Folsomia sanjiangensis, Wang, Baifeng & Wu, Donghui, 2012

Wang, Baifeng & Wu, Donghui, 2012, Two new species of Folsomia from north-eastern China (Collembola, Isotomidae), Zootaxa 3500, pp. 77-83 : 80

Folsomia sanjiangensis sp. nov.

( Figs 13–24 )

Type material. Holotype, female. Honghe Farm, Sanjiang Plain, Heilongjiang Province, China, N 47° 35ʹ, E 133 °31ʹ; 55 m alt., forest, 3.viii.2010, coll. Dong Liu. Paratypes: 13 females, adult and subadult from the same locality as holotype, forest and wetlands. All material deposited in Northeast Institute of Geography and Agroecology, Chinese Academy of Sciences.

Description. Body length up to 1.0 mm. White, pigment and ommatidia absent in alcohol. PAO broad, elliptical, almost as long as width of Ant. I, and 2.0–2.3 times longer than inner edge of unguis III, with a weak constriction and without inner "denticles" ( Fig. 13 ). Maxillary palp bifurcate, outer maxillary lobe with 4 sublobal hairs.

Labral formula 4/5,5,4. Ventral side of head with 4 postlabrial chaetae. Labrum with 4 basomedian and 3 proximal chaetae, with all papillae A–E, and full set of guard chaetae. Ant. I with 2–3 small basal microsensilla (1–2 dorsal and 1 ventral, the longer dorsal one absent in some specimens), and 2 ventro-lateral sensilla. Ant. II with 3 basal microsensilla and 1 latero-distal sensillum. Ant. III with 1 microsensillum and 5 sensilla (2 inner, 2outer, and 1 lateral). Ant IV with 1 subapical microsensillum and sensilla on Ant. IV weakly differentiated, 6-7 of them thickened ( Fig. 14 ).

Sensillar formula for Th. II–Abd. V: 4,3/2,2,2,3,5 (s), 1,0/1,0,0 (ms). Medial sensilla on Th. II–III, situated in front of p-row ( Fig. 15 ), whereas on Abd. I–III these sensilla situated in p-row ( Fig. 16 ). Abd. V with 2 leaf-like lateral sensilla ( Fig. 17 ). Macrochaetae 1,1/3,3,3,4 in number, acuminate and smooth. Medial macrochaetae on Abd. V 5-6 times longer than mucro. Abd. VI with a group of 7 foil-chaetae ( Potapov & Culik 2002; Potapov & Chimitova 2009); ( Fig. 17 ). Th. III tergum with 20 chaetae in p-row, sternum of the segment with 1–2 +1–2 ventral chaetae on Th. III. Unguis without inner and lateral teeth. Tibiotarsi of Leg I and II with 25–27 chaetae arranged in 4 rings, respectively ( Figs 18, 19 ). Tibiotarsi of Leg III with 39 chaeta ( Fig. 20 ). Retinaculum with 4+4 teeth and one chaeta on corpus.

VT wih 4+4 latero-distal and 5-6 posterior chaetae ( Fig. 21 ). Anterior furcal subcoxa with 19–24, posterior with 5-8 chaetae. Anterior side of manubrium with13-18 chaetae usually arranged as 3+3 (4+3), 1+1, 2+2, 1+1 and 2 unpaired in axial part ( Fig. 22 ), posteriorly with 4–5+4–5 latero-basal, 8–10+8–10 central, 3+3 distal, and 1+1 apical chaetae ( Fig. 23 ). Lateral sides of manubrium with 3+3chaetae. Dens with 36–40 anterior chaetae and 8 postrior chaetae (4 basal, 3 medial, aned usually a eighth,minute chaeta near the mucro can be observed ( Fig. 24 )). Mucro bidentate. Ratio manubrium: dens: mucro = 8.3–12.0: 15.7–20.0: 1.

Remarks. This new species belongs to sensibilis -group due to posterior position of median sensilla on abdomen, ommatidia absent, and Abd. V with 2+2 lateral leaf-like sensilla. It is similar to F. ancestor ( Potapov & Babenko 2000) , but it can be distinguished from F. ancestor by having 1–2 +1–2 ventral chaetae on Th. III (absent in F. ancestor ), and 3 chaetae on lateral sides of manubrium (2 in F. ancestor ).

Distribution. Heilongjiang province, China.

Ecology. Forest (broad-leaf forest and coniferous forest) and wetlands ( Deyeuxia angustifolia ).

Derivatio nominis. Named after the locality.

Figures

FIGURES 13 – 20. Folsomia sanjiangensis sp. nov.: 13, PAO; 14, Sensillar pattern of Ant. I – IV (dorsal side); 15, Pattern of sensilla and macrochaetae of Th. II – III (lateral side); 16, Pattern of sensilla and macrochaetae of Abd. I – III (lateral side); 17, Pattern of sensilla and macrochaetae of Abd. IV – VI (lateral side); 18 – 20, Tibiotarsus and foot complex of legs I – III.

FIGURES 21 – 24. Folsomia sanjiangensis sp. nov.: 21, Ventral tube (lateral side); 22, Chaetal pattern of manubrium (anterial side); 23, Chaetal pattern of manubrium (posterior side); 24, Chaetal pattern of dens on anterior (left) and posterior (right) sides.