Folsomia laconica 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 : 16-18

Folsomia laconica Potapov & Kuznetsova sp. n. Figs 6, 51, 52, 54, 55-57, 90

Type material.

Holotype, female, Far East of Russia, Amurskaya Region, Khingansky Reserve, near (~6 km W) Kundur, valley of Karapcha River, northern steep slope, mixed forest with Abies , litter, 19.viii.2014, coll. M. Potapov and N. Kuznetsova. 15 paratypes from the same location and ten paratypes from Khingansky Reserve, ~10 km E Uril, coniferous forest ( Pinus koraiensis , Abies , Picea ), 7.x.2009, coll. M. Babykina. Deposited in MSPU.

Other material.

Amurskaya Region, Khingansky Reserve, ~15-20 km SE Uril, oak wood litter, 8.x.2009, coll. M. Babykina. North Korea, Yanggang-do Province, ~1.5 km SE Mupho, litter under Rhododendron and Alnus , 5.vii.1985, coll. A. Szeptycki.

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 3+3 setae, no unpaired axial setae present. Dens with 17-20 anterior setae, its posterior side with three setae in basal part. Mucro bidentate.

Description.

Body size approximately 1.3 mm (Fig. 51). Without pigmentation. Cuticle with fine primary granulation ( “smooth”). Ocelli absent. PAO slender, not constricted or slightly constricted, 1.5-1.7 as long as width of Ant.I and 1.7-2.0 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 16-17 common setae, two ventral s-setae (s) 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. Ant.IV with stick-like organite.

Common setae sparse, macrosetae long (Fig. 51). Sensillary formula as 33/22224 (s), three s-setae lost: corner accp-s on Th.II, one of dorsal accp-s on Abd.IV, and as-s on Abd.V (Figs 55-56). 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 long and slender (accp1, accp2, accp3) and one latero-ventral, short ( ‘3+1’ pattern) (Figs 52, 57), accp3 s-setae as long as accp2 (ratio accp2: accp3 = 1.0-1.2). Macrosetae smooth and very long, 2,2/3,3,3 in number, medial ones on Abd.V slightly shorter than dens (dens: Md = 1.0-1.3) and 7.3-9.3 times longer than mucro. Metathorax with 3+3 ventral setae.

Unguis of normal shape, without lateral and inner teeth. Empodial appendage as long as ~0.5 of unguis. All tibiotarsi with additional setae: 28-29 on legs I–II and>35 on leg III. Upper and lower subcoxae of legs I–III with 0,1/3,7/6,8 setae, respectively. Coxae of leg I with three front setae. Tibiotarsal tenent setae pointed, few setae on dis tal half of tibiotarsi III slightly thickened. Ventral tube with 4+4 latero-distal and 6-7 posterior setae (4 in distal transversal row), anteriorly without setae. Tenaculum with 4+4 teeth and a seta. Anterior furcal subcoxae with 12-14, posterior one with five setae. Anterior side of manubrium with 3+3 setae (Fig. 54). Posterior side of manubrium with 5+5 latero-basal, two apical setae (ap), 2+2 setae in distal transversal row (M1, ml1), two pairs of lateral setae, and 4+4 in central part (Fig. 54). Dens with 17-20 anterior setae. Posterior side of dens crenulated and with six setae: three basal, two at the middle, and one subapical (Fig. 54). Subapical seta often hardly visible. Mucro bidentate. Ratio of manubrium: dens: mucro = 5.4-7.2: 7.8-9.3: 1.

Remarks.

Folsomia laconica sp. n. most resembles F. trisensilla sp. n. but differs having three (vs four) basal setae on posterior side of dens) (Figs 54, 63-64) and fewer common setae at the end of abdomen. The latter character is expressed in 2+2 dorsal p-setae on Abd.V (vs 3+3 in F. trisensilla sp. n.) and 2-3 p-setae between s-setae on Abd.IV (vs 4-5) (Figs 52, 53).

Distribution and ecology.

Known from three locations in Russian Far East and North Korea (Fig. 90). It occurs in forest litter.

Derivatio nominis.

The species shows the most laconic chaetotaxy of p-row on Abd.V.