1–1.4 as long as U 3. Ventral tube with 4+4 laterodistal and 4(5) posterior chaetae. Tenaculum with 4+4 teeth and 1–2(3) chaetae. Anterior furcal subcoxa with 14–16 chaetae, posterior with 4–6. Furca rather short. Anterior side of manubrium with a pair of distal chaetae and also with a pair of lateral chaetae in basal part. Posterior side with 10–12+10–12 chaetae on the main part and 3+3 on the laterobasal lobes ( Fig. 169 ). Dens anteriorly with 6 distal chaetae, one is distinctly stronger ( Fig. 170 ). Posterior side of dens almost smooth, with 6 chaetae (1 basal macrochaeta, 2+2 lateral, 1 subapical). Mucro large with two strong teeth (subapical largest), lamellae not differentiated ( Fig. 171 ). Ratio of manubrium: dens: mucro = 2,8–3,3: 1,6–1,9: 1. Each of the anal lobes with 3 tiny chaetae.

Affinity. The general appearance and short furca with massive mucro without lamellae indicate a close relation of W. magnomucrella with two other Asiatic montane species: W. beckeri (Stebaeva) , comb.n. (Siberia) and W. janetscheki (Yosii) , comb.n. ( Nepal). W. magnomucrella is distinguished by the increased number of laterodistal chaetae on VT (4+4, other species 3+3) and by furcal chaetotaxy: 6/6 chaetae on anterior/posterior side of dens ( beckeri 2/5, janetscheki 5/5), manubrium with 1+1 anterior and 20–22 posterior chaetae (2+2/ 18–20 in beckeri , 1+1/ 40 in janetscheki ).

Distribution. Known only from the type-locality.

Name derivation. The new species is named after large mucro.

Figures

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.

FIGURES 169–176. Weberacantha magnomucrella sp.n. 169, furca, posterior; 170–171, dens, anterior (170) and lateral (171); 172, PAO and ocelli; 173, ocelli D and H; 174, chaetotaxy of Abd.V (sensilla connected); 175, claw on leg 3; 176, general distribution of macrochaetae, sensilla and microsensilla on body.