Folsomia tubulata Potapov & Babenko

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 : 24-27

Folsomia tubulata Potapov & Babenko sp. n. Figs 70, 76-80

Type material.

Holotype, adult male, Russia, East Siberia, Yakutia (Sakha Republic), Lensky District, Chayandinsky allotment, July of 2011, coll. V. Boeskorov. Two paratypes from the same location. Deposited in MSPU.

Diagnosis.

Blind. Body slender. Dorsal macrosetae (Md) present on both Th.II and Th.III. Sensillary formula complete (43/22235; 10/100). Medial s-setae on body tergites set in p-row. Th.III with 2+2 ventral setae. Anterior side of manubrium with 1+1 setae, dens with 5-7 anterior setae. Mucro bidentate.

Description.

Body size 0.8-0.9 mm. Body slender, tubular (Fig. 70). Cuticle orthogonal, finely reticulated. Ocelli absent. PAO slender, not constricted or slightly constricted, 1.5-1.8 as long as width of Ant.I and 2.3-2.4 as long as inner unguis length (Fig. 78). Labium with five usual papillae ( A–E), guard setae e7 present, three proximal and four basomedian setae. Ventral side of head with 3 –4+3– 4 postlabial setae. Ant.I with eleven common setae, two ventral s-setae (s) and three basal micro s-setae (bms) (Fig. 78), two dorsal (middle-sized and short) and one ventral (short), Ant.II with three bms and one latero-distal s, Ant.III with one bms (not found in one specimen) and with five distal s (including one lateral), without additional s-setae. Organite short and small.

Common setae short. Sensillary formula as 43/22235 (s). Medial s-setae on Th. II–Abd.III situated in p-row, on Abd. I–III between Md and Mdl (Figs 76, 77). Tergal s-setae vary in length depending on position. Long s-setae: two accp-s on Th.II, medial accp-s on Th. III–Abd.II. Short s-setae: all as-s on Th. II–III, corner accp-s on Th.III, lateral accp-s on Abd. I–III, medial accp-s on Abd.III. Two dorsal accp-s on Abd.IV long, latero-ventral short. Abd.V with five s-setae arranged as four (as, accp1, accp2, accp3), long and slender, and one latero-ventral short ( ‘4+1’ pattern) (Figs 76, 77, 79), accp3 s-setae as long as accp2. Micro s-formula as 10/100 (ms), but ms-setae of Abd.I very small and hardly visible (Fig. 76). Macrosetae smooth and short, 2,2/3,3,3 in number, medial ones on Abd.V as long as 0.9-1.0 dens and 2.4-2.9 times longer than mucro. Metathorax with 2+2 ventral setae.

Empodial appendage as long as 0.4-0.5 of unguis. Tibiotarsi with 22 setae on legs I–II and 25-27 on leg III. Upper and lower subcoxae of legs I–III with 0,1/1,6 –7/3–4,5– 6 setae, respectively. Coxae of leg I with two front setae. Ventral tube with 4+4 latero-distal and three (seen in only one specimen) posterior setae, anteriorly without setae. Tenaculum with 4+4 teeth and a seta. Anterior furcal subcoxae with 6-7, posterior one with three setae. Anterior side of manubrium with 1+1 setae (Fig. 80). Posterior side of manubrium with 3+3 latero-basal, 4 –5+4– 5 on main part, and without setae on lateral sides (Fig. 80). Dens with 5-7 anterior setae. Posterior side of dens slightly crenulated and with three setae (two basal and one at the base of mucro. Mucro bidentate. Ratio of manubrium: dens: mucro = 3.0-3.5: 2.3-2.5: 1. Males present.

Remarks.

Within ' tatarica ' group, only F. baida (Ural Mts.) has medial s-setae in posterior position on all tergites. F. tubulata sp. n. shows more reduced furca: one pair of anterior setae on manubrium (vs two pairs in F. baida ), latero-central setae on manubrium absent (vs present), 5-7 setae on anterior side of dens (vs 9-10). Similar structure of furca is known for F. tatarica (steppe zone of Eastern Europe) which has another s-pattern on tergites (Table 1). Strong reduction of ms-setae on Abd.I is uncommon while calls for further study.

Distribution.

Known from the type locality.

Derivatio nominis.

The species is named after tubular shape of body.