Folsomia amurica Potapov & Kuznetsova

Potapov, Mikhail, Hasegawa, Motohiro, Kuznetsova, Natalia, Babenko, Anatoly & Kuprin, Alexander, 2018, Isotomidae of Japan and the Asiatic part of Russia. I. Folsomia ' inoculata' group, ZooKeys 750, pp. 1-40 : 9-10

Folsomia amurica Potapov & Kuznetsova sp. n. Figs 4, 29-31, 33-35, 36-39, 90

Type material.

Holotype, female, Far East of Russia, Amurskaya Region, Zeysky Reserve, ~50 km W Zeya, near “Gol’tsy” station, subalpine dwarf wood ( Pinus pumila ), ~ 1300 m alt., coniferous litter, 20.viii.2014., Ten paratypes from the same biotope and five paratypes from the same location, litter of mixed forest at 700 m alt., 21.viii.2014, coll. M. Potapov and N. Kuznetsova. Deposited in MSPU.

Other material.

Far East of Russia, Amurskaya Region, various biotopes nearby type locality: litter and rotten wood in mountain tundra, spruce and larch forests at different altitudes (from 400 to 1400 m alt.); Amurskaya Region, ~ three km W Arkhara, oak-forest, litter, 17.viii.2014, coll. M. Potapov and N. Kuznetsova.

China, Inner Mongolia Province, Da Hinngan Ling Mts, ~ 25 km W BaLin, young tussocky wet birch forest, litter, 12.viii.2014, coll. M. Potapov.

Diagnosis.

Blind. Dorsal macrosetae (Md) present on both Th.II and Th.III. Sensillary formula complete (43/22235; 10/100). Medial s-setae on body tergites long, set in p-row. Ventral setae on Th.III present. Manubrium on anterior side with 4 –6+4– 6 setae, no unpaired axial setae, dens with 23-27 anterior setae. Mucro bidentate.

Description.

Body size from 1.0 to 1.5 mm. Body without pigmentation, relatively tubular (Fig. 39). Cuticle with fine, hexagonal primary granulation ( “smooth”). Ocelli absent. PAO slender, constricted, 1.3-1.7 as long as width of Ant.I and 1.6-2.0 as long as inner unguis length. Labium with five usual papillae ( A–E), guard setae e7 absent, three proximal and four basomedian setae. Ventral side of a head with 4+4 postlabial setae. Ant.I with 15 common setae as a rule, two (rarely three) ventral s-setae (s) and three bms, two of which small, dorsal and ventral, the former set together with long seta-form third bms, Ant.II with three bms and one latero-distal s, Ant.III with one bms and with five distal s (including one lateral), without additional s-setae. Several tubular s-setae on Ant.IV. Organite large, rounded.

Common setae long. Sensillary formula as 43/22235 (s), 10/100 (ms) (Figs 36, 37). The most tergal s-setae thin and long. Medial s-setae on Th. II–Abd.III situated in posterior position, on Abd. I–III between Md and Mdl. Latero-ventral s-setae on abdominal tergites shorter than medial (Fig. 37). Abd.V with five s-setae arranged as three dorsal ones (as, accp1, accp2), long and slender, one lateral (accp3), clearly shorter (accp2: accp3 = 1.8-2.3), and one latero-ventral, short ( ‘3+1+1’ pattern) (Figs 29-31). p1-setae on Abd.V long (see Table 2). Macrosetae smooth and long, 2,2/3,3,3 in number, medial ones on Abd.V 1.5-1.8 times shorter than dens and 4.7-6.2 times longer than mucro. Axial chaetotaxy as 10 –11,6,/3–4,3–4,3– 4. Metathorax with 3+3 ventral setae of which one long and two short.

Unguis of normal shape, without lateral and inner teeth. Empodial appendage as long as 0.5-0.6 unguis. All tibiotarsi with additional setae: 26-29 on legs I–II and> 35 on leg III. Upper and lower subcoxae of legs I–III with 0,1/3,8 –9/5–6,8– 10 setae, respectively. Coxae of leg I with three front setae. Tibiotarsal tenent setae pointed, some setae on distal half of tibiotarsi thickened. Ventral tube with 4+4 latero-distal and 7-8 posterior setae (four in distal transversal row and 3-4 in more proximal position), an teriorly without setae. Tenaculum with 4+4 teeth and a seta. Anterior furcal subcoxae with 8-9, posterior one with five setae. Anterior side of manubrium with 4 –6+4– 6 setae, their position vary, unpaired setae absent (Figs 33-35). Posterior side of manubrium with 4+4 latero-basal, two apical setae (ap), 3+3 setae in distal transversal row (M1, ml1, L1), two pairs of lateral setae, and 3 –4+3– 4 in central part (Fig. 38). Dens with 19-24 anterior setae. Posterior side of dens crenulated and with six normal setae (four basal and two at the middle) and usually one rudimentary minute seta at the base of mucro (Fig. 38). Mucro bidentate. Ratio of manubrium: dens: mucro = 4.5-6.2: 7.2-9.3: 1. Males present.

Remarks.

The species most resembles F. macrochaetosa and F. imparis sp. n. and is characterized by the absence of unpaired setae on anterior side of manubrium, short accp3-s-setae and long p1 setae on Abd.V (Table 2).

Distribution and ecology.

Known from three neighboring localities of inner part of East Asia (Fig. 90). The species occurs in forest litter at different altitudes.

Derivatio nominis.

The species is common in areas around Amur River lowlands.