Folsomia tertia Potapov

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 : 20-23

Folsomia tertia Potapov sp. n. Figs 65-68

Type material.

Holotype, female, Far East of Russia, Khabarovsky Krai, vicinities of Khabarovsk, Bol’shoy Khekhtsyr Range, ~10 km N Korfovsky, mixed forest litter, 28.vi.2007, coll. E. Sokolova. Ten paratypes from the same location. Deposited in MSPU.

Diagnosis.

Blind. Dorsal macrosetae (Md) present on both Th.II and Th.III. Sensillary formula incomplete (33/22224; 10/000). Medial s-setae on body tergites long, set in p-row. Ventral setae on Th.III present. Anterior side of manubrium with 2+2 setae, no unpaired axial setae present. Dens with 13-16 anterior setae, its posterior side with four setae in basal part. Mucro bidentate.

Description.

Body size from 0.9 to 1.2 mm, shape of corpus rather tubular, slender. Without pigmentation. Cuticle with fine hexagonal primary granulation ( “smooth”). PAO slender, insignificantly constricted, 1.6-1.8 as long as width of Ant.I and 2.1-2.2 as long as inner unguis length. Labium complete, guard setae e7 present, three proximal and four basomedian setae. Ventral side of head with 4+4 postlabial setae. Ant.I with 14-15 common setae, two ventral s-setae (with one thick) and three basal micro s-setae (bms): two dorsal (short and long) and one ventral. 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. Organite normal, small.

Sensillary formula as 33/22224 (s), three s-setae lost (as in other species of the subgroup, Fig. 65). Micro s-setae as 10/000 (ms). Tergal s-setae thin and long, lateral s-setae on abdomen shorter. Medial s-setae on Th. II–Abd.III situated in posterior position, on Abd. I–III between Md and Mdl. Abd.V with four s-setae arranged as three ones (accp1, accp2, accp3), long and slender, and one latero-ventral, shorter ( ‘3+1’ pattern) (Fig. 66), accp3 s-setae almost as long as accp2 (accp3: accp2 = 0.8-1.0). With 3+3 medial p-setae on Abd.V: p1 and p3 long, p2 short. Seta p1 somewhat longer than a1 and accp1-s on Abd.V (a1: p1 = 0.7-0.8, accp1: p1 = 0.8-0.9). Macrosetae smooth and rather long, 2,2/3,3,3 in number, medial ones at the end of abdomen slightly shorter than dens (0.8-0.9) and 2.8-3.9 times longer than mucro. Metathorax with 3+3 ventral setae.

Empodial appendage as long as 0.55-0.60 of unguis. Tibiotarsi with few additional setae: 22-24 on legs I–II and ~29 on leg III. Upper and lower subcoxae of legs I–III with 0,1/3,7/3-5,~8 setae, respectively. Coxae of leg I with two front setae. Tibiotarsal tenent setae pointed, few setae of whorl of tibiotarsi insignificantly thickened. Ventral tube with 4+4 latero-distal and 5-7 posterior setae (four in distal transversal row and 1-3 in more proximal position), anteriorly without setae. Tenaculum with 4+4 teeth and a seta. Anterior furcal subcoxae with 7-9, posterior one with 5-6 setae. Anterior side of manubrium with 2+2 setae (Fig. 68). Posterior side of manubrium with 5+5 latero-basal, two apical setae (ap), 2+2 setae in distal transversal row (M1, ml1), one pair of lateral setae, and 3(2) +3(2) in central part (Fig. 67). Dens with 13-16 anterior setae. Posterior side of dens crenulated and with seven setae (four basal, two at the middle, and one very short at the base of mucro) (Figs 68). Two setae at the middle of dens often very short, one sometimes absent. Subapical seta often hardly visible. Mucro bidentate. Ratio of manubrium: dens: mucro = 3.1-4.1: 3.3-4.5: 1. Males present.

Remarks.

The new species belongs to the ' laconica ' subgroup due to incomplete s-set on body. It differs from two other members, F. laconica sp. n. and F. trisensilla sp. n., by reduced chaetotaxy on anterior (2+2 instead of 3 –4+3– 4 setae) and posterior sides (1+1 vs 2+2 lateral setae) of manubrium. F. tertia sp. n. has the shortest macrosetae among species of the subgroup and somewhat resembles members of the ' tatarica ' subgroup.

Distribution.

Known only from type locality.

Derivatio nominis.

The new species is the third (tertius in Latin) species of the ' laconica ' subgroup.