Aggressopygus sibiricus, Potapov & Babenko, 2014

Potapov, Mikhail & Babenko, Anatoly, 2014, About some unusual Asiatic taxa of Isotomidae (Collembola), Journal of Natural History (J. Nat. Hist.) 48 (29 - 30), pp. 1835-1851 : 1842-1845

Aggressopygus sibiricus sp. nov.

Figures 4A , 5 , 7A

Type material

Holotype: adult male. Russia, S Siberia, Altai Republic, Turochak District, road Biysk – Teletskoye Lake, vicinity of Verkh-Biysk , N 52.03°, E 87.08°, deciduous forest, litter. 2.07.2002. leg. Е. Sleptsova. One paratype from the same location and four paratypes from the same district, vicinity of Kebezen, N 51.92° E 87.1°, mixed forest ( Pinus, Abies, Betula ), litter. 1.06.2002. leg. Е. Sleptsova. Kept in MSPU.

Other material

Russia, S Siberia, Kemerovo District, vicinity of Kuzedeevo, N 53.32°, E 81.17°, ‘ Lipovy Ostrov’ , ~ 400 m alt., lime-tree forest, litter. 9– 10.05.1995. leg. O. Berezina. Deposited in MSPU .

Description

Length from 0.8 (adult male) to 1.1 (subadult female) mm. Without pigmentation. Cuticle with ‘smooth’ granulation. Ocelli absent. PAO broadly elliptical, slightly constricted, longer than width of Ant.I and twice as long as inner unguis length ( Figure 5G ). Maxillary outer lobe with 4 sublobal hairs, maxillary palp bifurcate. Labral formula as 4/ 5,5,4. A pair of lateral setae of subapical row tooth-like, with or without apical denticles ( Figure 5E–H ). Labium with 5 papillae (А–Е), 16 guard setae (including e7), papillae A and B thicker, 3 proximal and 4 basomedian setae present. Hypostomal papilla as common for the family, unmodified. Maxillary head compact, without long lamellae, Lam.6 broad, Lam.1 hidden behind Lam.6, not protruded ( Figure 5C ). Ventral side of a head with 3 + 3 setae, of which 2 + 2 posterior inserted close together. Ant.1 with 2 ventral sensilla (s) and 2 small basal microsensilla (bms), dorsal and ventral, the former set together with long setaceous microsensillum ( Figure 5G ), Ant.2 with 3 bms and 1 laterodistal s, Ant.3 with 1 bms and with 6 distal s (including 2 lateral), without additional sensilla. Sensilla on Ant.4 thin and tubular, organites stick-like.

Ordinary setae of body long and rather sparse. The longest setae on posterior segments of abdomen, furcal subcoxa and basal parts of legs ciliated. Axial chaetotaxy as 10,6/4,4,4(5),4 ( Figure 7A ). Sensillary formula as 4,3/2,2,2,3,5 (s), microsensilla (ms) as 1,0/0,0,1 ( Figure 4A ). Tergal sensilla well differentiated, on most tergites shorter and finer than common setae. Medial sensilla on Th.II–III situated in front of p-row, on Abd. I–IV in posterior position. Abd.V with 5 sensilla arranged with 3 dorsal long and slender (al, accp1, accp2), one lateral middle-sized sensilla (accp3) slightly thicker than dorsal, and one ventral ( Figures 4A , 7A ). Microsensilla thick and long. Macrochaetae long and ciliated, 1,1/3,3,3,4 in number, medial ones on Abd.V 1.3–1.7 times shorter than dens and 4.0–4.7 times longer than inner edge of unguis ( Figure 7A ). Foil setae well differentiated, with a cluster of cilia at the middle of the length. Thirteen foil setae arranged in two transversal rows as 4 + 4 anterior (fa1, fa3, fa5, fa7) and 5 posterior (fp0, fp2, fp4). Foil setae fp4 short. Th.III with 2 + 2 ventral setae.

Unguis of normal shape, without lateral or inner teeth. Unguiculus about half as long as unguis. Tibiotarsi with additional setae on all legs, some setae thickened ( Figure 5D ). Tibiotarsal tenent setae short and pointed. Spurs X and B 5 in Leg 3 of adult males (two specimens studied) much thinner and shorter than other setae on tibiotarsi. Ventral tube with 5 + 5 laterodistal and with 4 posterior setae arranged in two transversal rows, anteriorly without setae. Tenaculum with 4 + 4 teeth and one seta. Anterior furcal subcoxae with 15–17, posterior one with 8 setae. Anterior side of manubrium with 2 + 2 (more rarely with 3 + 2 or 3 + 3) setae ( Figure 5A, 5I ). Posterior side of manubrium with 5 + 5 laterobasal setae and 11 + 11 on main part, with 2 + 2 setae on lateral edges. Dens with 19–23 anterior setae. Posterior side of dens crenulated and with 5 normal setae (3 basal and 2 at the middle) and one rudimentary minute seta near base of mucro ( Figure 5A,B ). Mucro short, bidentate. Manubrium about half as long as dens.

Remarks

As the type species of the genus, Aggressopygus sibiricus sp. nov. possesses all diagnostic feature of the genus, viz. fused Abd.V–VI, tergal sensilla situated in prow of setae, well-developed foil setae on abdominal tip, and simple postantennal organ. It clearly differs from the only other known species of the genus, namely A. armatus sp. nov. (see description below), by different type of foil setae with cilia restricted to their central region, elongated sensilla on Abd.V, a pair of ‘teeth’ on labrum and ciliated dorsal macrosetae.

Distribution

Known from three localities in SW Siberia.

Etymology

Named from it distribution.

Figures

Figure 4. Habitus and chaetotaxy of Aggressopygus sibiricus sp. nov. (A), Aggressopygus armatus sp. nov. (B), and Microisotoma achromata (C).

Figure 5. Aggressopygus sibiricus sp. nov.: (A,B) furca, anterior (A) and lateral (B) views; (C) maxillary head; (D) tibiotarsus 3; (E,F) labrum, variation; (G) anterior part of the head; (H) apical row of labral setae, ventral view; (I) anterior side of manubrium, specimen from mountainous Shoria.

Figure 7. Posterior part of abdomen of Aggressopygus sibiricus sp. nov. (A) and Micrisotoma achromata (B). s – sensillum, ms – microsensillum, fa – foil seta, tc – ‘tiny’ seta.