Tetracanthella czernovae Kutyreva, 1980

Potapov, Mikhail, Brinev, Alexey & Sun, Xin, 2019, Isotomidae of Japan and Asiatic part of Russia. II. The genus Tetracanthella of the Far East, ZooKeys 855, pp. 31-54 : 43-45

Tetracanthella czernovae Kutyreva, 1980 Figs 36-39, 54

Type material.

Lectotype and one paralectotype (females) designated and labeled as: Primorski Krai: Shkotovski district, NE part of Livadiysky Range, Krinichnaya (= Falaza) Mt., coniferous forest belt with Picea and Abies , litter under Abies nephrolepis , 12.10.1977, leg. L. Kutyreva

Redescription.

Body length 2.0 mm (for subadult female). Body thick, tubular. Coloration dark, antennae white. Reticulation thin, polygons smaller than mesochaeta socket (Fig. 54). No smooth fields. Dorsal mesochaetae long, not shortened in axial part of tergites, (Md: p1 = 1.2-1,4). Abd. IV with p3 subequal to p1. Macrochaetae acuminate.

8+8 ocelli, G and H smaller. Four prelabral chaetae. Outer maxillary lobe with four sublobal hairs and simple maxillary palp. Labium with complete set of guards [A(1)B(4)C(0)D(4)E(7)], three proximal and four basomedian chaetae. Postlabial chaetae 4+4. With 7-8 chaetae between medial line and pc3 on head (Fig. 37). Frontal chaeta ap present.

Chaetotaxy abundant (Figs 36, 37). Axial chaetotaxy 12-14,8/6,6,6,6. Basic set of macrochaetae complete: 3(A),3(A)/3,3,3. Besides, additional macrochaetae present posterior to basic macrochaetae resulting full formula 3+ ’4’,3+’4’/3+’3’,3+’3’,3+’3’. Some chaetae of p-row also macrochaeta-like. Number of s-chaetae: 3,3/2,2,2,2,4 (s), 1,1/1,1,1 (ms). S-chaetae short, medial ones on Abd. I–III arranged lateral to Mdl macrochaetae. Sternite of Th. III without chaetae.

Coxa I without an external chaeta. Tibiotarsi with 1,2,2 long and clavate dorsal tenent hairs. Ventral tenent hairs weakly developed. Tibiotarsi I, II, III with 21, 21, 25 chaetae, respectively. Empodial appendage 0.7-0.8 as long as inner edge of claw, with apical filament.

Ventral tube with 3+3 laterodistal and four posterior chaetae. Retinaculum with 4+4 teeth and a chaeta. Anterior furcal subcoxa with 8-9 chaetae, posterior one with four chaetae (Fig. 39). Posterior side of manubrium with 8 –9+8– 9 chaetae on main part and 3+3 on basolateral parts (Fig. 39). Mucro bidentate, short. Anterior side of dens with two or three chaetae (differing in lectotype and paralectotype) (Fig. 38). Posterior side with six chaetae. Dens: claw III = 1.4-1.6. Manubrium: dens: mucro = 9-12: 4-5: 1. Inner and outer anal spines parallel, on high unsclerotised papillae. Medial mesochaetae (a1) of Abd. V slightly posterior to medial macrochaetae (a2). Arrangement of chaetae and spines on dorsum of Abd V as a2-a2/a1-a1 ~2.8; a2-a2/a2-eAS ~1.7. Males unknown.

Distribution.

The species is known only from type locality, by two specimens.

Discussion.

Tetracanthella czernovae belongs to the ' stebaevae ' group due to chaeta on coxa I missing and complete set of macrochaetae on tergites. The species how ever shares many essential characters, incl. appearance, with T. manschurica (' sylvatica ' group). Tetracanthella czernovae was briefly redescribed by Potapov (2001) from two specimens supposed to be syntypes. These two specimens from the collection of E. Kutyreva did not have labels indicating type status. We designate two specimens collected by L. Kutyreva as lectotype and paralectotype. Tetracanthella czernovae resembles T. wui Xie, Potapov, Sun, 2019 but differs by having more setae on the dens (2-3/6 vs. 1/5).

One individual from central Honshu (Japan, Nagano Prefecture: Chino, leg. M.P. and N.K.) is close to T. czernovae but obviously represents a new species differing by absence of additional macrochaetae on body and presence of additional chaetae on Tibiotarsi I and II. It is the second species of the genus Tetracanthella occurring in Japan.